mine surveying

First published 1989

Revised from the 1985 Russian edition

Translated from the Russian byV. Afanasyev

Ha allZAUUCKOM !l3blKe

Printed in the Union

of Soviet Socia/ist Repub/ics

ISBN 5-03-000073-9 @ H3~aTeJIbCTBO «He~pa», 1985@ English translation, Mir Publishers, 1989

Contents

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Preface

Chapter One. Subject-Matter of Mine Surveying. Historical NotesI.I. Subject-Matter1.2. Brief Notes on History of Mine Surveying

Chapter Two. General Figure of the Earth, Systems of coordina-tes, Control and Survey Underground Nets andSurface Surveys

2.1. General Figure of the Earth2.2. Geographic System of Coordinates2.3. System of Plane Rectangular Coordinates2.4. National System of Rectangular Coordinates2.5. Geodetic Reference Nets2.6. National Geodetic Nets2.7. Geodetic Bridging Nets2.8. Geodetic Survey Nets2.9. General Data on Surveys

Chapter Three. Graphical Documentation in Mine Surveying3.1. General3.2. Classification of Drawings and Rules of Mapping3.3. Drawing Materials. Technology and Rules for Making and Storage of

Mining Graphical Documentation3.4. Mechanization ,of Graphical Work3.5. Processes and Materials for Reproduction of Mining Graphical

Documentation

Chapter Four. Connection Surveys4.1. General4.2. Orientation of Underground Survey via Horizontal or Inclined

Adit4.3. Geometric Orientation4.4. Orientation down One Vertical Shaft4.5. Sequence and Organization of Work for Orientation down One

Vertical Shaft4.6. Plumbing Surface Points onto Oriented Mine Level4.7. Connection to Plumb Line Points in Orientation down One Vertical

Shaft4.8. Horizontal Connection Survey via Two Vertical Shafts4.9. Horizontal Connection Survey with Use of Gyrocompasses4.10. Vertical Connection Surveys

6 Contents

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Chapter Five. Horizontal Surveys of Underground Workings5.1. General on Underground Mining Surveys5.2. Horizontal Underground Surveys5.3. Underground Reference Nets of Plan Control5.4. Construction of Underground Reference Nets5.5. Survey Nets5.6. Types of Station Points of Reference and Survey Nets. Their

Fixation5.7. Theodolites5.8. Tests and Adjustments of Theodolites5.9. Centring of Theodolites and Signals5.10. Measurements of Horizontal Angles5.11. Measurements of Inclination Angles5.12. Measurements of Side Lengths of Theodolite Traverses5.13. Distance Measurements by Light Range Finders5.14. Detailed Survey of Underground Workings5.15. Office Analysis of Results of Underground Theodolite Survey and

Calculation of Point Coordinates5.16. Accumulation of Errors in Underground Theodolite Surveys

Chapter Six. Vertical Surveys in Underground Workings6.1. General6.2. Levels6.3. Levelling Staffs6.4. Geometric Levelling in Underground Workings6.5. Office Analysis of Results of Geometric Levelling6.6. Errors in Geometric Levelling6.7. Trigonometric Levelling6.8. Errors in Trigonometric Levelling

Chapter Seven. Surveys of Preparatory and Stope Workings7.1. General7.2. Instruments for Surveys of Preparatory and Stope Workings7.3. Surveys of Stope Workings in Coal Fields7.4. Surveys of Underground Chambers and Cavities7.5. Surveys of Preparatory Workings7.6. Surveys of Blast Holes7.7. Orientation of Sublevel Workings7.8. Measurements of Mining Workings and Reserves of Mineral In

Stocks

Chapter Eight. Special Surveys in Underground Workings8.1. Assigning Directions to Underground Workings8.2. Surveying of Workings Driven from Two Ends8.3. Preliminary Estimation of Accuracy of Face Connection

Chapter Nine. Surveying in Mine Construction9.1. General9.2. Surveying at Mine Camp9.3. Surveying in Construction of Mine Hoists9.4. Survey Work During Sinking of Vertical Shafts9.5. Survey Work for Arranging of Shaft Equipment

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9.6. Survey Work During Driving of Shaft Workings9.7. Survey Work During Driving of Vertical Shafts by Special Methods9.8. Survey Work During Deepening of Vertical Shafts

Chapter Ten. Surveying in Quarries10.1. General10.2. Reference and Survey Nets and Surveying Work10.3. Mine-Surveying Coverage of Drilling and Blasting Work10.4. Survey Work for Transport Servicing10.5. Survey Work in Trenching10.6. Survey Work in Open-Cast Mining with Conveyer Bridges10.7. Calculations of Volumes of Extracted Overburden Rock and

Mineral in Quarries10.8. Reclamation of Land10.9. Survey Work in Open-Cast Mining of Placer Deposits

Chapter Eleven. Rock Disturbance and Protection of SurfaceStructures

11.1. Introductory NotesI 1.2. General Data on Rock DisturbanceI 1.3. Rock Displacement ParametersI 1.4. Factors Responsible for Rock DisplacementI 1.5. Monitoring Rock Displacement. Observation StationsI 1.6. Calculations of Rock DisplacementI 1.7. Measures for Protecting Surface StructuresI 1.8. Construction of Safety Pillars

Chapter Twelve. Stability of Quarry Flanks12.1. Principal Causes and Kinds of Rock Deformation12.2. Factors Affecting Flank Stability12.3. Mine-Surveying Observations on Rock Mining Deformations in

Open-Cast Mining12.4. Stability of Working Benches and Flanks of Quarries12.5. Measures for Controlling Landslides12.6. Artificial Strengthening of Rock Massif

Chapter Thirteen. Mine-Surveying Control of Mining Safety13. I. Role of Mine-Surveying Service in Mining Safety13.2. Control of Mining Work near Old Workings13.3. Examples of Calculation and Construction of Dangerous Zones13.4. Construction of Zones of Elevated Rock Pressure13.5. Construction of Dangerous Zones for Mining Work in Seams

Liable to Coal, Gas and Rock Bursts

Chapter Fourteen. Mine-Surveying Control of Geological Explo-ration

14.1. Brief Data on Geological Exploration14.2. Mine-Surveying Control of Geological Work14.3. Topographic Basis of Geological Exploration14.4. Transfer of Plan of Exploratory Workings into Nature14.5. Layout of Exploratory Ditches14.6. Geodetic Control of Geophysical Prospecting Methods

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14.7. Mine-Surveying Work in Geophysical Prospecting14.8. Barometric Levelling of Geological Observation Objects

Chapter Fifteen. Mine-Surveying Work for Mineral Extraction inWater Areas of Seas and Oceans 349

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15.1. General15.2. Brief Data on Geomorphology of Ocean Bottom Relief15.3. Characteristics of Some Solid Minerals15.4. Mine-Surveying Service of Geological Prospecting and Mining in

Water Areas15.5. Marine Mine-Surveying Reference Nets15.6. Special Mine-Surveying Work in Water Areas15.7. Routine Mine-Surveying Work in Water Areas15.8. Determination of Plan Coordinates of Floating Vessels15.9. Depth Measurements15.10. Calculation of Volumes of Extracted Rock

Index

Chapter One

Subject-Matter of Mine Surveying.Historical Notes

1.1. Subject-Matter have increased drastically due to the realiza-tion of the latest achievements of science andengineering. There is a trend to form speciali-zed mine-surveyor teams for making aparticular kind of survey work at a numberof mining plants (for instance, mine-surveyinggroups for the orientation of mines with theuse of gyrocompasses or for surveying ofopen-cast pits by aerial and ground stereo-photogrammetry). The prime task of mine-surveying service, as earlier, is however thecompilation of plans of mining enterpriseswhich are required for the normal exploita-tion of mineral deposits and represent thecurrent state of deposits and underground orsurface workings and structures and buil-dings on the land surface.

Certain progress has been made recently inthe methods and techniques of mine sur-veying. New solutions have been proposedfor the orientation and construction ofunderground reference nets. High-precisiontheodolites and light range finders have comeinto use for the construction of reference nets.New instruments and methods have beenproposed for the surveys of quarries. Seriousinvestigations have been completed in thefield of mine surveying in the constructionand reconstruction of mines. In particular,special methods have been suggested for thesurvey work during mounting of hoistingmachines on tower head-frames and theconstruction of mine shafts. Laser instru-ments are finding ever wider use for directionassigning and control in vertical and horizon-tal workings, arrangement of equipment ofvertical shafts, track laying in horizontal

M odern mine surveying is a branch of themining science and industry which is concer-ned with surveys on the land surface andunderground during the prospecting andextraction of mineral deposits and the const-ruction of mining plants; the results ofsurveys are then used for plotting the plans ofmining workings and bedding conditions ofdeposits and also for the solution of variousproblems of the mining geometry.

At the early period of its existence, minesurveying could be characterized simply asunderground geodesy. In some countries, it isstill called in this way (for instance, 'geodesiesouterraine' in France). In the course of itsprogress, however, mine surveying has be-come a complex discipline which includes notonly the methods and techniques of thesurvey work (mine surveying proper), butalso the estimation of the accuracy of mea-surements and calculations based on themethod of least squares and the theory ofprobability; geodetic and mine-surveyinginstrumentation; mining geometry; studies ofdisplacements and pressure of rocks (mininggeomechanics), etc. All these aspects of minesurveying have the same objectives: to ensuresafe and efficient exploitation of mineraldeposits on the bases of the instrumentalmeasurements performed under particularmining and geological conditions of a mining

plant.Modern mine surveying has to cope with

more diversified and complex problems. Thequality and productivity of the survey work

111.1. Subject-Matter

workings, mounting of conveyers, laying ofpipelines, etc.

An essential progress has been done in themethods and instruments for plotting themining graphical documentation and in thematerials for making mine-surveying plansand sections. Field measurements and officework in mine surveying are now carried outwith the use of diverse and rather intricateinstruments and devices, in particular, high-precision optico-mechanical systems andelectronic devices. Among many achieve-ments in this field, it is worth to mentionsmall-sized mine-surveying gyrocompasses,optical range finders, devices for measuringthe curvature of boreholes, self-adjustinglevels, apparatus for the stereophotogram-metric surveys of open-cast pits and under-ground workings, coded theodolites withdirect input of measured results into electro-nic computers, special-purpose electroniccomputers for mine surveying, desk calcula-tors, etc.

Mine surveying also has to solve animportant group of problems associated withthe investigation of the configurations oflodes and their representation in specialgraphs and with the determination of theoptimal regimes of extraction of minerals forobtaining the final product having the speci-fied concentrations of useful and wastecomponents. This branch of mine surveying,called mining geometry, helps the minesurveyor in controlling measures for thepreservation of mineral deposits and efficientextraction of minerals.

Another important concern of mine sur-veying relates to the studies of mechanicalprocesses in rock massifs and in the elementsof working systems, which are induced bymineral extraction operations (mining geo-mechanics). The investigations of rock displa-cements and rock pressure have been espe-cially fruitful in the last 20-25 years. Regula-tions have been worked out for the protec-tion of surface structures, collieries and ore

mines against rock displacements. Methodshave been developed for preliminary calcula-tions of land surface deformations in under-ground mining of coal fields, which havemade it possible to introduce certain radicalmeasures for the protection of structuresagainst the harmful influence of undergroundworkings. Conditions have been formulatedfor safe extraction of minerals from depositsbeneath water basins. In open-cast mining,methods for the calculation of inclinationangles of pit flanks and measures for artificialstrengthening of slopes have been suggested.

A division of mining geomechanics isconcerned with the studies of the effects ofrock bursts. The mechanisms of appearanceof rock bursts have been investigated thor-oughly on the scientific basis and measuresfor preventing them have been developed.Mine surveyors carry out the investigationsof rock pressure in permanent, preparatoryand stope workings in coal and ore deposits.

As an engineering discipline, mine sur-veying is based on the concepts of fundamen-tal sciences, such as mathematics, physics,mechanics, and philosophy.

Measurements and calculations in minesurveying are carried out by the conventionaltechniques adopted in geodesy. Mine sur-veying is also associated closely with geodeticinstrumentation, geology, mining, productionmanagement, etc.

Mine surveyors have to participate in allstages of the operation of mining plants fromthe exploration of a mineral deposit and upto the abandonment of a mine after it hasbeen worked out, and to perform specificsurvey work at all these stages. .

Exploration of mineral deposits. In theexploration of mineral deposits, the minesurveyor makes land surveys, determines andtransfers into nature the positions of explo-ring workings (pits, ditches, adits, etc.), makesthe surveys of exploring workings, assayingpoints, seam outcrops, bedding elements ofmineral deposits and enclosin2 rock: and

Ch. 1. Subject-Matter of Mine Surveying12

mining operations; reclamation of land;planning of the preparatory and stopingmining work; development of quarterly,annual and perspective plans of the miningwork; and calculations of the balanced andindustrial reserves, losses, and dilution ofminerals.

When a mine is to be abandoned, the minesurveyor has to determine whether themineral has been extracted completely, tosurvey underground workings, and to pre-pare complementary mining plans. He alsoarranges the field books of undergroundsurveys and mine orientations and preparesthe main plans of the mining work forstorage.

compiles (together with geologists) the graph-ical documentation representing the shapeand bedding conditions of a deposit. Mine-surveying plans and sections plotted by theresults of geological prospecting are used forthe calculations of mineral reserves anddesign of mining plants.

Design and construction of mining plants.At the stage of mining plant design, the minesurveyor participates in construction sur-veying: the determination of the boundariesof mine fields according to the currentregulations on land allotment; design ofworking systems and surface structures;development of measures for the protectionof surface and underground structuresagainst harmful influence of undergroundworkings; compilation of the graphs of workorganization and plans of mining work forthe periods of construction and exploitationof a mining plant; and the calculations of thelosses and industrial reserves of minerals.

At the stage of mining plant construction,the mine surveyor is engaged in a wide circleof problems associated with transferring thedesign data into nature (levelling of a pay-outarea, layout of the centres and axes of shaftsand mining complexes, location of roads,etc.). He performs control on the constructionof hoisting complexes, sinking and equipmentof shafts, driving of permanent workings, etc.

Exploitation of deposits. The role of themine surveyor at the stage of exploitation isextremely important and includes the fol-lowing operations: surveying of workings;assigning of directions to workings; compila-tion of plans by the results of surveys; controlof the mining work in accordance with thedesign specifications and safety regulations;surveys for the connection of surface andunderground reference nets; continuous cont-rol of the completeness of mineral extraction;observations on rock displacements and rockpressure; development of measures for theprotection of structures, natural objects andmining workings against the harmful effect of

1.2. Brief Notes on Historyof Mine Surveying

Mine surveying actually appeared as soonas Man learned to do the undergroundmining work. Historical manuscripts, archeo-logical findings, and other materials havegiven evidence that people of the antiquitywere quite familiar with the art of construc-tion of fairly intricate mines and otherunderground objects. It may be referred, forinstance, to a 3500-years old Egyptianparchment showing a mine, which has beenfound in Italy. It is also known that Romansdrove an adit about 6 km long to drain waterfrom a lake. More than 100 vertical andinclined shafts were sunk for driving the adit,some of them being to a depth more than100 m. This is a clear evidence that Romanswere experienced well in mine surveying.

The first description of methods of under-ground surveying that has survived to ourtimes belongs to Heron of Alexandria (lstcentury B. C.). These methods included va-rious measurements, plumbing, and construc-tion of chains of regular geometrical figures(for instance, similar triangles) on the surfaceand underground, by means of which it waspossible to orient underground workings.

1.2. Brief Notes on History of Mine Surveying 13

instruments and are sometimes used inmodem mine-surveying practice. With thesuspension compass and suspension semi-circle, it was easier to construct undergroundsurveying nets; instead of a number oftriangles, it was now sufficient to layout abroken line in an underground working bymeans of a cord.

Practical mine surveying was given astrong impetus in the 1840's when work wasundertaken to drive long adits near Freibergand Harz in Germany. Prof. Weissbach andmine surveyor H. Borchers, who participatedin the work, proved the applicability oftheodolites and level instruments for minesurveying. These adits had a large length,intersected many mines, and were drivenfrom many points by meeting faces. Toperform this work, a detailed triangulationwas carried out on the surface, whichprovided a single coordination network forall the mines involved. Levelling surveyscarried out together with triangulation madeit possible to relate all points to a singleelevation system.

Roughly at the same time, the methods ofprecise orientation of underground surveyswere developed.

In the 19th century, theodolites andlevelling instruments came into wide use inmine-surveying practice in Germany. Newmine-surveyor's instruments appeared, suchas box compass, mirror compass, projectingplates, and large-Iength tapes for measuringthe depths of mine shafts.

In the second half of the 19th and thebeginning of the 2Oth century, well equippedworks for ~aking mine-surveyor's instru-ments were put into operation in Germany(Hildebrandt, Fennel, Zeiss). New methods ofmine surveying and estimation of observedresults were developed, in particular, themethod of connection surveys with connec-tion triangles, method of symmetrical junc-tion, and the method of range lines with theuse of the Weiss sleigh. Studies were carried

In the 16th century A. D. when the magne-tic needle compass came into use, minesurveying became more efficient and accur-ate. At that time, Agricola (Georg Bauer,1494-1555), a famous German scientist, pub-lished the book De re metallica libri XIIwhere Chapter V was devoted to the surveysof mining workings by means of a compasswith the circle divided into 12 sectors and byother methods. In particular, he described themethod of measuring the depth of a mine orthe length of an adit by means of an inclinedcord and plumb bobs.

Mine surveyors of those times still couldnot calculate the coordinates of the angularpoints of surveys. Initially, there were nosurvey plans, and the mine surveyor conten-ted himself with making the same survey onthe surface as underground (in a mine) andcould decide on the development of themining work relative to the boundaries ofallotment by the positions of survey pointson the surface. The plans of the mining workcame into common use in Germany at asubstantially later time, in the 17th century.At the end of that century, two kinds of themining work plans were employed: thoseplotted in the plane of a seam or vein andthose made as projections onto a verticalplane.

The mining work plans of that period werehowever oriented by a magnetic meridian.Only from the mid of the 18th century whenthe phenomenon of magnetic declination wasdiscovered (August Beyer, Von BergbauGrundlicher Unterricht, 1749), mine surveyorswere obliged to abandon the use of themagnetic meridian and change to the orienta-tion of mine surveys by an astronomicmeridian.

In Germany, the compass with sight vaneswas designed in the 16th century and thesuspension compass, in the 17th century.These instruments (the latter in combinationwith a suspension semicircle) were for manycenturies the most common mine-surveyor's

Subject-Matter of Mine Surveyin14 Ch

rock displacements in underground andopen-cast mining. The movements of theEarth's surface under the effect of under-ground workings were noticed already in the15th and 16th centuries, but attracted a keeninterest of mine surveyors in the 18th centuryand especially in the 19th century in Belgiumwhere the mining work began to endangersurface buildings and water-supply system inLiege. In the second half of the 19th century,the investigations of the laws of rock subsi-dence and caving were started, which resultedin the hypothesis of normals proposed byToilliez in 1838. Another hypothesis wassuggested by Gonot in 1858, according towhich the displacement of a worked-up rocklayer proceeded along the normals to theseam. In 1885, H. Fayol proposed the hypo-thesis of cupola based on the idea that thezone of rock subsidence was confined by acupola (dome-shaped) space.

At the end of the last century, J. Jicinskymarked in his works that the process of rockdisplacement should be influenced by thethickness of a seam, dipping angle, depth ofthe mining work, and properties of overlyingrock. Of large significance for understandingproperly the process of rock subsidence wasthe hypothesis suggested by R. Hausse (theend of the 19th century), which consideredtwo zones of rock subsidence: the cave-inzone and bend zone. In the first quarter ofthis century, the problem of rock displace-ments was investigated by a number ofresearchers. 0. Donahue determined a num-ber of subsidence angles. A. Goldreich discov-ered certain differences in the subsidence ofbed rock and detrital deposits. H. Briggsfound the correlations between the angles ofrupture and the compression and ruptureresistance of rocks and established thatsubsidence angles in hard and brittle rocksare steeper than in those having a lowerstrength.

In recent time, much attention has beengiven to the methods of prediction of rock

out on the effect of air currents on thepositions of plumb bobs in the orientation ofdeep shafts (Wilski's hypothesis).

In the first half of the 2Oth century,gyroscopic instruments came into use for theorientation of underground surveying nets.The first attempts for mine orientation bygyroscopes were undertaken in 1913-14 inPoland and Germany. At the beginning ofthe 192O's, a mine-surveying gyroscope wasdesigned and manufactured in Germany, butturned out to be inefficient. Wide applicationof gyroscopic orientation dates to 1947 (Ger-many). The earlier makes of mine-surveyinggyroscopes had certain drawbacks (largemass and dimensions, uncertain readings,etc.). In recent years, successful work on thedesign of gyrocompasses, gyrotheodolitesand gyroscopic attachments has been comp-leted in a number of countries. Gyrotheodo-lites have been employed efficiently for theorientation of underground surveying nets.

In the post-war years, many mine-sur-veying instruments were improved, and newinstruments based on utterly nowel operatingprinciples were developed, such as high-precision theodolites, self-adjusting levels,coded theodolites, optical and radio rangefinders, and laser instruments. Much workhas been done on the development ofinstruments for stereophotogrammetric sur-veys which are finding wide use in manycountries for underground surveying.

In recent time, the mine-surveying officework has been largely mechanized by theapplication of desk calculators, electroniccomputers, etc. Programs for solving mine-surveying problems in powerful electroniccomputers have been worked out.

Mine surveying is essentially an informa-tion science, and accordingly it has started towidely employ various automatic systems fordata collection, storage, processing andtransmission.

In modern mine surveying, there is astrong trend to increase the observations on

1.2. Brief Notes on History of Mine Surveying 15

the methods and techniques of undergroundsurveys.

Another important stage in the develop-ment of mine surveying is associated with thename of Prof. V. Bauman (1867-1923), authorof a number of fundamental works, such as ACourse in the Art of Mine Surveying (in threevolumes), On the Problem of Faults. Shifts andOther Types of Displacement of Veins andSeams. On the Problem of Evaluation ofM ineral and Ore Deposits, etc.

An exceptionally great contribution to themine-surveying science was done by I. Ba-khurin (1880-1940). He worked out a numberof issues in the theory of errors and themethod of least squares and their applica-tions for the estimation of accuracy andequation of mine surveys. Bakhurin wasconcerned with practically all aspects of minesurveying: survey control of workings drivenby meeting faces; theory of cumulative errorsin underground polygons; theory of randomerrors and method of least squares; theory ofphysical (in particular magnetic) and geomet-ric orientation of mines; errors of orientationvia one or two vertical shafts; mine-surveyinginstrumentation; rock displacements; etc. Theresults of his studies were~ummarized in thebook A Course of Mine-Surveying Art (1932).

The progress of mine surveying in thiscountry is also associated with the name ofProf. P. Sobolevsky (1868-1949) who isresponsible for a new branch of mine sur-veying which has later formed into anindividual discipline, mining geometry.

The development of mine surveying inrecent time, and especially in the last two orthree decades of the total scientific andengineering progress, has been associatedwith the improvement of existing and designof principally novel instruments, systems andtechniques of field and office work. Thescientific and applied aspects of mine sur-veying are being developed intensively. Mine-surveying problems are solved with wide use ofelectronic computers and automatic devices.

deformations. One of the first methods wasproposed by Keinhorst and Bals and basedon the assumption that a portion of work-ed-out area confined by subsidence anglesacted by a definite law on each point of theEarth's surface.

The progress of mine surveying owes muchto the contributions of Russian and Sovietscientists. The first in Russia mining regula-tions were issued by v. Tatishchev in1734.

In 1763, M. Lomonosov published hisbook On M easurements of M ines, the firstpublication in the country which dealtthoroughly with all aspects of mine surveyingof that time and was a part of the funda-mental work Principles of M etallurgy orMining. Lomonosov gave the descriptions ofthe suspension compass and suspensionsemi-circle, measuring rod, instruments forplotting mine-surveying drawings, etc. andsolutions of various mine-surveying prob-lems, in particular, the method of location ofthe surface of a vertical shaft to be connectedto a system of horizontal undergroundworkings.

In 1773, a mining school was founded inSt. Petersburg (now the Leningrad MiningInstitute). It had a mine-surveying classwhere students obtained profound training inthe subject.

A major event in the history of minesurveying in this country was the publication,in 1847, of the book The Art of MineSurveying written by P. Olyshev, professor ofthe St. Petersburg mining school (1817-1896).The author gave the description of a theodo-lite with an eccentric telescope and of ageodetic level, proposed the procedure for thecalculation of the coordinates of theodolitetraverses, and solved the problem of drivingan underground working by meeting faces.The introduction of theodolite surveys intothe mine-surveying practice and the prepara-tion of mine plans by point coordinates wereof extreme importance for further progress in

Chapter Two

General Figure of the Earth, Systems of Coordinates,Control and Survey Underground Nets

and Surface Surveys

the Earth, this point is usually related to thegeneral figure of the Earth which is under-stood in geodesy and mine surveying as thefigure obtained by mental continuation of thestill water surface of the Ocean. The surfaceobtained in this way is called the levelsurface. Its principal property consists in thatthe potential of the force of gravity on thatsurface is the same in all points, i. e. thesurface is always perpendicular to an upright(vertical) line, and therefore, is horizontaleverywhere. In the general case, it is possibleto draw an infinite number of level surfaces atdifferent distances from the Earth's centre,but one of these surfaces, i. e. that coincidingwith the mean level of the Ocean and conti-nued at that level under the continents, formsa figure that is taken as the general figure ofthe Earth and called the geoid.

Since the direction of an upright line maydepend on a number of factors, the geoid hasa complicated structure. The principal amongthese factors is that the force of terrestrialattraction is variable, since the Earth's radiusdiminishes at the poles and since the rocks ofthe Earth's mantle have different density. Thevariations in the force of gravity are mainlydue to the former reason (smaller radii of theEarth at the poles), though the latter reasonmay have an essential effect in some cases.

The geoid has flattened portions (obla-teness) near the poles, and its shape is toocomplicated for mathematical description.The results of satellite observations haveshown that the oblateness, expressed as thedifference between the lengths of an equa-torial and polar diameter. attains 42 km

2.1. General Figure of the Earth

The physical surface of the Earth is farfrom having a simple shape. Of the total areaof the Earth's surface equal to 510 mln kIn2,71 per cent fall on the bottom of seas andoceans and 29 per cent, on the land. Both theoceanic bottom and the continents have anintricate relief, especially the former. As hasbeen found by investigations, the Ocean insome places has depths more than 10 kIn.Some regions of the land reach altitudes upto 7-8 km. The analysis of the depth of theOcean and altitudes of the land on the basisof l-kIn height intervals has demonstratedthat their distribution has two distinct peaks:one at altitudes of loo m above the level ofthe Ocean and the other at roughly 4.5 kInbelow that level. It has been concluded onthat basis that the surface of the Earthconsists of two sharply distinct morpholo-gical elements: continents and oceans, thenatural boundary between these elementsbeing at a depth around 1.5 km below thelevel of the ocean.

Further, the local irregularities of thesurface relief make the shape of the Earth'ssurface extremely complicated so that thefigure of the Earth can hardly be describedmathematically.

Noting that the surface of water of theOcean has a rather simple shape and occu-pies almost 3/4 of the Earth's surface, itwould be reasonable to assume the figure ofthe Earth as the body confined by the watersurface of the Ocean. When determining theposition of a point on the physical surface of

2.2. Geographic System of Coordinates 17

by the formula:

a=(a-b)/a

When plotting the portions of the Earth'ssurface on maps and plans, an importantmatter is to choose the proper dimensions forthe ellipsoid which will approximate thegeoid and onto whose surface the physicalsurface of the Earth with all its natural andartificial details will be projected. Manyattempts have been made to determine thedimensions of an ellipsoid to approximatemost closely the geoid (the first in 1800 byJ.-B.J. Delambre, a French mathematician).

An ellipsoid of particular dimensions andoriented uniquely in the Earth's body, ontowhose surface the results of topographic,geodetic and mine surveying work are trans-ferred in a country, is called a referenceellipsoid (local ellipsoid).

p IFig. 2.1 Ellipsoid of revolution of spheroid

2.2. Geographic Systemof Coordinates

The positions of points on the surface ofthe Earth or spheroid are determined bymeans of geographic coordinates, i. e. geo-graphic latitude <p and geographic longitudeA. Geographic coordinates are reckonedrespectively from the equatorial plane andGreenwich meridian (Fig. 2.2).

770 m. It has also been established by satel-lite observations that the Earth has apyriform (pear-Iike) shape: the South pole hasturned out to be nearer by 45 km to theEarth's centre than the North pole. Inaddition, the South pole is located 25 m80 cm below the surface of oblated sphere,whereas the North pole protrudes by 18 m90 cm above that surface. Measurementshave also demonstrated that the Earth has'recesses' and 'ridges' which are traced clearlyagainst the profile of the complicated figureof the geoid. The largest 'recesses' are locatedto the south-west of India (depth 59 m) andnear the Antarctic continent (30 m). Thehighest ridges are located near New Guinea(57 m) and in France (35 m). It has also beenestablished that the Earth's equator is notcircular, but elliptical with one of its 'dia-meters' being larger by 200 m than the other.

In view of these circumstances, the idea ofusing the geoid as the basis for geodeticcalculations has been renounced. Amongregular mathematical surfaces, the one thatcan approximate most closely the geoidsurface is an ellipsoid of revolution obtainedby the rotation of an ellipse on its minor axis.This figure is called the Earth's ellipsoid, orspheroid.

The dimensions of the Earth's ellipsoid(Fig. 2.1) can be characterized by the lengthsof its major and minor half-axes, a and b, andby the oblateness a which can be deteri:nined2-1270

Fig. 2.2 Geographic system of coordinates

Ch. 2. Systems of Coordinates, Nets and Surface Surveys18

In the general case, when the deviations ofupright lines are neglected, geodetic andastronomic coordinates are replaced by thegeneralized concept of geographic coordi-nates.

In geographic coordinates, longitudes canbe reckoned: (I) eastward and westward ofthe Greenwich meridian, from 00 to 180°, andare called respectively easterly and westerlylongitudes; easterly longitudes are consideredto be positive and westerly ones, negative or(2) only eastward of the Greenwich meridian,from 0° to 360°, and are always calledeasterly longitudes.

Latitudes may vary from 0° to 90° and arereckoned north and south of the equator.The former are considered positive and thelatter, negative.

The longitude is the dihedral angle be-tween the plane of Greenwich (zero) meridianand the meridional plane of a point p and thelatitude is the angle made by a vertical line ina point p to the plane of equator.

The plane passing through the centre ofthe Earth and perpendicular to the axis ofrotation is called the equatorial plane. Theplane passing through a vertical line and theaxis of rotation of the Earth (or parallel tothe latter) is the plane of a geographic( astronomic) meridian. The lines of inter-section of the planes of geographic meridianswith the Earth's surface are called meridians.The lines formed by the intersection of planesdrawn perpendicular to the axis of rotation ofthe Earth with the Earth's surface are calledparallels of latitudes, or simply parallels.

The network of meridians and parallelsapplied on the surface of the Earth ellipsoidrepresents the coordinate axes of the geo-graphic system of coordinates.

If the geographic coordinates are determi-ned by astronomic observations (indepen-dently in any point on the Earth's surface),they are conventionally called astronomicgeographic coordinates «p, /I.). The positions ofpoints on the Earth's surface can also bedetermined by means of geographic coordi-nates obtained by geodetic observations andrelated to a normal to the ellipsoid surface;tt.ese are termed geodetic geographic coordi-nates and denoted as B (latitude) and L(longitude).

Since the surface of the geoid does notcoincide with that of the ellipsoid, normalsdrawn to the surface of the latter turn out todeviate from the directions of upright lines.The magnitude of deviation may be equal to3-4" on the average. Noting that the differe-nce of latitudes of 1" on the Earth's surfacecorresponds to a linear distance of 31 m, thepositions of points on the Earth's surface,when given in astronomic and geodeticgeographic Foordinates, may differ by 100 mon the average.

2.3. System of Plane RectangularCoordinates

Geographic coordinates are expressed inangular values. They are inconvenient forengineering calculations in geodesy and minesurveying. Besides, the linear measurementsof angular values turn out to be different invarious portions of the Earth's surface. Forthese reasons, a system of plane rectangularcoordinates seems to be more convenient forland and mine surveying and solving variousengineering problems when their resultsshould be plotted on maps and plans. Such asystem can largely simplify topographic andmine surveying, adjustment of reference nets,calculations of coordinates of referencepoints, processing of the results of surveys,etc. The plane system of coordinates alsoensures precise coincidence of plans ofadjacent areas, etc.

The initial lines in a system of planerectangular coordinates (Fig. 2.3) are twomutually perpendicular lines xx-yy lying in ahorizontal plane and called respectively theaxis of abscissae (x-axis) and the axis ofordinates (y-axis}. In contrast to mathe-

2.4. National System of Rectangular Coordinates 19

Fig. 2.3 System of plane rectangular coordinates

In land and mine surveying, the portions ofthe Earth's surface measuring up to 10 km inradius are considered to be flat (distortionsalong the length are not more than 1 cm andangular distortions, not more than 0.1"). Thelarger areas of the Earth's surface aredepicted, to minimize distortions, in specialprojections in which the Earth ellipsoid isconventionally developed on a plane. Inaddition, the projection on a plane is done insuch a way as to provide the coincidence ofboth geographic and rectangular coordi-nates.

matics, the axis of abscissae in land and minesurveying plans is arranged vertically andcoincides with the direction of a meridian.The intersection of these axes is the origin ofcoordinates (point 0). The coordinate axesdivide the plane of a drawing into fourquadrants which are numbered clockwisebeginning from the guadrant in the north-eastsection (see Fig. 2.3).

The abscissa x and ordinate y of points arethe lengths of the perpendiculars drawn fromthese points onto the coordinate axes. Thesigns of coordinates depend on the quadrantin which the points are located. The abscissaeof the points located in the first and fourthquadrant are positive and of those in thesecond and third quadrant are negative. Theordinates of the points in the first and secondquadrant are positive and of those in thethird and fourth quadrant are negative.,.

2.4. National Systemof Rectangular Coordinates

When the territories of a substantial areaare to be represented in topographic maps,the surface of the reference ellipsoid must be

20 Ch. 2. Systems of Coordinates, Nets and Surface Surveys

gular coordinates of points on a plane andthe geographical coordinates on the referenceellipsoid.

2.4.1. Gauss Conformal Projection

Among many requirements set forth tocartographic projections for topographicmaps, the principal one is that projectiondistortions should not exceed the errors ofcorresponding geodetic measurements. Thiscondition is approached most closely in theconformal projection proposed in 1820 byC. F. Gauss of Germany. It is based on thetheory of plane conformal coordinates, whichmakes It possible to obtain almost undistor-ted images of the terrestrial ellipsoid on aplane.

The essence of the Gauss conformalprojection consists in that the terrestrialellipsoid is enveloped by a tangent cylinderwhose axis is perpendicular to the minor axisof the ellipsoid. With this arrangement of thecylinder, it touches the ellipsoid along ameridian which is a common line of bothfigures (Fig. 2.4). Other meridians, whentransferred (projected) onto the cylinder, willbe increased in length. With moving fatherfrom the tangent (central) meridian, i. e. fromthe centre of zone, lengths will be distortedmore and more, and their distortions can bedetermined by the formula:

, y2L\l=l

2R2

developed in a plane. This procedure cannothowever be done without cutting and foldingthe spherical surface being developed. Theproblem is solved by using an auxiliarysurface which can be easily developed in aplane, such as a cylinder or cone. Theportions of the reference ellipsoid are projec-ted onto an auxiliary, geometrically regularsurface (cylinder or cone) and this is thendeveloped without folds and cuts. For moreconvenience, the auxiliary body is supposedto be tangent to the reference ellipsoid, andthe network of meridians and parallels of thereference ellipsoid is transferred (projected}onto the surface of the body to form acartographic grid on the map. Mter thecartographic grid has been transformed ontothe auxiliary tangent figure, the latter is cutand developed in a plane. The method bywhich the image of the Earth's surface istransferred from the sphere onto the plane iscalled a cartographic projection.

Cartographic projections involve certaindistortions of geographic objects relative totheir shape on the reference ellipsoid. By thenature of distortion, modern cartographicprojections can be divided into equiangular(equal-angle), equivalent (equal-area) andtheir derivatives. In equiangular projections,angles are not distorted, and therefore,projected figures retain their similarity to theoriginal ones. In equivalent projections, theareas remain equal, but the angles aredistorted, and therefore, the outlines offigures are distorted too. In derivative projec-tions, both angles and areas are distorted, butonly moderately.

Cartographic projections are studied bymathematical cartography where they areconsidered on a formalized basis as certainanalytical relationships between the coordi-nates of points on tM.e surface of a referenceellipsoid and the coordinates of their projec-tions on a plane. In the general form, theserelationships can be written as x = f1 «p, 1..)and y = f2 «p, 1..); they correlate the rectan-

where 1 is the length of a section on the Earth~phere; y is the length of an arc from thecentral meridian to the given section; and Ris the Earth's radius.

With the use of the Gauss conformalprojection, the surface of the terrestrialellipsoid is represented on a sheet of paper inthe form of individual figures as those shownin Fig. 2.5, which are called zones. As hasbeen established, the optimal zone for trans-ferring onto a tangent cylinder is a spheroidal

2.4. National System of Rectangular Coordinates 21

dihedron included between two meridianswith the longitude difference 6°. Thus, thesurface of the Earth is divided into 60 zones,a tangent cylinder being drawn to the central(axial) meridian of each zone. The surface ofthe spheroid within the limits of a particularzone is projected conformally onto thesurface of the cylinder.

of a zone (see Fig. 2.6). Ordinates calculatedfrom this new origin are called reducedordinates. If, for instance, the ordinates oftwo points of the eighth zone relative to thecentral meridian are Yl = 23730.00 m andY2 = -102280.00 m, the reduced ordinateswill be:

Yl = 23730.00 + 500000.00 = 523730.00 m

Y2 = -102280.00 + 500000.00 = 397720.00 m

Since the same numerical coordinates mayexist in all 60 zones, it has been agreed torelate the coordinates to a particular zone by

2.4.2. Zonal Systemof Rectangular Coordinates

The origin of coordinates in each zone istaken at the intersection of the centralmeridian of that zone with the equator(Fig. 2.6). The central meridian is the x-axis,and the image of the terrestrial equatorperpendicular to the central meridian is they-axis. The x-coordinates of points to thenorth of the equator are considered positiveand of those to the south, negative. They-coordinates of points to the east of thecentral meridian are positive and of those tothe west, negative.

The longitude of the central meridian isfound by the formula: Lo = 6N -3°, whereN is the zone number. The western boundarymeridian of the. first zone coincides with theGreenwich meridian.

In order to eliminate negative ordinates,the origin of coordinates is transferred by500 km to the west from the central meridian Fig. 2.6 Zonal system of rectangular coordinates


In some cases, however, the x-axis can betemporarily oriented relative to the magneticor astronomic meridian. In exceptional caseswhen the survey work is carried out in anuninhabited region, is not large in scope, andthere are no triangulation points, the x-axiscan be oriented by the direction of amagnetic needle, though orientation by theastronomic meridian is more preferable insuch cases. Mine survey plans obtained withthis orientation can be used for many years.

In contrast to magnetic declination, meri-dian convergence remains constant in time. Insome kinds of mine surveying work, a condi-tional system of coordinates can be adopted,with the Ox-axis directed arbitrarily, forinstance, along a line fixed by survey points.The conditional systems of coordinates areused in the mine survey servicing of construc-tion of shafts and hoisting complexes, orien-tation of mines via two shafts, and in anumber of other cases.

writing the number of a zone before acoordinate.

In the cases considered above, the ordi-nates of points located, say, in a zone No.8,should be written as follows:

Yl = 8523730.00 m and Y2 = 8397720.00 m

An important problem in mine surveying ishow to choose properly the directions ofcoordinate axes. In the Cartesian rectangularsystem, the Z-axis is always vertical anddirected upward, whereas the axes Ox and Oyare perpendicular to each other and lie in thehorizontal plane. The orientation of thesetwo axes must not be arbitrary. If thedirection of one of these axes is specified, thiswill uniquely determine the direction of theother axis. In land and mine surveying, theOx-direction is usually chosen (oriented inthe horizontal plane) so as to satisfy thefollowing conditions:

(a) the direction of Ox-axis must be easilyand precisely reproducible and

(b) the direction of Ox-axis at variousmining enterprises must permit the coinci-dence of plans of individual mines and largerenterprises.

The following cases of orientation of theOx-axis for mine surveying plans are pos-sible:

(a) orientation by a magnetic meridian;(b) orientation by an astronomic meridian;and .

(c) orientation by the central meridianwithin each zone of the national system ofcoordinates.

Orientation by (a) and (b) cannot satisfythe requirements given above, since themagnetic azimuth is not constant in time andspace, and the astronomic azimuth is notconstant in space. On the contrary, thecentral meridian retains its orientation andposition within the limits of a zone. Thus, theorientation of the x-axis should be preferablydone relative to the central meridian of azone.

2.5. Geodetic Reference Nets

The mine survey servicing of miningenterprises is unfeasible without a network ofreference points whose positions on the landare determined with a high precision.

The measurements on the surface andunderground involve errors which are accu-mulated if surveys are being done on indivi-dual areas not associated with one another.When represented on general mine surveyplans or topographic maps, these areas willthen be distorted to such an extent that theresults of surveys become useless. In thatconnection, mine surveying is carried out bythe principle 'from the general to particular',i. e. by providing first a general geodetic neton the territory of a country and thenreference survey nets for surveying of indivi-dual small isolated areas.

Points established on the surface andhaving precisely fixed coordinates are calledreference (control) points. or base stations.

2.6. National Geodetic Nets

Points ensuring the correct horizontal repre-sentation of the land surface are called plan(planimetric) control points, or horizontalcontrol points. Those which can characterizethe vertical relief of the land surface are calledelevation (height) control points. A system ofreference (control) points established on theterritory of a country makes up a geodeticnet.

Geodetic nets can be divided into nationalnets, bridging (densification) nets, and surveynets. Mine survey nets on the territory ofeconomic interests of mining enterprisesconsist of the P9ints of the national geodeticnet and geodetic nets of mine surveying andtopographic surveying carried out for servi-cing of mineral prospecting and constructionand exploitation of mining enterprises.

Some kinds of geodetic work on the landsurface are carried out by mine surveyors.They include: the development of the existingmine survey reference nets as required for thesurveys of mines and quarries; surveys of thepay-ore areas of mining enterprises; perio-dical layout, survey and levelling during theconstruction of minIng enterprises and exp-loitation of deposits in order to reflectcurrent variations on mine survey plans;surveys of rock dumps and stocks of mineral;surveys for determining the volume ofearth-moving work, for the reconstruction ofrailway tracks and other structures; surveysfor observing rock displacements, stability ofstructures, etc.


A national geodetic net may consist oftriangulation, trilateration, polygonometricand levelling nets.

A plan (horizontal) geodetic reference net ismainly constructed by the method of trian-gulation, i. e. by laying out triangles on theland surface. In each triangle, all three anglesare measured, which ensures a reliable con-trol of angular field measurements. For deter-

mining linear dimensions, the length of oneside of a triangle is measured (taped) and thelengths of the other two sides are calculated.The triangles of a net are arranged in acertain order, and their shape should be closeto equilateral where possible.

The vertexes of triangles are fixed on theland by special station markers fastened inthe ground. A metallic or wooden beacon(tower) is constructed above a station mar-ker. It carries a cylinder at the top whose axisshould be coincident with that of the marker.The cylinder serves as the sighting targetwhen making observations from other points.

The triangulation method makes it pos-sible to determine the horizontal (plan) coor-dinates for the vertexes of triangles. Triangu-lation rows which consist of triangles with anaverage side length of 20-25 km form first-class triangulation chains up to 200. km long(Fig. 2.7). Triangulation chains are laid off insubmeridional and sublateral directions so asto form the closed polygons of a peripherallength up to 1000 km. The side lying at theintersection of several chains (ab in Fig. 2.7)is a common of these chains and called theinitial side. Initial sides must be measuredwith a high accuracy. Since it is practicallyimpossible to measure lines 20-25 km inlength on the land surface, it is commonpractice to measure not an initial side, but atransverse side around 6 km long (ed inFig. 2.7), which is called the triangulationbase. In the base figure adbe, all interiorangles are measured, and the length of theinitial side is calculated by the known anglesand the known length of the base line. Infirst-class triangulation, the latitude and lon-gitude of the points at the ends of the initialside and the astronomic azimuth of that sideare additionally determined by astronomicobservations.

The territory within polygons of first-classtriangulation chains is filled in with a con-tinuous network of second-class triangula-tion triangles with the lengths of sides ran-


Class 1 chain

(i

/\.~.0="

:la

u

, 11

~

b

~1 ~2 C!J3 ~4

Fig. 2.7 Development of triangulation network: 1, 2, 3. 4-triangulation points of respectively first,second, third, and fourth class

built-up territories, a geodetic net consists ofpolygonometric traverses in the form of bro-ken lines representing closed or open poly-gons (Fig. 2.8). In that case, field work con-sists in measuring the angles in turning(change) points and the lengths of all poly-gonometric sides. Polygonometric nets areusually constructed by laying off the mainand diagonal polygons having commonchange points (5 and 19 in Fig. 2.8). Therequired accuracy of polygonometric nets canbe characterized by the data given in Table2.2.

ging from 7 km to 20 km depending on thepattern of terrain. In second-class triangula-tion, base lines are measured in one of every20-25 triangles. As in the first-class tri-angulation, the latitudes and longitudes andastronomic azimuth of base lines are deter-mined by astronomic observations. Furtherdensification of a plan control geodetic net iscarried out by third- and fourth-classtriangulation. The characteristics of referencenets constructed by Ist-4th class triangula-tion are given in Table 2.1.

In poorly accessible regions and densely


Table 2.1

Trian-gula-

tion class

Side

length,km

Mean angular

error (by

trianglemisclosures), s

Permissible

triangularmisclosure,

m

Mean measur-

ing error of

base (clos-

ing) sides

Mean measur-ing errorof base

123

Fig. 2.8 Polygonometry: 5, 19-common juncotion points; K, L, M -triangulation points

Polygonometry as a method for the con-struction of geodetic nets has become popu-lar in recent years, with the appearance ofhigh-precision light and ratio range finders,

which have largely facilitated linear mea-surements, the most labour-consuming pro-cedure in land and mine surveying.

Another popular method for the construc-tion of planimetric geodetic nets is trilatera-tion. Its essence reduces to the constructionof a network of triangles (as in triangulation)and measuring of the lengths of their sides(rather than angles). The latter are calculatedfrom the known lengths of three sides. Withthe known angles and the measured length ofone side (which is taken as the base line), thelengths of the other sides are calculated, afterwhich the coordinates of trilateration pointsare determined. In trilateration, lengths aremeasured by means of range finders whichcan ensure a high accuracy of linear measure-ments (up to 1/400000).

The elevation (height) control of variousland and mine survey operations is ensuredby levelling nets which may be of class I, II,

26 Ch. 2. Systems of Coordinates. Nets and Surface Surveys

To be performed

with highest

precision

s.JL

IO.JL

20JL

IIIIIIV

500-600

150-200

25

errors do not exceed 0.05 mm per kilometreof the levelling line.

Second-class levelling is carried out byrunning polygons connected to the points offirst-class levelling and attaining a length of500-600 km. The main object of second-classlevelling is to provide the precise basis forthird- and fourth-class levelling. In levellingnets of class II, the perimeters of polygonsand the lengths of level lines should notexceed 40 km and the lengths of lines be-tween junction points, 10 km. In third-classlevelling lines, the lengths of lines betweenhigher-class levelling points shoud notexceed 15 km and of those between junctionpoints, 5 kill. The lines of levels should beconnected with one another at every 3 km inbuilt-up territories or at every 5 km in freeterritories.

The height marks of triangulation andpolygonometric points of all classes and ofpoints of local plan reference nets are per-rnitted to be determined by class IV levelling.Trigonometric levelling is permissible for thedetermination of the heights of reference netpoints in exceptional cases, such as in moun-tainous regions.

The levelling lines of all classes are fixed onthe land by means of ground and wall benchmarks. The bench marks in the levelling netsof class I, II and III must be spaced atintervals of 5- 7 km. Fourth-class levelling isdone by wall and ground bench marks andpolygonometric stations. Wall and groundbench marks are established with intervalsnot more than 300 ill in built-up areas andnot more than 0.5-2 kill in free territories. Inlevelling lines run through settlements, atleast one bench or wall mark should beestablished in a settlement.

III and IV. First- and second-class levellingnets are the main basis for establishing thegeneral system of elevations for the entireterritory of the country. Third- and fourth-class levelling nets are the basis for topo-graphic surveys and for the solution of va-rious problems associated with geodetic andmine survey servicing of civil and industrialconstruction objects. The general characte-ristics of national levelling reference nets aregiven in Table 2.3. The permissible misclo-sure (mm) of traverses in local geodeticreference nets constructed by technical level-ling is equal to 50JL ' where L is the lengthof a traverse line, km.

Fundamental bench marks of a naturallevelling net should be established with adensity ensuring that every subdivision mapplotted on a scale 1/5000 include at least onebench mark. With topographic surveys on ascale 1/2000, the density of fundamentalbench marks should be such as to allow onebench mark for one-four map sheets.

First-class levelling is carried on the landalong the directions essential for the nationaleconomy and defence of the country andrelates to the most precise kinds of geodeticwork. Accordingly, it must be carried outwith the use of the most precise instruments.In modern levelling, random and systematic

2.7. Geodetic Bridging Nets

Geodetic bridging (densification) nets aredeveloped on the basis of geodetic net pointsand serve for the surveys of land surface on

272.7. Geodetic Bridging Nets

Table 2.4

Secondorder

First

orderParameter

0.25-3.0

1/20000:1: 40"

:1:10"3

0.5-5.01/500000

::!:20"::!:5"

5

0.25-3.01/10000

20°3

0.5-5.0

1/2000020°

5

3

90.80-0.30

15

0.12-0.60

Triangulation

Side length of triangles, kmMaximum relative error for base sideMaximum misclosure of triangleMean measuring error from triangle misclosuresMaximum length of chain of triangles, km

Trilateration

Side length of triangles, kmMaximum relative error of side measurementMinimum angle of trianglesMaximum length of chain of triangles, km

PolygonometryMaximum length of traverses, kmMaximum perimeter of polygonometric traverses in free

networks, kmLength of side of traverse, kmMaximum length of traverse from nodal point to highest-class

or highest-order point, kmMaximum number of sides in traverseMaximum relative misclosure of traverseMean measuring error of traverse

315

110000:t5"

2

15

1/5000

:t10"

scales 1/5000 to 1/500 and for performingvarious kinds of mine survey work.

Planimetric geodetic bridging nets can beconstructed as analytical nets or polygono-metric nets of the first or second order.Their main characteristics are given in Table2.4.

Analytical nets can be formed by triangu-lation as a continuous network or chains oftriangles or intersections (bearings). Analy-tical bridging nets of the first order can bedeveloped on the basis of geodetic referencenets of classes I, 2, 3 and 4; those of thesecond order can be developed on the basisof reference nets of all classes and a first-order analytical net. The analytical nets ofthe first order may have the sides from0.5 km to 5 km long and those of the secondorder, from 0.25 km to 3 km long. The angles

of triangles should be not smaller than 30°,and the number of triangles in a chain shouldbe not more than 10.

If the territory to be surveyed has noavailable points of geodetic plan control(of any class), it is permissible to develop theindependent survey nets of the first orsecond order for land and mine surveying. Inthat case, it is required to measure at leasttwo base sides separated from each other byat least 10 triangles.

The polygonometry of the first and secondorder can be developed in the form of indi-vidual traverses or a system of traverses withjunction points belonging to the nationalgeodetic reference net or first-order analyticalnet.

Of special significance are approach minesurveying points in reference nets. The ap-

28 Ch. 2. Systems of Coordinates. Nets and Surface Surveys

proach points must ensure the possibility ofrunning a hanging traverse with the numberof sides not more than three to a mine shaft.

Approach points should be located atdistances not more than 300 m from thecollar of a shaft. It is possible to use thepoints of triangulation, trilateration and po-lygonometric nets of class 1-4 or of first-orderanalytical nets as approach points. Thepay-ore area of a mining enterprise shouldhave at least three elevation bench markswith their heights measured by levelling of aclass not worse than four.

Table 2.5

Contourinterval

height, m

Level linelength intechnicallevelling,

km

Levellinelength in

trigonometriclevelling,

km

0.51.02.05.0

31015 2

5

and on territories where linear measure-ments are complicated, the base points of asurvey net can be deterniined analytically byconstructing a chain of triangles; by themethods of intersections and resections; or byconstructing a central system of geodeticrectangles.

The angles in triangles should, as a rule, benot smaller than 30°. Side lengths should benot less than 150 m. A direct intersection ismade from three points and a resection, byfour initial points. The misclosures of tri-angles should be not more than I '. Therelative error of initial sides in triangle chainsshould not exceed 1/2000. In closed areas, thebase points of a survey net can be deterniinedconveniently by running individual theodo-lite traverses or a system of theodolite tra-verses in which the points of a geodeticreference net serve as junction points.

Elevation survey nets are constructed bygeometric, technical and trigonometric(geodetic) levelling. Geometric levelling isusually employed in areas with the height ofcontour interval of relief up to I m andtrigonometric levelling, with greater contourinterval heights. The lengths of level linessupported by the levelling points of class I-IVand of closed level lines should not exceed thevalues given in Table 2.5.

2.8. Geodetic Survey Nets

Planimetric and elevation survey nets areconstructed on the basis of points of ageodetic reference net. In exceptional cases,when the area to be surveyed is not morethan 20 km2 for surveys on a scale of 1/5000or 10 km2, 1/2000, they can be based on thepoints of a survey net only.

Planimetric survey nets are developed byrunning theodolite, tacheometric or plane-table traverses or can be constructed analy-tically.

The number of points of a survey net isdetermined by the scale of a survey map andshould be equal, together with the points of ageodetic reference net, to at least four pointsper square kilometre of the territory for ascale 1/5000, 10 points for a scale 1/2000 or16 points for a scale 1/1000. The errors of thelocation of survey net points relative to thenearest points of a geodetic reference netshould not exceed the accuracy of a surveyingscale (i. e. should be not more than:!: 0.1 mmon the scale of the map).

Survey nets consist of base points andadditional points, i. e. points determined inthe survey net proper. Each survey sheetshould include at least three base points fixedby fundamental marks for a scale of 1/5000,at least two such points for a scale 1/2000 orone point for a scale 1/1000. In open areas

2.9. General Data on Surveys 29

2.9. General Data on SurveysThe results of survey work on the surface

are used for plotting maps and plans re-quired for mineral prospecting, solution ofproblems of design and construction of mi-ning enterprises, and for safe and efficientexploitation of deposits. These plans andmaps, drawn on a scale 1/5000-1/500, shouldshow all objects specified by the rules ofcompilation of topographic maps, as well asthe specific objects of a mining enterprise,such as fall-throughs and cones of influenceformed owing to mineral extraction; rockoutcrops on the surface; boundaries of mi-Ding allotments, etc.

The scale of surveying is chosen dependingon the kind of mining work to be carried outin the area. For instance, for detailed pro-specting and exploitation of large-sized de-posits, the surveys of the land surface shouldbe made on a scale of 1/5000 for a simplerelief with vertical contour intervals of 1 m or2 m or 1/2000 for an intricate (mountainous)relief with 2-m contour intervals. For thedeposits of small size and for the largedeposits of an intricate geological structure,the recommended scale of surveying is1/2000. The surface of small-sized depositsand of moderate-sized ore bodies of anirregular shape should be surveyed on a scaleof 1/1000 or 1/2000 with vertical contourintervals of 0.5 m or 1 m.

The land surveys for making constructionprojects and for the construction of miningenterprises should be carried out on thefollowing scales:

(a) 1/5000 with I-m or 2-m vertical contourintervals, for the development of engineeringprojects;

(b) 1/1000 with 0.5-m vertical contourintervals (or in exceptional cases, 1/500), formaking working drawings; and

(c) 1/1000 or 1/2000 with vertical contourintervals of 0.5 m or 1 m, for the design andconstruction of mining enterprises andsettlements.

Land surveys must be car:ried out withsuch an accuracy that the mean error ofpositions of clearcut objects and landcontours on maps and plans is not more than:1:0.5 mm or, for mountainous regions,:1: 0.7 mm. The mean errors of surveyingshould not exceed 1/4 of the height ofcontour interval for flat-relief areas (withangles of dip up to 2°) or 1/3 for a ruggedrelief. The mouths of shafts, pits, adits andother mining workings should be shown onplans and maps with an error of location notmore than 1 m in plan and 0.3 m in elevationirrespective of the survey scale.

Survey nets serve as the basis for terrestrialsurveys which can be carried out by variousmethods and instruments.

Aerophotogrammetric survey (aerial sur-veying) is a progressive method for makingtopographic maps and plans. It is carried outby making large-sized photographs by meansof a special aerial photographic cameramounted on board an aircraft. Recently,special survey aircraft have been employedfor the purpose, which are equipped withperfect photographic cameras, navigationinstruments, and an on-board computerwhich controls automatically the photographicprocess, i. e. the frequency of taking pho-tographs and the exposure. The variations ofthe terrain relief are detected by a radarsystem.

When taking aerial photographs, the air-craft flies forth and back along straightcourses (flight lines or strips) so that eachnext photograph overlaps the preceding one(forward overlap) by 60 per cent and thephotographs of adjacent flight lines (sideoverlap) by 40 per cent. Aerial photographsobtained in this way are processed by officeanalysis for compiling topographic plans andmaps. To ensure the specified accuracy oftopographic plans, aerial surveying must becarried out to meet the following require-ments:

1. The optical axis of a camera must not


oo"'

deviate during exposures from the verticalaxis by more than 2-3°.

2. The axes of flight lines must be parallelstraight lines.

3. The flight altitude must not deviate bymore than 3 per cent from the specified value.

On-the-ground stereophotogrammetry findswide application for surveying a rugged-relief terrain and open-cast quarries. It isperfllrmed by means of a phototheodolite,tho: combination of a theodolite and photo-graphic camera. The camera is set up succes-sively at two ends of a photographic base lineto make two photographs which constitute astereo-pair. The stereo-pair is examined in astereoscope to construct a topographic plan.

Tacheometric surveying is a kind of to-pographic survey employed on small areas orunder intricate relief conditions. It consists indetermining the elevation and plan locationsof points of terrain by measuring vertical andhorizontal angles and distances between thepoints. The results of tacheometric survey areprocessed for plotting the topographic planof the terrain in which the relief is depicted byhorizontal lines with the vertical contourintervals between horizontal sections taken

according to Table 2.6 depending on the kindof relief and the purpose of topographic plan.

In tacheometric surveying, the instrumentis set up at a fixed point called a station(Fig. 2.9) to measure the spatial polar coor-dinates of so-called picket points on theterrain: an inclination angle v, inclineddistance S to a picket point, and a hori-zontal angle 13 between the initial directionand the direction onto the picket point. Astaff is set up on picket points for surveyingdetails. A picket for surveying of details iscalled a contour picket and that for reliefsurveying; an elevation picket. If the picket isused both for detailed and relief surveying, itis called an elevation-contour picket, or staffpoint. The distances from the instrument tothe staff points and between the staff pointsdepend on the scale of surveying and verticalcontour interval (Table 2.7). The instrumentsfor tacheometric surveys are called tacheo-meters.

Plane-table surveying is made by means ofa plane table and ruler (Fig.2.10). Plane-table surveying differs from other methods inthat a topogrgphic plan is plotted directlyduring surveying (in the field). At presenttime, plane-table surveying is used only forlarge-scale surveys of very small areas ofterrain.

A plane table (see Fig. 2.10) has a table 1,tripod 4, and a base 3 which connects thetable with a tripod head. The table is fastenedon a metallic base (Fig. 2.11) consisting of abase plate 1, sighting device (with tangentscrew 2), three foot screws 3, a clamp 4, threescrews 5 for clamping the plane table, and abase housing 6. The tangent screw 2 servesfor rotating the plane table within smalllimits in the horizontal plane. The table baseis attached to the tripod head by means of anattachment screw 5 (see Fig. 2.10). The planetable is levelled (horizontally) by means offoot screws.

The ruler (2 in Fig. 2.10) is used for thegraphical construction of horizontal di-

2.9. General Data on Surveys 31

Fig. 2.9 Scheme of tacheometric surveying

1/5000 2 200200150150100100

300300200200150150

350300250200200150

12010070504030

0.5

0.5


56

4"--2

3

Fig. 2.11 Plane-table metallic base: 1- base plate;2-tangent screw; 3-foot screws; 4-clamp;5 -plane-table clamp screws; 6 -plane-tablehousingFig. 2.10 Plane table with ruler: I-table; 2-

ruler; 3- plane-table base; 4- tripod; 5- attachmentscrew; 6-additional ruler; 7-circular level; 8-cylindrical level; 9-vertical tangent screw;10-clamp; ll-cylindrical level of vertical circle;l2-telescope level; 13-telescope; 14-telescopesighting device; 15-stand

sheds, basins, etc. and all points where thesteepness of slope changes. The elevations ofthe characteristic points of precipices,caverns, dip pits, etc. should be indicatedrounded-off to 0.1 m. In addition to thehorizontal lines of the relief, each squaredecimetre of a plan on a scale 1/5000 shouldalso give the elevations of at least five cha-racteristic points of the topography (summitsof hills, road crossings, rock outcrops, etc.).

The elevation marks of each plan sheetshould be copied on tracing paper; if a plan isplotted in the office, its contour linesshould also be copied on tracing paper.

rections on the plane table and measuringdistances and inclination angle in particulardirections.

At present time, nomogram rulers areemployed, which make it possible to cal-culate elevations and horizontal distancesupon sighting the device (telescope) at a ver-tical staff.

In plane-table surveying, it is essential todetermine the elevations of summits, water

Chapter Three

Graphical Documentation in Mine Surveying

3.1. General

For proper functioning of a mining enter-prise, it is essential to have a file of graphicaldocuments, in particular, mine-survey draw-ings compiled by the results of geological,topographic and mine surveys.

A characteristic feature of mining graphicaldocumentation is that the informationcontained in it varies continuously in timeand space, which is caused by the dynamicsof mining production, variations of geolo-gical conditions, and some other circum-stances.

Mine-survey drawings are used in thedesign, construction and exploitation of mi-ning and associated enterprises. In parti-cular, they are used in the design of geolo-gical prospecting and mining operations,underground and surface structures, compi-lation of plans of aeration, power supply,water drainage and haulage in undergroundworkings and OI) the surface, solution ofproblems of protection of structures andnatural objects against harmful effect ofmining activity, problems of safety, account-ing for the motion of mineral reserves, miningoutput, mineral losses, and many otherproblems of interest in mining.

In that connection, mine-surveying draw-ings must have the required completenessand accuracy. Besides, they must be clear andeasily readable and measurable. This is en-sured by the application of modern drawingmaterials and instruments, advanced me-thods of preparation and complementation of

graphical documents, and high skill ofdraftsmen.

Mine-surveying service plays the majorpart in the compilation of mining graphicaldocumentation since this is based on themeasurements and calculations made bymine surveyors. .

In mining practice, the following defi-nitions and concepts associated with mininggraphical documentation are in use.

Projections are graphical representations ofparticular spatial objects on the plane ofdrawings. In mine surveying, orthogonalprojections are preferably used, especiallytheir variety, projections with numerical(hypsometric) data. Orthogonal projectionsmay be made on horizontal, vertical orinclined planes. For more clear represen-tation, axonometric and affine projections arealso employed.

Plans are drawings of orthogonal pro-jections of objects onto a horizontal plane.They are widely used for the representationof the Earth's surface and mining workings.Survey plans usually contain the elevationmarks (height coordinates) of particularpoints or are constructed in isohypses; in thelatter case, they are essentially projectionswith numerical data.

Vertical projections are drawings of objectsprojected onto a vertical plane. Such do-cuments are often compiled for steeply dip-ping seems (veins) and similar elements whenhorizontal projections would involve largedistortions. If the strike of a deposit variessharply, it can be projected onto a number of

34 Ch. 3. Graphical Documentation in Mine Surveying

vertical planes each of them being arrangedparallel to the strike of individual portions ofa deposit.

In some cases, projections onto the planeof a seam are employed.

Sections are the representation of the de-tails of an object, which are located in acertain section plane. In mine-surveyingpractice, the most common types of sectionsare geological sections and sections of mi-ning workings which depict the enclosingrock, some details of a working, supports,and other objects.

In sections, objects and details may beprojected onto vertical, horizontal or inclinedplanes.

Vertical geological sections are most oftenconfined to the lines of exploratory or mi-ning-production workings.

Profiles are graphs depicting, in a verticalsection, only the contour or part of thecontour of an object considered, for instance,the terrain relief, rocks in the roof or foot of aworking, haulage tracks, etc.

Sketches are rough drawings of objectswhich are made by hand, i. e. without the useof rules and other drawing instruments. Forinstance, a mine surveyor makes sketches inthe field book when carrying out instru-mental surveys or taping of mining workings,measuring the reserves of a mineral in store,etc.

Scales. Objects are depicted in mine-sur-veying plans by diminishing the results ofnatural (field) measurements. The degree ofdiminution of a line in a plan is determinedby the scale, i. e. a dimensionless fractionalnumber in which the numerator is unity andthe denominator shows how many times aline depicted in the plan Can be laid off alongthe corresponding horizontal distance in theterrain. This is what is called the numericalscale of lengths, or simply numerical scale.Consequently, s/S = I/M, where M is thedenominator of the numerical scale.

In plans, numerical scales are written as

simple fractions, for example, 1/500, 1/1000,1/2000, 1/10000, etc. Thus, if a numericalscale 1/1000 has been adopted for a plan, thismeans that horizontal distances on the ter-rain will be diminished on the plan to one-thousandth. It is distinguished between largeand small scales: the larger the denominator,the smaller the scale. A plan drawn on alarger scale can depict more details of thelocality. The scale of a plan or map is chosenaccording to specifications and depending onwhere the plan will be used.

Using numerical scales, horizontal distan-ces on the terrain can be transformed intolines on a plan and vice versa. For instance,if the horizontal distance of a line on theterrain is equal to 174.30 ill and the scale ofplan is 1/2000, the length of the correspon-ding line on the plan will be 174.3: 20 == 8.71 cm; if a line on a plan made on a scale1/5000 is equal to 10.2 cm, the horizontaldistance on the terrain corresponding to thatline will be 10.2 x 50 = 510 ill.

Distances on plans can be measured withan accuracy permitted by the resolving powerof man's eye, which is usually taken equal to0.1 mm (with the critical angle of vision 60"and the distance of best vision to an object250 mm, the resolution is equal to 0.073 mm,or roughly 0.1 mm). The corresponding ho-rizontal distance in nature (on the terrain) iscalled the accuracy of scale. For the scales1/500, 1/1000, 1/2000, 1/5000, and 1/10000,the accuracy is respectively equal to 0.05 ill,0.1 ill, 0.2 ill, 1 ill, and 2.5 ill.

The scale of a plan is chosen according tothe dimensions of an object in nature and byconsidering the accuracy of the scale so thatthe finest details on the plan can be by afactor of 5-10 larger than 0.1 mill. For in-stance, if individual derails of constructionobjects on the site of a mining enterprise havesizes of an order to 1 ill, the mOSt suitablescale for their depiction will be 1/2000 or1/1000.

3.2. Classification of Drawings and Rules of Mapping 35

Survey objects are depicted on maps andplans in their actual shape and in a sizeaccording to the map scale. Conventionalsigns are used in mining graphical docu-mentation for objects which cannot be drawnin their actual shape on the drawingscale.

In cases when a drawing contains theelements of terrestrial surface and under-ground workings and their geological cha-racteristics, terrestrial elements are drawn inthe flfSt place, then the elements of under-ground workings, and lastly the elements ofgeological characteristic are drawn.

The contours of the elements of an object,which lie in the plane of a drawing are drawnin solid lines and those which are beyondthat plane, in dotted lines. The contoursof elements determined on the basis ofdescription information are drawn in dottedlines.

Secondary drawings are prepared byreproducing (copying) the original drawings.They must be complemented and correctedwhen a need arises and can be used forvarious practical purposes, for instance, forthe compilation of exchange and calendarplans of mining work development, specialplans for accounting the reserves, mines stockand loss of a mineral, plans of mine venti-lation, plans for the prevention of accidents,etc.

3.2. Classification of Drawingsand Rules of Mapping

As regards their compilation, all minesurveying drawings can be divided into pri-mary (originals) and secondary (copies, du-plicates, and reproductions).

Primary drawings are mapped directly bythe results of a survey, which are recalcu-lated to a single coordinate system. If aparticular object cannot be surveyed di-rectly (this mainly relates to undergroundworkings), it is permissible to map it on anoriginal drawing on the basis of descriptiveinformation or another graphical documen-tation; an appropriate note should then bemade on the drawing.

Original (primary) drawings are the maintechnical and juridical documents for sol-ving various problems of. mining geometry.They are prepared on a special base in asystem of plats, which ensures their pre-servation and non-deformability and prov-ides certain convenience in use.

Original graphical documentation shouldhave an accuracy characterized by the data ofTable 3.1.

Table 3.1

Error in: Maximumvalue,mm

:to.2

The main requirements to secondarygraphical documents are that they shouldcontain all the essential information as re-quired by the purpose and that this informa-tion should be drawn clearly.

Graphical documentation should pre-ferably be drawn on the scales: 1/500, 1/1000,1/2000, 1/5000 or 1/10000; the scale 1/25000is recommended for cartograms and generalcharts, and scales 1/5, I/lO, 1/20, 1/50, I/lOOand 1/200, for small objects.

::1:0.6

Mutual arrangement of intersectionpoints of a rectangular coordinategrid

Position of stations of a control orsurvey net relative to the coordinategrid

Mutual arrangement of the neareststations of a control or survey net

Position of conspicuous pointsrelative to the nearest stations ofa control or survey net

Mutual arrangement of the nearestconspicuous points

Ch. 3. Graphical Documentation in Mine Surveying36

3.3. Drawing Materials.Technology and Rulesfor Making and Storageof Mining GraphicalDocumentation

Reinforced paper is a combination of lav-san and conventional paper, i. e. a lavsan filmis sandwiched between two paper layers. Itcombines favourably the drawing propertiesof paper and high physico-mechanical pro-perties of lavsan. Reinforced paper is manu-factured in various versions with variouskinds of paper and different thickness oflavsan film and has a number of applic-ations.

The matter of storage of originals made onplastic materials deserves special attention.They should be kept in an isolated room at atemperature within + 16° to + 20°C andair humidity 50-80 per cent. The best methodof storage of originals (plats) is to keep themin the suspended state. General charts madeon plastics can in exceptional cases bekept in rolls (rolled together with spacingpaper where possible).

3.4. Mechanizationof Graphical Work

In modern practice, graphical work islargely facilitated and made less labour-con-suming by the use of principally novelengineering means which make it possible to'mount' drawings from unified standardprefabricated graphical elements.

The first to be named among these meansare decalcomania means (decals), i. e. multiplyrepeated paint images of alphabet letters,digits and conventional signs applied onto afilm material. The draftsman chooses therequired sign, places the film on the drawing,and rubs at the other side of the film with ahard object. In this way, the paint image isdetached from the film and transferred ontothe drawing. Decals can be restored multiplyby repeated rolling with a special paint.Decals are used widely for making inscrip-tions on drawings, compiling plans fromconventional symbols, schemes of electriccircuits, for marking of documents, cataloguecards, etc.

Up to a recent time, all mining graphicaldocumentation was made on a paper base:original plans of mining workings on high-quality drawing paper glued on a reinforcingsubstrate (aluminium plates, cloth, etc.) andsecondary plans, on light-sensitive paper(copy paper) or tracing paper. At present,synthetic drawing materials (based on lavsanor therylene) are being used widely for ma-king mining graphical documentation.They have a higher durability and strength,can withstand multiple corrections, retainstable dimensions under atmosphericinfluence, and possess a better transparency.

Synthetic drawing films are manufacturedin a number of varieties with differentphysico-mechanical properties of the drawingsurface, depending on their application andthe method of fixation of the image (by ink,graphite or synthetic pencil, engraving,diazotype copying, printing, etc.).

Polyethylene terephthalate (1avsan) film(glossy, double-oriented) is employed formaking various copies with the application ofsilverless light-sensitive layers. Mechanicallymatted lavsan is widely used in drawing. Theglossy drawing surface of the lavsan filmrequires no matting additives if special inksare used for drawing. The film is highlytransparent and ensures a high quality ofcopies. On the other hand, its white surfaceensures a high contrast of drawings.

An offset lavsan film is suitable for makingoffset plates by electrographical and pho-tomechanical methods or by drawing. A platemade by the photomechanical method can beused for making up to 10000 copies.

A templet drawing film possesses thermo-adhesive properties, which makes it possibleto mount various templets on it.

3.5. Processes and Materials 37

pying; microfilm copies can also be madewhen needed.

All used templets and substrates can berestored. Templets are detached from the filmbase and the latter is cleaned from the tracesof a pencil and ink, and from decals. Re-stored materials can be used anew.

As has been shown by experience, decalscan be used both in specialized and non-specialized production of graphical docu-ments. They can be manufactured in anydesign institution or enterprise provided withphotoprocessing laboratory equipment.

Templets, i. e. applications of standardelements, conventional signs, inscriptions, etc.have also found wide use in modern drawingpractice. The method of templets has manyadvantages and largely accelerates the draw-ing process, since drawings are compiledfrom individual standard elements. Templetsare produced in a number of varietiesdiffering from one another in the type ofsubstrate (paper, thin cardboard, film, foil,etc.), the method of application of the image,and the principle of fixation of templets on asubstrate. Adhesive templets are the mostpopular; they have an adhesive layer on theback side, which is protected by non-stickingpaper. The latter must be removed beforeapplying a templet into its place in a draw-ing. Such templets have however certaindrawbacks: they can be used only 4-5 times; itis difficult to move a templet on the sub-strate in the case of variation design; templetstaken off from the substrate are liable totwisting; etc.

These drawbacks have been eliminated in anew method of templet mounting which usestemplets prepared on a polyethylene tere-phthalate film base with the working(contact) layer made of a material fusible at80-120°C. As the fused layer solidifies, it fixesfirmly the templet on a substrate (paper orfilm). Templets are mounted by means of athermal handle. For temporary fixation of atemplet on a drawing, it suffices to touch thetemplet with the handle in a single point. Forfinal fixation of a templet, the handle isapplied in four or more points. Mter mountingthe templets, the required textual and gra-phical additions are made in the drawing byusing decals. The final original drawing ischecked and reproduced by diazotype co-

3.5. Processes and Materialsfor Reproduction of MiningGraphical Documentation

The principal processes for the repro-duction of drawings of mining graphicaldocumentation are diazo type copying, elec-trophotography, and offset printing.

Diazotype copying is the most popularprocess for the reproduction of original draw-ings made on transparent materials. Theoriginals are reproduced on diazo-paper anddiazo-film. Light-sensitive diazotype mate-rials are manufactured industrially in a widerange and differ from one another in the kindof a light-sensitive layer and base and me-thods of development. Diazotype copying isperformed in rotary copying machines andcopying frames.

Electrophotography is among the mostadvanced modern processes of reproductionof graphical images. It is distinguishedfavourably by high productivity, facsimilereproduction of images, simple technolo-gy, and possibility of copying of opaqueoriginals.

Electrophotographic process is based onthe use of certain semiconductors whoseconduction changes under the effect of light.When a layer of photosemiconductive ma-terial is exposed to light, there forms a latentelectrostatic image in it, which is developedby a powder material whose particles areattracted to the portions of the seleniumlayer, that carry induced electrostatic char-ges.

Offset printing is the most efficient andsimple process of the reproduction of docu-

38 Ch. 3. Graphical Documentation in Mine Surveying

elements of a large area should be filled withink at least three times and checked on anilluminated screen so that their optical den-sity is sufficiently high; and

(d) linear dimensions in colour-separateddrawings should not differ from the originalsby more than :to.15 mm at sides and:to.20 mm along diagonals; the arrangementof the whole situation in a plan should satisfythe same accuracy standards.

The process of preparation of colour-se-parated originals by illumination drawingsconsumes much time and labour and isinsufficiently accurate. In a novel process,colour-separated originals are prepared bydiazotype copying of contour images madeon tracing paper, synthetic drawing films, etc.

Synthetic drawing materials are findingever wider use and accordingly, in variousnovel technological schemes and processes.For instance, transparent materials withthermo-adhesive properties have largelysimplified the process of preparation of ge-neral charts at mining enterprises. Transpa-rent plats of the original documentation arediazo-copied on the film and mounted by thethermotemplet method on a base as frag-ments of a general chart. The latter is diazo-copied on cartographic paper or diazo-film.Later, the obsolete fragments of the generalchart can be replaced by new ones.

ments and has been for a long time in use incartographic engineering. Offset printing en-sures a higher quality of printed graphicaldocumentation than is possible in diazotypecopying on map paper and is well suitable formaking multicolour prints. In addition, itrequires much less labour for manual pain-ting and offers the possibility for makingmulticolour composite prints, for printing inor eliminating some graphical elements, etc.

Offset printing of maps at map-makingagencies is carried out from colour-separatedoriginals (separation drawings or simply se-parations) which are prepared directly atmining enterprises. Colour separations, as thename implies, describe the graphical situationin a single colour, for instance, red, black, etc.and are used for making correspondingcolour-separated printing plates.

Colour-separated drawings should meetvery high requirements:

(a) they are drawn on synthetic transparentmaterials 70-100 ~m thick; thinner films arepreferable, since they diminish the parallacticeffect during copying onto printing plates;

(b) the films must be without dents, folds,scratches, etc. and have no spots, marks,pencil lines, etc.;

(c) line elements, especially inscriptions andshadings, should be well filled with ink,without clearances and breaks; the shaded

Chapter Four

Connection Surveys

4.1 General Connection survey via horizontal or incli-ned workings is carried out by runningpolygonometric traverses or geometric ortrigonometric levelling traverses through theworkings.

Connection surveying (orientation) via ver-tical workings is done by special methodswhich can be divided into geometric andphysical.

The geometric methods of orientation ofunderground survey employ plumb bobs(plummets) sunk into vertical shafts of mines.The coordinates of plummets and the di-rection angles of plumb:-connecting lines aredetermined by'measurements on the Earth'ssurface.

The physical methods include the magnetic,gyroscopic, and optical method.

The magnetic method utilizes the ability ofa magnetic needle to line up along a line ofthe magnetic field of the Earth. Though beingrather simple, it has an essential disadvan-tage; owing to local magnetic disturbances,the orientation of the magnetic needle issubject to unpredictable variations in parti-cular places. For that reason the magneticmethod is not popular and employed only inrare cases when its low accuracy is sufficientfor orientation of underground workings.

The gyroscopic method uses a pendulumgyroscope (gyrocompass) whose axis per-forms harmonic oscillations about an equi-librium position which coincides with theplane of astronomic meridian on the stationpoint of the instrument. Modern high-pre-cision gyrocompasses are reliable instruments

The object of connection survey (orienta-tion) is to ensure underground surveying inthe coordinate system adopted on the Earth'ssurface. Connection survey is essential formining work expansion, correct location ofunderground workings relative to objects onthe surface, protection of surface structures,determination of the depth of mining work,construction of boundaries for safe mining,combined working of adjacent seams, andconnection of underground workings. Con-nection surveys are carried out rarely, mainlybefore constructing a new mine and later, forpreparation of new mining levels. Connectionsurvey belongs to the most critical kinds ofsurveying work and must be done with thehighest accuracy and under reliable control.

A distinction is made between the hori-zontal and vertical connection surveys.Horizontal connection survey has to tackletwo problems: (a) orientation of underground;surveys, i. e. determination of the directionangles of the initial sides of an undergroundsurvey net and (b) centring, or plumbing, ofan underground survey, i. e. determination ofthe coordinates x and y of the initial points ofan underground survey net. Vertical connec-tion survey is carried out for transferring aheight mark from the Earth's surface downinto the mine.

Depending on the method of opening adeposit, connection surveys can be run viahorizontal, inclined or vertical workings orshafts.

40 Ch. 4. Connection Surveys

for gyroscopic orientation of undergroundsides of reference survey nets, because ofwhich the gyroscopic method has found wideuse as being the most precise and leastlabour-consuming.

The optical method of orientation ofunderground survey is not very popular,since the available instruments have an insuf-ficient resolving power in deep mines wherethe atmosphere may often be moist anddust-laden, and thus fail to ensure the re-quired accuracy of measurements.

In modern mine surveying practice, orien-tation of underground workings is mainlyperformed by the gyroscopic or geometricmethod (via one or two vertical shafts).

Errors incurred in connection surveyscause subsequent errors in the determinationof points of underground survey nets.

If the coordinates x, y of an initial point 1are found with errors (Fig. 4.la), these will becarried over without change into the co-ordinates of all subsequent points of anunderground survey net. Therefore, an error1-1' of the planimetric position of the initialpoint which has appeared on centring, willresult in a parallel displacement of points 1-6into positions 1'-6'. An error in the deter-mination of the height mark (z) of an initialpoint gives a similar effect.

An angular error of orientation (orien-tation error) gives a different effect. If thedirection angle of the initial side is found withan error m" (Fig. 4.1b), the net 1-5 will beturned into the position 1-5'. The root-meansquare displacement of the last point will be:M = (mJp')s (4.1)

where m" is the rms error of orientation,minutes; p' is the number of angular minutesin a radian (p' = 3438'); and s is the length ofthe closing side of a traverse.

This formula shows that the effect of anorientation error on the planimetric posi-tions of points increases in proportion to thedistance from the initial point. For thatreason, orientation is the most critical part ofconnection survey and must be performedwith the highest accuracy.

In order to avoid appreciable errors, orien-tation must be done twice by the samemethod or different methods.

Discrepancies in the results of orientationof one and the same side of a traverse shouldnot exceed the following permissible values:

(a) 3' for direction angles in geometricorientation;

(b) 2' for direction angles in gyroscopicorientation; and

(c) 5 cm for planimetric position of theinitial point in the plumbing of a survey netvia vertical workings.

In order to satisfy these requirements, theroot-mean square error m" of a single orienta-tion must not exceed l' in the geometricmethod and 40" in the gyroscopic method oforientation. To minimize the effect of anorientation error on the positions of distantpoints in underground survey nets, it isrecommended to make gyroscopic orienta-tion of intermediate sides of nets in mineswhere field wings exceed two metres inlength. Thus, the maximum rms displacementM of a point of an underground survey net,as calculated by formula (4.1) with due con-sideration of the error of orientation

(a) 2' 4'f:;:-1=::$;~' 3 ' 5 ' 6 ,

~ 0 2 4 ,~ "'0--

1 3 5 6

5'

~ a=C~~---~ ---, 2' 3 4'

,m (X '0- ---0 ,...0

2 3 5--0--

4

(b)

Fig. 4.1 Effect of centring error (a) and orienta-tion error (b) on positions of points of undergroundtheodolite traverse

4.3. Geometric Orientation 41

(carried out twice), will be: If a mine is entered by two adits, thetheodolite traverse must be run to closure.

In mines opened by inclines with thedipping angle of more than 70°, directionangles must be transferred only by usinggyroscopic orientation.

M= x 2000 m= 0.4 mfi x 3438'

4.2. Orientation of UndergroundSurvey via Horizontalor Inclined Adit

If a deposit is opened by a horizontal entry(adit) or an inclined entry (incline), the under-ground survey can be oriented by running apolygonometric traverse from the surfaceinto the mine (Fig. 4.2).

If only one adit or incline is available, thetraverse is run from an approach station onthe surface, say, B, to the first side of theunderground survey net. A back traverse lineis run usually through other, temporarilyestablished points. The polygonometric tra-verse run to a side CD in the figure makes itpossible to calculate the direction angle aCDof the side and the coordinates of a point C:

aCD = a AB + 131 + 132 + ...+ 13n :!: 180°.nXc = xB + /1 cos aB1

+ 12cosa12 + ...+ IncosanCYc = YB + /1 sin aB1

+ 4sina12 + ...+Insinanc

where 131' 132' ..., 13n are the measured angles;n is the number of measured angles; aB1' ...,anC are the direction angles of sides; and /1, 4.

In are the measured lengths of sides.

4.3. Geometric Orientation

Connection survey with the use of plum-mets can be performed via one, two or morevertical shafts. In any case it has to handletwo problems: the problem of projection andthat of connection (junction).

The procedure of projection consists essen-tially in that a straight-Iine segment is tran-sferred by means of two plumb bobs from thesurface onto the mine level to be oriented.The projection procedure should be carriedout so that the line segments on the surfaceand in the mine lie in the same vertical plane.

The junction procedure includes two steps:connection on the surface and connection inthe mine. The former determines the coor-dinates of the plummets and the directionangle of the line that is projected from thesurface, and the latter is done to transfer thedirection angle and plumb-line coordinatesto the first (fixed) side of an undergroundtheodolite traverse.

There are several methods of junctionwhich differ from one another in the shape ofjunction figures at plumb-bob lines. With all

:~ //I D

ri %,ri ?:1

""~ ~2~~,(/////////////~~---0-- ~n-~B 11 1 ' 2 13 3 ---0--- n In C

~ ~.

~ //j

~

Fig. 4.2 Orientation via adit


methods of junction, however, the matter ofprojection is tackled essentially in the sameway.

4.4. Orientationdown One Vertical Shaft

This kind of orientation is carried out bymeans of two plummets hung from the sur-face through the shaft onto the mine level tobe oriented. The procedure requires carefulpreparatory work, long-term outage of hoi-sting vessels in the shaft, and certain specialsafety measures. The procedure must be per-formed in a clearly correlated sequence andwith coordinated actions of all the specialistsengaged in it. For that reason, the chiefmining surveyor has to work out a detailedplan of the organization and methods ofsurveying work which specifies, in particular,the required outage time of hoisting means inthe shaft and the essential safety measures;the plan is to be approved by the chiefengineer of the mining enterprise. Beforestarting the work, all members of the surveyteam are instructed by the chief miningsurveyor in their duties and in details of theplan.

The survey work of orientation down onevertical shaft can be divided into two stages:

(I) the preparatory stage which includesthe operations and steps that should beperformed before stopping the hoist in theshaft and

(2) the main stage which covers the ope-rations of centring and orientation to becarried out when the shaft hoist is stopped.As a rule, the main fan of the mine is switchedoff for the time when observations of plum-met oscillations are to be carried out.

nection survey via a vertical shaft. Thismethod is the most labour-consuming andrequires certain special techniques, but theinstruments and appliances employed in it, aswell as some of the operations describedbelow, are typical for all kinds of geometricorientation, in particular, for connectionsurveys via two or more vertical shafts.

The preparatopy stage includes the followingoperations.

I. Approach points are established on thesurface at a distance not more than 300 mfrom the shaft collar. Existing stations of ageodetic net of class I to 4 in the vicinity ofthe shaft can be used as approach points. Thecoordinates and direction angles of approachpoints must be determined with an accuracycorresponding to analytical or polygonomet-ric nets of the first order. The approachpoints should be established so that thehanging polygonometric traverse of the se-cond order to be run immediately to the shaftcollar between the initial point for directconnection of plumb lines and an approachpoint contains not more than three sides.This traverse should be run twice or beclosed or else be tied to higher-order stationpoints.

2. A number of (at least four) permanentstation points (marks) are established in theworkings of the mine level to be oriented, sothat the coordinates x, y and direction angletransferred into the mine can be fixed tothem.

3. A set of instruments, appliances andfixtures is prepared for accomplishment ofconnection survey work with the specifiedaccuracy. The survey instruments and ap-pliances must be tested and adjusted beforestarting the work. The mass of plummets andthe type and diameter of wire are chosendepending on the depth of the shaft and thespeed of air in it.

4. The points are chosen for hanging theplumb bob lines in the shaft so as to obtainthe largest distance between the plummets

4.5. Sequence and Organizationof Work for Orientationdown One Vertical Shaft

This section will describe in detail thesequence and organization of work for con-

4.5. Sequence and Organization of Work 43

3. Small plumb bobs (of a mass of 3-5 kg)on wires are passed through the holes in thetop platform along the shaft to the level to beoriented so as to avoid large swings. Practi-cally both plumb bobs are sunk simultaneous-ly with a speed of 1 mjs. It should be checkedthat the wires have no -knots, bends, etc. alongthe entire length.

4. Upon sinking the plumb bobs, the teamunderground replaces them by the mainlarger plummets and places these into dash-pots.

5. Centring plates with scales, mirrors andother devices are placed on the platforms onthe underground level to observe the oscilla-tions of plummets. If the strings of freelyhanging plummets are stable (their oscilla-tions do not exceed 0.4 mm), the centringplates can be aligned immediately with theplummets.

6. It is checked that the plummet stringsdo not touch the shaft walls. This can bedone by two methods: (a) a light ring cut outof cardboard or another available material is'mailed down' along the wire, i. e. is let toslide down to the bottom or (b) the distancesbetween the plummets as measured on thesurface and in the mine are compared; thediscrepancy between them must not exceed2mm.

7. Observations of plummet oscillationsare carried out to determine the centralpositions of the plummets, after which theplummets are fixed in the centring plates andthe free positions of the plummet wires arechecked again by comparing the distancesbetween the plummets as measured on thesurface and in the mine.

8. All linear and angular parameters of theconnection triangles are measured on thesurface and in the mine.

9. Upon finishing the cycle of observa-tions, a check measurement of the distancebetween the plummets on the surface and inthe mine is made again. If the discrepancy iswithin the permissible value, it is now pos-

and the most favourable figures for solvingthe connection problem. Places are assignedfor the construction of platforms for winches,scales, guide pulleys, projection and centringplates, plummet dampers (dash-pots), etc. soas to ensure the stability of plummets duringthe entire time of observations. If there isenough place in the underground workingsnear the shaft and the mining operations inthe shaft will not be interfered, some of theseprocedures (construction of platforms forwinches, arrangement of winches and guidepulleys, closure of the sump, etc.) can becarried out at an earlier stage.

5. Building materials are prepared for theclosure of the shaft, construction of plat-forms, attachment of fixtures in the shaft andon the mine level to be oriented. Vessels withviscous liquid for plummet damping andother devices are prepare,d for the work.

6. Auxiliary workers (shaft fitters, carpen-ters, hoist operators) to be engaged in theconnection survey work are instructed in thejob, and a reliable telephone service is estab-lished between the working teams on thesurface and in the mine.

At the beginning of the main stage ofsurvey work, the performers and the auxiliarypersonnel in the shaft and at the hoist areplaced under the authority of the surveywork supervisor, usually the chief surveyor ofthe mine. Persons not engaged in surveywork are strongly prohibited to be present inthe underground workings and shaft buildingand on the platforms. The performers aredivided into two teams or groups: one forwork on the surface and the other, on thelevel to be oriented.

The operations at the main stage arecarried out roughly in the following sequence.

I. Wood platforms are constructed on theshaft collar and in the shaft proper. Smallholes are provided in the platforms for pas-sing through plummets.

2. Winches, guide pulleys, centring plates,etc. are fastened on the platforms.

Ch. 4. Connection Surveys44

~

///////////;"J;!;;;///////////////////;

Fig. 4.3 Plummet arrangement for orientationthrough vertical shaft: 1 -hand winch; 2- guidepulleys; 3 -centring plates; 4- guard platform;

5-plummet; 6~dash-pot

sible to start disassembling of .the surveyingequipment. The main plummets are replacedby lighter plumb bobs and these are lifted tothe surface. During lifting the plumb bobs,the work of all kinds in the shaft and near itand on the platforms is prohibited.

With properly organized work and goodcoordination between the working teams, themain stage of surveying can be completed in8-12 hours. The principal scheme of arran-gement of plummets for orientation via avertical shaft is shown in Fig. 4.3.

level being oriented do not usually lie in thesame vertical plane with the plumb linepoints 01, O2 on the surface (Fig. 4.4). Inother words, it is impossible to form avertical plane in a shaft that would passthrough all four points indicated. The root-mean square error for this case can be foundby the formula:

Au" = p'e/c (4.2)

where e are the rms linear deviations of thepoints of both plummets on the level beingoriented from the respective points on thesurface and c is the distance between the

plummets.Since the permissible discrepancy between

two independent orientations is not morethan::!: 3', the rms error of an orientationshould be not more than 1'. If the rms errorof surface connection and connection in themine is taken to be not more than::!: 30", therms error of projection, Au, should notexceed the following value:

Auperm = J Au; + Au; ~ 42"

To ensure this accuracy of projection, therms linear deviations e should not exceed 0.4,0.6, 0.8, I, and 1.2 mm for the distancesbetween the plumb lines respectively 2, 3, 4, 5,and 6 m.

This accuracy can only be attained byobserving the rules listed in Sect. 4.7. It isessential to choose the distance between theplumb lines as close as possible to the shaftdiameter.

For handling successfully the problem ofprojection, of special importance is the obser-vation of mean (central) positions of plum-mets on the oriented level. Observations of

4.6. Plumbing Surface Pointsonto Oriented Mine Level

Owing to the effects of various externalforces, plumb line points 0'1, o~ on the mine Fig. 4.4 Determining angular projection error

4.6. Plumbing Surface Points onto Oriented Mine Level 45

~

N

".I ~"5.

.4

'5~

::;:::

2

4.-3

5.

A

7 4 '5Fig. 4.5 Centring plate with scales: 1- body;2-mirror socket; 3-pyramid; 4-clamp screws;5- pyramid-adjusting screws; 6- slit for plumb bobstring; 7- plate-fastening sockets; 8 -plumb bob;9-plug; M, N -scales

Fig. 4.6 Observation of pl~mmet oscillations onscales by means of two theodolites

plummet oscillations can be made by twolinear scales, a centring plate (Fig. 4.5.), eye-piece scales, and other devices.

Irrespective of the type of instrument usedfor the purpose, the problem consists essen-tially in observing the motions of oscillatingplummets in two vertical planes and deter-mining their mean positions in each plane.These points are then fiXed. Figure 4.6 showsthe scheme of observation of a plummet 01by using two theodolites. The extreme pointsof positions of plummets are fixed by readingoff on the scales at the exterior or interioredge of the plummet wire. The number ofreadings to fix the extreme position of thewire shou)d be not less than 11-13. Thereading on the scale N 1 corresponding to themean position of the plummet is calculatedby the formula:

N 1 mean = 0.5 (I;IN./n + I;rN./n) (4.3)I I

where IN. is an extreme left reading on thescale N; for the first plummet; rN. is anextreme right reading on the scale N ;; and nis the number of observations of extremepositions of the plummet 01 on the scale N 1.

Similar observations and calculations aredone on the scale M l' Observations of themean position of the second plummet O2 arecarried out simultaneously by using twoother theodolites. The plumb line points arefixed according to the calculated data ontheir mean positions, the distance betweenthem is measured as accurately as possibleand compared with the distance between theplumb line points as measured on the surface.The observers should try to place the inst-ruments and scales so that the angle y will beclose to 90°, The accuracy in the determina-tion of the mean position of a plummet willnot be worsened if the angle y ranges between45° and 135°. If the space available is toorestricted, it is recommended to observe theoscillations of a plummet by means of amirror and theodolite.

This method is more intricate and time-

46

o Scale N

Fig. 4.7 Observation of plummet oscillations ontwo scales by using mirror and theodolite

Ch. 4. Connection Surveys

~

plate by means of two mutually perpendi-cular pairs of screws 5 (see Fig. 4.5).

~

~ oc ~ ~Ni. ~

, " W, ...

~

~~

~

III

consuming. The principal scheme of deter-mining the mean position of a plummet bymeans of a mirror and theodolite is shown inFig.4.7.

The reading on the scale N I correspondingto the mean position of a plummet is calcu-lated by the formula

N1mean = (N1 + N2 + ...+N1)/i (4.4)

where

N1 = (IN + 2,N + IN )/4I I 2

N 2 = (IN + 2,N + IN )/4, etc.2 2 3i = (nr -I) + (n, -1)

In these formulae, IN. IN. IN. and 'N ' 'N .'N. are the left ind fight readings 6fth~

extreme positions of the plummet O Ion thescale N I; and nr and nl is respectively thenumber of right and left readings.

In order to observe the oscillations of theplummet on the scale M I' the theodolite issighted on the mirror which is arranged at anangle of 45° to this scale. Then a readingM I mean corresponding to the mean positionof the plummet on the scale M I is taken.According to the readings N I mean !and M I mean'the plummet 0 I is fixed rigidly in the centring

4.7. Connection to Plumb LinePoints in OrientationDown One Vertical Shaft

The root-mean square error of transferringthe direction angle from the initial side of atraverse to the plumb-connecting line andfrom the latter to the traverse side of anunderground reference net on the mine levelbeing oriented, should not exceed 30" foreach of these two procedures. Consideringthis requirement and the possibilities of ar-rangement of plummets in a shaft, one choo-ses the connection method that is mostsuitable for the purpose. Among these meth-ods, the method of connection triangle ismost popular (Fig. 4.8.). Two points fixedearlier on the surface and in the shaft, say, Aand C. and two points projected by plum-mets, 01 and O2, form two connection triang-les: AO1O2 on the surface and CO1O2 in theshaft.

The connection triangles will have a fa-vourable form and ensure the specified accu-racy of connection if the angles a and 'Y of thesurface triangle and the angles P 1 and 'Y1 ofthe underground triangle do not exceed 2-3°and the ratios a/c and, b1/C1 are as small aspossible. The connection procedure is startedupon finishing the projection, and the obser-vations and measurements on the surface andin the shaft are usually carried out concur-rently. Before making the connection work, itis required to determine the expected errorsin calculated angles, m« and m{i1 by theformulae:m« = (a/c)m1" m{i1 = (b1/cJm1'1 (4.5)

It is then permissible to solve the connec-tion problem by the method of connectiontriangle if the expected errors of angles a andPi do not exceed :t20". It is required tomeasure all the three sides a, b, and c of a

4.7. Connection to Plumb Line Points

Fig. 4.8 Junction by method of connection triangle

approximate formulae:

a = (a/c)y, 13 = (b/c)y

Pi = (b1/cat = (a1/C Iyl'

If a or ~l exceeds 20°and ~ or al is smallerthan 160°, the angles can be found by theformulae of sides:

for the surface triangle:

tan {a/2) = J(P -b)(P -c)/[jJ(P -a)]

tan (~/2) = J"iii=--a)(P -c)/[jJ(P -b)]

and for the underground triangle:

tan {afl) ,(4.8)= J(Pl --bJ(P

tan (fil/2)CJI[P1 (Pi aJ]

= J(P1 -aJ(p1 .'.'.CJI[P1 (P1 -hJ]

whereP = (a + b + c)/2 and P1 ~ (a1 + b1 + cJ/2

Mter the angles have been calculated, acheck is done by. adding the angles for eachtriangle, The sum of angles must not differ bymore than 10" from 180°, The discrepancy(within the permissible value) is distributedevenly between the calculated angles.

Before solving the connection triangles, thelinear measurements are checked by colilpa-ring the measured distance between theplummets to its value calculated by theformula:

triangle AO1O2 and the angles 0, E, and yonthe surface at a point A and the sides a1, b1,and c1 ofa triangle CO1O2 and the angles 01,El and Yl at a point C in the shaft.

The rIllS errors of the measured angles atpoints A and C must not exceed m = 7". The

differences of the measured angles 1 points Aand C (see Fig. 4.8), ° -(E -Y) and 01 --(El -YJ, must not exceed :!:20". Theseangles are adjusted by distributing the discre-pancies, obtained by the reiteration method,equally between all the angles.

Each side of connection triangles is mea-sured at least five times by a steel tape at aconstant tension, taking readings with anaccuracy of up to a miliimetre. The arithme-tic mean of these measurements is taken asthe final result. The discrepancy between theindividual readings must not exceed:!: 2 mmand the root-mean square error of the finallength of a side must be not more than:!: 0.5 mm. The results of these field mea-surements are then used for calculations inoffice analysis.

The solution of connection triangles andthe calculations of the direction angle and thecoordinates of the points of the initial sideCD in the mine are carried out as follows.

If the acute angles a and ~1 do not exceed20°, use can be made of the sine fofIllulae:sin a = (a/c) sin Y, sin ~ = (b/c) sin Y

(4.6)Sin~l = (b1/cJsin Ylsinal =(al/cJsiny

If a or 131 is less than 2°and 13 or a1 is morethan 178°, the angles can be calculated by the c= Ja2 +b2 2abcos'Y

Table 4.1. Solution of Connection Triangle with Angles a < 20° and p > 160'

Survey place

m ) 2

tan ap" --.!!.

b

2(tana )2 m = -m +

.tany yOta

{3~A

/1 b +

2

3

4

5.03138.05103.0220

12

II

5

22

23

24

0.0311.63

a

b

c

a

13

y

tan a

tan a/tan ytan a

3.8-m,

tany

asin a ~ -siny

c13 ~ 180000'00"

t2.4"25 ( ~m ) :

tany y 14.44

:to.29 mmma

26 tan ap'

m.

a

bsin 13 = -siny 18 0.000060

27tanap"~

a0.38

0.0188266 16 :!:0.3 mm 28( tan ap"~)2

mtan ap" -=-C

( tan ap"~)2

siny mb0.14

siny

c

sinn

m"

b

mc

0.006229

0.031341

19

17

0.000040

:!: 0.23 mm

29

3080.41

9 sin 13 0.050150 20 mcc

tany

0.00010

0,019

31 m; 14.99

:1::3.8"10 131 2°52'29" 21 32 m,

1047'45"

177°07'31"

1°04'00"

4.8. Horizontal Connection Survey via Vertical Shafts 49

Table 4.1 (Continued)

Calculation of length of line c

.;.,c = a2 + b2 -2abcosy

1234567

02

b2

2Ccalc

Ccalc

1°04'00"

0.999827

5.0313

8.0510

40.5070

81.0140

81.0000

8

9

10

II

ycosy

ab

ab2ab

2ab cos y

25.314064.8186

9.13263.0220

12

13

3.02200.0000

Cmeas

Ccals--Cmeas

as the arithmetic mean of two connectionsurveys.

The calculations for connection trianglesare made in table sheets. A table sheet for acase when the angles a are smaller than 200and 13 are larger than 160° is shown in Table4.1.

The method of connection triangle is simp-ler in measurements and calculations thanthe other methods available, ensures a highaccuracy if the triangles are stretched, and forthese reasons has found wide practical appli-cation.

Other methods of connection through asingle shaft, for instance, the method ofconnection rectangle with two- or single-sidedconnection schemes, the method of symmet-rical connection, etc., will not be discussedhere, since they are substantially more la-bour-consuming and therefore came out ofuse a few decades ago.

The permissible discrepancy is not morethan 3 mm for the surface triangle and 5 mmfor the underground triangle.

The direction angle of an underground side(see Fig. 4.8) is calculated by two polygons(one through plummet 01 and the other,plummet O2) using the following formulae:aCD = aBA + I: + (a + aJ + 1:1 -3 x 180°

(4.10)aCD = aBA + 0 -(P + PJ + 01 -3 x 180°

(4.11)The coordinates of the initial point C in

the shaft are calculated by two polygons (seeFig. 4.8):x'c=xA+hcosaAO +h1cosao c (4.12)1 1Yc=YA+hsinaAo +hlsinao.c (4.13)

1 1

Xc = xA + acosaAo + a1cosao c (4.14)

2 2

Yc=YA+asinaAo +a1sinaoc (4.15)2 2

The direction angles of the initial under-ground side CD, as transferred by two poly-gons, should be fully coincident, and thecoordinates of a point C may have discre-pancies within the accuracy of side measu-rement, i. e. up to 2 or 3 mm. If it is impos-sible to make a check by a different connec-tion survey, orientation through one verticalshaft is repeated upon placing the plummetsinto new positions. The final result is found

4.8. Horizontal Connection Surveyvia Two Vertical Shafts

The analysis of the total error of connec-tion survey, including the projection andconnection errors, shows that with the con-nection through a single vertical shaft theprojection error, which is the principal errorin this kind of survey and depends mainly on

4-127(!


Fig. 4.9 Orientation via two vertical shafts

the distance between the plummets, cannotalways be diminished to the permissible va-lue. In the orientation via two vertical shafts,however, the angular error of projection isnot as critical, since the distance between theplummets is substantially greater. For thatreason, the connection survey via two verticalshafts is the most accurate and reliable amongall kinds of geometric orientation. For in-stance, with the distance between the plum-mets of 50 mm and a linear error of projec-tion of 2 mm, the angular error, according toformula (4.2), will be:

l1a" = p".: = 2 x 206265 = 8"

c 50000

i. e. is substantially smaller than the errorscaused by other factors.

In view of this circumstance, with thedistance between the plummets of 50 m ormore, it is permissible to perform connectionon an underground level to freely hangingplummets.

In the scheme of orientation via two ver-tical shafts, as shown in Fig. 4.9, the geomet-ric connection between the sui:face and un-

derground survey nets is effected by means ofthe plummets hung in two shafts.

Connection survey via two vertical shaftscontains the following main stages:

(I) projection of plumb line points 01 andO2 from the surface onto the mine level to beoriented. The main instruments and applian-ces, the order to plummet hanging in shafts,etc. are essentially the same as in the orien-tation via a single vertical shaft;

(2) connection to the plummets on thesurface and in the mine. The connection onthe surface can be performed by one of thetwo schemes as follows:

(a) if the distance between the shafts is notlarge, theodolite traverses with the number ofsides not more than three (A-I-01 and A-11-02) are run from one and the same point(A) to the plummets;

(b) if the shafts are at a large distance fromeach other, an approach point is establishedat each of them, so that theodolite traverseswith the number of sides not more than threecan be run from these points to the plum-mets.

The connection to the plummets in the

4.8. Horizontal Connection Survey via Vertical Shafts 51

4.8.1 .Estimating the Accuracyof Direction Angleof Plumb-Connecting Lineon the Surface

Let side 1-1' be the initial side from whicha polygonometric traverse with a junctionpoint 2 has been run (Fig. 4.l0a). The root-mean square error of the direction angle of aplumb-connecting line can be found by theformula: .

mine is performed by running a theodolitetraverse between the plumb line points (01-1-2-3-4-5-02).

The accuracy of theodolite traverses oil thesurface must correspond to first- or second-order polygonometry and that on the levelbeing oriented, to the accuracy of undergroundreference n(;ts. The underground traversebetween the plummets should be stretchedwhere possible, i. e. be of the least feasiblelength, and include as few points as possible.

In Soviet practice, technical instructions onmine surveying specify that the root-meansquare error of the direction angle of aplumb-connecting line relative to the nearestside of the reference net on the surface shouldbe not more than 20". That is why, beforemaking the connection survey, it is essentialto estimate preliminarily the accuracy of thedirection angle of the plumb-connecting lineand that of the direction angle of the side ofthe underground reference net, so that therillS error of the underground direction canbe within the permissible limit of 1 '.

M~o o =1 2

v (4.16)

where mp = 10" is the rms error of angularmeasurements; 11 is the coefficient of influenceof random errors in length measurements; Siare the lengths of sides of a polygonometrictraverse from the junction point to plumbline points 01 and O2 (in the case considered,the side lengths S2-01' S2-3' and S3-0J; <Pi is the

angle made by a side i and direction 0102; c

(b)

Fig. 4.10 Preliminary estimation of accuracy of survey work: (a) for direction angle of plumb-colJnectingline on surface; (b) for direction angle of side of underground survey net

Table 4.2

.2Si sm IpiSi-

desVer-texes

R, R:

223

7

82

12

496724

144

2-012-3

3-02

181

26

[R;iJ = 6917 [sisin2<p;J = 45

provided that ~ = 0.001 m1i2, mfl = 20", andc=115m.

The calculation is done in the followingsequence.

I. The root-mean square errors Ma offl

direction angles of traverse sides incurred bythe errors of angular measurements are de-termined by the formula:

Ma = (mfl/c)J[Ji"!] (4.17)fl

where mfl is the rms error of angular mea-surements; Ry is the projection onto the line0102 of the distances from each plummet tothe points of the traverse section whichconnects the plummet with the side in ques-tion (including one point of that side). Thevalues of Ry are determined on the surveyplan (Table 4.3).

Substituting the numerical values into for-mula (4.17), we obtain:

for the first side of connection traverse(I-II):

20J23650115

= 27'M"pVIl-VIlI

is the distance between the plummets (herec = 75 m); Ry. are the projections onto theline 0 102 of 'the distances from the plumbline points 01 and O2 to the points oftraverses run from the junction point to theseplummets (here: Ry , Ry .and Ry ); p" == 206265"; and n is the nfImber ofrJeasuredangles between the approach point andjunction point (here n = 2).

The magnitudes of Ry. are taken from thesurvey plan; the terms s; sin2 <Pi are determi-ned on the plan by double projection of sidelengths.

The calculation of [R; .J and [Si sin2 <PiJ isshown in Table 4.2. I

Substituting the numerical values intoformulae (4.16), we have:

M~0,02--

102 x 6917 4 x 1010 x I x 10-6 x 45

752+ 752\I

-+-2 x 102 = 25"

4.8.2. Estimating the Accuracyof Connectionby Connecting Polygon

Suppose that a polygonometric traversehas been run through points I, II, III, IJ-: J-:n, nI, and nII (see Fig.4.10b). It is re-quired to find the error of direction angles ofthe first, last, and middle side of the traverse

2. The root-mean square errors M~ of thedirection angles of traverse sides incu;red byerrors in linear measurements of side lengthsare found by the formula:

Ms = (J.1/c) p" j;;"Sj;;;-;p-; (4.18)

where Si are the lengths of traverse sides and<Pi are the angles between the sides and theline 0102.

The values of Si sin2 <Pi are found by doublegraphical projection of individual sides of the

534.8. Horizontal Connection Survey via Vertical Shafts

Table 4.3

traverse (Fig. 4.11 ):

Side 01-1 I-II II-III III-IV IV-Vsisin2<pi 0 52 8 0 0

V-VI VI-VII VII-VIII VIII-O2 [sisin2<pJ12 60 5 0 137

M. = 0.001/115 x 2 x 105 Jill = 20"

3. The root-mean square errors of thedirection angles of traverse sides relative tothe p1umb-connecting line 0102 are calcula-ted by the formula:

M« = JM;. + M; (4.19)..

for the first side of traverse (I-II):

M = /362 + 202 = 42"~1-II V :Ju T ~v

for the last side (VII-VIII):

M = /272 + 202 = 34"~VII-VIII V ~ I T ~v

and for the middle side (IV -V):

M = /122 + 202 = 23"~IV-V V l~ T ~v

On the basis of these preliminary calcula-tions of errors, the work superviser (chiefsurveyor) chooses the techniques and inst-ruments which can ensure the specified accu-racy of mine surveying.

The entire complex of angular and linearobservations on the surface and in the mine iscarried out before hanging the plummets intothe shafts. Mter hanging the plummets, theirpoints are connected by measuring the anglesat the first and last points of the connectingpolygon and the distances from these pointsto the plummets.

The coordinates x, y of the plummets O 1and O 2 on the surface are determined by theresults of measurements of the approachpolygons (see Figs. 4.9 and 4.10a). All lengthsmeasured on the surface and in the mine arecorrected for calibration, temperature, angleof dip, tape sag, and reduction of lengths tothe surface of reference ellipsoid and the

Fig. 4.11 Double projection of side length of

connecting polygon

tanaOlO2 = (Y°2 -YOl)/(XO2 -XOl) (4.20)

c = (XO2 -XOl)/COS UOlO:

= (yO -Yo )/sin Uo O2 1 1 2

or (4.21)

1, ,2 .,-- --'2(X X )2 + (y y )202 -01 02 -01

the conventinnal system in the mine (c'). Thediscrepancy A c = c' -c must not exceed thepermissible value A Cperm which can be foundby the formula:

Acperm= 2 (mi/p2/[R~;J + ~2(SiCOS2<pJ + 1..2c2

(4.24)

where Rx. are the distances from the points of,

the underground polygon to the plumb-connecting line 0102; I.. = 5 x 10-5 is thecoefficient of influence of systematic errors oflinear measurements; and mfJ is the root-mean square error of angular measurements.Other terms are the same as in the precedingformulae. The values of R x. are determinedon the surveying plan. ,

If the discrepancy is within the permissiblevalue, all lengths of the underground con-nection polygon are corrected according tothe formula:

Asi = -(AC/C)Si (4.25)

Then, corrections are determined for thedirection angles of the underground connec-tion polygon in order to recalculate thispolygon into the coordinate system on thesurface. These corrections are found by theformula:

Aa = ao o -a' o o (4.26)1 2 1 2

The direction angles of the sides of anunderground connection polygon will be:

ai=ai+Aa (4.27)

In calculations by formula (4.20), the valueof c obtained for the larger increase ofcoordinates is taken as the final value,whereas that calculated for the smallerincrease is used as a check value.

Then the coordinates of points of theunderground connection polygon are calcu-lated in the conventional system of coordi-nates. As a rule, the point 01 is taken as theorigin of the conventional coordinate systemand the axis of abscissae is directed.along thefirst side, 01-1. In that case, x'o = y'o = 0

d ' 0 1 1an ao1-1= .

After that the direction angle of aplumb-connecting line, a' o o , and the dis-

1 2tance between the plummets ID the mine, c',are determined in the conventional coor-

dinate system:

tana'o o = y'o jx'o (4.22)1 2 2 2

, , j ., , j ,c o o = Yo sm a o o = x o cos a o o12 2 12 2 12

(4.23)

It is now essential to compare the plummetdistances as calculated by the coordinates ofthe unified system on the surface (c) and in

It is now possible to calculate the coordi-nates of all points of the undergroundconnection polygon from the measuredlengths of sides, corrected lengths of sides,and corrected direction angles. The coor-dinates of a plummet 01 on the surface aretaken as the initial coordinates. The r;oordi-nates of a plummet O2 obtained by therecalculation of the underground connectionpolygon and on the connection on the surface

plane of Gauss projection. The last twocorrections are found by the formulae:ASel = (y/2R)s, Aspr = -(H/R)s

where y is the mean ordinate of the connec-tion survey region; R is the mean radius ofthe Earth; H is the absolute elevation; and s isthe measured length of the traverse side.

The calculated coordinates are used fordetermining the direction angle of a plumb-connecting line, Qo 0 and the distance be-

l 2tween the plummets, c, by the formulae:

Table 4.4. Calculation of Direction Angle and Length of Plumb-Connecting Line in the Coordinate SystemAdopted on the Surface and in the Conventional Coordinate System

Surface coordinate system

L\y

L\x

Ay

sina

I1x

cosa

tan a = Y02 -Y01Xo -X2 01

0102 =c = =

ba c

125

13211.86813325.417

-113.549

9

10

11

12

13

14

15

16

17

77810.27877938.922-128.644-128.644-15.095-113.549

98.4541.306641

307°25'39"

1820

22

Aysin a

c

-113.5490.991279

114.548

YO2

YO1A.y

YO2 +XO2

YOl +XOldx+dy

dx+dyL\x

dy

L\x-dytan (a + 45'

a+45°

34678

64 598.41064613.505

-15.0957.522292

262°25'39"

19212324

~x

cosa

c

Cc

-15.0950.131781

114.546114.548

XOl

XOldx

tan a

a

Conventional coordinate system

y' ,tana' = 02- Y01 dy'

x ' ,° -X A ,, 0, uX

.ix' + .iy'= (Y~2 + X~2)cosa'

tan(a' + 45°) = ., .-,

-(y' + x' )01 01

Ax' + Ay'

25

26

29

2.2240.0002.224

33

34

35363738

394041

-112.2910.000

-112.291-112.515-114.515

2.224

-116.7390.981898

223°53'15"

424446

Ay'

sina'

c'

2.224

0.019416

114.545

YO2

YO1

Ay'

YO2 + XO2

YO1 + XOl

dx' + dy'

dx' + dy'

dx'

dy'

dx' -dy'

tan (a' + 45°)

a' +45°

da=

=a-a'

a

a'

da

2728

303132

-114.5150.000

-114.5150.010421

178°53'15"

43 d.x'45 cosa'

47 c'48 c'c

-114.5150.999812

114.537114.537

XO2

XOl

':\X'

tan a'

a'

495051

262°25'39"

178°53'15"

83°32'24"

"'.:=...cC

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can be used for checking. The discrepancybetween them must be within the accuracy ofcalculations.

If other methods have not been used fororientation, connection survey via two verti-cal shafts must be carried out twice. The finalresult is taken as the arithmetic mean of twoprocedures. It is recommended to make theconnection survey via two vertical shafts incombination with gyroscopic orientation ofthe sides adjoining the plummets. An exam-ple of calculation for orientation via twovertical shafts is given in Tables 4.4 and 4.5.

If a mine field is opened by three or morevertical shafts connected by undergroundworkings, it is recommended to make con-nection survey through the shafts with theuse of redundant measurements.

4.9. Horizontal ConnectionSurveywith Use of Gyrocompasses

The wire of a plummet hanging in a shaft issubject to the action of a number of factorswhich tend to deviate it from the verticalposition. The most important among thesefactors are air currents in the shaft andunderground workings, and abundant waterdrip (downpour). These factors have beeninvestigated and can be accounted for byspecial formulae.

These factors have however become lessimportant with the appearance of gyroscopicinstruments which can determine the direc-tion angles of any traverse side in a mine withan accuracy to 10-20". In that connection,geometric methods of orientation now haveonly a limited application, mainly in theconstruction of new mines. Repeated orienta-tions in exploited mines are mostly carriedout by means of gyrocompasses. Further, theessential disadvantage of geometric orienta-tion via a single shaft by means of twoplummets is that the distance between theplummets is too short and a direction angle

cannot be transferred underground with asufficiently high accuracy. A practical meritof gyroscopic orientation is that the directionangle of one or several sides of an under-ground survey net can be determined with ahigh accuracy in any place of the mine fieldand at any distance from the shafts. Thesecircumstances have predetermined wide po-pularity of the connection survey method inwhich the coordinates x. y of an initial pointof an underground polygon are determinedby means of a plummet sunk into the shaft,(the problem of projection), and directionangles are then measured by the gyroscopicmethod.

Under production conditions, the prob-lems of centring and projection are tackledseparately and in the following sequence.

The projection problem is solved by meansof a plummet hung in the vertical shaft. Themethod and equipment in this case are essen-tially the same as in orientation via a singleshaft by means of two plummets. It should benoted, however, that, since the directionangle of the initial traverse side will then bedetermined by the gyroscopic method, theprojection can be carried out in a simplifiedway without spending time for the stabiliza-tion of a plummet, determination of itscentral positions on scales, etc. on the surfaceand in the mine.

A polygonometric traverse of an accuracyof not less than second-order is run on thesurface from the initial side 31-32 to thecentring point, i. e. the plummet point °(Fig. 4.12). The angle ~A at a point A and thedistance from that point to the plumb line 0,I AO' are measured in the shaft; the directionangle of a side A-B (IlAB) is then determinedby the gyroscopic method.

The direction angle of a side O-A iscalculated by the formula:

IlAO = IlAB -~A :J: 180° (4.28)

and the coordinates of the first point (A) of anunderground side, by the formulae:

4.9. Horizontal Connection Survey by Gyrocompasses 59

4.9.1. Theoretical Principlesof Gyroscopic Orientation

Mine surveying has in recent time becomeless labour-consuming and more accuratedue to the appearance of reliable small-sizedand explosion-proof gyrocompasses.

The operating principle of a mine-sur-veying gyrocompass is based on the dailyrotation of the Earth and the property of afree gyroscope to rotate freely in threemutually perpendicular planes (Fig. 4. 13). Agyroscope is called balanced if its centre ofgravity coincides with the suspension point O(the point of intersection of the three axes).Balanced gyroscopes in which there is nofriction in the suspension supports are calledfree. Free gyroscopes can exist only theoreti-cally. Practically, the centre of gravity isalways displaced somewhat relative to thesuspension axis and there always is friction,though slight, in suspension supports.

A free gyroscope (Fig. 4.13a) comprises amassive spinning disc, or rotor 2, which issuspended in two gimbals. The rotor ismounted in the inner gimbal 4 and outergimbal 7 on bearings 1,3, and 5. This systemallows the rotor to rotate freely on the

Level 950 m

Fig. 4.12 Solving projection problem for deter-mining initial point coordinates of undergroundpolygon

XA = Xo + loAcosuoA

(4.29)YA = YO + loAsin aoA

This method is used especially widely atmining enterprises with large mine fields andblock-type vertical shafts located at a dis-tance of 5-6 km from the main shafts. Theconnection survey made by this methodincreases substantially the accuracy andreliability of the survey reference net in theentire wing of a mine.

(a)

y

Fig. 4.13 Free gyroscope (a) and pendulum gyrocompass (b)

principal (spin) axis x, rotation axis of theinner gimbal y (sensitivity axis), and rotationaxis of the outer gimbal z (precession axis). Asthe disc is rotating simultaneously on thethree axes, the suspension point O remainsimmobile, and the x axis acquires stabilityand do~s not react to rotation of a base 6, inother words it retains a stable orientation in

space.If the moment of an external force is

applied to the x axis of a quickly rotatinggyroscope, this axis turns (precesses) in theplane perpendicular to the force applied. Theangular velocity of precession, O>pr' is directlyproportional to the moment of external forceM ex and inversely proportional to the rota-ting velocity H of the gyroscope:

O>pr,= M ex/ H (4.30)

If one of the degree of freedom of agyroscope is restricted, the centre of gravity,which develops an additional pendulum loadon the sensitivity axis y, will displace down-ward along the z axis into a point O 1. Thissystem is called a pendulum gyrocompass(Fig. 4.13b). A weight Q causes the x axis toadopt a position parallel to the horizonplane. With quick rotation of the system, thex axis is arranged in the meridional plane.The daily rotation of the Earth, when obser-ved from the North pole, is seen to occuranticlockwise (Fig. 4.14). As the Earth rotateswith an angular velocity 0>, the horizon planerotates in space with an angular velocity 0>1around the local meridian and at the sametime the meridional plane rotates with anangular velocity 0>2 around a vertical line.The angular velocities 0>1 and 0>2 depend onthe local latitude <p:

0>1 = o>cos2 = o>sin1, determines variations in theheight of the Sun and stars above the horizonline and the vertical component 0>2, varia-tions of their azimuthal positions.

The principal axis x of a gyrocompass setup to a point O at a latitude <P and at anangle (1 to the meridian will change itsposition continuously relative to the horizonplane under the action of Earth's dailyrotation, so that its north end will risecontinuously above the horizon. The princi-pal axis is acted upon by the moment of theforce of gravity of the pendulum weight,which is applied in a vertical plane and tendsto turn the axis in the horizontal planetowards the meridian.

The angular velocity of rotation of thehorizon plane, 0)3' around the sensitivity axisy, which underlies the operating principle of agyrocompass, is called the useful componentof Earth's rotation and can be determined bythe formula:

0)3 = O)cos<psin(1 (4.32)

If the gyrocompass axis lies in the horizonplane at (1 = 00, then 0)3 = 0. At (1 = 90°, 0)3has the maximum value. The angular velocity0)3 also depends on the latitude of the stationpoint which is determined by angle <p. At<P = 90°, 0)3 = 0, i. e. the gyroscope cannot beoriented at Earth's pole. At the equator, 0)3attains a maximum.

In all positions, except for that at (1 = 0,the principal axis x of a pendulum gyro-compass develops a moment of the gravity

E ,x

Fig. 4.14 Components of Earth's rotation

external force, M ex' and the maximum guidemoment Mg (at a = 900) and can be found

m~xby the formula:

E = Mex/ Mg (4.36)

max

The correction E is introduced with aproper sign when calculating the gyroscopicazimuth of a side being oriented.

4.9.2. Mine Surveying Gyrocompasses

There are several types of gyrocompasseswhich can be divided into three groups by the

force (guide moment of gyrocompass):

Mg = H 0) cos <p sin a (4.33)

In all station points of a gyrocompass, theguide moment M 9 overcomes the forces ofinertia and friction in the gimbal supportsand tends to turn the principal axis towardsthe meridian. The gyrocompass axis movesrelative to the meridian with the total angularvelocity of two oscillations in space: with aconstant angular velocity 0)2 in the meri-dional plane and with a variable angularvelocity of precession of the axis under theaction of the gravity force, O)p.., whichdepends on the pendulum moment M of agyrocompass and the angle of inclination e ofits axis to the horizon (see Fig. 4.13):

O)p.. = (M//l) sine (4.34)

If the gyromotor is brought into rotationalmotion, the gyrocompass axis will performcontinuous harmonic oscillations about anequilibrium position coinciding with themeridional plane. The axis of symmetry ofharmonic oscillations relative to the meri-dional plane is called the axis of the equilib-rium of a gyrocompass and the positions inwhich the velocity of motion of the axis isequal to zero and the motion is reversed arecalled the points of the gyrocompass axis.

The time during which the gyrocompassaxis performs a single elliptic oscillation andreturns into the initial position is called theperiod of continuous oscillations of a gyrocom-pass which is expressed by the formula:

T= 21t.JH/MO) cos<p (4.35)

Under the action of friction forces, how-ever\ the oscillations of the gyrocompass axisare gradually attenuated, the amplitude ofoscillations A i decreases, and the pattern ofmotion of the axis changes from elliptical tothat along a twisting helix. This results in adeviation of the gyrocompass axis by anangle E from the meridional plane. Themagnitude of E depends on the moment of an

Fig. 4.15 General view of gyrocompass typeMVT2: l-angle-measuring unit; 2-rotatable hous-ing; 3- base; 4- foot screws; 5 -connecting cable;6-power supply unit; 7-instrument casing; 8-gyro attachment; 9-endless micrometer screw

",,'-2

454~ 59 ~1 5.2

I

II~.y/9

c-I0

!.11~

--12

---13

1-14

-15

:~~45-

43-

42-

41-

40-

39

38-

37-

36

35

34-

-18---19

-20-21

-22-2324

-25-26-27-28

-29-30

----31Fig. 4.17 Gyrocompass type MVT4: 1-explo-sion-proof glass; 2- illuminating lamp; 3- illumina-ting mirror; 4 -illuminating prism (upper); 5 -il-luminating prism (lower); 6-eyepiece; 7-haircross; 8-upper rectangular prism; 9-lower rectan-gular prism; 10- objective; 11- worm screw;12-rhombic prism; 13-protective glass; 14-sensi-tive element; 15-torsion suspension; 16-lockingdevice; 17 -lower clamp of torsion suspension;18-locking clamp pin; 19-top of locking device;20-current lead; 21-transducer; 22-damper;23-top cover of gyro unit; 24-operating modeswitch; 25-switch cam; 26-lock; 27-gyro unit;28-storage battery; 29-battery fastening; 30-ba-lance weights; 31-lower damper; 32- magneticscreen; 33- bottom cover of gyro unit housing;34- gyro unit housing; 35- button spring;36, 37 -connecting ring of gyro unit housing;38 -lower nut of arrester; 39- SE rod; 40- uppercover of gyro unit; 41- tripod leg; 42, 43- tripodhead; 44-locking device sleeve; 45-SE mirror;46, 47-fixed casing of base; 48-control device andupper clamp of suspension; 49- scale; 50- fixedbisector

33-32-

Fig. 4.16 Gyrocompass type MVT2: 1- autocol-limator; 2-illuminating unit; 3-illuminating lamp;4-illuminating prism; 5-eyepiece; 6-upper rec-tangular prism; 7- objective; 8 -lower rectangularprism; 9-rectangular prism; 10-upper clamp oftorsion suspension; 11- connector assembly; 12 -

fixed mirror; 13-SE mirror; 14-protective glass;15-torsion suspension; 16-cable; 17-brushes;18-collector; 19-cable coupler; 20-1ocking de-vice; 21- gyro attachment fastening; 22- band-typecurrent lead; 23-sensitive element; 24-magneticscreen; 25- gyromotor; 26 ~ gyro unit casing;27~arrester head; 28-base; 29-base-tuming mech-anism; 30-fixed bisector; 31-central hair line;32-scale; 33-movable bisector; 34-theodolite


the SE mirror. The sensitive element can befixed in the non-working state by an arrester.

The observations of forced oscillationsconsist essentially in taking readings on thecircle in the points of reversion and determi-ning the actual position of equilibrium.

The design of a gyrocompass type MVT2may be seen in Fig. 4.16.

The gyrocompass MVT 4 (Fig. 4.17) hasbeen developed on the basis of type MVT2and has principally the same design.

In recent time, a mine surveying gyrocom-pass type MVB4M (Figs. 4.18 and 4.19) hasbeen developed in this country. The designershave managed to reduce the mass and dimen-

design, method of centring, and suspension ofa sensitive element.

I. Gyrocompasses with liquid suspensionand electromagnetic centring.

2. Gyrocompasses with liquid suspensionand electromagnetic centring on needle, inexplosion-proof or common embodiment.

3. Gyrocompasses with torsion suspension,such as types MVT2, MVT4, and MVB4Mdeveloped in this country, which are small-sized, reliable and high-precision instrumentsrelatively simple in manufacture andoperation.

The gyrocompass type MVT2 (Fig. 4.15) isintended for the orientation of undergroundsides in connection surveys and especially formeasuring the direction angles of traversesides in the construction of mine surveyreference nets. It belongs to the best instru-ments in the world designed for mine sur-veying. The mass of the instrument togetherwith the power supply unit and tripod is33 kg. The time of start is 30 minutes and theaccuracy of measurement of direction anglesis 20-30". The gyrocompass is positioned bymeans of a base 3 having a housing 2 whichcan be rotated around the vertical axis bymeans of an endless micrometer screw 9. Therotatable housing carries at the top anangle-measuring unit 1 which is essentially anoptical theodolite, and at the bottom a gyroattachment 8 in which a sensitive elementwith gyromotor is suspended from a torsion.The instrument is power supplied from anelectric storage battery arranged in anexplosion-proof casing.

The torsion is made of three strips connec-ted together at flat sides, which makes itpossible to obtain a low specific torque. Theoscillations of the axis with the sensitiveelement (SE) about the meridional plane areobserved by means of a mirror mounted inthe top portion of SE and rigidly fixed to theaxis.

The standards of the theodolite carry anautocollimator to observe the oscillations of

Fig. 4.18 General view of gyrocompass type

MVB4M


sions of the instrument and the time fordetermining a gyroscopic azimuth roughlyby 50 per cent compared with the gyro-compass type MVT2. In contrast to MVT2,the new gyrocompass is intended not only forbasic geodetic surveying, but also for every-day (current) mine surveying associated withthe construction of underground referencenets and for measuring horizontal angles.Like MVT2, the instrument type MVB4M isa pendulum gyrocompass with torsion sus-pension and comprises a gyro unit, gonio-meter with multi-faced mirror, and powersupply unit (transducer and storage battery)arranged in a common housing which ismounted on a tripod for operation andreplaced into a casing for transportation.

Tests have shown that the gyrocompassestypes MVT2 and MVB4M ensure roughlythe same accuracy of orientation. Horizontalangles can be measured by the gyrocompasstype MVB4M with an accuracy of enginee-ring theodolites.

Technical characteristics of gyrocompasses

MVT2 MVB4M

30 40Fig. 4.19 Gyrocompass type MVB4M: 1- gyrounit cover; 2-storage battery; 3-torsion suspen-sion; 4~transducer; 5-catch; 6-current lead;7- arrester; 8 -locking device; 9- SE magneticscreen; 10- gyromotor; 11-multi-faced mirror;12~measuring unit casing; 13-mirror for verticalsighting of telescope; 14-rectangular prism;15-vertical sighting head; 16-teleobjective; 17-pentaprism; 18-fixed mirror; 19-photographicobjective; 20- hinged mirror; 21- graticule of scalemicroscope; 22-eyepiece; 23-light filter; 24-il-luminating prism; 25-illuminating lamp; 26-il-luminating unit; 27- fixed mirror scale; 28- mag-netic screen on gyro unit housing; 29-arresterpinion; 30 -lower sleeve of arrester; 31 ~ uppersleeve of arrester; 32- sensitive element; 33 -lowerclamp of suspension; 34 -pin with balance weights;35- upper clamp of suspension; 36- protective capof upper clamp

20 15

15 10

37

3

192

Error of determination of

gyroscopic azimuth of a

side, s Time for determination of

gyroscopic azimuth, min ..

Number of starts without

recharging, at least. Mass of instrument set ready

for operation at station

point, kg. Number of units in the set. .

The principal design feature of the gyro-compass type MVB4M which distinguishes itfrom type MVT2 and determines the schemeof gyroscopic azimuth of a side, is the provi-sion of a goniometer with multi-faced mirror;this has made it possible to diminish substan-tially the mass and dimensions of theinstrument.


In the modern mining practice where minefields and dangerous zones are continuouslyincreasing and it is impossible to ensurepermanent planimetric positions of points ofa reference net, an efficient method fordecreasing the influence of angular errors innets and increasing the reliability of sur-veying is the introduction of reference netswith gyroscopic polygons in which the direc-tion angles of all sides are determined by thegyroscopic method, i. e. by means of gyro-compasses.

side; Go is the gyroscopic azimuth of theinitial side; and Yo is the meridian conver-gence in the station point of the gyrocompasson Earth's surface.

The gyroscopic azimuths of sides on thesurface and in the mine must be measuredtwice. The difference between the two obser-vations must not exceed 2'. Their arithmeticmean is taken as the final result. The formulafor determining a gyroscopic azimuth is asfollows:

G = (N -N 0) + E (4.38)

where N is the reading on the gyrocompasscircle corresponding to the direction onto apoint on the surface or at the undergroundside being oriented; N 0 is the circle reading atthe equilibrium position of the sensitiveelement; and E is the correction for twisting ofthe torsion suspension.

The junction direction N on the surface orof an underground side is determined twice,at the beginning and end of a start and at twodifferent positions of the vertical circle. Thedifference between the two measurementsshould not exceed 30". The final result isfound as the arithmetic mean of the twoobservations.

The difference between the direction angleao and gyroscopic azimuth Go of a side BCon the surface constitutes the gyrocompasscorrection 0.

A start in the mine determines the gyro-scopic azimuth G of an underground side DEto be oriented. The direction angle of DE is:

a = G + 0- Y (4.39)

where Y is the meridian convergence for theunderground station point of a gyrocompass.

Substituting from formula (4.37) into (4.39),we obtain:

a = ao + G- Go + 01' (4.40)

where 01' is the difference of meridian conver-gences for the gyrocompass station points onthe surface and in the mine, which can be

4.9.3. Gyroscopic Orientation

This kind of orientation can be carried outeither independently or in combination withother methods. It is obligatory in opening adeposit by means of inclined shafts withangles of dip more than 70°. At least twosides at each mining level must be oriented bythe gyroscopic method. In the reconstructionand construction of mine survey referencenets, a side is oriented gyroscopically in eachsection.

The direction angle of an oriented sidemust be measured independently twice, thediscrepancy between the two observationsbeing not more than 2'. The principaldiagram of the determination of directionangles by the gyroscopic method is illustratedin Fig. 4.20.

In the gyroscopic orientation of a side, it isrecommended to make four starts of thegyrocompass, the first and the fourth beingdone on the surface at one and the same sidewith a known direction angle and the secondand third, at the oriented side in the mine.The first start before sinking into the mineand the fourth, after completion of observa-tions in the mine, are performed in order todetermine the gyrocompass correction (0}which can be calculated by the formula:

8 = no -Go + Yo (4.37)

where no is the direction angle of the initial

,-17711


c ,'gIT

"io

si

c..,..0

Ili1 -1

o

1--c' 'Y c; r

~;I y

Fig. 4.20 Determination of direction angles of sides by gyroscopic method: BC and DE-respectivelyinitial and oriented sides; B and D-station points of gyrocompass on surface and in mine; Ao andA -astronomical azimuths of initial and oriented sides; no and n-direction angles of initial ~nd orientedsides; Cg and C;:-directions of gyroscopic meridians; Go and G-gyroscopic azimuths of initial andoriented sides; L" and C'-directions of astronomical azimuth in points B and D; o-gyrocompasscorrection; 't-measuring unit constant; Yo and y-meridian convergences in points B and D; x andy -rectangular plane coordinates


Fig. 4.21 Determination of gyroscopic azimuth of a side: DE-oriented side; A1. A2, A3' A4 -amplitudesof gyroscopic wobbling of sensitive element; Cg-djrection of gyroscopic meridian; N 1. N 2. N 3' N 4 -circlereadings corresponding to reversion points of gyrocompass axis; No-circle reading at equilibriumposition of gyrocompass axis; G-gyroscopic azimuth of side DE; E-twisting angle of suspension

found by the formula:

01' = 1.10YO -I.1Y (4.41)

where Yo and yare the ordinates of stationpoints B and D of the gyrocompass on thesurface and in the mine, km (to be foundgraphically on the plan) and 1.10 and 1.1 are thecoefficients depending on latitude (to befound in tables).

5.

If the ordinates of gyrocompass stationpoints on the surface and in the mine do notexceed 10 km, then ~o = ~ and formula (4.41)takes the form:

01' = ~o (yo -y) (4.42)

The equilibrium position N o of the sensi-tive element (Fig. 4.21) is found from theobservations of four successive points of


Table 4.6. Determination of Equilibrium Position of Oscillating Sensitive Element

Rever-sion

points readings readingsmean inter-mediatevalues

mean inter.mediatevalues

h divisions divisioru

10 30353944

30003000

9II9

II

22242224

38184228

1010

232323

282835

19.4

63.8

20.5

63.4

234

41.641.9

N o = 10 23 31 no = 41.7

Table 4.7. Calculation of Junction Direction

Junction direction

N' 8 10 24 N" 8 10 08 N = 8°10'16'

10 36 9 57

8 10 30 8 10 0.2

Table 4.8. Calculation of Error for Twisting of Torsion and Suspension

-0 02 5241.7 N 10 24 15 "',

45.0 N~ 10 44 07 +0 20 40'Vc

52" Ho 10 23 31 D 20.2

2'52"'I', +0 20 40'l'c +0 00 53


Table 4.9. Calculation or Gyroscopic Azimuth Table 4.11. Calculation of Meridian Convergence

N 8 10 16

+99.3+99.1

-1.3 -1.5

36.5 36.5~

G 357 47 380. -0'50" .0'55"

Table 4.10. Calculation of Gyrocompass Error

Initialsides Polyamy-Novy

12, 35 40,43

Starts

G~ 7 35 17 35 22l6

points. The correction for twisting of thetorsion and suspension is calculated by theformula:

E = '11/ D (4.44)

where D is a coefficient determined as theratio of the specific guide moment to thespecific torque of the torsion and '11: is thetwisting angle of the torsion:

'11 = '11 t + '11 c (4.45)

Here '11 t is the zero of torsion suspensiondetermined by the formula '11 t = t (no -nc);t = 52" is the scale value of an autocollima-ting telescope; no is the suspension zero; andnc is the scale reading of an autocoltimatingtelescope corresponding to the positiQn of afixed bisector in the determination of thesuspension zero; the term '11 c can be found asthe difference of circle readings N c -N ocorresponding respectively to the mean valueof oriented direction and the equilibriumposition of the sensitive element, i. e.:

'11 c = N c -N o (4.46)

In practice the results of observations andcalculations of direction angles in gyroscopicorientation are recorded in a record book(Tables 4.6-4.12).

Go 17 35 29 17 35 35

+0 23 4(j +0 24 10B

where N l' N 2' N 3' and N 4 are the readingson the gyrocompass circle at reversion

No 10 23 31

N -N o 357 46 45

E +0 00 53

4.10. Vertical Connection Surveys

km. The height mark transfer should be madeindependently twice.

If the dipping angles of opening workingsexceed 5-8°, height marks are transferred bytrigonometric levelling. The procedure re-quires the use of theodolites with the verticalcircle accuracy of not worse than 30". Heightdifferences at each side of a traverse line aredetermined twice: in the forward and backdirection. The height mark transfer is perfor-med independently twice. The difference inheights, mm, in this case must be not morethan

L\h = :t 10~ (4.47)

where nl' n2 is the number of sides in the firstand second trigonometric levelling line.

Most coal mines are opened by verticalshafts where height marks can often betransferred by means of a long steel tape orlength-measuring winch.

4.10.1. Transferring a Height Markinto a Mine by Meansof Steel Tape

In this method of height mark transfer(Fig. 4.22), the hand winch 4 with a measu-ring steel tape 7 wound onto its drum "isplaced on a temporary platform 3. The tapewith a light weight (3-5 kg) is let to sink ontothe pit bottom level; then the light weight isreplaced by a standard weight 2 correspon-ding to that with which the tape has beenstandardized. Measurements are made asrequired by surveyor's levels 6, set up on thesurface and in the mine. Level readings aretaken on a staff 1 (asur) set on an initial benchmark R.ur and on a tape 5 (n...r).

At the pit bottom level, readings are takenfrom the station point of the surveyor's levelon the tape 5 (nm) and on the staff 1 (llm) seton an underground bench mark Rm.

During levelling, air temperature is measu-red at the surface ( t sur) and at the pit bottomlevel (tm). Then, the position of the tape is

changed by lor 2 m along the height and thehorizons of the instruments are changed tomake another series of observations.

The height difference for each series ofobservations is found by the formula:

hmeas = nsur -nm + asur -am (4.48)

The values of hmeas as calculated by twoseries of measurements must not exceed thepermissible deviation L1h = (10 + 0.2H), mm,where H is the depth of a shaft, m. Uponaveraging of hmeas' the following correctionsare determined:

(a) for tape standardization, L1/1, which istaken according to the tape certificate;

(b) for thermal expansion of the tape


4

~I~iilli~2

5 3

4

Fig. 4.23 Measuring winch

Al2 = al(t -to), m, where a is the tempera-ture coefficient of linear expansion of the tape(for steel, a = 1.2 x 10-5); t = 0.5(tsur + tm)is the average temperature of air in the mine;to is the temperature at which the tape hasbeen standardized; and 1 = nsur -nm is theinterval measured by the tape in the mine, m;

(c) for elongation of the tape under theaction of its own mass A13= fyg/2E, m,where y is the density of the tape metal (forsteel, y = 7874 kg/m3); 9 = 9.81 m/s2 is theacceleration due to gravity; 1 is the length ofthe hanging portion of the tape, m; and E isthe elastic modulus of the tape metal (forsteel, E = 2.5 x 1011 Pa);

(d) for elongation of the tape due to thedifferent mass of the weights used in standar-dization and measurements Al4 = 100[(P --Po)/EF], m, where P is the mass of thestandard weight, kg; P o is the mass of theweight used in the tape standardization, kg;and F is the cross-sectional area of the tape,mm2.

The elevation of a bench mark in the mine,Rm, is determined by the formula:

H m = H sur + hmeas (4.49)

where H sur is the elevation of the initial benchmark on the surface and h meas is the measuredheight including all corrections.

the wire is let to slide over a length measure 1and a guide pulley 2 into the shaft, andreadings are taken on the scales at thebeginning and end of the procedure (Fig. 4.24).In depth measurements, aweight-staff 3 withcentimetre marks is attached to the end of thewire and the check staff 4 is fastened lor 2 mabove the weight-staff (in the top position ofthe wire, the check staff is not shown in thefigure). This scheme of height transfer ismuch similar to the scheme with the use ofsteel tape.

An observer on the top platform takes thefollowing readings: N sur on the counter andmeasuring disc scale; tsur on the thermometerof the measuring disc; Asur on the scale of theweight-staff by means of the surveyor's levelplaced at the station point on the surface; andasur on the staff set up on the initial benchmark Rsur by means of the surveyor's level atthe station point on the surface.

Then the check staff is lowered onto thelevel glass of the levelling instrument and allobservations are reneated.

4.10.2. Transferring a Height Markinto a Mine by Meansof the Measuring .Winch

The measuring hand winch shown inFig. 4.23 has a drum 3 with a steel wirewound onto it. As the handle 5 is turned, asystem of rollers 4 rotates the drum and ameasuring disc 2 which makes one full turnper metre of unwound wire. The number offull turns is indicated by a counter 1, whereasincomplete turns are indicated with anaccuracy to 1 mm on the scale provided atthe rim of the measuring disc.

In order to measure the depth of a shaft.

4.10. Vertical Connection Surveys 73

Fig. 4.24 Transferring height mark into mine bymeans of measuring winch

The weight-staff is then lowered onto thepit bottom level to take similar readings: N mon the counter and scale of the measuringdisc; t m on the thermometer in the pitbottom; Am on the scale of the weight-staff bymeans of the surveyor's level set up in the pitbottom; and am on the staff placed on thebench mark to be controlled by means of thesurveyor's level in the underground stationpoint. As on the surface, these measurementsare repeated on the check staff.

These measurements conclude the firststage of observations. After that, the posi-tions of the wire and surveyor's levels arechanged and the observations are done in theinverse order, i. e. starting from the pitbottom level. The height difference betweenthe bench marks Rsur and Rm is calculated foreach series of observations by the formula:

hmeas = Nsur -Nm + asur -am -Asur + Am

(4.50)

If the discrepancy between the obser-vations is within permissible value, thearithmetic mean of hmeas is calculated and thefollowing corrections are determined:

(a) for wire diameter fj.ll = 0.0017tdl, m,where d is the wire diameter, mm;

(b) for standardization of the disc fj.12 == (k --'- 1) I, m, where k is the actual length ofthe circumference of the measuring disc asgiven in the certificate;

(c) for thermal expansion of wire caused bythe temperature difference in the shaft fj.13 ==0.5all(tm-tsur)' m, where al is thetemperature coefficient of linear expansion ofwire and t sur and t m are the temperatures onthe surface and in the mine; and

(d) for thermal expansion of the measuringdisc considering the difference in temperaturesduring standardization and measurements,fj.14 = a21(tsur -to), m, where a2 is thetemperature coefficient of linear expansion ofthe disc and to is the temperature of discstandardization.

The elevation of the bench mark in themine (Rm) is calculated by the formula:

Hm = Hsur + hmeas + fj.4 + fj.12+ fj.13 + fj.14 (4.51)

Chapter Five

Horizontal Surveys of Underground Workings

5.1. General on UndergroundMining Surveys

The mine survey service of mining enterp-rises has to tackle matters of timely andaccurate determination of the spatial positionof undergound workings and all other objectsessential for the mining production. Thespatial coordinates obtained by mine SUf-veying are the basis for compiling andsupplementing mining work plans and otherkinds of graphical documentation, as well asfor the solution of various problems ofrational and safe exploitation of mineraldeposits.

The principal objects of mine surveying

tural characteristics of deposits and enclosingrocks;

(g) points of mineral assaying; and(h) location of surface and underground

artificial structures and stationary equipmentin underground workings (hoists, ventilatingand pumping plants, various chambers,explosive stores, locomotive sheds, medicalservice, etc.).

The mine survey service solves its problemsby constructing reference and survey nets atthe mining enterprise.

Underground survey nets are understoodas a combination of geometrically interrela-ted polygonometric traverst:s and levellinglines which are balanced (adjusted) jointly orseparately. Underground reference nets arethe principal geometrical basis for makingthe surveying work and dealing with parti-cular mine survey problems aimed at ensu-ring rational and safe exploitation of adeposit.

The errors permissible in the measure-ments of horizontal and inclination angles

Table 5.1

are:(a) underground workings (opening, prepa-

ratory, development, stoping, draining, ex-ploratory, etc.);

(b) boreholes (prospecting, operating, un-watering, water-observation, etc.);

(c) boundaries of safe mining work, safetyand barrier pillars;

(d) contours of inundated, gas-laden, andcaved workings, centres of underground fires,isolating partitions and other ventilationstructures, gas blower sites, areas and con-tours dangerous in gas or rock outbursts,rock bump, water inrush, floating earth,sources of underground waters, etc.;

(e) characteristic points of bedding ele-ments of mineral deposits (dipping angles,capacity, characteristics of quality and struc-ture);

(f) points for documentation of geologicaldisturbances and other textural and struc-

0.00005 0.0120" 0.001

5.2. Horizontal Underground Surveys 75

and side lengths in polygonometric traversescan be characterized by the data given inTable 5.1.

5.2. Horizontal UndergroundSurveys

The principal kind of horizontal survey inunderground workings is theodolite sur-veying which consists of angular and linearmeasurements and subsequent calculation ofthe rectangular coordinates x, y of surveypoints. The straight lines laid between themine survey points in underground workingsform closed or open polygons, or theodolitetraverses. Each theodolite traverse is orien-ted, i. e. tied to the points of an earlier (initial)survey.

Several types of underground theodolitetraverses and methods of their connection areemployed most often in Soviet mine sur.,veying practice, which can be classified bythe redundant initial data and the type of

control. By these features, theodolite tra-verses may be divided into free and non-free.

Free theodolite traverses are referenced toonly one point with fixed coordinates andone fixed direction angle; they may besubdivided into open (hanging) and closed.

The line of an open theodolite traverse maybe stretched (Fig. 5.la) or broken (zig-zag)(Fig. 5.lb). Such traverses are controlled by arepeated theodolite survey. Closed traverses(Fig. 5.1 c) are controlled by comparing thesum of the measured angles and the sum ofcoordinate increases with their analyticalvalues.

Non-free theodolite traverses have redun-dant initial data. They can be run:

(a) between the fixed points and fixeddirection angles: in that case complete cont-rol is ensured in terms of direction angles andcoordinates (Fig. 5.1d);

(b) between the fixed direction angles withthe initial coordinates of one point, i. e. withcontrol in terms of direction angles (Fig. 5.le);

(dl (el

(Xn+1

~I cr-'L~

(bl

(f)

Fig. 5.1 Types of theodolite traverses: (a), (b), (c) free traverses; (d), (e), (/), (g) non-free traverses

76 Ch. 5. Horizontal Surveys of Underground Workings

optimum accuracy sufficient for the purpose.An insufficient accuracy can spoil the surveywork and require unjustified expenditures onits amendment; in some cases, inaccuratesurvey work can have serious consequencesendangering the safety of mining workers. Onthe other hand, an excessive accuracy invol-ves a large loss of labour and time ofsurveyors on unproductive and useless work.

That is why the mine surveyor must beable to select pro~rly the suitable method ofsurveying and the required accuracy.

3. Mine surveying must be carried outunder an appropriate and timely controlboth in the field (in underground workings)and in the office analysis of the results ofsurveys. First of all, it is essential to make acheck, or control, before starting a surveyorcontinuing a theodolite traverse, i. e. tomeasure the horizontal angle of an earliersurvey in the junction points. The differencebetween the initial value (known from theearlier survey) and the measured value of acontrol angle must not exceed I' for thetheodolite traverses of a reference net or 2' forthe traverses of a survey net. With a largerdifference in the measured control angle, itshould be supposed that the points of theearlier survey have been displaced and theprojected theodolite traverse must be tied toother points which are known to be stable.

The elements of a survey (side lengths,angles, height differences) must be checked inthe course of survey measurements so thatprobable errors can be revealed and cor-rected in situ.

For instance, when measuring distances,control can be ensured by measuring forwardand back; in angular measurements, a checkreading on the circle can be taken, etc.

The measured angles of a closed polygon(traverse) can be checked by comparing thesum of angles with their analytical sum. Themeasured lengths can be checked by thediscrepancies in coordinate increases and byother methods of control.

(c) between two points with fixed coordi-nates and with an initial direction angle, i. e.with control by the coordinates of the fixedpoints (Fig. 5.1.f); and

(d) between two points with fixed coordi-nates, with the initial direction angle beingunknown; in that case, control is possible bythe length of the closing line of the traverse(Fig. 5.1g).

In cases under (b), (c), and (d), a completecontrol of whether a theodolite traverse hasbeen run properly is not ensured, because ofwhich a repeated traverse is run or the linesand angles are measured repeatedly.

Horizontal surveys in underground wor-kings may involve certain difficulties whichincrease labour consumption, reduce theaccuracy of measurements, and increase theerror accumulation. Among the principalfactors causing such difficulties are: conti-nuous mobility of the underground objectsbeing surveyed and rock displacementaround workings resulting in uncertain spa-tial position of permanent survey pointsunderground; certain limitations in selectingthe most favourable shapes (schemes) oftheodolite traverses and the best lengths oftraverse sides (some sides may turn out to betoo short); constricted conditions forsurveying in underground workings; poorillumination of working places; dust-Iadenatmosphere in mines; etc.

In order to minimize the influence of thefactors indicated on the accuracy of surveysand to avoid unproductive labour expen-ditures, it is essential to adhere to thefollowing main principles in surveying work:

I. Mine surveying should proceed from themore general and more precise procedures tomore particular and less accurate work, i. e. itshould start from constructing reference nets,after which survey nets are plotted, andfinally, the surveys of particular miningobjects and other details are performed.

2. In any kind of surveying work, allmeasurements must be done with the

5.3. Underground Reference Nets of Plan Control

For reliable and efficient performance ofmine surveying, it is essential, before startingthe work, to study carefully the conditions ofthe field work, to draft the plan of construc-tion of survey traverses by the results ofreconnaissance and consider in it the existingpeculiarities, narrow places, etc., to deter-mine the set of surveying instruments andequipment, to test and adjust the instru-ments, to assign performers for the surveywork and acquaint them with the surveywork plan, and, when required, to makepreliminary calculation of the accuracy ofsurveys.

5.3. Underground Reference Netsof Plan Control

Underground reference nets of plan (hori-zontal) control are the principal geometricbasis for all horizontal angle-measuringsurveys. They are created in the principalopening and advance workings (adits, incli-ned shafts, crosscuts, inclines, brake inclines,fringe, group and haulage drifts) by runningthe theodolite traverses of a particularsystem.

The system of construction of referencenets can be characterized by certain specificfeatures, in particular as regards the shape ofpolygonometric traverses, provision of addi-tional ties, lengths of sides, and number offixed direction angles.

Depending on the bedding conditions ofdeposits and methods of opening, there aresix principal systems of construction ofunderground reference nets which are emp-loyed in Soviet mine surveying practice(Fig. 5.2).

I. The scheme of construction of a refe-rence net for working a single horizontalseam is shown in Fig. 5.2a. This scheme istypical for deposits opened by vertical centraldoubled shafts and is essentially a system ofpolygonometric (theodolite) traverses run inthe drifts of main directions and other

workings parallel and perpendicular to them.2. In working of single gently dipping and

inclined seams where the deposit is openedby inclined shafts and ventilation shafts aredriven at the flanks of the mining field, it canbe distinguished between two versions of areference net depending on the workingsystem employed:

(a) with a continuous working system,theodolite traverses are run twice in leveldrifts (Fig. 5.2b);

(b) with the system of longwall retreatingon strike, survey traverses form closedpolygons adjoining one another (Fig. 5.2c).

With advancement of mining work in thesystems indicated, theodolite traverses areconnected to the initial fixed points on thesurface.

3. In mining a suite of gently dipping orinclined seams where the deposit is openedby vertical central doubled shafts with a maincrosscut and ventilation shafts are driven atthe flanks of the mining field, two versions ofa reference net are possible:

(a) theodolite traverses form a system withjunction points (Fig. 5.2d); and

(b) if a longwall mining system is emp-loyed, the reference net includes theodolitetraverses with junction points and closedtraverses (Fig. 5.2e).

4. In mining a suite of steeply dippingseams where the deposit is opened by verticalcentral doubled shafts with a main crosscut,the construction of a net depends on thelocation of mine workings on the main levels:

(a) a system of closed-traverses adjoiningone another; such nets can be formed inmining a suite of seams where the fringe orgroup haulage drifts and auxiliary crosscutsare driven (Fig. 5.2./);

(b) a system of polygons with closedtraverses and repeated control traverses. Thisversion may appear in mining a suite of thicksteep seams liable to self-ignition, whichrequires that fire pillars be left between theworkings (Fig. 5.2g).

Ch. 5. Horizontal Surveys of Underground Workings78

(c)(b)

(f)(e)

[~I~1-- ~:=L---

centre of a mining field; further, some sides oftheodolite traverses may turn out to be tooshort. These factors lead to substantial erroraccumulation and non-uniform accuracy of anet;

(b) if the reference net points are displacedand the number of additional ties (fixedcoordinates and fixed direction angles) isinsufficient, then a need arises to run anappreciable number of repeated theodolitetraverses.

In existing systems, and the more so, withever increasing dimensions of mining fieldsand mining depths, these drawbacks becomeespecially sensible. This circumstance has ledto the appearance of more advanced systemsof construction of underground reference netswith autonomous orientation of a net by

5. In high-capacity ore deposits wherevertical shafts are driven both in the centreand at the flanks, theodolite traverses are runin crosscuts and fringe drifts and connectedto the points of plummets hung in verticalworkings (Fig. 5.2h).

6. In underground mining of salt depositsopened by vertical central doubled shafts, areference net is Conned as a system ofadjoining closed polygons (Fig. 5.21).

The considered systems of construction ofreference nets have certain essential draw-backs in view of the specifics of miningconditions:

(a) redundant fixed direction angles, sidesand coordinates may be limited in number oreven absent. As a rule, the orientation ofreference nets is most often carried out in the

5.4. �onstruction of Underground Reference Nets 79

(a) (b) r~-r-r--I I I I I

@---6-L-1--b-L-

(cl

1 2 3-:§)- -;:::)- ---C]- ~ ---{::J- @):::J

,..d

(d) ~

@ '0-

(e)

-J-r§r ~

Fig. 5.3 Examples of arrangement of sides with reduridant direction angles: l-initial side; 2-traverse;3- side with redundant direction angle

gyroscopic instruments, i. e. with inclusion ofredundant (fixed) direction angles (Fig. 5.3).

The mine surveying practice quite oftenuses free hanging theodolite traverses runtwice. In order to avoid the need in running arepeated traverse in autonomous determina-tion of direction angles by a gyrocompass, apolygon is divided into sections (Fig. 5.3a). Ina similar manner, additional ties can beincluded into the theodolite traverses be-tween two fixed sides (Fig. 5.3c).

In adjoining. free closed traverses of largeextension, the reference direction angles aremeasured in each closed traverse (Fig. 5.3b).

In non-free theodolite traverses controlledby point coordinates, a repeated survey isdone by measuring the direction angles of thesides adjoining the points (plummet points)with fixed coordinates or the sides close tothem (Fig. 5.3d). A similar construction ofa reference net with additional ties is possiblein a version when the net is developed from ajunction point to points with fixed coor-dinates (Fig. 5.3e).

5.4. Construction of UndergroundReference Nets

Underground reference nets are const-ructed according to an engineering designwhich should consider the actual positions ofthe existing mining workings and theirexpected development and establish the mostfavourable system of the net, the distancesbetween the sides with reference direction

angles, points and methods of junction of theconstructed net to the reference net on thesurface, points for setting up permanentstation marks, and the order of net adjust-ment. The work of construction or reconst-ruction of a reference net is carried out in thefollowing order:

(a) reconnaissance is carried out in under-ground workings and permanent stationmarks are revised, located and fixed;

(b) the sides of a net are oriented bygyroscopic instruments;

(c) angular and linear measurements intheodolite traverses are carried out;

(d) the net is centred and the theodolitetraverses are connected to the points of themine survey reference net on the surface;

(e) the results of measurements are proces-sed preliminarily and estimated for accuracy;

(I) the net is adjusted and the pointcoordinates are calculated; and

(g) the coordinates of permanent stationmarks are recorded in a list.

The object of reconnaissance is to investi-gate the underground workings in which thereference net has to be constructed, to specifythe system of the net, and to choose places forsetting up permanent station marks. It is alsoessential to consider the conditions underwhich permanent station marks will bepreserved longer and will be convenient forsurvey work.

Permanent station points are set up ingroups of three or four. The spacings betweenthe points in a group are usually equal to


remotest point of the net, considering thesupposed (planned) development of miningwork (usually for 5- 7 years).

The root-mean square error of location ofa point relative to an initial point A of areference net (Fig. 5.4) can be determined bythe formula:

(Lrf)k+(Lrf)n +

50-100 m and the spacings between thegroups must be not more than 500 m. Thechosen places for setting up permanent andtemporary points are fixed in the under-ground workin~ and on sketches.

The orientation of underground referencenets is carried out by means of small-sizedgyrocompasses. These instruments offer thepossibility for constructing a reference net asa system with intermediate (redundant) direc-tion angles and a system of local nets, inparticular at the mining field flanks.

The essence of the system of a reference netwith redundant direction angles consists inthat a polygonometric net of a length morethan 2 km is divided into sections with fixed(gyroscopic) direction angles. The number ofangles in section should be not more than 20.The direction angle of one of the sides ismeasured by a gyrocompass independently ineach section, and the results of angularmeasurements are combined and adjusted.The direction angles of the sides in thesections determined in this way are taken asfixed angles and their relative weights areconsidered.

Nets with redundant direction angles havean advantage of being more uniform; further,the positions of the remotest points of a netcan be determined with a higher accuracy.Calculations have shown that the accuracy ofthe final point of a theodolite traverse of alength of 5000 m, divided into sections (of alength of 1 km), increases by a factor ofseven. Besides, it is possible to control theerrors in the positions of the points of a netwithin wide limits in accordance with thelocation of the sides having redundantdirection angles, which increases the reliabi-lity of the net.

In mine survey reference nets, gyroscopicsides are located roughly in every 20 traversesides. In order to check 1hat the locations ofgyroscopic sides in a projected reference netare chosen properly, calculation is carried outto determine the error of location of the

where I and II are the numbers of sections, kis the number of the last section of a net; ~and A. are the coefficients of random andsystematic influence in side length measu-rements by a tape; ii is the length of a traverseside, m; L is the distance between the pointsA and 1; m; mp and m« are the rms errors of aturning angle 13 and direction angle a; r i is thedistance from a theodolite traverse point tothe centre of gravity O of the given section, m;R is the distance from each point of ahanging traverse to the final point 1; m; D arethe lengths of intervals connecting the pointsA and T through the centre of gravity O ofthe net sections, m; and p" = 20~65".

The coordinates of the centre of gravity ofa section are calculated as the arithmeticmean of the coordinates x, y of points in the

5.5. Survey Nets 81

Table 5.2

Permissible angular discrepancybetween half-sets, min

in dippingworkings

at junctionsbetween

horizontal and dip-ping workings

31-4546-6061-70

1.3

1.8

2.5

22.54

and back) and the discrepancy between thetwo measurements must not exceed 1/3000 ofthe side length.

The sides of a length more than 50 m arerecommended to be measured by light rangefinders. If the discrepancy between thereadings of a measured length in the first andsecond phase does not exceed 2-3 mm, themeasurement can be limited to a single set.The maximum discrepancy between themeasurements at different frequencies mustbe not more than 8 mm.

The engineering design for mine surveyingshould specify that the error in the locationof the remotest point of the underground netrelative to the initial point of the under-ground reference net or the closest points ofthat net on the surface should be not morethan 0.8 mm on the map or plan. Thisrequirement is dictated by the specified accu-racy of graphical construction of miningwork plans. As is known, the permissibleerror of the position of a contour point of thewalls of the main working on a plan relativeto the points of a mine survey reference neton the surface is taken to be equal to 0.8 mm,while the positions of the walls are determi-ned by taping directly from the net pointswith an accuracy to 5 cm.

section. The values of I, L r, R, and D arefound on the plan of the projected net.

In cases when the mining work is carriedout at distances more than 1.5-2 km from theshafts of a mine and the points of a surveyreference net are subject to displacements,local reference nets are constructed at theflanks of the mining field and oriented by thegyroscopic method.

The horizontal angles in polygonometrictraverses of reference nets are measured bytheodolites reading with an accuracy notworse than 30". The rms error of angularmeasurements must not exceed 20".

When polygonometric traverses are run inunderground workings with dipping anglesup to 30°, horizontal angles (forward to theleft) must be measured by the method of setsor, in extreme cases, by the reiterationmethod. In the latter case, the differencebetween a check value and final value of anangle must not exceed 45". If angles aremeasured by the method of sets, the discre-pancy between the half-sets must be not morethan 60".

In undergound workings with dippingangles more than 30°, horizontal angles mustbe measured only by the method of sets (notless than two) under the observance of thefollowing rules:

(a) before each set, the instrument iscentred once more and the vertical axis is settruly vertical; and

(b) before making a second set, the initialreading is shifted by 180°.

With measurements in underground wor-kings with dipping angles more than 30°, thediscrepancies between the angles measured inindividual sets must not exceed the valuesgiven in Table 5.2.

The side lengths in theodolite traverses canbe measured by standardized steel tapes (of alength of 20 m, 30 m or 50 m), linen tapes orlight range finders.

In length measurements by steel tapes,each side must be measured twice (forward

5.5. Survey Nets

Underground survey nets are the basis forsurveying of mining workings and solution of


Table 5.3

Type oftraverse

Pernlissiblediscrepancy betweentwo measurements

of side

mp m,

TheodoliteGoniometer

40"

10'

60" closed 1/150010' open: 1/1000, 1/200

tween the check and final values of an anglemust not exceed 1.5'; in the method of sets,the discrepancy between two half-sets mustbe not more than 2'. The angles in theworkings with dip angles more than 300 mustbe measured in two rounds with resetting ofthe initial reading roughly by 180° before thesecond round.

In goniometer traverses, angles can bemeasured by goniometers or theodolites in asingle repetition or set. The permissiblediscrepancy between the check and finalvalues of an angle or the discrepancy ofangles in half-sets must be not more than 5'.Before starting a theodolite or goniometertraverse, a check measurement of the lastangle of the previous run is made. Thediscrepancy between the earlier and currentmeasurements of this angle must be not morethan 2' in theodolite traverses or 8' ingoniometer traverses.

The side lengths of theodolite traverses aremeasured by standardized steel tapes twice,shifting the tape after the first measurement.It is permissible to make both measurementsin the same direction. The deviations ofintermediate plumb-bob lines from the tra-verse line must not exceed 1/200 of the lengthof the smaller interval. Tape readings aretaken to a millimetre.

In goniometer traverses, side lengths canalso be measured by linen tapes or opticalrange finders with a relative accuracy notworse than 1/300. Tape readings are takenwith an accuracy to a centimetre.

problems of mine geometry and are con-structed in the form of theodolite andgoniometer traverses. Theodolite traversesare run in all preparatory workings except forthose in extraction sections and blocks whichcan be surveyed by goniometers.

The permissible root-mean square errors inmeasurements of horizontal angles mp andinclination angles m" are given in Table 5.3.

The points of a theodolite traverse serve asthe basis for tackling various problems ofmining geometry within the limits of a blockor panel and for surveys of indicated wor-kings.

Goniometer traverses are developed on thebasis of theodolite traverse points and serveas the basis for surveying of preparatory andstoping workings. The fixed points of atheodolite or goniometer traverse in theseworkings are used only once in surveying ofthese workings or for connection of prepara-tory workings within the limits of a face.

Theodolite and goniometer traverses insurvey nets are usually c.osed or are runtwice. When theodolite traverses are run inmain workings to supplement the plans forfurther development of reference nets, it ispermissible to run free traverses with mea-surements of left and right forward angles(except for workings approaching pillars ordangerous zones).

The angles in theodolite traverses aremeasured by theodolites. In theodolite tra-verses run in the workings with dip anglesless than 30°, angles are measured in a singlerepetition or set. If angles are measured bythe repetition method, the discrepancy be-

5.6. Types of Station Pointsof Reference and Survey Nets.Their Fixation

Depending on the purpose and existenceterm of a survey net, the points of theodolitesurveys (station marks) are divided intopermanent and temporary.

Permanent station marks are the basis forthe development of reference nets. They are

5.6. Station Points of Reference and Survey Nets 83

Temporary station marks are fixed in theroof of underground workings, top beams ofsupport frames or on steel arcs. If a workingis driven in a hard rock without supporting, astation mark (centre) can be fixed directly inthe roof rock (Fig. 5.7 a) or in a wooden plugdriven into a cut hole (Fig. 5.7 c). Figure 5.7 bshows a station mark to be fixed on woodensupports and Fig. 5.7 d, a mark for fasteningon metal lining.

established in the bottom and robf ofunderground workings so as to ensure theirstability and existence for a long time. Inview of this, permanent station marks areestablished where possible in the areasbeyond the zones of influence of supportpressure or underworking, weak enclosingrocks and rocks liable to heaving.

Some types of permanent station mark forestablishing in the footwall of workings areillustrated in Fig. 5.5. A permanent stationmark usually consists of a metallic rod25-30 mm in diameter and 200- 700 mm longwhich is concreted in a drill hole (Fig. 5.5a)or pit (Fig. 5.5b and c). The top face of therod is marked by drilling a hole or bypunching a circular (up to 2 mm) orcross-wise mark. For longer preservation,some types of permanent station mark have apressed-in copper or lead plug at the top,with a punch mark made in it.

Permanent station marks established in theroof of workings should be convenient forplumbing a theodolite under them. For thispurpose, they have a drilled hole around2 mm in diameter for passing the line of aplumb bob (Fig. 5.6). Permanent stationmarks and special bench marks can also beestablished in the side walls of undergroundworkings. They are usually fixed by con-creting.

Fig. 5.6 Pennanent station marks for setting inroof of underground workings: (a) in concrete;(b) in wooden plug; (c) hole for plummet line


(a) (bl (c) (dl

t++~

~

-g-~Fig. 5.7 Temporary station marks

Station marks in underground workingsare fixed so that a plumb bob can be hungquickly and conveniently and the plumb linebe always in the same position.

For quick identification of permanent andtemporary station marks, metal plates (mar-kers) with their numbers are fastened onsupport props or on the opposite side walls ofa working. In underground workings withoutsupporting or with concrete lining, thenumbers of station marks are marked on theside walls by an oil paint using a template.

Upon establishing of permanent and tem-porary station marks in underground wor-kings, their positions are marked on sketchesin the surveyor's field book and in coordinatecalculation book. The established permanentstation marks are transferred onto the miningworking plans. Each kind of permanentstation marks is provided with a certificate.All permanent points must be numbered.

Mining theodolites differ from those emp-loyed for surface survey work in certaindesign features associated with the specificconditions of surveying in undergroundworkings.

The principal parts of a mining theodoliteshould not corrode under the action ofchemically aggressive water. They shouldhave small dimensions and low mass and beprovided with illuminating devices. Theoptical systems should be hermetically sealedto prevent mechanical damage and penetra-tion of dust and moisture inside. The possi-bility should be provided for automaticcentring and for mounting of a theodoliteand signals on tripods and console holders.The telescope of a mining theodolite usuallyhas an upper centre (thorn) for centring theinstrument under a station point by means ofa suspended plumb bob. It should permitfocussing onto objects beginning from adistance of lor 2 m. Mining theodolitesshould allow the measurement of inclinationangles up to 90°, because of which somemodels are provided with an eccentric tele-scope in addition to the central one.

Theodolite, type T2 (USSR), is a preciseinstrument with a rotating limb and two-

5.7. Theodolites

Theodolites are the principal type of aninstrument for making underground angular

surveys.

5.7. Theodolites 85

ja)

Fig. 5.8 Theodolite, type 2T2: (a) general view;1 ~objective; 2-optical sighting device; 3 -micro-meter head; 4- vertical clamp; 5- vertical tangentscrew; 6- horizontal clamp; 7- horizontal tangentscrew; 8-clamp screw of base (support); 9-adjusting screw of vertical circle level; IO-leveltube; Il-horizontal circle aperture; (b) field ofvi~wof scale micrometer (reads 17 o 25' 26.5" on

horizontal circle)

sided optical wedge-type micrometer. Theinstrument has coaxial sighting devices, anoptical centring device, and a detachabletribrach which permits surveying by athree-stand scheme. The telescope is providedwith two optical sighting devices for roughaiming at objects.

By the consumer's request, the instrumentcan be supplemented with a box compass,striding level, two-sided optical centringdevice, eyepiece attachment, range finderattachment, and other auxiliaries. The theo-dolite is designed for class-3 and class-4triangulation and polygonometry and canmeasure horizontal angles with an accuracyto :t: 2-3".

Theodolite, type 2T2 (USSR), shown inFig. 5.8a, is a more advanced model anddiffers from the former in the following: thesystem of a vertical axis is non-repeating; thereading device takes readings from twodiametrically opposite sides of angle-mea-suring circles, which eliminates the effect ofeccentricity of these circles: for more conve-nience, the field of view of the reading micro-scope shows additionally the numbers of tensof minutes; and the telescope gives a betterimage. The tangent screws are set coaxiallywith winged-knob clamp screws. Both pairsof screws are arranged at the same side of theinstrument for a quicker change from azi-muth-sighting to vertical plane-sighting ofthe telescope.

The telescope graticule has two horizontalhairs (stadia hairs); one of the vertical hairs isdoubled.

The horizontal and vertical circles of thetheodolite have 20'-value graduations and 10numbering. The horizontal circle has double(bifilar) graduation lines and the vertical one,single lines.

The images of graduation lines andnumbers are projected in the field of view ofthe reading microscope by means of adouble-channel optical system. Changingfrom one optical channel to the other is


Fig. 5.9 View field of scale microscope of theodo-lite, type T5 (reads: 74 o 55.0' on horizontal circleand 12 o 06.0' on vertical circle)

and polygonometric nets of the lst and 2ndorder.

The theodolite TSK differs from TS by theprovision of a compensator whicb automa-tically eliminates the error in measuredvertical angles, caused by the deviation of thevertical axis of the instrument. The workingangular range of the compensator is ::t 3'. Inview of this, the vertical circle alidade has nospirit level. The compensator also ensuresprecise levelling of the collimation axis of thetheodolite, and therefore, the instrument canalso be used as a level.

The high-quality telescope of theodolitesTS and TSK has a magnification of 27 andthe focussing range from 2 m to infinity.Optical sighting devices for rough aiming ofthe instrument are provided at the top andbottom of the telescope. Precise aiming of thetelescope is effected by means of tangentscrews. The angle-measuring circles haveI-degree graduations. Readings are taken bymeans of a scale microscope arranged nearthe telescope eyepiece. The scale microscopeshows simultaneously the graduation lines of

performed by means of a handle. With thehandle set horizontally, the field of view ofthe microscope shows the images of thedouble lines of a horizontal circle and withthe vertical position of the handle, it showsthe lines of the vertical circle.

The field of view of the reading microscopeis shown in Fig. 5.8b. The central apertureshows the images of graduation lines of twodiametrically opposite sides of a circle, whichare separated by a halving line. The upperaperture shows numbered degrees and belowthem, a scale of six numbers (from O to 5),which indicates tens of minutes. The apertureat the right is the micrometer scale with onedivision corresponding to one second of thearc.

To take a reading, the micrometer head isoperated to align carefully the top andbottom images of the lines of a vertical circleor respectively those of the double lines of ahorizontal circle. If two numbers of wholedegrees are seen in the upper aperture, thetrue one is that which does not pass beyondthe limits of the ten-minute numbered scale.The number on this scale just below thedegree number gives tens of minutes. Then,whole minutes and seconds are read offrespectively on the left-hand and right-handpart of the micrometer scale.c It should be noted that before aligning the

vertical circle graduation lines, it is requiredto align the ends of the level bubble image byan adjusting screw.

Theodolites T5 and T5K (USSR) areprecise instruments with a cylindrical repeat-ing system of vertical axes. The horizontalcircle can be locked with or unlocked fromthe alidade by means of a repeater lock. Therepeating system of vertical axes allowshorizontal-angle measurements by the meth-od of reiteration or the method of sets. Theseinstruments are designed for measuringhorizontal and vertical angles in under-ground workings when constructing refe-rence nets and on the surface in analytical

5.7. Theodolites 87

the vertical and horizontal circle (Fig. 5.9)and its scale is graduated to single minutes.Angles are measured by reading off thedegrees on the limb scale and the minutes onthe microscope scale; the seconds are esti-mated by eye as a fraction of the microscopescale division. The reading accuracy is equalto 0.1 of the scale value of the microscope, i. e.:t 0.1 " or :t6".

Theodolites 2TS and 2TSK (2TSKP) (USSR)are further modifications of type T5. Theseinstruments are of the non-repeating type.

In the theodolite, type 2T5K (Fig. 5.10a),the functioncof the level of the vertical circlealidade is performed by ap optical compen-sator with a self-adjusting index. Angles areread off at one side of the circles. For easiercalculation of vertical angles, the verticalcircle is numbered in sectors from 0 to75° and from 0 to minus 75°. The tangentscrews of the telescope and vertical circlealidade are coaxial with the correspondingwinged-knob clamp screws; both pairs ofscrews are arranged at the same side of thetheodolite.

The telescope is fully reversible, i. e. can betransited at both ends, and focussed bymeans of a rack-and-pinion gear. The eye-piece can be adapted to the observer's visionby means of a diopter ring which should berotated until the cross hairs are seen sharp.The two extreme horizontal lines of the crosshairs (above and below the cross) are stadiahairs. The telescope is provided with twocollimation sights for rough pointing toobjects. When using a sight, the observer'seye should be at a distance of 25-30 cmfrom it.

For aiming at an object, the telescope isrotated on the horizontal axis and thetheodolite body, on the vertical axis. Preciseaiming is made by operating micrometertangent screws 5 and 7 when winged-khobclamp screws 4 and 6 are locked. A specialhandle is provided for changing the sectionsof horizontal circle (in angular measure-

Fig. 5.10 Theodolite, type 2T5K: (a) general

view; l-objective; 2-optical sighting device;3 -level tube; 4- vertical clamp; 5- vertical tangentscrew; 6- horizontal clamp; 7- horizontal tangentscrew; 8-clamp screw of base (support); 9-footscrew of base; IO-horizontal circle aperture;(b) view field of scale microscope (reads 127 o 05.6'on horizontal circle and 0 o 34.0' on vertical circle)


measuring the horizontal and vertical anglesin theodolite and tacheometric traverses, forthe construction of plan and elevation surveynets on the surface and in undergroundworkings, and for measuring distances (byusing the stadia hairs of the telescope).

These theodolites have a repeating systemfor measuring horizontal angles by thereiteration method and are convenient forassigning directions to mine workings.

The principal parts and units of the instru-ments are protected against dust, dirt andmoisture. The telescope can be plunged(transited) at both ends. It is of the internal-focussing type and is focussed by rotating theeyepiece ring. Optical sighting devices arran-ged at both sides of the telescope serve forrough aiming at objects. Precise aiming isdone by means of a micrometer screw andtangent screws when the correspondingclamp screw is locked. The eyepiece of themicroscope for reading off on the horizontaland vertical circles is located near the tele-scope eyepiece.

The vertical axis of the theodolite is settruly vertical by means of bubble level whichis centred by adjusting screws.

Theodolites of these types have a hollowvertical axis for centring over a station pointby means of telescope. The eyepieces of thetelescope and reading microscope are provi-ded with zenith attachments which permitthe observations of objects at angles above45° to the horizon and theodolite centringover a point. A diagonal eyepiece (optional)can also be used for zenith and nadir sightingand centring over a point.

Theodolites, types T30 and 2T30, aremainly designed for surface surveying, butare often employed for surveys in under-ground workings.

Theodolite type T30M (USSR) shown inFig. 5.lla is a mining theodolite. It has aspecially designed vertical axis (spindle) and areversible bubble level for the operation ofthe instrument in both upright and inverted

ments). To change from one section toanother, the handle should be turned and atthe same time pressed down along its axis.The setting of the horizontal circle in aparticular section is additionally controlledby indexing in the aperture of horizontalcircle finder.

The horizontal and vertical circles haveI-degree numbered graduations. The gradua-tion lines and numbers are projected in theplane of reading scales of the microscope.The image of the vertical circle is tinted blueand that of the horizontal circle, yellowish-green. The illumination of the field of viewcan be controlled by a hinged mirror. Thescales are focussed for distinct vision byrotating the diopter ring of the microscopeeyepiece.

The field of view of the microscope oftheodolite 2T5K is illustrated in Fig. 5.10b.The images of the reading scale and thevertical and horizontal limb are projectedrespectively in the upper and lower aperturesof the field of view. Each division of thereading scale corresponds to one minute ofthe arc. The fractions of minutes can beestimated by eye with an accuracy to 0.1 of adivision. The reading index is the hair of thelimb. Th~ reading error is equal to 0.05-0.1 ofa scale division, or 3-6". The readjng scale ofthe vertical circle has two rows of numbers.The lower row (with the minus sign) is usedfor reading off when the vertical limb hairwith the same sign is seen in the reading scaleaperture.

The certified accuracy of angle measure-ment ( :1: 5") is ensured in measurements bythe method of full sets (with the instrumentpositioned 'face left' and 'face right'). In orderto eliminate the division error of the horizon-tal circle, the latter should be reset after eachfull set by 180°: n (where n is the number offull sets).

Theodolites T30, 2T30, and T30M (USSR)are angle-measuring instruments of technicalprecision ( :1: 30"). They can be employed for

5.7. Theodolites 89

positions, which is essential in undergroundsurveys. The sighting devices on the telescopehave a centre mark for centring (plumbing)the instrument under a point by means of aplumb bob.

For ease of operation in undergroundworkings, the reading scales are providedwith an illuminating system which can beswitched on by a button either for a shorttime to take a reading or for continuousillumination.

The reading microscope arranged near thetelescope eyepiece has the field of view inwhich the images of the vertical and horizon-tal circles are projected simultaneously(Fig. 5.llb). The reading scales have 60 one-minute divisions. The graduations of thevertical circle (limb) are projected against theupper reading scale in the field of view andthose of the horizontal circle, against thelower scale. A reading can be taken by eyeestimation to 0.5 or 0.25 of a division, i. e.with an accuracy to 30" or 15".

A version of the former instrument is typeT30ME theodolite with an auxiliary eccentrictelescope (Fig. 5.l2a); an eccentric telescopewith a bracket is also obtainable optionallyto the type T30M theodolite (Fig. 5.l2b).

Theodolite, type T30ME (with an eccentrictelescope) i\ designed for surveys in steepunderground workings and for surface sur-veys connected with sighting of the telescopein the directions close to the vertical. Theeccentric telescope has the same opticalcharacteristics as the central telescope and isalso provided with optical sights.

Theodolite TheoO1O (GDR) is a precisioninstrument provided with a rotating limb, alens-and-mirror telescope, and a two-sidedoptical wedge micrometer. It has a detachabletribrach and an optical plummet. The advan-ced versions of this instrument, Theo010A(Fig. 5.l3a) and TheoOlOB, have an optico-mechanical compensator of the vertical circleand an erect-image telescope. The field ofview of the reading microscope of type

""

Fig. 5.11 Theodolite, type T30M: (a) generalview; 1- theodolite base; 2- horizontal clamp;3- horizontal tangent screw; 4- illuminating at-tachment; 5- diopter ring; 6- microscope eyepiece;7- telescope focussing ring; 8- optical sightingdevice; 9-telescope clamp screw; 10-vertical tan-gent screw; 11 -level tube; 12 -lever for locking ofhorizontal circle with alidade; 13-1ock; 14-zenith(prism) attachment; 15- diagonal eyepiece; (b) viewfield of scale microscope (reads 23 o 54' 30" onhorizontal circle and 15 0 12' 30" on vertical circle)

Fig. 5.12 Theodolite, type 2T30ME: (a) general view; l-central telescope; 2-eccentric telescope;3 -level tube; 4- horizontal clamp screw; 5- horizontal tangent screw; 6- base clamp screw; 7- verticalclamp screw; 8-focussing rack-and-pinion; (b) eccentric telescope to theodolite, type 2T30M

(b)

/1(a) .

4 6""

5

,10

.3

7-

8-Fig. 5.13 Theodolite, type Theo010A: (a) generalview; 1 -objective; 2- optical sighting device; 3- op-tical centring device; 4 -micrometer; 5 -verticaland horizontal clamps; 6-circle switch; 7, 8-verticaland horizontal tangent screws; 9-foot screw;lO-illuminating mirror; (b) view field of scalemicrometer (reads 112 o 27' 35.0" on horizontal

circle)

9-

915.7. Theodolites

lb)

Fig. 5.14 Theodolite, type Theo020A: (a) generalview; l-objective; 2-optical sighting device;3-optical centring device; 4-eyepiece; 5-verticaland horizontal clamps; 6- disconnection of verticalcircle; 7-illuminating mirror; 8-vertical tangentscrew; 9-horizontal tangent screw; IO-foot screw;(b) view field of scale microscope (reads 235 o 050'on horizontal circle and 256 0 52.0' on vertical

circle)

TheoO1O theodolite is shown in Fig. 5.l3b.These instruments are intended for triangu-lation and polygonometry on the landsurface.

Theodolite TheoO20 (GDR) is a repeatingtheodolite of technical precision. It has anoptico-mechanical compensator on the ver-tical circle (instead of a bubble level), anoptical centring device, and a detachabletribrach which allows the instrument to beused in surveys by a three-stand scheme.

Improved models, TheoO20A (Fig.5.l4a)and TheoO20B, have a new unique system ofcoaxial tangent and clamp screws for simul-taneous locking of the vertical and horizontal

axes and a more perfect reading system(Fig. 5.14b).

These instruments are intended for theconstruction of survey nets in mines and onthe surface and of reference nets in under-ground workings.

Theodolite TheoO80 (GDR) is a compactoptical repeating theodolite with a detachablebase for three-stand scheme surveys; it canalso be mounted on console holders. Limbgraduations have double numbering: one ofthem being read off when the instrument ismounted in the common upright positionand the other when the theodolite is mountedon a console holder in an inverted Dosition.


Fig. 5.15 View field of reading-off microscope oftheodolite, type Theo080 (reads 359 o 28' onhorizontal circle and 96 o 04' on vertical circle}

The field of view of a reading-off microscopeis illustrated in Fig. 5.15. The instrument isintended for supplementary surveys in under-ground workings.

is swinged slightly and if the image of theobject again deviates from the cross hairs, themove of foot screws is made more tight bymeans of tightening nuts.

2. The bubble level of the horizontal circlealidade is adjusted (when required) so thatthe bubble level axis can be truly perpendi-cular to the vertical rotation axis of thetheodolite. For checking, the bubble level isarranged amid the line of two foot screws ofthe tribrach and, by rotating these screws inopposite directions, the bubble is moved intothe centre. The alidade is then turnedthrough 180°. If the bubble deviates from themid position, half of its deviation is taken offby operating the foot screws and the otherhalf, by means of the adjusting screws of thebubble level. After that the alidade is rotatedthrough 90° and the bubble is centred bymeans of the third foot screw. The check isrepeated until the required conditions aresatisfied.

3. The position of the telescope cross hairsis tested and adjusted. The horizontal line ofeyepiece cross hairs must be perpendicular tothe vertical axis of rotation of the theodolite.For this test, the theodolite is mounted onthe tripod, and its vertical axis is arrangedtruly vertical. Then a convenient point ischosen, and its position relative to the hori-zontal line of the eyepiece cross hairs isobserved when rotating the instrument stan-dards by the horizontal tangent screw. fftheimage (point) deviates from the horizontalline, it is required to take off the eyepiece cap,slacken four fastening screws, and turn theeyepiece so as to horizontalize the horizontalhair. Upon adjustment, the eyepiece is fasten-ed again and the cap is screwed into place.

4. The collimation error, which canappear if the collimation axis of the telescopeis not perpendicular to the axis of rotation ofthe telescope, is measured and eliminated.For this, telescope is set roughly horizontallyand aimed at a remote object. Readings aretaken at two positions of the circle: 'face left'

5.8. Tests and Adjustmentsof Theodolites

Before starting the survey work, theodo-lites, tripods, and sighting devices are testedin order to avoid the influence of probableerrors on the results of angular measure-ments.

1. The tripod and tribrach are tested forstability. To test the tripod for stability, thetheodolite is mounted on it and the verticalaxis of the instrument is set truly vertical. Thetelescope is then sighted on a distinct object,and the tripod table is swinged slightly backand forth. If the image of the object is thennoticed to deviate from the telescope crosshairs, the wing nuts at the tops of the tripodlegs must be tightened more firmly.

After the tripod has been made rigid, thestability of the tribrach is tested. The tribrach

5.9. Centring of Theodolites and Signals 93

(FLJ and 'face right' (FRJ. Then the clampscrew of the tribrach is loosened, the theo-dolite is rotated through 180° and lockedagain by the clamp screw. The telescope isaimed at the same object and two newreadings are taken at two positions of thecircle: FL2 and FR2. The collimation errorcan then be calculated by the formula:

(FLl -FRl :t 1800) + (FL2 -FR2 :t 180°)c=

4

For correcting the collimation error, theeyepiece cap is taken off to open an access tothe adjusting screws of the cross hairs, andthe horizontal circle is set at a reading that isdetermined by the formula:

FR = FR2 -c

The graticule (cross hairs) is moved hori-zontally by means of the adjusting screwsuntil the cross is aligned with the image of theobject chosen earlier. The check is repeateduntil the condition is satisfied. The permissiblecollimation error should not exceed 30".

5. The zero point (zero offset) is tested andadjusted. The zero point in the reading on thevertical circle when the collimation axis ofthe telescope is truly horizontal and thebubble of the bubble level of the verticalcircle alidade is in the zero point.

The zero point of the vertical circle must beknown and accounted for in surveys or beexcluded. The zero point value is determinedby sighting on one and the same point,preferably closer to the horizon, at twodifferent settings of the circle and in thegeneral case can be calculated by the formula:

FL + FR + 180°ZP=

2

by moving the graticule vertically by meansof the adjusting screws. The test is repeated ifrequired.

When testing and adjusting the zero point,it is essential to observe the position of thelevel bubble on the horizontal circle alidade;if the bubble is moved aside, it must becentralized by means of the foot screws oftribrach.

6. The compensator is tested. This test iscarried out to check whether the verticalcircle reads the same when the vertical axis ofthe instrument deviates within ::t: 3'. For thistest, a distinct point is chosen and thetheodolite is mounted on the tripod so that-one of the foot screws is oriented in thedirection of that point. The bubble of theadjusted cylindrical bubble level is broughtinto the central position so that the main axisof the theodolite is truly vertical. The theo-dolite is then tilted by 2-3 " i. e. by 4-5 level

divisions, towards the selected point by ope-rating the foot screw facing that point. Afterthat the theodolite is levelled by the othertwo foot screws.

With a tilted position of the theodolite, thetelescope is sighted on the selected point, andthe reading is taken on the vertical circle. Theprocedure should be repeated with the instru-ment tilted by 2-3' in the reverse direction,i. e. towards the observer.

The difference between the readings takenwith the instrument tilted in two oppositedirections should be not more than 0.1.Otherwise, the theodolite should be sent tothe manufacturer for adjustment.

5.9. Centring of Theodolitesand Signals

When running a theodolite traverse inunderground workings, the instrument is setup successively in the traverse points and,before making angular and linear measure-ments, should be prepared for operation, io eoit should be centred and levelled. and its

If the reading is less than 90°, add 360°.For the correction of the zero point, the

vertical circle is set at the reading FL-ZPand the cross of the graticule is aligned withthe image of the selected point on the object


m. .=J-2 ~2b2 [l;(a2 + b~) + lfh(a2 + b2 -2abcosa)]'.' a

(5.2)

telescope should be prepared for observa-tions. The plumb lines are hung or signals(sighting marks, or targets) are established inthe "points to be sighted.

Centring is essentially the placing of atheodolite or signals into a position in whichtheir vertical axis is brought into coincidencewith the vertical line passing through thecentre of a survey mark.

Suppose that we have to measure a hori-zontal angle a = BAC (Fig. 5.l6a). If thetheodolite is not centred properly, its verticalaxis may turn out to pass through a pointA l' rather than through A. Then, the measu-red angle will be a1, but not a. The differenceL\a = a -a1 is called the error of angularmeasurement caused by inaccurate centring ofthe theodolite, and the horizontal distanceAA1 = I is the linear error of theodolitecentring. Suppose now that the signalsat sighting points B and C have been centredpoorly (Fig. 5.16b). In that case, L\a' = a --a2 is the error of the horizontal anglemeasurement caused by inaccurate centringof the signals, and the horizontal distancesbetween points BB1 and CC1 are the linearerrors of signal centring.

If the linear errors of theodolite and signalcentring occur simultaneously, the total error

(a)

A

Fig. 5.16 Deternlination of measurement error ofhorizontal angle caused by inaccurate centring of(a) theodolite and (b) signals

where a and b are the horizontal projectionsof the side lengths of the measured angle andI,h and Is are the linear errors of theodoliteand signal centring.

Taking, for instance, that a = 21 m, b == 28 m, 11 = 175°, Is = 0.001 m, and I,h == 0.002 m, the error of angle 11 will be equalto 24".

The analysis of formula (5.2) suggests thefollowing conclusions:

I. The effect of the signal centring error isindependent of the magnitude of the mea-sured angle.

2. The effect of the theodolite centringerror depends on the magnitude of the angleand is the highest for angles close to 180°.

3. The effect of the errors of theodolite andsignal centring is inversely proportional tothe lengths of the sides making the measuredangle and increases with the difference in theside lengths.

As may be seen, all these factors, whichworsen the accuracy of horizontal anglemeasurements owing to poor centring oftheodolite and signals, are typical for theconditions of surveying in undergroundworkings. In that connection, the matter oftheodolite and signal centring is of primeimportance in mine surveying.

Three main methods of centring are usedin the mine surveying practice: with a mecha-nical plummet, with an optical plummet, andautomatic centring.

In centring with a mechanical plummet, thetheodolite is mounted on a tripod or consoleholder, its vertical axis is set truly vertically

of measurement of horizontal angles may bequite substantial.

The root-mean square error in the measu-rements of horizontal angles caused by inac-curate centring of the theodolite and signalscan be determined by the formula:

5.9. Centring of Theodolites and Signals

(a) (b) (c) (e)

Fig. 5.17 Types of centring string plummets

plummet is connected with a string 1 bymeans of a threaded plug 2 at its top;

(b) a plummet with a retractable point;(c) and (d) controllable plummets with

respectively external or internal pulleys onwhich the string is wound; and

(e) a controllable plummet with an internalreel, which is the most convenient type inoperation, since its centring point 6 can bequickly set at the desirable height. On pres-sing the top portion of a sleeve 1, theplummet string can be freely unwound to therequired length. In order to raise or lower theplummet, the operator holds the plummetbody 4 by one hand and rotates the sleeve bythe other. Depending on the direction ofrotation, the string will be either wound ontothe reel or unwound from it. To fasten thestring to the plummet, the sleeve is taken outupon removing a nut 2, and one end of thestring is passed through the slot in the rim ofa reel 3 and got made into a knot. The otherend of the string should be passed throughtwo side holes and one central hole in thesleeve, after which the plummet can be as-sembled. At the end of plumbing, the plum-met point should be retracted by turning asleeve 5.

and the telescope is set into the horizontalposition. The string of plummet is passedthrough the hole of a survey mark and theheight of plummet suspension is controlled sothat the plummet point is just to touch thetop centre of the theodolite. After that theinstrument is moved on the platform of thetripod or console holder until the point of thefreely hanging plummet is exactly over thetop centre of the instrument.

Upon making these operations, the con-tinuation of the vertical axis of the theo-dolite will pass through the centre of thesurvey mark if only the top centre of theinstrument (with the telescope arrangedstrictly horizontally) lies in the vertical axis ofrotation of the telescope and the plummetpoint lies in the same vertical line with theplummet string.

When plummets are used as signals, thesighting axis of the telescope is aimed at theirstrings.

The following types of mechanical (string)plummets are used in the modern minesurveying practice (Fig. 5.17): (a) a simplecentring plummet which has a massive metalbody 3 sharpened at the bottom; the sharp-ened portion ends with a steel point 4; the

Ch. 5. Horizontal Surveys of Underground Workings

3

~

~- ~

Fig. 5.18 Optical plummet: I-protective glasses;

2-mirror; 3-objective; 4-graticule; 5-eyepiece

The essence of the automatic centring of atheodolite and signals consists in that theattachments mentioned make it possible toset up the theodolite in the points where asignal was set up before, and vice versa. Thisensures that the vertical axis of the instru-ment, which passes through the centre of asurveying mark, restores automatically itsgeometrical position when the theodolite andsignal setups are interchanged. This inter-changing requires no additional centring.

Survey with Automatic Centring ofTheodolite and Signals. The sequence of sur-vey with automatic centring of theodolite andsignals is as follows. Suppose that a checkingtheodolite traverse is to be run between twogroups of fixed mine survey points: A, R, Cand D, E, F (Fig. 5.20). To do this, supports(bases) (see Fig. 5.19) on tripods are set up inpoints A and C and centred by means of anoptical plummet and the theodolite is set upand centred in a point R. Signals c are thenmounted on the bases in the points A and Cand the checking angle ARC is measured by

The surveys in underground workings arecarried out with the use of illuminatingplummets whose body incorporates, in ad9i-tion to the string-winding mechanism, also apower source, an electric lamp, and a conicaltransparent cap. Illuminating plummets arealso employed successfully in the orientationof underground workings and check surveys.

It is usually warranted by plummet manu-facturers that the deviation between theplummet point and the centre of a string holeis not more than 0.5 mm. This can be check-ed by hanging a plummet and setting up twotheodolites at a distance of 5- 7 m from it sothat the sighting axes of the two instru-ments, when pointed to the plummet, makean angle of roughly 90°. The telescopes of thetwo instruments are sighted on the plumbline so that the plumb line and plummetpoint are within the bisector of cross hairs. Ifthe image of the plummet point in at leastone telescope is beyond the bisector, theplummet tested should be repaired orrejected.

For more accurate centring, modern theo-dolites and signals are provided with opticalplummets or optical centring devices. Theformer are built in into an instrument, whilethe latter are detachable optical plummetsand optical centring devices may be eitherone-sided or two-sided. A one-sided opticalplummet permits centring by a vertical col-limating ray to be performed either onlyupwards or only downwards. The scheme ofan optical plummet for centring above asurveying mark is shown in Fig. 5.18. Bypointing the telescope to the zenith, thetheodolite can also be centred under a sur-veying mark.

In the mine surveying practice, when thereis no need to fix the intermediate vertexes oftheodolite traverses, it is common practice toemploy automatic centring of theodolites andsignals on tripods or console holders by usinga special set of attachments, such as thatillustrated in Fig. 5.19.

5.9. Centring of Theodolites and Signals 97

b

A

d

9

Fig. 5.19 Set of attachments to theodolite T30M for surveying by three-stand scheme

the theodolite in the point B. Then thetheodolite and forward signal are interchan-ged on their bases and the rear signal is setup on a tripod (or console holder) in a point7

A similar survey with lost points andautomatic centring of theodolite and signalscan also be performed by using consoleholders instead of tripod stands. This methodis usually resorted to in steeply dippingworkings or where the mine traffic is inten-sive. The set of attachments for this method

4

The signal in the point 1 is set into theupright position by means of a level tube on abracket and, then the angle BCl and thelength of a side Cl are measured. Thetheodolite and forward signal are theninterchanged on their bases and the rearsignal on the tripod is reset onto a next pointto run the traverse to the second group offixed points D, E, and F where, as in thepoints A, B and C, the bases are set up bymeans of an optical plummet or a theodo-lite.

This order of survey is characterized bythat the theodolite and signals can beinterchanged without intermediate centring,the traverse vertexes between the fixed pointsare not fixed, and the survey is done by usingthree stands. For that reason this method isalso called the survey with lost points, orsurvey by a three-stand scheme.

7-1270

Fig. 5.20 Scheme of theodolite traverse betweentwo groups of reference points


of survey (see Fig. 5.19) contains consoleholders with adapters (e), centring plates withspherical level tube (a), a clamp (b) forfastening a console holder to wooden ormetallic mine supports, pin (1), prism attach-ment (h) for an objective, and a level tube (g).

As has been found by experiments, theerrors of centring of theodolites and sig-nal~ by various methods are as follows:1.2-1.5 mm in single centring with stringplummets, 0.8-1.0 mm in optical centring,and 0.3-0.8 mm in automatic centring.

2. The alidade is unlocked and, by rotatingthe instrument clockwise, the telescope issighted on the forward signal in a point C totake the reading a2(a2 = 58°23'.5).

3. The telescope is reversed, the limb isunlocked and turned together with the ali-dade to sight the telescope on the rear signal;no reading is taken.

4. The alidade is unlocked and rotatedcounter-clockwise to sight the telescope onthe forward signal and take the readinga3 (a3 = 116°47'.7).

5. The left-forward angle ~ and its checkvalue ~ch are calculated by the formulae:~ = (a3 -aJ/2 (5.3)

~ch = a2 -al (5.4)

If the discrepancy between the measuredand check angle is more than 1.5 of theinstrument accuracy (:!: 1.51), the angle mea-surement must be repeated.

When running theodolite traverses ofhigher accuracy, the measurements ofhorizontal angles are repeated more thantwice. In that case, in the first position of acircle (say, FL), the limb is moved n times tosight the telescope on the rear signal and thealidade is also moved n times to sight thetelescope on the forward signal. Readings aretaken only on the first and second sighting,and the check angle is calculated by theformula ~ch = a2 -al. The total value ofthe angle measured n times will be equal toa3 -al. After that, the telescope is reversedand sighted n times on the rear and forwardsignal in a different position of the circle.Only one reading, a4' is taken after the lastsighting on the forward signal. With n fullrepetitions, we have:

~ = a4 -a1 + R360° (5.5)

5.10. Measurementsof Horizontal Angles

The operation of measuring a horizontalangle includes centring a theodolite under orover a fixed point in an underground wor-king, sighting on signals, and taking readingson the scales.

The sequence of signal sighting and theorder of reading on the scales depend on themethod of angle measurement employed by asurveyor.

In mining workings, left-hand angles alonga survey traverse are usually measured by themethod of repetitions (reiteration method),method of sets or, less frequently, method ofrounds.

5.10.1 .Reiteration Method

In view of the wide use of repeatingtheodolites in the mine surveying practice,the method of repetitions (reiteration meth-od) has become very popular in measure-ments of angles. It consists of the fol-lowing operations.

I. The zero division of the alidade of ahorizontal circle is roughly aligned with thezero mark of a limb, after which the latter isunlocked and the hair cross of a telescope issighted on the rear signal set up in a point B(Table 5.4). The reading 01 is taken on thescale 01 (01 = 0000'.2).

2n

where R is the number of full revolutions ofthe alidade around the limb.

The number of full revolutions of the

5.10. Measurements of Horizontal Angles 99

alidade around the limb can be determinedby considering the measured check angle andthe number of performed repetitions:R = (2n 13ch + a1 -a4)/360° (5.6)

5.10.2. Method of Sets

The measurement of an angle (for instance,CDE, Table 5.5) by the method of sets iscarried out in the following sequence.

1. The limb is locked in a position when itroughly reads 00, the telescope is sighted onthe rear signal (point C), and the reading a 1 istaken on the horizontal circle and recordedin the field book (01 = 10°07'.5).

2. The alidade is unlocked and the tele-scope is sighted on the forward signal (pointE) to take the reading 02 (02 = 68°31'.0). Themeasured angle in one position of the circle,i. e. in the first half-set, is 13' = 02 -01 (13' == 58°23'.5).

3. The limb is turned through 60-90° andlocked. The telescope is reversed and sightedagain on the rear signal; the reading 03 isrecorded in the book (03 = 190°07'.5).

4. The telescope is sighted again on theforward signal to take the reading 04 (04 == 248°30'.9), and the angle measured in thesecond position of the circle is calculated:1311 = 04 -03 (1311 = 58°23'.4). The mean anglecalculated by the two half-sets13m = (13' + 1311)/2

is taken as the final value (13m = 58°23'.45).In angle measurements by the method of

two sets, the sequence of operations isessentially the same, but the limb for thesecond set is turned initially at a readingclose to 90°.

1. The zero divisions of the limb andalidade are roughly aligned, and the alidadeis locked. With the limb unlocked, the te-lescope is sighted on the initial signal (forinstance, point B, Table 5.6) set in the centreof a bench mark, and the reading at is takenand recorded in the book (at = 00003'.0).

2. The alidade is freed (with the limb beingfixed) and the telescope is sighted on thesignal set in the centre of a bench mark D. Inthis case, the theodolite is rotated clockwise.The reading a2 is taken and recorded in thebook (a2 = 28°08'.1). .

3. The alidade is rota-ted clockwise in thesame sequence and the telescope is sighted onthe signal in a point C to take the reading a3(a3 = 58°26'.7).

4. The observations of the first half-roundare finished by sighting the telescope on thesignal set in the initial direction B and takinga check reading. This makes it possible toprove that the limb was fixed during theobservation of the point (a4 = 00°03'.1).

In order to eliminate the instrument errorof the theodolite, the same angles between thegiven directions are then measured at adifferent setting of the circle (FR). In thesecond half-round, observations are made inthe reverse direction and the alidade is rota-ted counter-clockwise.

The second round is performed in the samesequence, but the limb is initially set at areading close to 90°.

Upon completing the measurements at thesecond setting of the circle, the collimationerror is calculated by the formula: 2c == FR -FL ::!: 180°; its magnitude is indi-cative of the accuracy of measurements. Afterthat the mean values of the directions obtai-ned by two measurements are calculated. bythe formula: (FL + FR ::!: 180°)/2. The pro-cedure is finished by calculating the correcteddirections, i. e. by calculating the mean initialdirection from the mean directions found; inour case, the corrected direction is(00°02'..80 + 00°02'.90)/2 = 00~02'.85.

5.10.3. Angle Measurements byMethod of Rounds

The procedure of angle measurement bythe method of rounds consists essentially inthe following.

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Fig. 5.21 Measurement of horizontal angle by eccentric telescope

The measurements of horizontal angles inunderground workings with the angles of dipmore than 300 are made only by the methodof sets under the provision of the followingadditional conditions:

I. If a repeating theodolite is employed, itslimb must be locked for the entire time ofmeasurements.

2. The theodolite for measuring hori-zontal angles must be provided with a stri-ding level and permit plumbing of its verticalaxis of rotation before each set.

3. The alidade of the theodolite shouldalways be rotated in one direction only.

5.10.4. Measurements of HorizontalAngles by Means ofEccentric- TelescopeTheodolites

The horizontal angles in steep workingsare measured by means of the eccentrictelescope of a theodolite. The scheme ofmeasurement of a horizontal angle I-II-III bythe eccentric telescope with the circle at right

is shown in Fig. 5.210 and with the circle atleft, in Fig. 5.21b. In order to measure theangle between the directions II-I and 1I-111,for instance, with the circle at right, thetelescope is sighted successively on signals Iand III. In that case, the horizontal axis ofrotation of the telescope moves from posi-tion II-I into 1I-2, i.e. its setting is changedby an angle 13" and therefore, the angle 13, willbe measured instead of 13. Similarly, with thecircle at left, the angle 13! will be measuredinstead of 13.

As may be seen in Fig. 5.21, the exteriorangles <p and <p' are the sums of the twointerior angles of the triangles which are notadjacent to them, i. e.

<p=13,+'1=13+o (5.7)<p' = 13! + 0 = 13 + '1 (5.8)

Hence:

13 = 13, + '1 -O (5.9)

13 = 131 -'1 + O (5.10)

Adding these equations, we get:

213 = 13, + 13! (5.11)

5.10. Measurements of Horizontal Angles 103

lite; O is the inclination angle of the rotationaxis of an instrument; u is the angle betweenthe direction of inclination of the principalaxis of an instrument and the direction ofrotational axis of telescope when sighted onthe forward signal; ~ is the horizontal anglebeing measured; and h f and h r are the anglesof inclination of collimating rays when sight-ed respectively on the forward and rearsignal.

The analysis of formula (5.13) shows thatthe error mfJ of angular measurement is at amaximum at ~ = 180° and at a change froma horizontal to an inclined workipg or viceversa. In that case, the magnitude of an errorincreases proportional to the slope and mayattain rather high values (3-5' or even more).

orI:} = (I:}r + I:},)/2 (5.12)

It follows from formula (5.12) that thecentral angle is equal to the half-sum of theangles measured in two half-sets. This eli-rninates the influence of the telescope eccen-tricity. An eccentric telescope can also beused for angular measurements by the reite-ration method. In that case, it should benoted that, in order to determine the checkangle, the instrument must be sighted on thesignals of measured directions at two dif-ferent positions of a circle.

The accuracy of measurements ofhorizontal angles by an eccentric-telescopetheodolite depends on the difference in theside lengths of the measured directions andon the inclination of the theodolite tele-scope axis. For that reason, when establi-shing the points of a theodolite traverse it isdesirable that all sides be roughly of the samelength. The vertical axis of the telescope mustbe adjusted by means of a striding level.

5.10.6. Accuracy of HorizontalAngle Measurements

The accuracy of measurement of ho-rizontal angles is influenced by gross,systematic and random errors.

Gross errors may appear owing to theinclusion of improper bench marks into thetraverse being run, poor fixation of plummetsin the centres of bench marks, instability oftripod (console holder), etc. To avoid grosserrors, before sinking into the shaft, thesurveyor must prepare all the initial data,write them in the theodolite survey fieldbook, and instruct the workers engaged inthe setting and illumination of plummets(signals) and other related jobs. In the shaft,he must check that all the bench marks arereliably fixed and belong to the traverse lineto be run.

Systematic errors depend on the environ-mental conditions and inaccuracies in themanufacture and assembly of instruments, forinstance, improper mutual arrangement ofsome elements or non-perpendicularity ofthe geometrical axes of theodolite. Thesesystematic instrumental errors can be mi-nimized by regular examinations of theodo-

5.10.5. Errors in MeasuringHorizontal Angleswith Steeply Inclined Sides

When running theodolite traverses in steepworkings, the most critical source of errors isnon-verticality of the principal axis oftheodolite which causes an additional incli-nation of the rotation axis of telescope andthus worsens substantially the accuracy ofangular measurements. The dependence ofthe error of a measured horizontal angle onthe inclination angle of collimating rays andinclination of an instrument axis can beexpressed by the formula:mIl = o[cosutanhf -cos(u -~)tanhr]

(5.13)

where mp is the root-mean square error of themeasured horizontal angle depending on theinclination of the principal axis of theodo-


As follows from formulae (5.12) and (5.13),the total error of angular measurement with nrepetitions will be:

J 2 2

2 2 m, mvm/J = Jm~, + m~.. = -2 2 + -(5.17)I v n n

The limb reading and sighting errors canbe calculated by the formulae:

t "' .0'mi = 2"J2 \J..vJ

mf} = 60"/v (5.19)

where t is the accuracy of horizontal circlereading and v is the telescope magnification.

Accuracy of angular measurements by themethod of sets. In this case, the accuracy ofmeasurements depends mainly on the errorsof signal sighting and circle reading. There-fore, the error in establishing each direction1S:

mIl = ~ (5.20)

and the error of a horizontal angle measuredin a full set is:

mIl = 0.5J4(mf + m~)

or

lites, signals and other instruments and byusing the appropriate methods of angularmeasurements.

Random errors mainly appear owing toinstrumental errors, incorrect setting of theo-dolites and signals, and incorrect sightingand reading. The specific environmental con-ditions in underground workings, inparticular, restricted space, water drip, anddust-laden, atmosphere, and also the spe-cifics of fixation of bench marks (in theground or roof) set forth additional requi-rements to the instrument setting and tech-niques of observation in angular measure-ments.

In view of these specific conditions anddifficulties in the performance of survey work,special care should be given to the centring oftheodolites and signals (especially when tra-verse sides are relatively short) and tomaking the observations strictly accordipg tothe adopted method, since these factors caninfluence substantially the accuracy of mea-sured angles.

Accuracy of angle measurements by thereiteration method. As may be seen from thedescription of the reiteration method, theangle 13 measured by n full repetitions isdetermined by the readings at and a4. Themagnitude of 13 is calculated by the formula:

B=a4-a1+R.360-o (5.14)

(5.21)

mIl = ~ (5.22)

2n

The error of the measured angle, mp ,caused by the limb reading error mi will bJ:

J m2 m2

-.!.-+~

n n

m =/In

5.11. Measurementsof Inclination Angles

In theodolite surveys of undergroundworkings, the inclination angles are measuredat the same time with horizontal angles.These are needed for determining the hori-zontal distances of the sides of theodolitetraverses and the elevations between the

If an angle is measured in n sets, the errorof the mean arithmetic value of that angle isdetermined by the formula:

5.11. Measurements of Inclination Angles 105

Fig. 5.22 Measurement of inclination angle of underground working by central-telescope theodolitl

4. The telescope is reversed, and the sameoperations are repeated with a different set-ting of the circle.

5. The magnitude of the measured incli-nation angle is calculated by one of theformulae:

FL -FR -180°(5.24)

2

v = FL -ZP (5.25)

v = ZP -FR -180° (5.26)

where v is the inclination angle; ZP is thezero point of a vertical circle; and FL andFR are the readings on a vertical circle withthe latter at the left ('face left') or at the right('face right').

If the readings FR, FL and ZP in calcu-lations of inclination angles are less than 90°,they should be increased by 360°.

Upon making angular and linear measu-rements at a station point 17, the theodolite

v=

traverse points. The inclination angle of theside of a theodolite traverse is essentially theangle between the collimating ray {sightingline) and its projection onto the horizontalplane. Suppose that we have to determine theinclination angle of a collimating ray 1-2passing through a point 2 fixed on a plumbline {Fig. 5.22). To do this, the followingoperations should be carried out.

I. The telescope of theodolite is sighted ona plummet hung at a point 18. The clampscrews of the limb and alidade are locked.Manipulating the tangent screw of the tele-scope, the hair cross of the telescope isaligned with the point 2 fixed on the plumbline.

2. The level bubble of a vertical circle levelis centred by the micrometer screw of thealidade, and the accuracy of sighting ischecked.

3. The readings are taken from the micro-scope.

Ch. 5. Horizontal Surveys of Underground Workings

is set up under the centre of a mark 18 tomake a check measurement oNhe inclinationangle in the reverse direction (onto the PQint17).

In measurements of inclination angles, it isalso required to measure the instrumentalheight i and the sighting height v which arethen used to determine the height differencebetween the traverse points and the dippingangle of the working, since the inclinationangle of a collimating ray does not alwaysdefine the dipping angle of a working.

Dipping angles larger than 50° can bemeasured by central-telescope theodolitesprovided with special attachments on theobjective and eyepiece or by eccentric-tele-scope theodolites. The procedure of angularmeasurements in this case is similar to thatdescribed above. An eccentric position of thetelescope (with eccentricity e) results howeverin that the measured angle v' differs some-what from the actual inclination angle v(Fig. 5.23). Let us demonstrate how an actualinclination angle v can be found from themeasured and known values v', I, and e. Thetriangles I-11-B and A-11-B in Fig. 5.23 havethe common' side lIB, and therefore, it maybe written:

I sin v = I' sin v' and I' = ji'=-'ii (5.27)

Fig. 5.23 Measurement of inclination angle byeccentric telescope

close to 90° or when the lengths of traversesides are less than 20 m, it is required tointroduce corrections for telescope eccen-tricity.

The accuracy of measurement of inclina-tion angles depends mainly on the errors ofsignal sighting in a vertical plane, mv , errorsof limb reading, mi, and errors mt which cane~

Ti

1sin v = 1 sin v' or sin v = sin vi

v(5.28) Table 5.7

Incli-

nation

angle

Error for telescope eccentricity withinclined length of traverse side, m

10 15 20 25

40°

50

60

70

80

214" 96"307 137448 198710 315

1455 650

35"

49

72

109

234

9"

12

18

78

58

2" 1"

3 2

5 3

8 5

15 9

It is known from the experience that theerror of measurement of inclination anglesincreases with an increase of inclination inthe measured direction and a decrease of thelength of traverse sides.

The corrections (in seconds) to the inclina-tion angles as measured by an eccentric-te-lescope theodolite of an accuracy of 30" aregiven in Table 5.7. As may be seen from thetable, when measuring the inclination angles

4"58

1226

5.12. Measurements of Traverses Side Lengths 107

appear due to inaccurate centring of the levelbubble of the vertical circle alidade (in. theo-dolites without compensators). Thus, theerror of measurement of an inclination anglein one full set can be determined by theexpression:

(.)

(5.29)m =" v 2

Fig. 5.24 Measuring steel tapeswhere 't is the scale division of the verticalcircle level tube; the nns errors mi and mv canbe determined by fonnulae (5.18) and (5.19).

The common material for measuring tapesis carbon or stainless steel. Some types ofsteel tapes are shown in Fig. 5.24.

The lengths of sides of theodolite traversesare usually measured by a tape held freely inair (catenary taping). The sides of a traverseare divided into intervals which are some-what shorter than the length of a measuringtape to be used. Plumb lines along a side are,as a rule, aligned visually. For measuring thelengths of sides in dipping workings, inter-mediate plumb lines are aligned by means ofa theodolite with the collimating ray directedalong the measured inclination angle. Marksin the form of movable knots and the like areprovided on the strings of plummets.

When chaining the intervals, the tape isapplied so that it does not touch the plumbbobs. In the extreme interval at the theo-dolite, the tape is applied to the horizontalaxis of rotation of the telescope. The readingson the tape are taken simultaneously at aplumb line and the horizontal axis of rotation

5.12. Measurements of SideLengths of TheodoliteTraverses

Length measurement is one of the mostimportant and labour-consuming operationsof theodolite traversing in underground wor-kings, Depending on the specifics of surveywork and the reqmred accuracy, length mea-surements can be carried out by using mea-suring tapes, light range finders and otherinstruments.

5.12.1 .Length Measurement byTapes

Steel tapes 20 m, 30 m and 50 mlong havefound wide use for length measurements intheodolite traversing. The most convenientamong them are 50-m tapes, since they makeit possible to measure in shorter time andwith greater accuracy.

Imf + m; + m:


The standardization error L\lst is takenaccording to the tape certificate.

Using these corrections, the corrected in-clined length 4" of a measured interval isdetermined, then the horizontal distance isfound by the formula 1 = 4" cos O whichincludes the inclination angle O measuredearlier.

When calculating the theodolite traversesof a reference net, the additional correctionsmust be introduced into the horizontal dis-tances in order to reduce these to the sea level(mean level of the surface) and Gaussprojection plane (see Para. 4.8.2).

where q is the mass of I m of tape, kg; Q isthe force of tape tension in measurements, N;and 11 is the measured length of an interval.

The temperature correction is determinedby the formula:Alt = 11 a (tm -tst) (5.32)

where a is the coefficient of linear expansionof steel; tm is the temperature of measu-rement; tst is the temperature at which thetape is standardized; and 11 is the measuredlength.

5.12.2. Standardizationof Measuring Tapes

Tapes for measuring the side lengths ofreference and survey nets must be stan-dardized in order that the relative error maybe not more than 1 :40000.

Measuring tapes are usually standardizedon a comparator, or check base. If this isnon-available at the mining enterprise, stan-dardization can be carried out by comparingthe tape with a new standardized tape pro-vided with a certificate. The certificate gives,as a rule, the corrections per metre and forthe whole length of a tape and the tempera-ture conditions and tension in standardiza-tion. The comparison of measuring tapes canbe carried out on a smooth surface whereboth tapes can be stretched at full length andtensioned by spring balances with a force notless than loo N.

The zero marks of the two tapes arealigned by means of a millimetre rule, afterwhich the deviation of the tape being checkedrelative to the standard one is measured atleast twice.

If the section being checked is shorter thanthe standard section, the deviation is thoughtto have the 'minus' sign, if otherwise, it hasthe 'plus' sign. The deviations thus measuredand the certificate data for the standard tape

of telescope or simultaneously at two plumblines. Since in most measuring tapes the firstdecimetre is graduated in millimetres and theremaining length of the tape, in centimetres,the readings with an accuracy to a millimetreare taken only at the initial end of the tape; atthe other end, the centimetre mark should bealigned with a plumb line. Readings are takentwo or three times, every time shifting thetape along the side being measured.

The length of each side in undergroundtheodolite traverses is measured twice, i. e.forward and back. For the back measure-ment, the intermediate plumb lines are shiftedby 2 or 3 m, which ensures the check ofmeasured lengths.

The accuracy of length measurements inmines is largely influenced by the errorscaused by the sagging of the tape under itsown weight, inaccurate standardization of thetape, difference of temperatures during mea-surements and standardization, poor aligningof plumb lines, and some other factors.

To obtain a greater accuracy of measuredlengths, which is of essential importance inthe construction of reference nets, certaincorrections are introduced into the measuredresults.

The correction for tape sagging can befound by the formula:

1095.12. Measurements of Traverses Side Lengths

same way as described earlier, but the devia-tions for each metre of the tape being checkedare determined by means of the scale plateson the check base. Upon completion of thecheck work, the certificate is filed for thetested tape.

A field check base can be arranged on asmooth area of ground. Two bench markswith centre lines are fixed in the ground at adistance of 100 m or 200 m from each other.The distance between the bench mark centresis measured several times by means of invaror steel wires with a relative accuracy notworse than 1 : 50000. Then the comparatorbase is measured by the tape to be checkedand the mean distance is calculated to deter-mine the standardization correction. In prac-tical measurements by the checked tape, thestandardization correction is introduced pro-portional to the measured length, and con-sidering the error of length.

A field check base can also be constructedin a mine. In that case, bench marks are

are used to compile the certificate of thechecked tape.

Two types of comparator, or check base,are employed in the mine surveying practice:stationary check bases for control of metreintervals and the whole length of tapes andfield check bases to standardize the wholelength of tapes.

A stationary check base (Fig. 5.25) is awooden shelf 3 to 20 m long, which ismounted on steel brackets along the wall of abuilding, underground working, etc. Theplace for a check base should be chosen sothat the temperature of air can be constantalong its entire length. An axial line is drawnon the top surface of the check base andscale plates with 0.5-mm divisions (Fig. 5.25a)are attached to it symmetrically in l-mintervals. One end of the tape is fastened tothe check base, whereas the other end ispassed over a pulley and loaded by a weightthat develops the required tension.

The standardization is done much in the


usually established in the side wall of anunderground working. The procedure ofstandardization is essentially as describedearlier.

or

5.12.3. Kinds and Causesof Accumulated Errorsin Measurementsby Meta!lic Tapes

Inaccuracies in the measurements of sidelengths in underground traverses can occurdue to gross, systematic and random errors.

Gross errors mainly appear owing to thecarelessness of persons engaged in surveywork (for instance, the omission of wholeintervals in long sides, etc.). These errors canbe revealed by repeated measurements.

Systematic errors obey a unique law ofaccumulation and measurement. They maybe either permanent (when both the sign andmagnitude of an error are known) or va-riable, i. e. with the magnitude varying fromone measurement to another.

An example of permanent systematic er-rors is, for instance, the error caused by poorstandardization of a measuring tape.

Random errors may appear irrespective ofthe instruments and measuring methodsemployed. The nature of their occurrence inindividual measurement is usually unknown.The probable sources of random errorsare uneven tension of a tape in variousmeasuremems, poor alignment of interme-diate plumb lines, uncertain readings on thetape scale, etc.

Let us find the expressions for estimatingthe random and systematic errors which canappear in length measurements.

Let the total effect of a number of randomerrors be such that the interval 1 is measuredwith the total root-mean square error ml'. Ifthe length being measured contains n suchintervals, then

mL = mr In (5.33)

I'

mL =m,JL/j/,since n = L/I.

Denoting m,/ j/ = a, we get:

mL = a JL (5.34),

As may be seen from this formula, therandom error of a measured side lengthincreases proportional to the square root ofL. The coefficient a is called the coefficient ofrandom influence; it can be determined expe-rimentally.

Depending on the influence of randomerrors, the relative error of length measu-rement decreases with an increase in thelength of a line:

mL,/L= a/JL (5.35)In order to estimate the systematic error,

let us suppose that the interval 1 is measuredwith a systematic error m. .Therefore, theentire length Lof a line, including n intervals,can be measured with a systematic error:mL = m.n

.ormL = m.L/I

.With m./l = b, mL = bL, i. e the systematic

error increases proportional to the length of aline.

Depending on the influence of systematicerrors the relative error of length measu-rement is constant for particular measuringconditions and independent of L:

mL /L= b.The total root-mean square error of mea-

surement of a side length depending on m,and m. can be determined by the formula:

mL =..ja2L+b2L2 (5.36)

The coefficients of random and systematicinfluence, a and b, can be found experimen-tally. To do this, the given length in a mine is

5.14. Detailed Survey of Underground Workings 111

5.14. Detailed Surveyof Underground Workings

measured with the common and higher accu-racy, and the results of more accurate measu-rements are considered to be faultless(true). After that, the difference between thecommon Li and more accurate measurements(LTi) is found:

d,=L.-L T ., , ,

Using this difference, it is possible to cal-culate a and b:

a= J ~ and b=0n -[L]

bLiwhere di = dj

Mine survey plans, profiles and sectionsshould represent all the elements and detailsessential for the geological and mine-en-gineering characteristic of a deposit: thegeometrical form and spatial location ofunderground workings, geological structureof a section or deposit, mechanisms andstructures in a mine, etc. Surveying ofthese elements, which is called the survey ofdetails, or detailed survey, consists in measu-ring the lines and angles that determine thelocation of the characteristic points of thesedetails relative to survey traverse lines. De-tailed survey can be carried out either at thesame time when the survey traverses arebeing run or at a different time.

The accuracy of location of detailsdepends on the object of surveying and thescale of the survey plan. If the results ofsurvey will be used for analytical calcula-tions, the accuracy of detailed survey mustcorrespond to the accuracy of analyticalcalculations.

Detailed survey for compiling a surveyplan should be done with an accuracy atwhich all details can be shown properly onthe scale of the survey plan. For instance, ifthe scale of a plan is 1/5000, the linearmeasurements in detailed survey can be madewith an accuracy of 0.5 m; for a plan scale1/1000, the accuracy of linear measurementsto 0.1 m is quite sufficient. The angularmeasurements in detailed surveys do notrequire an especially high accuracy: angularvalues can be read off with an accuracy to5-10'. Detailed surveys can be carried out bythe method of ordinates, polar method,method of cross bearings, etc. The first ofthem is however most popular in surveys ofpermanent and development workings.

When running a theodolite traverse in aworking, the clear cross section of the wor-king in each instrument station point is

5.13. Distance Measurementsby Light Range Finders

Light range finders are employed in minesurveying mainly in the case of the centra-lized construction of reference mine surveynets when the majority of sides of theodolitetraverses exceed 50 m in length.

The measurement of the length of a theo-dolite traverse by this method consists essen-tially in determining the time 't required for alight beam to cover the distance between thetwo points being measured in the forwardand back direction.

Light range finders have a light sourcewhich emits a narrow light beam onto thereflector placed at the other end of the line tobe measured; the reflected light beam enters alight detector. The signals from the lightsource and light detector are fed into arecording device. Since the light source andlight detector are combined and arranged inthe same point, the light beam covers twicethe distance being measured. Thus:D = v't/2

where v is the velocity of light in air and 't isthe time during which the light signal coverstwice the distance being measured.


~~

/x

~

,/

~,~O-.0

Fig. 5.26 Sketch of detailed survey by method of ordinates

dipping angles and capacities of seams(veins), probable tectonic disturbances andtheir main parameters, etc.

measured by a tape. The measured distancesfrom the theodolite centre to the right, left,top and bottom are recorded in the fieldbook.

The positions of the points of details aredetermined by measuring the distances fromthe beginning of a theodolite traverse side tothe perpendiculars drawn from these pointsonto that side and the lengths of the perpen-diculars proper (ordinates).

The density of measurements depends onthe curvature of workings. In detailed surveysby the method of ordinates, it is recommen-ded to choose two intervisible theodolitepoints so as to measure the distance betweenthem by a tape (such as points 17 and 18 inFig. 5.26). The zero mark of the tape shouldbe aligned with the projection of one of thefinal points of the traverse.

The distances 01' 02' etc. are measuredwith an accuracy to 10 cm and recorded inthe field book as an increasing total from thestarting point. The ordinates h1, h2, etc. aremeasured with an accuracy to 2-3 cm. Themeasured values oi, hi, the cross-sectionaldimensions of the working along the traverseand other details are written on the sketch(outline) of the working. Using the method ofordinates, detailed survey can be performedquite quickly, and its results can be trans-ferred easily onto the plan of a mine working.

Detailed survey should also fix sharp chan-ges of the bedding elements of a deposit,

5.15. Office Analysis of Resultsof Underground TheodoliteSurvey and Calculationof Point Coordinates

The office analysis of the results of anunderground theodolite survey includes thefollowing procedures:

(a) control of mine (field) books and pre-liminary analysis of the measured linear andangular values;

(b) calculation of horizontal distances;(c) determination of the closure error of

angles (angular discrepancy) and directionangles upon the distribution of this error;

(d) calculation of the increase of coordi-nates, determination of the linear discrepan-cy, and distribution of this discrepancy pro-portional to side lengths; and

(e) calculation of the corrected increases ofcoordinates and the coordinates of the pointsof a theodolite traverse.

For successful office analysis, the recordsin the field book and the book of calculatedcoordinates should be made accurately aridcarefully. It should be noted that these mine-engineering documents also have juridicalvalidity. As a rule, as the field books havebeen controlled and it has been established

5.15. Office Analysis of Results 13

For hanging traverses run twice,

1;/1 =2m /1 ~ perm v nl -1- n2

The discrepancy f /1 obtained in this way,provided that it does not exceed the permis-sible error, is distributed equally for eachmeasured angle, with an opposite sign. Aftererror distribution, the calculated directionangle of the final side in an open traverse andthe initial direction angle in a closed traversewill be true.

If the angular discrepancy exceeds thespecified permissible value f /1 ' the traverseangles must be measured anew.

The direction angles of sides of a theo-dolite traverse with measured left forwardangles can be calculated by the formula:an = an-l + /31 ::t: 180°

and with measured right forward angles, bythe formula:an = qn-l -/3r ::t: 180°

The horizontal distances of sides are calcu-lated by the formula:s = Scosv

where S is the inclined length of a side andv is the angle of inclination of that side. Withthe horizontal distances and direction anglesof theodolite traverse sides being known, it ispossible to determine the increases of rectan-gular coordinates by the formulae:dx = scosa = scosr

}dy = ssina = ssinr

that the results obtained are within thespecified allowances, the controller makescorresponding records in them. All erroneousrecords are struck out and the correctedvalues are written instead and signed by thecontroller.

The analysis of linear measurements isstarted from calculating the arithmetic meanof side lengths.

The preliminary analysis of angular mea-surements consists in calculating the meanvalues of measured angles. The checked meanvalues of angles and horizontal distances arewritten in the book of calculated coordinates,and the angular error {discrepancy) is thendetermined by various formulae, dependingon the kind of theodolite traverse. Forinstance, for an open traverse with measuredleft forward angles, the formula is as follows:f fJ = l80°n + !:13 -{l1f -l1in) -360° R

where n is the number of measured angles, l1inand 11 I are the direction angles of the initialand final side respectively; and R is an integeror zero.

For a closed traverse, the angular error isdetermined as the difference between theactual and theoretical sums of interior anglesof a closed polygon:f fJ = !:13" -!:13th

In that case, the discrepancy f fJ must notexceed the permissible angular error:

ffJ = 2mfJJnperm

Table 5.8

Measuredparameter

Quadrant

II ill IV

a, degrees

r, degrees~x

~y

0-90°

r=a

1270

Table 5.9. Calculation Sheet: Point Coordinates of Theodolite Traverse

Nos. Horizontal angles

of

points measured corrected

Directionangles a'

Tabulatedangles a' Natural values

Horizontaldistances

stan (1' orcotan (1'

cosa' sin a'

D

20' 00'00"-9"

30'43" 177° 30'34"177'

17 3034 17° 3D' 34" 23.468 0.953667 0.300863 0.315480-9"

00312 179 1790022

16 3056 16 3056 21.508 0.958743 0.284276 0.296509

3 80-9"

44 43 80 44 34

277 1530 82 44 30 20.809 0.126343 0.991987 0.127364-9"

1405 16513564 165

2622926 82 2926 26.367 0;130689 0.991424 0.131820-9"

5209 177 5200177

26021 26 80 2126 29.489 0.167505 0.985871 0.169905

6 183

-9"

1527 1831518

263 36 44 83 36 44 27.361 0.111257 0.993792 0.111952

94-9"

3147 94 31 38~s

149.0021780822

c

Lf3m=1058 0925

Lf3perm=10580822

IIlPnM = 2mp In = 2 x 20" J7 = 1'46"

111=+1'03"

Increases of coordinates, m Coordinates

Nos. of

points

D

2000.000 2000.000

+5

22.381

+I

7.060 + 7.060 7.061+ + + 22.386 +

2022.386 2007.061 2+5

20.620

+I

6.114 +6.114+ +"20.625 + 6.115+

2043.011 2013.176 3+5

2.629

+I

20.642 +2.629 + 2.634 -.20.641+

2045.645 1992.535 4+6

3.446

+1

26.141 -3.446 3.440 -26.140

2042.205 1966.395 5+6

4.940

+2

29.072 -4.939 -4.934 -29.070

2037.271 1937.271 6+6

3.044

+1

27.191 -3.044 3.038 -27.190

2034.233 1910.135~/1x

34.2001:L\y

89.872 + 34.233 -89.865+.

34.233 89.865 c+

fAx = -0.033, JAy = -0.007

f.=~=0.034, t=s

0.034~=~

~s 3000~ = ~ < -,

4400 3000

8.


The linear discrepancy,h, of a traverse lineis found by the formula:

h = ~1y + f1x

Permissible linear discrepancies are speci-fied depending on the purpose of theodolitesurvey, kind and length of traverse line, andthe availability of fixed points.

If the linear discrepancy is within theperIilissible value, the errors in coordinateincreases are distributed with an oppositesign proportional to the lengths of sides:

0.-. =&"

The quadrantal bearings r and the signs atAx and Ay can be found in Table 5.8.

Upon the calculation of coordinate in-creases Ax and Ay. it is recommended tomake check calculations by one of the formu-lae:Ax = Aycotanr

orAy = Ax tan r

The calculation of coordinates for an opentheodolite traverse run between points C andD (see Fig. 5.20) with the known coordinatesXc, Yc and XD' YD can be done as follows:

Xi = XD + AXD-1 ' Y1 = YD + AyD-1

X2 = Xi + AX1-2 ' Y2 = Y1 + Ay1-2

Xc = X7 + Ax7-c YC = Y7 + Ay7-C

Adding the left- and right-hand parts ofboth columns, we get:

xc=xD+LAxYc = YD + L Ay

whenceLAxcalc = Xc -XD (5.37)

LAycalc = yc -YD (5.38)

Since the measurements of angular andlinear values in theodolite traverses involvecertain errors, the left-hand parts in formulae(5.37) and (5.38) are not equal to their right-hand parts, and therefore

-D

LAxcalc -(Xc -XD)1D

LAycaIc -(yc -YD)1

ayi [S] ~i

.0 =&s.Axi [S] ,

Noting the calculated errors °Ay' and °Ax", ,

the corrected increases of coordinates arethen determined by the formulae:

L\x'. = L\x. + 0., , -aX.

,

L\ y '. = L\y .+ 0.1 , -ayi

The coordinates of the points of a theodo-lite traverse are found by the formulae:x. = x.

1 + L\x'., 1- -1

Yi=Y~l:!:L\y'i

The calculations of coordinates of under-ground theodolite traverse points are carriedout by the formulae given above by one ofthe following methods: with the use of loga-rithmic tables; with the use of desktop calcu-lators and tables of trigonometric functions(Table 5.9); or by using electronic computersand special standard programs.

f/1x (5.39)5.16. Accumulation of Errors

in Underground TheodoliteSurveys!£\y (5.40)

where f &x and f &yare the linear discrepanciesof coordinate increases of an open theodolitetraverse along the axes of abscissae andordinates respectively.

The positions of points in an undergroundsurvey are determined with certain errors, sothat the calculated coordinates of the pointsof a theodolite survev do not corresDond to

5.16. Accumulation of Errors 117

Since angles are measured independentlyof the side lengths of a traverse, the coordi-nate errors depending on Mx .My and Mx .My can be determined sepa&tely.fJThen it ;spossible to calculate the total errors of thecoordinates of the point N by the followingformulae:

M -/~. -.:x -", "- '.

the actual positions of these points in space.As the number of measured angles and thelengths of sides in traverses are increased,these errors are accumulated, i. e. the pointswhich are more distant from the beginning ofa traverse are determined with an ever increa-sing error. The error in the determination ofthe final point of a traverse depends substan-tially on the configuration (shape) of a trav-erse line and mainly on whether the traversecontains the sides of a short length andangles close to 90°.

M~p + M;.

My=J~~The total error of the planimetric position

of the point N will depend on the errors ofmeasured angles, M p .and measured sidelengths, M s:

M2 = M~ + M; = Mi + M; (5.41)

5.16.1. Root-Mean Square Errorsof the Position of Final Pointof Free Theodolite Traverse

Suppose that a free theodolite traverse isrun from the initial fixed point I (Fig. 5.27), inwhich the left forward angles 13i and horizon-tal projections of sides Si are measured. It isrequired to determine the errors of the coor-dinates of the point N of the free traverserelative to a point 1. The traverse is run froma side II-I with fixed values of coordinatesand a direction angle (l1I -I. The error of thecoordinates of that point is the sum of theerrors of measurement of horizontal angles,M /1' and of side lengths, M s.

smceM~ = M~p + M;p and M; = M~s + M;s

The errors Mx and M y can be determinedp p

graphically. Let the angle 131 be measuredwith the rms error mp (see Fig. 5.27). In thatcase the polygon 1-2,1. .., N will be turnedthrough an angle mp about a point 1, so thatthe point N will oc6upy a new position N'.The displacement of the point N can befound from a rectangular triangle 1 N N' :NN' = R1 tan mp1 (5.42)

Since at small angles it may be taken thatm

tan 13 = 13"/p", we have: NN' = -!!..l-R1. Thep

displacement of the point N along the axes xand y will then be:N'N" = (mp /p) R1 and N'N" = (m

p /p) R11 y 1 xwhere R1 and R1 are the projections of theshortest distance R1 from the polygon vertex1 to the point N onto the coordinate axesand p" = 206265".

If all horizontal angles are measured withthe same accuracy mp1 = mp2 = ...= mp; == mpn = mp, i. e. if any angle 13; is measured

with the same error mp;, it can then bewritten that the displacements of the point N

Fig. 5.27 Detern1ining errors accumulation infree polygon


traverse is displaced along a straight line £iconnecting that vertex with the initial point 1.Then, the errors along the coordinate axes forthe final point N will be:

Mx = b£N and My = b£N (5.45)s x s .

along the axes Ox and Oy are respectivelym.. m..~ R. and --1:1 R. .

p 'y p 'x

The total displacement of the point Nalong the axes x and y under the influence ofrandom errors of measurement of all angleswill be:

sys sys

where LN and LN are the projections ofx y

closures LN onto the axes of abscissae andordinates respectively.

Using formulae (5.44) and (5.45), we canwrite:

nM2 = a2 ~ s.cos2a + b2L2

Xs L.. , I N;

/=1

(5.46)n

M2 =a2 ""' s.sin2a.+b2L2y. £.., , I Ny

i=l

"M2 = M2 + M2 = 02 ~ S + b2 L 2

.x. y. L.. t N

i=l(5.47)

" -sys -

where Mx and M y are the errors of thes s, ,

coordinates of the final point of a free poly-gon caused by the influence of random errorsin length measurements and Mx and M ys s

sXs sysare their errors caused by the Influence of

systematic errors in length measurements.The random components M; and M y2

s s, ,

can be found by the formulae:n

M; = a2 ~ sj cos2a.s L.. I

1 j=l

n+ a2 ~ S cos2a. + b2L2

£., i. N;=1 .

(5.48)

(5.44)

"02 ~ s.sin2a. + b2L2

£... I I N

i = 1II

M 2 2 L .2y = a S. sm a..' Ir i=l

Under the influence of a systematic error oflength measurement, each ith vertex of a

m2 " "M2 = --7 L Rf + 02 L Si + b2L~

p i=l i=l

The total error of the coordinates of thepoint N caused by the errors of linearmeasurements will be:

Let us now find the errors of the coordi-nates of the final point of a free theodolitetraverse, M~ and M; , which are caused bythe errors in Sthe meas~rement of side lengths.The errors Mx and My are the sums of therandom and systematicSerrors in the measu-rement of each polygon side. Therefore, wehave:

M~ = M~ + M~s s sr sysM2 = M2 + M2

y. y, Y. Using formulae (5.43) and (5.46), we canobtain expressions for the root-mean squareerror of the position of the final point N of afree polygon in the coordinate axes:

5.16. Accumulation of Errors 19

5.16.2. Root- Mean Square Errorof the Position of FreeTraverse Point in the Knownand Perpendicular Directions

In practical surveying, it is often requiredto determine the errors in the positions ofpoints of a free polygon relative to a criticaldirection. For instance, when a working isbeing driven towards an abandoned section,it is essential to know the error of theposition of the face in the direction of theworking being driven; when driving a work-ing from both ends, it is essential to know theconnection error in the direction perpen-dicular to the working axis. Suppose that theaxis x' of a rectangular system of coordinatescoincides with the direction of driving ofa working, CD (Fig. 5.28a) or is perpendicularto the direction AB of a working being drivenfrom both ends (Fig. 5.28b). Let the chosensystem of coordinates be denoted x'y'.

According to formula (5.48), the rms errorof the position of a face relative to the known(specified) direction M x' can be expressed bythe following formula:

mf32 n nM2, = -~ R~ + a2 ~ s.cos2a' + b2L2,x 2 £... 'y' £... I I x

p 1=1 i=l(5.49)

where R; , is the projection of the distancebetween the vertex i and the final point ofa polygon onto the direction perpendicularto that for which the error M x' is determined;a; is the angle between the line Si and thedirection relative to which M x' is determined;and 4' is the projection of the closing lineL onto the axis x', i. e. onto the directionrelative to which M x' is determined.

The terms Ry' and sicos2a'; can be deter-mined graphically.

5.16.3. Root- Mean Square Errorof Direction Angle of Sideof Free Theodolite Traverse

The direction angle of the nth side ofa theodolite traverse can be calculated by theformula:

a" = ao + ~1 + ~2 + ...+ ~" I 180° x n

where ao is the direction angle of the initialside of a traverse and ~1' ~2' ..., ~" are themeasured angles of the traverse.

Let us denote: mIl' mIl ' ..., m Il the rms1 2 "errors of measured angles; ma the rms error

"of the direction angle of the nth traverse side;and ma the rms error of the direction angleof the rnitial side.

(b)

Fig. 5.28 Driving underground working: (a) in direction of worked-out sections; (b) in working drivenfrom both ends in direction A-B.


Then, the fIllS of the direction angle of thenth side of a traverse will be:

man = JI-=i (5.50)

(5.51)

If the angles are measured with the sameaccuracy, then m. = m(J ;;;:

Considering theO rms error of the directionangle of the initial traverse side, m~- , the rms

, / -.2 , 2+ 2man = V mao -r nm/i

Chapter Six

Vertical Surveys in Underground Workings

6.1. General

Vertical survey, or levelling, is a surveyprocedure in which the height differences(elevations) of some points over others aremeasured in a certain sequence, and then therequired heights of points are calculated fromthe heights of initial points and the heightdifferences measured.

Vertical surveys are carried out in order todetermine the height marks of individualpoints established in underground workings,to assign the specified slope (grade) to wor-kings, to plot longitudinal and vertical profi-les and sections, to determine th~ heightmarks of the characteristic points of deposits(seams); these measurements are essential forthe solution of mining geometry and minegeometrization problems.

Vertical surveys can be made by twomethods: (a) geometric, or direct, levellingand (b) trigonometric, or indirect, levelling.The former method is employed in under-ground workings with small inclination ang-les (up to 5°) and the latter, in steeperworkings.

Levelling reference nets are extended allover the mining field and are later used as thebasis for vertical surveys in undergroundworkings. Additional levelling lines are runupon advancing the main workings through500 m (for survey scale 1/2000) or 300 m (forsurvey scale 1/1000).

The height control in mines is ensured bybench marks set in the solid rock in the footwall, side walls and roof of workings or in the

foundations of stationary underground in-stallations and structures. The permanentstation marks or polygonometric and theo-dolite traverses can also serve as heightcontrol points. The height transfer by geo-metric levelling should satisfy the followingrequirements:

(a) the discrepancies of measured heightsof points should not exceed 50 mm Jfin polygonometric traverses or 80 mm JLin theodolite traverses (where Lis the lengthof a traverse line, km);

(b) staff spacings should not exceed 200 min length and differ from one another bymore than 10 m;

(c) levelling lines between the initial benchmarks should be closed or run forward andback;

(d) the discrepancies of height differencesat a station, as read off on the black and redface of staffs or at two different settings of thelevel instrument, should not exceed 10 mm;and

(e) before starting the levelling procedure,the available station points should bechecked for stability.

The discrepancies between the height diffe-rence established earlier and the test oneshould not exceed 10 and 20 mm respectivelyin polygonometric and theodolite traver-ses.

When transferring the height marks inunderground workings. by trigonometric le-veiling, the following accuracy requirementsshould be observed:

(a) the permissible discrepancy of a zero

122 Ch. 6. Vertical Surveys in Underground Workings

"-,

..'5

~I>

-11°1- 150 J.1251.

Fig. 6.1 Special station plugs used in under-

ground workings

footwall (Fi"g. 6.la) and side walls of workings(Fig. 6.lb). The bench marks set in thefootwall are preferable, since they are lesssubject to deformations due to rock displace-ment during exploitation of deposit.

Bench marks should be established at eachlevel of a mine and preferably in places lessprobable to be disturbed by stoping. As arule, bench marks are established in pitbottom and main horizontal workings so asto provide a levelling control net within thelimits of the entire mining field.

For the identification of bench marks,marker plates are nailed to mine liningsupports, which bear the number of a benchmark and a letter M which indicates that thebench mark in question is an elevation point,rather than the point of a plan control net. Incases when marker plates cannot be fastenedto mine lining, they are replaced by cor-responding inscriptions made in a fast painton the mine lining or side wall rock.

6.2. Levels

All existing levelling instruments, or levels,can be divided into two main types by themethod of levelling of the sighting axis:instruments with a level tube on the telescope(dumpy levels) and those with a tilting anglecompensator (automatic-aligning, or simplyautomatic levels).

offset (horizon point) in the measurements of (.)inclination angles is 1.5' in polygonometrictraverses and 3' in theodolite traverses;

(b) the discrepancy of height differencesdetermined for a line by levelling forward andback should be not more than 1/2000 of theside length in polygonometric traverses or1/1000 in theodolite traverses;

(c) the discrepancy of two measured heightsof a theodolite and signals should be notmore than 5 mm in polygonometric traversesor 10 mm in theodolite traverses; and

(d) the discrepancy in the height differencesof the entire line of levels in polygonometrict~aversing should be not more than

Ah = [s]/4 v'l/n + siwo/3

where [s] is the total inclined length of theforward and back traverse, m; n is the totalnumber of sides in the forward and backtraverses; and O is the mean inclination angleof traverse sides; in theodolite traversing,this discrepancy should be not more than120 mm JL, where L is the traverselength, km.

Side lengths should be measured in accor-dance with the specifications for linear mea-surements in polygonometric and theodolitetraversing (the discrepancies between twomeasurements should not exceed respectively1/3000 and 1/1000). Vertical angles are mea-sured at two different positions of the circleand in the forward and back direction. Theheights of the instrument and signals aremeasured twice by a metallic tape. The heightdifference for each traverse line is determinedby levelling forward and back.

The heights of the points of the survey netare determined by using polygonometric sta-tion marks as the initial points.

The bench marks to be set in the footwallor roof of workings may be of the samedesign as the station marks of undergroundhorizontal reference nets. Special station plugsand marks can also be used for setting in the

6.2. Levels 123

96.2.1. Dumpy Levels

Level type N-3 (Fig. 6.2a) is an instrumentintended for technical levelling. Its maincomponents are a telescope 13 with a cylind-rical level tube attached to it; a telescopesupport 10 mounted on a vertical axis; atriangular plate (tribrach) 7 with foot screws6; and a spring plate (trivet stage) 5 having athreaded hole for an attachment screw bymeans of which the instrument is fastened ona tripod.

(a)

.13 2

Fig. 6.3 Level type N-IOL (USSR)

The cylindrical level tube with the scalevalue of 15" is arranged in a box 1 togetherwith an optical prismatic system whichbrings the images of the ends of level bubbleinto the field of view of the telescope (Fig.6.2b). The sighting axis of the telescope canbe arranged truly horizontally by manipula-ting the levelling screw 9 until the images ofthe bubble halves are perfectly coincident.The cylindrical level tube is provided withfour adjusting screws covered with a lid.

The instrument has an additional circularlevel tube 8 with three adjusting screws forrough adjustment of the vertical axis into atruly vertical position. For rough sightingon an object, the telescope can be turned inthe horizontal plane manually when theclamp screw 3 is unlocked; precise sighting isdone by locking the clamp screw 3 andturning the sighting (azimuth) screw 4. Theimage of cross hairs in the view field of thetelescope is made sharp by rotating thediopter ring of an eyepiece 12. The telescopeis focussed onto a staff by means of afocussing wheel 11. Tough sighting of thetelescope on a staff is made by using a vane 2.

Level type N-I0L (Fig. 6.3) is a small-sizedFig. 6.2 Level type N-3 (USSR): (a) general view;(b) field of view


Fig. 6.4 Level type NiO60 (GDR): 1- telescope;

2-sphericallevel; 3-pivoting mirror; 4-cylindri-callevel

Fig. 6.5 Level type Ni-Bl (Hungary): l-tele-scope; 2-cylindricallevel tube in casing; 3-scalemicroscope eyepiece; 4 -levelling screw; 5- endlesssighting screw

instrument for technical levelling and has thefollowing characteristics: telescope magnifica-tion 23, scale value of cylindrical level (at 2mm) 45*, that of circular level 10', stadiafactor loo :t 1 %, and scale value of thehorizontal circle (limb) 10.

The instrument has rotatable portion con-sisting of a telescope 9, cylindrical level with aprismatic system, 8, circular level 3, levellingscrew 4 for precise horizontalization of thesighting axis, and a stationary portion with ahorizontal circle 7.

The prismatic optical system brings theimage of the ends of level bubble into the fieldof view of the telescope; these images must bemade coincident by means of the levellingscrew before taking a staff reading.

The graticule (cross hairs) has a verticalhair and three horizontal hairs of which thetwo extreme (shorter) ones serve for distancemeasurements (stadia hairs). A sharp image ofthe cross hairs is obtained by turning thediopter ring 2 of the eyepiece and a sharpimage of a staff, by turning the focussingknob 1.

For setting up on a station point, theinstrument is mounted on the ball-and-sockethead of a tripod 5 so that the bubble of thecircular level will be in the centre.

For measuring horizontal angles, the tripodis set above the centre of a bench mark bymeans of a plummet. The limb readings aretaken by an index arranged in a window 6.

Level type NiO60 manufactured by CarlZeiss, Jena (GDR) is a small-sized instrument0.9 kg in mass (Fig. 6.4). It can transfer heightmarks with a root-mean square error of :t 6mm per kilometre of a level line. The shortestsighting distance is 1.5 m. The instrument isquite convenient for underground applica-tions. The telescope is of the internal-focussingtype with the field of view wider than 2°. Thecylindrical level with the scale value 60" isprovided witq a pivotable mirror.

Level MOM Ni-Bl is manufactured inHungary (Fig. 6.5). All sensitive parts of the

6.2. Levels 125

instrument are dust- and moisture-protected.Rough sighting is done manually and precisesighting, by a sighting device. The level hasno clamp screw.

When measuring height differences by aNi-BI level, the rms error does not exceed:!: 3-4 mm per kilometre of a level line. Theinstrument is provided with a levelling screw.The horizonta position of the level tube iscontrolled by the method of prismatic align-ment of the ends of level bubble.

The instrument is provided with a horizon-tal glass limb of 76 mm in diameter and scalevalue 1°. The readings are taken by means ofa scale microscope whose eyepiece is arran-ged near the telescope eyepiece. With themicroscope scale value 10', the accuracy ofreading is 1'.

6.2.2. Test and Adjustmentsof Dumpy Levels

T he axis of a circular level must be parallelto the rotating axis of an instrument. Thebubble of circular level is brought into thecentre by means of foot screws (for level typeN-IOL, by moving the instrument on theball-and-socket head of tripod). The upperportion of the instrument is then turnedthrough 180°. If the bubble does not movefrom the centre, the condition is satisfied. Ifotherwise, the bubble is moved by adjustingscrews towards the zero point through halfthe deviation arc and then brought into thecentre by operating the foot screws (for leveltype N-IOL, by moving the instrument on thetripod head). The test and adjustment proce-dure is then repeated.

T he vertical hair of the graticule must beparallel to the rotating axis of the instrumentand the horizontal hair, perpendicular to thataxis. The rotating axis of an instrument isfirst arranged truly vertical. The vertical hairis sighted on the line of a plummet hung at adistance of 20-25 m from the level instrument.The condition is satisfied if the. vertical hair

coincides fully with the plummet line. Ifotherwise, the eyepiece of telescope should betaken off to allow access to the graticulemount which is fastened by three screws. Thetop and bottom screws must be slackened bya full turn and the mid one, by a quarter-turnto shift the cross-hair plate if needed. Thenthe telescope eyepiece is set in place tocheck the position of the vertical hair. Uponthe adjustment of the cross-hairs, the screwsof the mount must be tightened (first the midscrew and then the top and bottom screws),after which the telescope eyepiece is fastenedin place.

T he sighting axis of the telescope must beparallel to the axis of cylindrical bubblelevel. This is the principal condition to besatisfied by a level. The test is carried out bythe method of double levelling forward be-tween points A and B arranged at a distanceof 50-75 m from each other and fixed byspikes or pegs. A staff is set up on one of thepoints, say, B, and a level instrument, on theother (A) (Fig. 6.6a). With the horizontalposition of the bubble level axis, the readingai is taken on the staff in the point B and theheight Vi of the level instrument is measured.Then the level and staff are interchanged totake the reading a2 on the staff and measurethe height V2 of the instrument in the newposition (Fig. 6.6b).

If the sighting axis is not parallel to thebubble level axis, but makes an angle i withthe latter, i. e. the sighting axis is nothorizontal, then the readings taken on thestaff will contain an error x and the truereadings will be as follows:a'i = ai + x

}, (6.1)a2 = a2 + x

Denoting the height difference of the pointB over A as h, we can find from Fig. 6.6 that:h = Vi -a'i = vi -ai + x (6.2)

orh = a~ -V2 = a2 + x -v2 (6.3)


(al

corrected as follows. By operating the level-ling screw, the horizontal hair is set on the

readinga2 + sjp" (6.6)

on the staff set up in the point A or on the

readingat + sjp" (6.7)

on the staff set up in the point B. Then, theimages of the ends of the level bubble arealigned by means of adjusting screws. Thistest can also be made by levelling the samepoints A and B from the mid forward.

The level instrument is set up at equaldistance from these points, the staffs are setup in the points A and B, and the readings aand b are taken on them (Fig. 6.7a). If thesighting axis is parallel to the bubble levelaxis, then h1 = at -b1; if otherwise, h2 == a2 -b2. If the instrument is set up at equaldistances from the staffs, then a2a1 == b2b1, and therefore, h1 = h2 = h, i. e. thetrue height difference is obtained irrespectiveof whether the test condition is satisfied. Forbetter accuracy, the height difference is mea-sured two or three times changing the instru-ment horizon, and their mean value hm istaken as the final result.

~

Fig. 6.6 Check of parallelism of sighting axis andaxis of cylindrical bubble level by double levelling

forward

2s ,--,

where p" = 206265" and s is the distancebetween the points A and B, Inm. The angle ishould be measured at least twice, with thediscrepancies between the measured valuesnot more than 5". The final value is taken asthe arithmetic mean of all measurements.

If the angle i has been found to be greaterthan 10", the non-parallelism of the axes is

Fig. 6.7 Check of parallelism of sighting axis andaxis of cylindrical bubble level by double levellingfrom mid forward

1276.2. Levels

(a}

(bl.~ O -=F::: r' O Zl

E , r ZI

s ~ '

=='i=i1 ~ z 1£ -£I , ,

p ZI

Id)

=40~~ ~ J~z

v ~z(e)

Mter that, these points are levelled forwardupon setting up the instrument over one ofthese points, say, A (Fig. 6.7b). In that case,the height difference will be:

h2=v-b3 (6.8)

where v is the height of the level instrumentand b3 is the reading on the staff set up in thepoint B.

If the discrepancy between the height dif-ferences measured by levelling from the midforward is less than 4 mm (x ~ 4 mm), thesighting axis of the telescope can be regardedto be parallel to the axis of the cylindricallevel. Otherwise, it is required to calculate thetrue reading on the staff set up in B from thetrue height difference (hm) obtained by thelevelling from the mid and the height of theinstrument v, by using the formula:b~ = v -hm (6.9)

after which the sighting axis of the telescopecan be adjusted parallel to the bubble levelaxis by the method described above.

Fig. 6.8 Optical schemes of level compensator:6.2.3. Automatic Levels

Level instruments with cylindrical bubblelevels require careful levelling before opera-tion and continuous checking of the bubbleposition when taking readings. This draw-back is eliminated in automatic-aligning (orsimply automatic) levels in which the sightingline of telescope is automatically horizonta-lized by means of a special compensator(stabilizer-compensator) of a mechanical, op-tical or optico-mechanical type.

Let us consider the schemes of stabilizationof the sighting line by compensators in mo-dem automatic levels. Suppose that the sigh-ting line of the telescope is in a truly horizon-tal position zz 1 (Fig. 6.8.a). In this position ofthe axis, the reading on a staff will be correct.Let the sighting axis of the telescope be nownon-horizontal and make an angle E with thehorizontal plane (Fig. 6.8b). In that case, thecentre of cross hairs will be displaced from

the horizontal line and occupy a position Z'l'Since the cross hairs are usually arranged inthe rear focus plane of the objective, thedisplacement Zlz'l of its centre can be exp-ressed as ZlZ'l = 1 tan £ or, since the angle £ issmall, ZlZ'l ~I£, To take a correct readingwith an inclined position of the sighting line,the cross-hair centre should be displaced insome or other way from the horizontal lineand be in a point z l' This procedure isperformed by compensators whose principalschemes will be discussed below,

1, The compensation 1£ can be introducedby displacing the cross hairs from a point Z'linto Zl by turning the level PZ'l on a point Pthrough an angle £' (Fig, 6.8c).

2, The image of a staff (Fig. 6,8d) can bedisplaced so that the true staff reading isaligned with the centre of cross hairs (comnen-


-I(a) (b)

~ 7 8\ " ) 9

--tr

10"

-11

Fig. 6.9 Level type N-I0KL (USSR): (a) general view; (b) optical scheme of compensator

sing. The instrument is provided with ahorizontal circle 3 having 1° limb divisions.Index readings can be taken with an accuracyto 0.10. The instrument has no azimuth screwand the telescope is sighted onto objects byturning the instrument body by hand. Thetelescope is focussed by a knob 2.

Rough levelling of the instrument is effec-ted by means of a circular bubble level 5 withthe scale division 10'. The cross-hair mount isprovided with adjustment screws to correctthe position of the sighting axis. The devia-tions of the cross hairs from the true verticalor true horizontal position can be correctedby turning the entire eyepiece unit uponslackening the clamping screws.

The prismatic compensator of the instru-ment ensures the horizontal position of thesighting axis at the inclinations of the instru-m...n~ support up to::!: 15'. The optical schemeof a level is essentially as follows (Fig. 6.9b).Upon passing through the objective 6, lightrays fall onto the reflecting faces of a largerpentaprism 7, change their direction by 90°,and enter the sensitive element (rectangularprism) 11 of the compensator. Upon doublereflection in the prism 11, light rays enter asmaller pentaprism 8 where their direction

sation with rotation of the sighting raythrough an angle EJ.

3. The sighting line is displaced parallel toitself to pass through the centre of cross hairs(Fig. 6.8e).

According to the compensation schemesshown in Fig. 6.8c and d, the lever oroptical system placed in a point p for thecompensation of an inclination angle mustsatisfy the condition fE = SE'; and for theschemes in Fig. 6.8e, the required condition isf = ks, where E' is the angle of deviation of theray by a compensator, s is the distance fromthe compensator to the cross hairs or thelength of the path of sighting rays from thepoint of incidence onto the optical system(prism or mirrors) of the compensator to thecross hairs, and k is the compensation factor(k = E' IE). The compensators of modernautomatic levels ensure the compensation ofthe sighting axis within the angles from:!: 6'to :!:40'.

Automatic level type N-1OKL (Fig. 6.9a) isintended for technical levelling with a root-mean square error of 8-10 mm per kilometreof a single run.

The direct-image telescope (I, 4) of theinstrument is placed in a heat-insulated ca-,

1296.2. Levels

is changed again by 90° and finally get intothe lens system 9, 10 of the eyepiece. Thepentaprisms are fixed and the rectangularprism is mounted in a tilting frame suspendedon two bearings. The axis of suspension ofthe rectangular prism is chosen so that thedistance from the main rear plane of theobjective to that prism is equal to the opticaldistance from that prism to the cross hairs. Inthat case the coefficient of angular magnifi-cation of the compensator is k = 13/a = 2,where a is the inclination angle of the telesco-pe and 13 is the deviation angle of the sightingray of the compensator.

The telescope is focussed by means of afocussing knob 2 which moves the rectan-gular prism 11 vertically in a slide.

Level N-3K;Fig. 6.10) is intended for classIV and techJlical levelling. It can transferheights with a root-mean square error of::!: 3 mm per kilometre of a level line. Withthe distances between the level and staffs upto 100 mm, height differences can be mea-sured with an rms error within::!: 3 mm.

The instrument is provided with an optical(prismatic) compensator having an operatingangular range::!: 15'. The collimation line ishorizontalized automatically with an accura-cy to ::!:0.4". A circular bubble level with 10'scale graduations facilitates rough setting ofthe instrument axis into the vertical position.

The instrument has a horizontal circle witha scale microscope, w,hich makes it possibleto employ the horizontal circle for controlsurvey and tacheometric survey on flatterrain.

The optical scheme of the instrument isillustrated in Fig. 6.10b. The telescope properconsists of a front lens 1 and focussing lens 3of the objective, cross hairs 5, and an eyepiece6. The compensator is arranged between thefocussing lens 3 and cross hairs 5 and com-prises two prisms 4 and 7, the former being

Fig. 6.10 Level type N-3K (USSR): (a) generalview; (b) optical scheme of compensator

9-1270


fastened internally in the telescope tube 2and the latter suspended on crossed steelwires 8. The oscillations of the compensatorsuspension are damped by a piston-type airdamper 10. The steel wires intersect in thecentre of gravity 9.

Level NiO25 (GDR) is intended for techni-cal levelling and, if employed under normalconditions, gives a root-mean square errorwithin :t2.5 mm per kilometre of a doublerun (Fig. 6.1 la). The sighting line is hori-zontalized automatically by a compensatorarranged between the focussing lens andeyepiece of the telescope and consisting oftwo rectangular prisms 1, 3 which are moun-ted on a pendulum 4 and a fixed roof prism 2(Fig. 6.llb). If the instrument is inclined by acertain angle E, the pendulum will alsodeviate by the same angle E under the actionof the force of gravity. This arrangement

(a) .3

ensures automatic horizontalization of thesighting line. A double-action air damper5 brings the pendulum to the state of rest inless than I s. The working angular range ofthe compensator is::!: 10'. The mean error ofthe horizontalization of the sighting axis isnot more 0.5". The instrument compensatoris insensitive to jolting during transportation.

Precise aiming of the level at a target iseffected by an endless sighting screw. Theinstrument has a horizontal circle with 10°divisions. Ocular estimation can be madewith an accuracy to I '.

Level type NiOO7 (GDR) is intended fortechnical and precise levelling (Fig. 6.12).Precise levelling is carried out by using aparallel-plate micrometer provided on theinstrument and precision staffs with invartape. When used for technical levelling, i. e.without the parallel-plate micrometer andwith centimetre-graduated staffs, the instru-ment gives a mean error of::!: 2 mm perkilometre of a level line; in precise levelling,the accuracy is ::!:0.5 mm.

The pendulum-type compensator of thelevel NiO07 has an air damper and cancompensate tilting angles up to::!: 10'. Roughlevelling of the instrument is effected by

Fig. 6.11 Level type NiO25 (GDR): (a) generalview; 1-endless sighting screw; 2-circular bubble

level; 3-rnirror; 4-telescope focussing screw; (b)optical scheme of compensator

1316.2. Levels

(a)

Fig. 6.12 Level type NiOO7 (GDR): 1- telescopewindow; 2-telescope; 3-focussing screw; 4-clam-ping handle; 5-sighting screw; 6-circular bubblelevel; 7 -micrometer drum

means of a circular bubble level. The telesco-pe has a large magnification (31.5 X) and canbe aimed with a high accuracy.

The level is manufactured in two versions:with and without the horizontal circle. Thehorizontal-circle microscope is located justunder the telescope eyepiece. The glass limbof the horizontal circle has a scale value of10', but ocular estimation can be made withan accuracy to tenths of that value.

Level type Ni-B3 (Hungary) can be emp-loyed for class III and IV and technicallevelling (Fig. 6.13). The root-mean squareerror of levelling is not more than::!: 2 mmper kilometre of a level line. The instrumenthas a glass limb with a scale microscopewhich reads with an accuracy to::!: 1 '. Therotation axis of the instrument is set uprightby means of a circular bubble level with thebubble image being transferred into the fieldof view of the telescope. .

Fig. 6.13 Level type Ni-B3 (Hungary): (a) generalview (l-telescope eyepiece; 2-optical microscopeeyepiece; 3- endless sighting screw; 4- focussingscrew; (b) optical scheme of compensator

The compensator of Ni-B3level (Fig. 6.l3b)has three rectangular prisms, two of them (1and 2) being movable and the third (3) beingfiXed. The compensator has the workingangular range::!: 8' and the mean error oflevelling of the collimation line is not morethan::!: 0.4".

Fig. 6.14 Level type TN-6

6.2.4. Tests and Adjustmentsof Automatic Levels

Test of the circular bubble level. The axis ofthe circular bubble level must be parallel tothe vertical axis of rotation of the telescope.The bubble of the circular level is broughtinto the centre by operating two foot screws.The upper portion of the instrument (tele-scope) is then turned through 180°. If thebubble deviates from the centre, it is movedback through half the deviation arc by meansof its adjusting screws. After that the bubbleis brought into the centre by operating thefoot screws of the instrument.

Mter this procedure, the instrument upperportion is turned through 90° to check thatthe bubble does not move from the centre. Ifotherwise, the test and adjustment must berepeated.

The horizontal line of cross hairs must beperpendicular to the vertical axis of rotation ofthe telescope. The test and adjustment in thiscase is essentially the same as for dumpylevels.

The collimation line must remain truly hori-zontal when the axis of rotation of the in-strument is tilted within the range of workingangles of the compensator. Pegs are driveninto the ground at two points, say A and B(Fig. 6.15a), spaced at a distance of 100:!: 0.2

(a) x ,

~K "

~---~'\

Irb

a<

I

~

50:!:.0.1 m D.1.

50.:!:.0.lm

Levels types TN-6 (Fig. 6.14), TN-7, andTN-9 have been designed specially for under-ground work. These small-sized instruments(0.7 kg, 1.8 kg, and 2.5 kg in mass respective-Iy) are intended for technical levelling. Leveltype TN-7 has a wide-range compensatorwhich can stabilize tilting angles up to :t6°.The working angular range of levels typesTN-6 and TN-9 is :t30'. Levelling work inconstricted underground workings is facilita-ted by the provision of a diagonal eyepieceon the instruments.

The levels of these types are provided witha horizontal angle-measuring circle whichmakes it possible to assign directions, carryout station fixing, and survey flat areas by thepolar method.

The optical system of the telescope has ahigh illumination power and gives an erectimage of objects. The tripod has an extenda-ble top portion to quickly change the instru-ment horizon.

6.3. Levelling Staffs 133

5~ "\

0"-/

Fig. 6.16 Positions of bubble in circular level when determining compensation error

m from each other, and the level is set upmidway between them (in a point D). Theheight difference between A and E is mea-sured at least three times without changingthe horizontal setting (horizon) of the in-strument. The mean height difference cal-culated by these measurements, hl = a -b, isfree from all instrument errors, since, with thearms AD and DE equal to each other,x' = x". The instrument is then transferred toa point C (Fig. 6.15b) to make new measu-rements of the height difference h2 betweenthe points A and E. If the discrepancybetween the measured height differences ismore than 2 mm, i.e. hl -h2 > 2 mm, it isrequired to adjust the collimation axis upondetermining the corrections by the formulae:

dl d2x= f f

of the distances being levelled, i. e. the dif-ference of arms must be not more than I m.

The height differences between the staffpoints are measured successively, the levelaxis being perfectly upright and tilted at themaximum working angle of the compensator(v). The latter measurements are made withvarious positions of the circular level bubble(I, 2, 3, 4 and 5 in Fig. 6.16). At least fivemeasurements are done for each staffdistance.

The systematic error of the compensatorper minute of deviation of the instrument axisis then calculated by the formula:

-(hv -ho)p"O'c -2sv

v=d J. J1 -d2 dl -d2

where x is the correction to the reading onthe farther staff; y is the correction to thereading on the nearer staff; and dl and d2 arethe distances from the instrument to thesestaffs.

To make the adjustment, the level tele-scope is aimed at the farther staff and thehorizontal line of cross hairs is aligned withthe true reading on the staff by operating theadjusting screws of cross-hair mount.

Determination of the compensation -error.This test is carried out in the field bymeasuring the height differences with thelengths of instrument arms of 5 m, 25 m,50 m, and 100 m, i. e. with the distancesbetween the staffs 10 m, 50 m, lOO m, and200 m. The level must beset up.in the centre

where h" is the mean height difference mea-sured with the instrument axis tilted at thecompensator working angle; ho is the meanheight difference obtained with the instru-ment axis in upright position; s is the lengthof the collimation line, mm; p" = 206 265";and v is the angle of inclination of theinstrument.

If O"c > 0.5", the instrument must be adjus-ted at the manufacturing works.

6.3. Levelling Staffs

Levelling staffs are made of well-seasonedpine or spruce wood. They may have adifferent length: 4 m or 3 m for surface workand up to 2 m for underground work. Sometypes of staff are made of transparent mate-rials, which largely facilitates reading-off inunderground workings. Wooden staffs are

@

mainly associated with the fact that theexisting bench marks for levelling may be setin the roof and footwall of a working. Ineither case (with a bench mark set in the roofor footwall), a staff is set up so that itsstarting end is applied to the bench mark. Letus consider some probable schemes of geo-metric levelling in underground workings.

initially impregnated with a drying oil andpainted white, after which patterned gra-duations are applied by means of a templateor special machine. Staffs for technical level-ling have l-cm graduations. For easier rea-ding, centimetre graduations are grouped soas to form clearly seen decimetres. In novelmakes of mine survey staffs, graduations areapplied on a plastic, reflecting coating orlavsan film.

Levelling staffs must be checked periodi-cally to establish their accuracy. A checkmust determine the mean length of a metreinterval, errors of decimetre groups, andprove that graduations are applied correctly.The discrepancy between the actual lengthsof decimetre groups must not exceed ::I: 1mIn. Staffs are checked by means of a stan-dard metre; the use of standardized steeltapes is also possible.

(a)

fb

~~

a<

~ I A ,

6.4. Geometric Levellingin Underground Workings

Geometric levelling can be employed inunderground workings with dipping anglesnot more than 5-8°. The procedure includesrevision and fixation of bench marks, level-ling proper, and office analysis of field ob-servations.

The principal aim of revision is to checkwhether the levelling project in question ischosen correctly. The operation consists instudying the state of the workings and exis-ting points of reference nets. Additionalbench marks may be set up by the results ofrevision.

Levelling under the conditions of under-ground workings is recommended to be car-ried out by the method 'from the mid'(two-staff technique). Staff readings are takenwith an accuracy to 1 mm.

Geometric levelling in mines does notdiffer principally from surface levelling, butthe schemes of underground levelling arecharacterized by a greater diversity. This is

Fig. 6.17 Schemes of geometric levelling in

underground workings

1356.4. Geometric Levelling in Underground Workings

1. Levelling is carried out by bench marksset in the footwall of a working (Fig. 6.170).In this case the height difference of a point Bover a point A will be determined by thedifference of readings on the staffs set on theforward and rear points (bench marks):

h=o-b

I. If the surveyor's level employed is of thetype with the level tube on the telescope, theinstrument is set up roughly over the centreof a change (turning) point and prepared forobservations. The telescope of the instrumentis first sighted on the staff set on the back-side point, and the reading is taken on theblack face of the staff. The telescope is thenpointed to the forward staff, and the readingis taken on the black face of that staff. Mterthat, repeated readings are taken on the redfaces of both staffs or with a different positionof the telescope. At once a check is donewhether the readings are taken correctly. Forthis, the height difference between the changepoints is calculated for the first and secondpair of staff readings. The results of levellingare recorded in a field book of a form likethat given in Table 6.1.

If the discrepancy between the two heightdifferences thus determined does not exceedthe permissible value, the rear staff is takenoff from the common turning point and setup successively on intermediate points. Uponcompleting the survey work on the givenstation, the levelling instrument is transferredonto a next station, and the staff on the pointof known elevation is transferred onto thefore-side common point of a next levellinginterval, while the forward staff remains inplace. The work on the new station is re-peated as described above.

2. If the l~vel instrument employed is of theautomatic-aligning type, it is set up roughlyin the mid between two common (change)points so that one of its foot screws is on thesighting line. The instrument is initially sight-ed on the rear staff, and the reading is takenon the staff black face. The operation of thecompensator is checked by turning slowly thefoot screw. The compc:nsator operates pro-perly if the staff reading is not changed onrotation of the screw. The telescope is thenreversed and sighted on the forward staff totake the reading on the black face of thatstaff. The operation of the compensator is

where h is the height difference; a is thereading on the rear staff; and b is the readingon the forward staff.

2. Levelling is carried out by bench marksfixed in the roof of a working (Fig.6.17b).The height difference of the point B over thepoint A is found as the difference of readingson the staffs suspended from the forward andrear point: h = b -a.

3. Levelling is done by two bench marks,with one of them (rear) fixed in the roof andthe other (forward), in the footwall (Fig.6.l7c).In this scheme, the height difference isthe sum of readings on the two staffs, takenwith a 'minus' sign:

h = -(a + b)

4. Levelling is carried out by two benchmarks, the rear one being fixed in the foot-wall and the forward one, in the roof of aworking (Fig. 6.l7d). The height difference ofthe forward bench mark over the rear onewill be determined as the sum of readings onboth staffs: h = a + b.

The considered particular cases of determi-nation of height differences with variousschemes of bench mark arrangement can becovered by a common rule: the height dif-ference between two bench marks in anylevelling scheme is equal to the forward staffreading (foresight) minus the rear staff rea-ding (backsight); the staff reading on a benchmark located in the footwall is taken to bepositive and that on a bench mark arrangedin the roof, to be negative.

In geometric levelling in an undergroundworking by the two-staff method, the fieldwork consists essentially in the following.

136 Ch. 6. Vertical Surveys in Underground Workil

Table 6.1. Technical Levelling Book

Work placePerformed by

Level N-IOLSouth entry

~ta- P~gs,tions pOInts

Notes,sketches

21 116958591212589913506039

242.849151153

-104-10210099

25022506354346360364

-2870-2864

5222 1018

5706

J3166001

242.697103

23 -241.450 242.800100

12505940

242.700L)U4

4 24 -1252 -1152

-5948 -5841

-1255 -1606

-5935 -6294

-1556 -1615

-6242 -6299

1314

5996

I:R = -22188

21528

Page-to-pagecontrol -680

240.296350

239.946362

26 239.584

-242.4511;h.. = 3368 dh = 398

-2970

I:F -2280721351

1:h 67365940

-1456 796

Checked by Date

checked again. If the compensator operatesproperly, the staffs are turned by their redfaces to the instrument and measurementsare repeated, but reading-off on the red facesis now started from the forward staff.

Geometric leyelling can be used for verticalsurvey of haulage tracks in weakly inclinedand horizontal workings. Levelling is carriedout by change points arranged in intervals of10 m or 20 m by means of a linen tape. Thepoints are marked by chalk on one of thetrack rails and fixed by a suitable method onthe side walls of the working. Track levellingis done in traverses supported by the pointsof a levelling reference network. Levelling

from a single point is also feasible, providedthat it is carried out forward and back. Thelevel instrument is set up roughly in the midbetween two change points, and staff rea-dings are taken with an accuracy to a mil-limetre.

In mine track levelling, the initial benchmark may be the last change point of apreceding levelling line, provided that the lastheight difference is checked and the dis-crepancy does not exceed 1 cm. The dis-crepancy of levelling lines must not exceed30 mm JL, where L is the length of a line inhundreds of metres.

6.6. Errors in Geometric Levelling 137

At the same time with levelling work, theheight of the working at each change point ismeasured.

The corrected height differences are usedfor calculating the height marks of the pointsby the formula

H. = H, 1 + h. , ,- ,

where Hi is the height mark on a subsequent

point, Hi-l is the height mark on a preceding

point, and hi is the height difference between

these points.

The height marks of intermediate points

are calculated by means of the instrument

horizon (elevation head), which is determined

by the formula EH = HB + b, where HB is

the height mark of the rear point and b is the

black-face reading on the staff set on that

point. In this formula, b is taken with a 'plus'

sign if the peg is set in the footwall of a

working and with -a 'minus' sign if it is set in

the roof.

The height marks of intermediate points

(pegs) are calculated by using the elevation

head: Hc = EH ::!: c, where Hc is the height

mark of an intermediate point and c is the

reading on the staff set up on that point. The

staff reading c is taken with a 'minus' sign if

the staff is set up in the footwall and with a

'plus' sign if it is set up in the roof.

Upon calculation of the height marks of

the change and intermediate points, a profile

of the working is plotted on a horizontal

scale 1/2000 to 1/500 and vertical scale 1/200

to 1/50. The vertical scale is usually taken 20

times as large as the horizontal scale.

6.5. Office Analysis of Resultsof Geometric Levelling

The office analysis of mine measurementsin geometric levelling includes the control ofthe field books, calculation of height dif-ferences at stations, page-to-page control,adjustment of calculated height differences,and calculation of the heights of reference netpoints and change points in track levelling.

If levelling is carried out by means ofdumpy levels or levels with self-adjustingsighting axes, two height differences are mea-sured on the black and red faces of staffs ateach station, after which the mean values ofheight differences are calculated as the arith-metic mean of two readings. The calculationsare checked by page-to-page control which inthe case of geometric levelling (see Table 6.1)is made by the formula

}:;R -}:;F = }:;hi -}:;h2 = 2hm

where }:;R is the sum of readings on the staffsset on rear points; }:;F is the sum of readingson the forward staffs; }:;hi is the sum of heightdifferences read off on the black face of astaff; }:;h2 is the sum of height differences readoff on the red face of a staff; and }:;hm is thesum of mean height differences.

The misclosure of a closed line is fh = }:;hiand that of a line run between the benchmarks isfh = }:;hi-(HA -HB), where HA andH B are the heights of initial bench marks.

The permissible discrepancies are intro-duced with an opposite sign into the cal-culated height differences as corrections de-termined by the formula O = (n/N)fh' where nis the number of stands (tripods) in the line tobe corrected and N is the number of stands inthe entire levelling line. The sum of cor-rections should be equal to the actual dis-crepancy taken with an opposite sign.

6.6. Errors in Geometric Levelling

If the height mark of the initial point isknown, -the height mark of the final point ofgeometric levelling can be found by theformula:

H i = H, + ~h.In I

where Hin is the height mark of the initialpoint and ~hi is the sum of the heightdifferences of a levelling line, which areusually obtained by levelling from the mid.


the telescope magnification is M = 20, thesighting distance to the staff 1 = 50 ill, and't= 20":

mo=J~= 1.Omm

Hence the rms error of a height differencein levelling from the mid, with the distancebetween the instrument and the staff 50 m,will be:

m=~=1.4mm

The formulae given above make it possibleto determine in advance the rms error oflevelling with an instrument of specifiedcharacteristics and under particular condi-tions or, on the contrary, to choose anappropriate instrument and method of level-ling to ensure the required accuracy.

Each height difference is determined as thedifference of staff readings, i. e. hi = ai -hi,

Let us determine the root-mean squareerror of the sum of height differences. Forthis, let the rms errors of height differences bedenoted as mi. m2. m3. ., '. mn, Since thedistances between the change points of theline of levels are practically equal to oneanother and the work is done by a singleinstrument and under roughly identical con-ditions, the measured height differences canbe taken to be equal to one another, i, e.mi = m2 = m3 = , , , = mn = m.

Thus, the rms error of the sum of heightdifferences is m; = nm2,

The errors of height differences are in-fluenced predominantly by the errors of rea-dings on two staffs and therefore:

m2 = m~ + m~ = 2m~

,:"here mo is the rms error of a staff read-mg.

The error of a staff reading can be causedby an error of sighting and an error of leveltube setting. The reading error caused by asighting error can be recommended to befound by the formula:

6011-Im =v Mp"

where M is the telescope magnification; 1 isthe sighting distance (to the stafI), m; andp" = 206000". The accuracy of level tubesetting is taken equal to 0.l5t" (here t is thelevel tube division). Thus, the reading errorcaused by inaccurate setting of the level tubecan be found by the formula:

0.l5t"--;;--I

m -t- p.

The total reading error will be:

-;: 2 2mo -v mv + mt

6.7. Trigonometric Levelling

Trigonometric (indirect) levelling is resor-ted to in underground workings with a dipangle more than 5-8° where geometric (direct)levelling becomes inefficient. Theodolites em-ployed for indirect levelling should have theaccuracy of vertical circle reading not worsethan 30". Trigonometric levelling is usuallycarried out at the same time with establishingthe underground horizontal (planimetric)control (polygonometric traversing).

Theodolites are mounted on the platformsof console holders. Measurements are madewith the use of sighting marks or heightcompensators; disc-type signals are recom-mended at dipping angles greater than 30°. Ifplummets are used, marks should be provi-ded on their strings for easier sighting.

Vertical angles are measured in one setluf.'..rd and back. The measurements arechecked by observing that the zero point is ina constant position. The permissible differen-ce between zero point positions may be seenin Table 6.1. The instrument height i and thesighting height v are measured twice by a

By way of an example, let us calculate theroot-mean square error of a staff reading if

6.7. Trigonometric Levelling 139

(a)

-s --

-~--=-

~

.,

Fig. 6.18 Schemes of trigonometric levelling in

underground workings

measuring tape. Tape readings should betaken with an accuracy to I mm.

If trigonometric levelling is to be carriedout over polygonometric points, the fol-lowing conditions should be observed:

(a) the difference of zero point positionsshould not exceed 1.5';

(b) the discrepancy of the height differencesmeasured by levelling forward and back forthe same side should be not more than1/2000 of the length of that side; and

(c) the difference between two measure-ments of the height of a theodolite or signalsshould be not more than 5 mm.

If trigonometric levelling is to be carriedout over the points of a theodolite traverseline, the following conditions are essential:

(a) the difference of zero point positionsshould not exceed 3';

(b) the discrepancy of the height differencesof a side, determined by two independentmeasurements, should be not more than1/1000 of the length of that side;

(c) the difference between two measure-ments of the height of a theodolite or signalsshould be not more than 10 mm; and

(d) the height discrepancy of a traverseshould be not more than 120 mm JL. whereL is the length of a level line, km.

The lengths of trigonometric levelling linesare measured according to the specificationsfor linear measurements in undergroundpolygonometric traverses. Each height dif-ference is measured twice: by sighting for-ward and back, and the arithmetic mean ofthe two measurements is then found. Cor-rections to the calculated mean height diffe-rences are determined by distributing thetraverse misclosure between the height diffe-rences proportional to the lengths of sides orby considering the relative weights of heightdifferences.

Let us consider some probable schemes oftrigonometric levelling in underground wor-kings.

I. Suppose there are two statiQn marks A


than B, then according to Fig. 6.l8b we have:

h=S sinv+v-i

3. With the point A set in the roof and thepoint B in the footwall (Fig. 6.l8c), the heightdifference can be found by the formula:

h = -S sin v + v +i

4. If the points A and B of trigonometriclevelling are set in the roof of a working(Fig. 6.18d) and the theodolite stands in theupper point (point B), then the height dif-ference will be found by the formula

h=S sinv-v+i

6.8. Errors in TrigonometricLevelling

The error of location of the final point intrigonometric levelling is determined by theerror of location of the initial point of atraverse and the error in determining theheight differences. In this case, the error indetermining the location of the initial pointwill not be considered. We shall only analysethe accumulated errors caused by the errorsin determining the height differences. If theroot-mean square errors of height differencesare denoted as mi' m2' m3, ..., mn, the sum ofheight differences will be calculated with anerror:

and B set in the footwall of an undergroundworking (Fig. 6.180). It is required to mea-sure the height difference of B over A. Tomeasure the inclination angle of a side AB,the theodolite can be set up either in thelower point A or in the upper point B; let itbe first set up in A. Then a plummet is hungover the point B and a mark (say, the point ofstring connection or the plummet point) ischosen so as to sight the theodolite telescopeon that point.

The height difference for the scheme shownin Fig. 6.180 can be calculated by two for-mulae, one of which includes a horizontaldistance s and slope v and the other, the sineof an inclination angle v and inclinedlength S.

Denoting the sighting height by v and theinstrument height by i, we obtain for the firstcase:

h+v=stanv+i

and therefore

h=stanv+i-v

For the second case:

h+v=S sinv+i

and therefore

h=Ssinv+i-v

If the theodolite is set up in the upper pointB, the formulae for height differences will bewritten as follows:

h=s tanv+v-i

h=Ssinv+v-i

As may be seen, the structure of theformulae with sin v and tan vis essentially thesame and only the trigonometric function isdifferent. Below, we shall use only the for-mulae with the sine of an inclination angle.

2. If the points A and B are set in the roofof a working and the theodolite is set upunder the point A which is at a lower height

M 2- 2 2 2 2-mi + m2 + m3 + ...+ m"

The rms error of a height difference willthen be expressed as follows:m2 = m2 sin2v + m2S2/p 2 + m~ + m2

h .v, v

where m. is the mean error of measuredlength of a line, which can be found by theformula m; = ~2S + A 2S2 (here ~ is the coef-ficient of random influence; A is the coefficientof systematic influence in linear measure-ments; and S is the inclined length of a line); vis the inclination angle of a line; p" = 206

1416.8. Errors in Trigonometric Levelling

265"; m" is the error of measured verticalangle; mi is the error of measured height of aninstrument; and mv is the error of measuredsighting height. The last two errors may betaken to be equal to each other, i. e. mi = mv.

In view of what has been said above, thepreceding formula can be rewritten as fol-lows:

v = 25°; ~ = 0.0015; I.. = 0.0001; mv = mi ==2mm:

m~ = 0.00152 x 30000 x 0.422622

+ 0.00012 x 300002

S2m2 = ,,2Ssin2v + A.2S2sin2v + m2- + 2m?h 2 ,

p

Let us calculate the root-mean squareerror of height difference determined by tri-gonometric levelling for the following data:sighting length S = 30 m; inclination angle

+ 2 x 22 = 17.6 mm

Thus, m" = 4.2 mm.If the height difference is measured when

levelling forward and back, then:, r

m" = m,j.J2 = 3 mm

Chapter Seven

Surveys of Preparatory and Stope Workings

(b) cavities into which only instruments(automatic or semiautomatic) can be intro-duced (usually through vertical holes) that iscavities formed through leaching of salts,underground chambers containing petroleumand gases, deep ore chutes, bins, etc.; and

(c) cavities which are accessible neither forobservers nor instruments (chambers left inthe level-chamber systems of working, cavingcones on the surface, voids formed in seamsworked out by the caving system, etc.).

c. Blasting workings: deep blasting holes,mine chambers, and wells.

The list of survey objects includes allpreparatory and stope workings, various ho-I~s and chambers, fill-in strips, fill-in boun-daries, drainage, ventilation and fire-fightingfacilities, haulage tracks; elements of thegeological structure of deposits, i. e. places oftectonic disturbances, thinning and wash-outof deposits, visible rock-mineral contacts,points of mineral assaying and other ele-ments essential for proper exploitation ofdeposits; elements of occurrence of rock pres-sure, i. e. fissures, inrushes, domes, etc. whichare important for solving the problems ofefficient and safe exploitation of mining wor-kings.

The surveys of preparatory and stope wor-kings involve the determination of details ofthe geological structure of a deposit or. itsparticular areas (the shape and bedding con-ditions of deposits, tectonics, distribution ofquality of the mineral, etc.); determination ofthe dimensions and spatial position of miningworkings for the construction of mine surveyplans and solution of analvtical Droblems

7.1. GeneralThe progress in mining technology is lar-

gely due to the introduction of mining sys-tems with a large number of preparatory andstope workings whose position and state canchange substantially both in space and time.Deposits of more intricate shape are workedout by more complex mining systems wherethe problem of accurate and timely coordina-tion of underground workings becomes ofcrucial importance.

As has been found, the surveyors of mo-dern mining enterprises spend the major partof their time on survey work for servicingpreparatory and stope workings in extractionsections and stoping blocks.

From the standpoint of mine surveying,underground workings can be divided intothe following groups:

A. Preparatory workings which can befurther subdivided by the conditions of sur-veying into workings with the angles of dipup to 45°; those with the angle of dip morethan 45°; and connecting workings and outletworkings (draw holes, funnels, winzes, etc.).

B. Stope workings which are subdividedinto: faces in gently dipping and inclinedseams; faces in steep seams; faces in layerwiseworked-out seams; faces with an open sto-ping area; shrinkage stopes; and chambers(cavities) of large volume. The latter type ofworkings is again subdivided into threegroups:

(a) cavities in which the observer withinstrument can be present (chambers left inthe chamber-and-pillar systems of working,large-sectioll tunnels, etc.);

7.2. Instruments for Surveys 143

associated with driving underground wor-kings of the planned dimensions; and ensu-ring safe conditions of mining.

The surveys of underground workings arebased on survey nets which can be formed byrunning theodolite or goniometer traverses.The initial points for theodolite traverses arethe points of polygonometric traverses. Ang-les in theodolite traverses are measured bytheodolites of a root-mean square accuracynot worse than 30". If theodolite traverses arerun in workings with the angle of dip lessthan 30°, horizontal angles can be measuredin a single repetition or set. The differencebetween the check and final values of anangle should not exceed 1.5' in measurementsby the method of repetitions and 2' in thoseby the method of sets.

The error of centring of the theodolite andsignals in theodolite traverses should be notmore than 1/2000 of the horizontal length ofthe smaller side of a measured angle.

In underground workings with the angle ofdip more than 30°, horizontal angles shouldbe measured by two rounds, with the circlebeing reset roughly by 180° before the secondround. The discrepancy between the anglesobtained in individual sets should not ex-ceed 2'. The discrepancy between the anglesmeasured by half-sets should not exceed thevalues given in Table 7.1.

The discrepancy between the two measure-ments of one and the same side of a theo-dolite traverse should not exceed 1/1000 of

the side length and the linear discrepancyshould be not more than 1/2000 in closedtraverses with gyroscopic sides or 1/1500 intraverses run between two sides of a poly-gonometric traverse.

The sides of theodolite traverses are mea-sured twice: in inclined workings, in forwardand back direction with simultaneous measu-rement of the inclination angle of the measu-red line; in horizontal workings, both measu-rements can be done in the same directionwith measuring the length of intervals if theline is longer than the length of a measuringtape. Steel tapes for the measurements mustbe standardized to have the relative error notmore than 1/40000 of their total length; it ispermissible in taping to stretch the tapewithout spring balance.

Stope workings can be surveyed by run-ning goniometer traverses with the use oftheodolites or instruments of a lower ac-curacy. Goniometer traverses should be con-nected at both ends to the points of atheodolite traverse. The accuracy of gonio-meter traverses can be characterized by thefollowing data: root-mean square error ofangular measurements 10'; ultimate length ofa traverse 0.3 km; discrepancy between twomeasured lengths of a line 1/100; and lineardiscrepancy in traverses run between twosides of a theodolite traverse, not more than1/200.

The points of a survey net should belocated at distances not more than 50 m froma face. In places where mining workingsapproach dangerous zones, this distanceshould be not more than 20 m. In the lattercase, the coordinates of the points of surveycontrol are determined twice.

Table 7.1

Angle of dip of wor- Permissible angular discrepancy be-kings, degrees tween half-sets, min

at junctions bet-ween horizontal

and inclinedworkings

in inclined wor.kings

31-4546-6061-70

234

345

7.2. Instruments for Surveysof Preparatoryand Stope Workings

The most popular instruments employed inmine surveying practice for the surveys of

144 Ch. 7. Surveys of Preparatory and Stope Workings

formed in the telescope. The magnitude ofdisplacement of the images relative to eachother depends on the distance to the stadiapole.

The ranging pole (Fig. 7.2a) is made in theform of a rectangular glass plate having fourhorizontal hairs (to read off tens of metres),two inclined hairs, and a horizontal scalewith five square divisions, each of themcorresponding to 1 m in distance measure-ments.

Before taking a stadia reading, the tele-scope is sighted on the mid of the stadia pole(along the height). The telescope tube is then

(a)

Fig. 7.1 Goniometer type UTa: l-horizontalcircle; 2- vertical circle; 3- telescope; 4 ~ bracket;5- horizontal axis; 6- index; 7 ~ hinge joint

(c)

preparatory and stope workings are engi-neering theodolites and goniometers; suspen-sion compasses and suspension semicirclesare also in use.

Since the surveys of stope workings mostoften are to be carried out in a restrictedspace, instruments for the purpose shouldhave small dimensions and a low mass andensure the specified accuracy of measure-ments of the worked-out area.

Goniometer type UTG (Fig. 7.1 ). The tele-scope of this instrument has a double-imagerange finder with the stadia factor K = 500.The goniometer set includes a ranging (sta-dia) pole. The telescope is of the internal-focussing type with the focussing range from2 m to infinity. The telescope system has twooptical wedges, each of which covers half theobjective and deviates the collimation ray bythe same angle but in different directions..Thus, two images of the stadia pole are

Fig. 7.2 Ranging pole for UTG goniometer (a)and field of view of goniometer UTG (b and c)

7.2. Instruments for Surveys 145

This is a repeating-type instrument providedwith stadia hairs.

The limb of horizontal circle has five-degrees graduations. The readings on thehorizontal and vertical circle are taken bymeans of a measuring drum with an accuracyto 1'. The stadia hairs permit the measure-ments of distances from 5 to 30 m with anaccuracy of 1/200 and from 30 m to 40 mwith an accuracy of I/lOO. The telescope ofthe instrument carries a sighting-and-rangingrod.

Mine surveyor's goniometer-tacheometer(Fig. 7.4) is intended for the surveys of pre-paratory and stope workings and assigning ofdirections in driving workings; it can also beused for tacheometric surveys on the surface.

The instrument is essentially a repeating-type goniometer with the telescope havingthree pairs of stadia hairs. Two of tliem servefor distance measurements by means of asighting-and-ranging rod and the third pair,

Fig.7.3 Goniometer type UT-3: I-base; 2-limb; 3-vertical circle; 4-clamp screw; 5-sightingscrew; 6-telescope; 7-sighting-and-ranging rod

moved by means of the alidade tangent screwuntil one of the left-hand inclined hairs ismade coincident with anyone of the right-hand horizontal hairs at which tens of metresare read off. The whole metres and de-cimetres are then read off on the left-handportion of the horizontal scale, beginningfrom the first black square. If the inclinedhair coincides with a figure '5', it is requiredto subtract 5 m from the read-ofT number oftens of metres. Metres and decimetres areread off in a common way; for instance, thereading shown in Fig. 7.2b is: 30 -5 + 3.5 == 28.5 m. In all other cases, i. e. when theinclined hair does not coincide with '5', theread-ofT number of tens of metres is leftunchanged; for instance, the reading inFig. 7.2c is 10 + 1.6 = 11.6 m.

The range finder of the goniometer typeUTG can measure distances with a relativeaccuracy 1/100 to 1/200.

Goniometer type UT -3 (Fig. 7.3) is design-ed for the surveys of preparatory and ac-cessible stope workings, orientation of suble-vels via inclined or vertical workings, andheight mark transfer to subleve~ workings.

10-1270


Fig. 7.5 Goniometer-tacheometer type UTO-3

by means of a common levelling staff. Therange of measured distances is from 2 m to 40m and a relative accuracy of 1/200 fordistances up to 30 m and 1/100 for thoseabove 30 m.

The telescope of the instrument is mountedeccentrically and permits the measurementsof vertical angles within the limits :t 90°,

The goniometer portion of the instrumenthas worm-and-gear mechanisms instead ofreading circles. The readings are taken onmeasuring drums with estimation by eye totenths of a division, which corresponds to 1minute of arc.

Goniometer-tacheometer type UTO-3(Fig. 7.5) is designed for the surveys of uilder-ground workings and can also be used for thetacheometric surveys and surveys of quarriesin open-cast mining.

The instrument has an erect-image bro-ken-type telescope 1 with a diagonal eyepiece10. A wide-angle finder 2 is provided forquick aiming at objects. The goniometer hasan optical reading system in the form of ascale microscope. For convenience of anobserver, a reading eyepiece 3 is made ro-tatable.

The vertical and horizontal circles arearranged in the housing 8 of the goniometer.The vertical axis, base 6, and reversible leveltube 4 are designed so that the goniometercan be mounted in the upright or invertedposition on a console holder 7, as well as inthe upright position on a tripod. The gonio-meter is aimed at an object by means of'endless' tangent screws 5 and 9 respectivelyfor horizontal and vertical sighting. Theinstrument can be centred under and over apoint by means of a mechanical or opticalplummet.

The instrument can measure vertical anglesbetween -65° and + 90° and distances inmines between 2 m and 50 m. The readingaccuracy of the vertical and horizontal circleis 1-2 minutes and the root-mean squareerror of angular measurements, not morethan 3 min.

Distances are measured by means of stadiahairs with a stadia factor loo, which ensuresthat the relative accuracy of measurements isnot more than 1/100. The instrument has ver-tical and horizontal pairs of stadia hairs.

Measurements underground are made byusing a special stadia pole with a transparentscale which can be arranged either hori-zontally or vertically.

Suspension compasses and suspension semi-circles can be used for measurements pro-vided that there are no large magnetic massesin the vicinitv.

1477.2. Instruments for Surveys

Fig. 7.6 Suspension compass

A suspension semicircle (Fig. 7.7) is used tomeasure the vertical angles of the sides ofcompass traverses and consists of a limb I,plumb bob 2 and two hooks 3 to hang thesemicircle on a cord 4. Limb graduations

A suspension compass (Fig. 7.6) consists ofa round housing 1 and a suspension 2 whichcan be fastened on a cord 3. The housing ishinged in the suspension and can be arrangedhorizontally. The limb 4 of the compass hasone-degree graduations increasing anticlock-wise from 0 to 360°. The point axis 5 in thecentre of the housing carries a sensitivemagnetic needle. In the non-operating state,the magnetic needle is fixed by an arrester.For surveying, the suspension compass issuspended from a cord with the zero markfacing forward; the readings can be taken atboth ends of the needle.

Before using the compass, the needle istested for sensitivity. For this, the compass issuspended on a cord and the reading is taken.Then the needle isdisbalanced by a magneticmass and let to come to rest, after which thesecond reading is taken. The needle is consi-dered to be sufficiently sensitive if the dif-ference between the two readings does notexceed the read-off accuracy. Otherwise, itssensitivity should be improved.

The insufficient sensitivity of the magneticneedle may be caused by some defects of thepoint axis and needle pivot or by the de-magnetization of the needle. The former faultcan be eliminated by polishing the point axisand needle pivot or by replacing them andthe latter, by applying one pole of a per-manent magnet to the needle and drawing itfrom the needle centre to the opposite poleend of the needle several times (up to 20).

10.

D E F' F~////////////////////////////////'l/ ~/;;;;T--- --0--

//

~

increase from 0 in the mid of the semicircle to90° at its ends. Inclination angles can bemeasured with an accuracy to I 15'.

Telescopic rod. The thickness of depositscan be measured by means of a telescopic rod(Fig. 7.8) which has the measuring rangefrom 1.6 m to 4.4 m, root-mean square errorIo.01 m, and mass 2.5 kg.

The rod consists of three telescopic alumi-nium tubes 1, 2, 3, a support foot 4, stoppers5, 6, and an indicator 7 with a clamp screw 8.The lower side of the indicator is covered bya reflecting foil which reflects the light ofminer's head lamp and makes the point ofrock contact readily visible.

, oo0 I0

000O

, ~. 9 ---o

b b. o

,/ 9

a a' , 0.0

/ ~ ~ ~ ~ ~-(JJ

--0 0--- -

////////////////////////////////~C C. B A

Fig. 7.9 Face survey in stepped-face overhand

stope system

ing, the position of a stope face is determinedby the tape measurements of bench elements.Referring to Fig. 7.9, a point C is first es-tablished along the line of points A and B ofa first-order survey traverse in the haulingentry. The distance from the point C to thebase of the nearest bench (up dip) is thenmeasured by a tape, which gives a point a.The tape is then stretched along the bench(on the strike) to obtain a point a'. In thisway, all benches are measured by the tape upto the ventilation entry. After that, the tapetraverse is connected to a point F. The surveyof details is then carried out by the method ofordinates, and a sketch is plotted which givesall dimensions and details essential for thecompilation of mining work plan and cal-culation of the voluII1e of the extractedmineral.

The orientation of the tape traverse isperformed by means of triangles constructedon junction sides FF' and CC'.

In steep seams where the mineral is beingworked out from the bottom upwards, the

7.3.1 .Surveys of Stope Workingsin Steep Seams

The positions of stope faces in steeplydipping seams of deposits are mainly de-termined by linear measurements which aremade successively along the entire length of aface. On deposits which are worked out withmineral extraction on the strike, the line of aface is determined by measuring the distancesfrom the face to the survey traverse pointslocated in cross adits or entries of the upperand lower level.

With the overhand stope system of work-

7.3. Surveys of Stope Workings in Coal Fields 149

7.3.2. Surveys of Facesin Gently Dipping Seams

For the surveys of faces in gently dippingseams, a survey traverse with temporary orlost points is run along the line of a face(Fig. 7.11), after which tape measurementsare made from the vertexes (or sides) of thetraverse to determine the position of the faceand the dimensions of left pillars, filled-insections, etc. In this survey, the thickness andangle of dip of the seam are also measured,and the peculiarities of seam structure aresketched. The traverse points should be loca-ted as close as possible to the face front.

Horizontal angles in the survey traverseare measured in one set by engineeringtheodolites or goniometers (such as typesUTG and UT -3). The inclined lengths of

Fig. 7.10 Face survey by means of cord andsuspension semicircle

line of a stope face can be determined bymeans of a suspension semicircle or special'bar'. In the former case, a fixed point 19 ischosen on the theodolite traverse in a ven-tilation entry (Fig. 7.10), and a plumb bob issunk through the raise to fix the point A at itsend. Cords are stretched from this point alongthe line of the stope face; the lengths of cordsections are measured by a tape and theinclination angles of cords, by a suspensionsemicircle. The cords should be stretched in aplane parallel to the wall of deposit. Forcontrol, the line of a face is closed onto thetheodolite traverse via the second raise (ontoa point 16). The survey of details is made bythe orthogonal method from the cord sec-tions.

Survey by using a 'bar' can be carriedout in practically vertical seams of a lowthickness. The 'bar' is essentially a 2-mwooden rod with decimetre divisions. Aplumb bob and semicircle are attached in itscentre, which makes it possible to arrange the'bar' horizontally. Survey is made from astraight line laid out by means of the 'bar' onthe side surface of a seam. The ends of astraight line are connected to the points of acontrol survey established in raises. Thediscrepancies between the heights of points atthe end of a traverse must not exceed 1/200 ofthe traverse length.

Fig. 7.11 Face survey utilizing survey net ongently dipping seam

traverse sides are measured by a linen tape orby goniometer stadia hairs. If goniometerswith eccentric telescope (types UTG andUT -3) are employed, the inclination angles ofsurvey traverse sides should be measuredtwice, i. e. forward and back. The actualinclination angle is found as the half-sum ofmeasured values.

for linearity by means of engineering theodo-lites or goniometers.

The junction of a goniometer traverse to atheodolite traverse can be effected by meansof a connection triangle. For this, thegoniometer is set up in a point 1 in the entry(see Fig. 7.11) to measure the angle 'Y of theconnection triangle and angle 13. The lengthof the first side a of the goniometer traverse ismeasured. If the first point is chosen so thatthe connection triangle angle 'Y does notexceed 5°, the junction angle <p can becalculated by the formula:<p = 180° -(I + a/c) 'Y

where c is the length of the polygonometrictraverse side.

If a traverse is run in a face with the solepurpose to check the face linearity, its con-nection to the polygonometric traverse is notneeded.

7.4. Surveys of UndergroundChambers and Cavities

As the mineral is being extracted under-ground, there are formed voids and cavitiesof various configuration and size. These cavi-ties may be filled with air, gases, salt water,petroleum, etc. From the standpoint of minesurveying, underground cavities are dividedinto accessible and inaccessible. Undergro-und cavities are regarded to be inaccessible ifobservers have no access to their walls or ifthis is forbidden for some or other reason.Accessible cavities can be surveyed by themethods discussed earlier, whereas the sur-veys of inaccessible cavities have certainspecific features.

In view of a large diversity of miningconditions, it may be distinguished betweenthe following trends in the surveys of under-ground workings of large volume: surveysbased on the tacheometric principle of deter-mination of coordinates of inaccessible spa-ces; surveys based on the photogrammetric

7.3.3. Survey Work in Faceswith Powered MiningComplexes

For the normal exploitation of facesequipped with powered mining complexes, itis essential to ensure survey control of thelinearity of a face and the position of apowered complex in it.

For controlling the position of the comp-lex, pickets are established at intervals of 10m or 20 m in the main entry and ventilationentry. The lines connecting like points inboth entries should be perpendicular to theaxes of entries. The position of the complex iscontrolled by measuring the distances fromits ends to the like pickets in the entries. Withhorizontal and gently dipping seams, thesedistances should be equal, i. e. the complexshould be located perpendicular to the axesof the entries. For dipping seams (with theangle of dip 15-25°), these distances shouldnot be equal, since in that case the anglebetween the face conveyer and the axis ofhauling (conveyer) entry must be equal to91-93°. Thus, the hauling (conveyer) facemust be advanced to some or other extentdepending on the type of complex, lengthof face, and mining and geological condi-tions.

The linearity of a face with a poweredmining complex must be checked at leastonce a month. The check for the linearity of aface ofa small length (60-100 m) can be donevisually or by taping from change points ortheodolite traverse points. The faces of alarge extension (above loo m) are controlled

7.4. Surveys of Underground Chambers and Cavities

principles of coordinate determination; and I I

surveys in which coordinates are determinedby the conversion of physical quantities intogeometrical.

151

Theodolite No.2II

2

~Section 2~-1 ,

I~s~!!.o!!.~ --

~

TiTheodolite No.1

Fig. 7.12 Tacheometric survey of chambers bytwo theodolites

7.4.1 .Tacheometric Surveysof Underground Cavities

The tacheometric method of surveying isbased on a polar spatial (spherical) system ofcoordinates. The positions of points of anobject being surveyed relative to the standpoint of the instrument are determined bymeasuring two angles (horizontal and ver-tical) and a linear parameter.

The volume and contours of a chambercan be determined by the method of in-tersections by two angle-measuring instru-ments from two points. Theodolites are setup in two points with known coordinates.Using a light projector set up in one of thetwo points, light spots are formed on themost characteristic portions of walls of thecavity and fIXed with both instruments bymaking intersections, i. e. by measuring thevertical and horizontal angles. The resultsobtained are then used for the analyticalsolution of the problem.

The method of angular intersections isusually employed in cases when special in-struments for surveying of inaccessible spacesare non-available.

The survey work is started by plotting thevertical sections of the chamber to besurveyed, with intervals of 5-6 m. Horizontalangles 131' 132' etc. in the stand point of atheodolite No.1 between the direction I-IIand the directions onto the points of in-tersection of profiles with chamber walls (01'02' etc.) are measured by a protractor with anaccuracy to 10 (Fig. 7.12). For surveying inthe chamber, the theodolite is set up in apoint I and oriented onto a point II, andhorizontal angles 131' 132' etc. are set outsuccessively. With each sighting of the theo-dolite.,No.l, light marks 01' 02' etc. are

Conned on the chamber wall at the specifiedheight. After that, light marks Conned by atheodolite No.2 are aligned with the lightmarks a1, a2, etc. produced by the theodoliteNo.1. The readings are taken on the horizon-tal and vertical circle of the theodolite No.2(respectively 13'1' 13~, etc. and 0'1' o~, etc.).These measurements make it possible todetermine the positions of the points ofspecified profiles.

This method is rather simple and not verylabour-consuming. With the sighting lengthup to 50 m, the contours of chambers can bemeasured with a relative error of 1/200. Adrawback of the method of light marks isthat it is impossible to survey the wall inwhich a theodolite is set up.

Some makes of tacheometers (such as typeBRT-006, GDR) are provided with a double-image (coincidence) range finder. The practiceof application of type BRT-006 tacheometerhas shown that the instrument can measurelengths up to 40 m with a satisfactory accura-


its width is measured by a measuring device(Fig. 7.13).

The telescope and projector are focussedsynchronously, which facilitates and speedsup observations. With measured distancesranging from 4 m to 100 m, the relative erroris 11100 to 11200.

Recently, lasers have come into use in minesurveying as sources for making light marksin the measurements of inaccessible distances.This increases the range of measured dis-tances anrl the accuracy of measurements.

The essence of the method of laser rangingin underground chambers consists in that atacheometer (such as type BRT-006) and alaser are set up in an approach working neara chamber to be measured. The laser togetherwith collimator serves as a laser light-markprojector. Laser marks are projected on thewalls of the chamber by a specified program-me. The horizontal hair of the tacheometertelescope is sighted on the centre of a lasermark. With an arbitrary position of a mov-

-.., ' , ~ , .'" 1

" ~ ~~,"' /

11 11

III II

11'

Fig. 7.13 Scheme of projecting (I) and measuring(2) systems of tacheometer type TG-4

-2

11 11 I

il ll !i I

II 1111

1I73

-111' 1 1-.Iii

~ -IIi i/!1 ~

cy (1/100). At larger distances, the accuracyworsens substantially, since double images ofa light mark cannot be brought to coincid-ence quite precisely.

In recent time, light-projection tacheome-ters have come into wide use; their rangefinders operate on the principle of two knowndirections formed by a telescope and lightprojector. An example is the type TG-4tacheometer which has a projection-visualrange finder with a variable basis andconstant parallactic angle at the instrument.A light mark is formed by the projector, and

7

//6

Fig. 7.14 Electro-optical tacheometer typeMIFT -2: 1- eyepiece; 2- frequency switch; 3- tan-

..gent knobs; 4 -laser switch; 5 -cancel button;6- scale illumination switch; 7- vertical and ho-rizontal circle readings; 8-distance readings

7.4. Surveys of Underground Chambers and Cavities 153

able pentaprism, two images of the mark areinitially seen in the eyepiece. The two imagesare brought to coincidence, and the readingsare taken on the basal scale and vertical andhorizontal circles. Experience has shown thatthis method of surveying with type BRT -006tacheometer is applicable at distances up to60 m and gives a relative error around 1/400.

An electro-optical tacheometer typeMIFT -2 has been developed in this countryfor tacheometric surveys of inaccessiblechambers and cavities (Fig. 7.14). It consistsof an angle-measuring instrument and elect-ro-optical laser range finder. Laser beamsemitted by the projector are reflected directlyfrom the rock, rather than from specialreflectors. A survey is done by the polarmethod from an approach working. Theroot-mean square error of measured verticalangles is 0.5' and that of horizontal angles,1.5'. The rms error of distance measurementin the range from 7 m to 80 m is around 20cm.

Fig. 7.15 Scheme of short-base stereophotogram.metric survey of underground workings

7.4.2. Photogrammetric Surveysof Underground Cavities

The method of short-base stereophoto-grammetric survey of underground cavitieswas proposed at the beginning of the 1950's.A base-measuring bar 1 (Fig. 7.15) is set upon a tripod in a safe place in the chamber tobe measured or in an approach working. Atits ends the bar carries two wide-angle short-focus photographic cameras 2 whose axes areparallel to each other. The base-measuringbar is set by means of a sighting diopter 3perpendicular to a survey control-net sideand the side wall of the working is photo-graphed. The two photographs (stereopair)are viewed through a stereoscope, whichmakes it possible to observe a stereomodel ofthe photographed object diminished in aratio b'/b, whet"e b' = 65 mm is the eye base(interpupillary distance) and b is the base ofphotographic cameras.

This method is principally based on directintersections, since the two overlapping pho-tographs make a stereopair. Measurementson stereoscopic photographs are made jointlyby the principle of stereoscopic viewing.

A method of photogrammetric surveyingof sections in horizontal workings by meansof a light beam is employed with success inthe USSR, GDR, CSSR, and other countries.In this method, a photographic camera is setup on a tripod in a working, .the camerashutter is opened and, by moving a lightsource, the internal contours of the workingin the plane perpendicular to the camera axisare gradually illuminated.

The principal complications of this methodare associated with ensuring that the illu-minated plane is strictly perpendicular to thecamera axis and also with scaling of photo-graphs. In order to eliminate these difficulties,an instrument set FS-6 has beel;1 designed inthis country, which makes it possible toobtain the scaling basis together with aphotograph of the cross section of a working.


The instrument set includes a photographiccamera, power supply unit, light projector,reel with synchronizing cable, and four tele-scopic scaling rods. The total error in mea-surements of cross-sectional areas is :t 1.5% .

natural untwisting of the logging cable (thetime of cable untwisting may amount to 1.5 hin boreholes of a depth of 1000 m). After that,surveying proper can be carried out, whichconsists in measuring the depth to which theborehole tool has been sunk, the velocity ofsound propagation at the level of the obser-vation point, and the radii of the horizontalsection of a chamber.

The velocity of sound propagation at thelevel of an observation point is determinedon brine samples taken beforehand from theborehole. The radii of the chamber aremeasured by the sonar which automaticallyturns on the vertical axis in the borehole.Ultrasonic waves emitted by the sonar arereflected from the walls of the chamber andenter the receiver of the acoustic system. Thereceived signals are recorded by the receiver,amplified in an electronic unit, and transmit-ted as electric pulses through the loggingcable to the on-ground station.

Large vertical workings and other air-filledcavities can be surveyed by means of a sonarprofilograph type ZPR-2 developed in thiscountry.

7.4.3. Sound Rangingof Underground Cavities

The physical methods of mine surveying ofunderground cavities are based on the prin-ciples of transformation of acoustic, radioand light waves into values which can cha-racterize the direction and length of ameasured section. Modern instruments de-signed on these principles mostly measure thetime of passage of acoustic or radio wavesfrom an emitter to an object and back.

Sound waves (in particular ultrasonic wa-ves) have turned out to be most suitable formeasuring of cavities (sound ranging). Theyhave a relatively low velocity of propagationin air, because of which the time of theirpropagation can be measured with a ratherhigh accuracy. For instance, ultrasonic rang-ing can measure relatively short distanceswith a root-mean square error :!:20 mm.

Sound ranging has found wide applicationfor surveys of underground cavities formedthrough salt leaching and of vertical work-ings of large cross-sectional area. A boreholesonar 'Luch' has been designed in this count-ry for surveying of brine-filled undergroundcavities. The apparatus is mounted on atruck and consists of two portions: a bore-hole tool and instrument stand. The boreholetool is connected with the on-ground equip-ment by a logging cable which also serves tohold the tool in a borehole.

Surveying of brine-filled cavities is a la-bour-consuming procedure. Before making asurvey, it is required to depressurize theunderground chamber to be measured, dis-mount the rig head, extract the brine-liftingpipe string, sink the borehole tool to thebottom of a chamber, and allow time for

7.5. Surveys of PreparatoryWorkings

The surveys of preparatory workings arecarried out for plotting detailed plans andsections within the limits of a stoping blockor extraction section and for determining thecoordinates of particular points essentialfor the solution of various analytical prob-lems.

These surveys should include all detailslarge enough to be visible on compiled plansand profiles. When surveying details, linearmeasurements should be made at the level ofthe mid section of a working with anaccuracy to 5 cm or, in rough surveys, toIO.cm.

Angular measurements in the surveys ofpreparatory workings can be done by using

7.6. Surveys of Blast Holes 155

Fig. 7.16 Survey of connection working bynon-free plummet method

the line in several points so as to form abroken line A-I-2-B lying in a vertical plane.

Then, the horizontal angle at the point Abetween the junction side of the earliertheodolite traverse and the side A-l is measu-red, which makes it possible to calculate thedirection angle of the side A -1. The samedirection angle is taken for sides 1-2 and 2-B.The lengths of the lines A-l, 1-2 and 2-B aremeasured by a tape and the inclination anglesof these lines, by a suspension semicircle. Theresults of measurements are used for cal-culating the coordinates of points 1, 2, and B.

theodolites, goniometers, suspension com-passes and semicircles.

Preparatory workings in seam depositsare, as a rule, surveyed by theodolites. Theuse of suspension compasses is possible forsurveying preparatory workings in seam andore deposits, provided that there are nomagnetic masses which might induce mag-netic disturbance.

Preparatory workings must be surveyedtwice: the first time during driving a working(additional survey) and the second time at theend of driving a complex of workings. Alldetails obtained by a survey are sketched in aspecial field book or on margins of the booksof angular and linear measurements of surveynet traverses.

Surveying of steep preparatory workingsinvolves certain difficulties compared to thatof gently dipping workings: it is more difficultto transport and set up instruments; the angleof inclination of the vertical axis of aninstrument can influence substantially theaccuracy of horizontal angle measurements.

Central-telescope theodolites can be usedfor survey work in workings with the dippingangle up to 55°. Hanging theodolites aremore expedient in workings with the dippingangle up to 65°. Workings with the angle ofdip more than 65° are surveyed by eccentric-telescope theodolites.

When surveying connecting workings andoutlet workings (outlets), it is essential todetermine the position of their side wallsrelative to the initial directions or points. Thesurveys of day holes and ore chutes of a smallextension can be carried out by simplermethods, for instance, by the method ofnon-free plummet, which is essentially asfollows.

For surveying a connection working(Fig. 7.16), a polyamide line (or cord) is hungfreely between the survey point A at thelower end of the connection working and thepoint B where it is connected to a verticalshaft. Plumb bobs (1,2) are suspended from

7.6. Surveys of Blast Holes

The efficiency of drilling and blasting ope-rations depends substantially on the correctposition of blasting workings in the rockmassif, especially when these wbrkings havean appreciable length and are intended forprimary (mass) blasting.

The correct position of the centres and

156 Ch. 7. Surveys of Preparatory and Stope Worki ngs

termining the horizontal angle ARC anddistance RC to set out the point C in theground. The point C is then established in thechamber roof and an angle-measuring in-strument is set up under it and orientedrelative to the direction CR in order to assigndirections to future blast holes. The orienteddirections are fixed by means of wooden barsfastened under the chamber roof. Beforedrilling, plumb bobs are hung from the barsto orient the blast holes in plan.

In cases when directions should be assig-ned to inclined blast holes, an angle-mea-suring instrument is set up in the point C inthe chamber at the same height with therotation axis of the drilling rig. Upon hanginga plumb bob from the wooden bar, and thusfixing the direction in the horizontal plane,the required inclination angle is set on thevertical circle of the instrument and points mand n are marked on the chamber wall andplumb bob line (Fig. 7.18); these points deter-mine the inclination of the blast hole to bedrilled. After drilling a fan of blast holes, acontrol survey is carried out.

When assigning directions to parallel blastholes (Fig. 7.19), points I, 2, 3, etc. are set outalong the line between points A and R in theworking. An angle-measuring instrument is

axes of blast holes in accordance with theblasting work plan is closely linked with thequality of survey and layout work performedby mine surveyors.

Surveying of deep blast holes consists inconnecting the hole mouth to the points ofthe survey net (goniometer traverses) anddetermining the depth of the holes and thedirections and inclination angles of their axes.The error in determining the depth of blastholes must not exceed 0.2 m and that of theirdirection in plan and inclination angles, 30'.

The techniques of surveying of deep blastholes depend on the drilling direction (ho-rizontal, inclined or vertical), arrangement ofblast holes (parallel or fan-like), and thedrilling equipment employed.

With a fan-like arrangement of l?last holes(Fig. 7.17), they are drilled from chambersconstructed so that the point of arrangementof the drilling rig ( C) is at the intersection ofblock boundaries (in plan). Upon driving achamber, survey work is carried out to de-termine the chamber contours and the di-rection AB and to calculate the coordinatesof the point c. These results serve for de-

Fig. 7.18 Assigning direction to blast hole invertical plane

7.7. Orientation of Sublevel Workings 157

".../

c

~~~~1( 15.41\ I ~~-~;;;"--o::j

,0'"',

0,"'I

0,1(0)'

number of levels are to be oriented succe'ssi-vely, this discrepancy must not exceed m == 14'IJ~, where n is the number of levels. Atleast three station points should be es-tablished at the oriented level.

Orientation can be effected through twovertical workings connected on the orientedlevel; through one vertical working; throughone inclined working; or by the gyroscopicmethod.

15.0

'J~~B

Fig. 7.19 Assigning directions to parallel horizontal blast holes

set up successively on these points to layoffangles 131' 132' 133' etc. Looking through thetelescope, the centre and number of a blasthole are marked on the wall of the working(most often with chalk). After drilling, a checksurvey of blast holes is done. The depths ofvertical blast holes are measured by a tape orwire cable with numbered I-metre marks.The depths of horizontal and inclined blastholes are measured by a steel wire 3-4 mm indiameter, which is pushed up to the holebottom and then withdrawn, and the lengthof the immersed portion of wire is measuredby.a tape. It is also possible to make thesemeasurements by means of self-straighteningelastic steel tapes 50 m long or light-metalbars 1-1.5 m long which can be joined withone another to form a measuring bar up to40 m in length.

7.7.1. Orientation of SublevelsThrough Two Vertical Workings(Raises)

Orientation through two vertical workings(raises} is made essentially in the same way asorientation via two vertical shafts: two plumbbobs are hung in the vertical workings; thecoordinates of plumb lines on the initial(upper} level are determined by connecting topolygonometric or theodolite traverse points;a theodolite traverse is run on the orientedlevel between the plumb lines; the horizontalangles in this traverse are measured with aroot-mean square error of 40" and thelengths of sides, with a relative error of1/1000. The relative discrepancy between thelengths of a plumb-connection line calculatedon the oriented and initial level should notexceed 1/1000.

In cases when sublevel workings are openedby two vertical workings with one of thembeing stepped (Fig. 7.20}, orientation can bedone by the indirect solution of a triangle010203. Connecting polygons 01-1-2-02and O2-3-4-5-03 are run on the levels to beoriented and a connecting polygon 01-A-B-C-D-03 on the main level. The coordinates ofplumb lines 01 and 03 are determined byconnecting them to the theodolite traverse onthe main level. The connecting traverses onthe oriented levels are constructed in a con-ditional coordinate system, and the lengths ofthe triangle sides 0102 and 0203 are calcu-lated. The side 0103 and direction angle

7.7. Orientationof Sublevel Workings

The orientation of survey nets in sublevelworkings should be carried .out so that themaximum error of orientation in a block of asize not exceeding 120 m relative to thetheodolite traverse points of the main levelwill be not more than 10'. Orientation shouldbe made twice, and the discrepancy betweentwo measurements must not exceed 14'. If a

Ch. 7. Surveys of Preparatory and Stope Workings158

Vertical projection

~-IcF;:-:::::.:::.:::: -!I~-llr =- , 0--I. I -.~- --

Ll! ~

~

~b-A 0-8 o.c 0 D

Fig. 7.20 Orientation via two vertical workings,with one of them being stepped

no o are calculated by the results of surveyon1tfie main level. Having found the trianglesides 0102 = a, 0203 = b, and 0103 = c, theangles of the triangles are calculated by theformulae:

b2 + C2 -a2 a2 + C2 -b2

7.7.2. Orientation of SublevelsThrough One Vertical Working(Raise)

Orientation through one vertical workinghas to solve essentially the same problems asorientation through one vertical shaft, i. e. theproblem of projection and that of junction(connection).

Since the depth of a vertical working (raise)is usually not large, the projection problemcan be solved by using for plumbing a brasswi,re or polyamide resin line 0.5-0.6 mm indiameter. Plumb bobs should have a rela-tively low mass, up to 4-5 kg. The distancebetween the plumb lines must be not lessthan 0.5 m. The discrepancy in the measureddistances between the plumb lines on theoriented and initial level must be not morethan 3 mm. The mean positions of plumbbobs are determined by observing the oscilla-tions of plumb lines on the reading scale of atheodolite telescope. To solve the junctionproblem, the bisector of cross hairs must beset symmetrically relative to the extremepositions of a plumb line.

The problem of junction in the orientationof sublevel workings is usually solved bymeans of connection triangles or by themethod of plumb-connecting lines.

The angles of triangles are calculated bythe same formulae as in orientation througha vertical shaft (see Ch. 4).

A check of the side lengths of connectiontriangles can be done by calculating thedistance between the plumb bobs, for triang-les with the angle 'Y not more than 5° by theformula:

ah(l -cosy)

h-a

c = (b -a) +

and for those with the angle greater than 5°,by the forrnula: .

C2 = a2 + b2 -2abcosy

The difference between the measured and

7.7. Orientation of Sublevel Workings 159

Q p

Fig. 7.21 Orientation via vertical working bymeans of two plumb bobs

calculated lengths of sides must not exceed4mm.

Connection by the method of plumb-con-necting lines can be used effectively on thelower level when the depth of the sublevel isnot large; this method is generally applicableprovided that the distance between theplumb lines on the upper level is sufficientlylarge.

Connection to the plumb lines of an orientedlevel can also be performed without usingangle-measuring instruments. For this, plumbbobs are suspended from a wire drawnbetween the points P and Q tFig. 7.21). Inthat case, the direction angle of a plumb-connecting line is equal to the direction angleof a line PQ. To transfer the coordinates ontothe level being oriented, it suffices to measuredistances QA and BP. For the connection ofthe plumb lines, a theodolite is set up on themain level in a point C (roughly at theplumb-connecting line). The telescope issighted on the rear (farther) plumb line and isfocussed on the closer plumb line, the limband alidade being locked. If the cross hairbisector does not coincide with the closerplumb line, the theodolite is shifted on the

tripod table until coincidence is attained. Theprocedure is repeated until the vertical axis ofthe instrument is precisely on the plumb-connecting line, after which the point, isfixed. Then the angle !3 between the plumb-connecting line and the first side CD of atraverse is measured by a theodolite. Thedistance from the point C to the closer plumbline is measured as well.

By the results of measurements on themain level, it is now possible to calculate thedirection angle of a plumb-connecting lineand the coordinates x, y of one of the plumblines. Now that we know the direction angleof a plumb-connecting line, and therefore,that of a line PQ, and the distance QA, wecan calculate the coordinates of a point A onthe oriented level.

Gyroscopic orientation of survey nets insublevel workings is carried out by thetechniques disclosed in Ch. 4.

The orientation of sublevel workings viainclined raises can be carried out by severalmethods, in particular, by the popular methodof nonlree plumb line which is resorted to incases when the workings on the main andoriented level and the inclined working havethe same direction. The essence of themethod (Fig. 7.22) consists in that a polyami-de resin line or soft wire is attached by oneend in a point B on the upper level and aweight P is fastened to its lower end on themain level. The line or wire is 'broken' inpoints C and D by two guys AC and DEattached to it at the upper and lower level.Both guys should lie in the same verticalplane.

Theodolites or goniometers are set upunder the points A and E on the upper andlower level respectively. When sighting in thetelescope, the plumb-fastening point B isdisplaced until the direction AB coincideswith the vertical hair in the telescope. Afterthe plumb line and guys are arranged in thesame vertical plane, the directi()n angle canbe transferred from one level onto the other


the upper level (Fig. 7.23). The second theo-dolite is set at the lower level and centredunder a point C, and a special staff isattached to its objective part. The telescopeof the upper theodolite is pointed to the topcentre mark of the telescope of the lowerinstrument, and the reading is taken on thevertical circle. The theodolite set up in thepoint Cis first sighted on a point D to takethe reading on the horizontal circle, afterwhich the instrument telescope together withthe staff attached to it is set horizontally. Byrotating the upper instrument on the verticalaxis, the horizontal hair line of its cross hairsis roughly aligned with the axis of the staff onthe lower instrument. By operating thetangent screw of the horizontal-circle alidadeof the upper instrument, the horizontal hair

A B

by measuring junction angles ~ and ~l byinstruments set up in points A and E in asingle full repetition. The distances dl, d2, CDand the distances from the points A and E tothe horizontal rotation axes of the instru-ments are measured twice by a tape. Theinclination angle v of the section CD of anon-free plumb line is measured by asuspen-sion semicircle with an accuracy to 15'. Thedirection angle of the oriented side is cal-culated by the formulaaAI = a37E + ~l -~ :t 2 x 180°

and the coordinates x, y of a point A, by theformulae:xA = XE + (dl + CDcosv -d2)cosaED

YA = YE + (dl + CDcosv -dJsinaED

The method of mutual orientation is alsowidely used. It employs two goniometers ortwo eccentric-telescope theodolites. In thelatter case, one of the theodolites is set up at

7.8. Measurements of Mining Workings 161

(..8 D direction angle aED of a line ED, which is theinitial angle for the orientation of the surveynet on the sublevel. Then the inclined dis-tances and inclination angles of line sectionsare measured to transfer the coordinates x, yand z from the point C to the point E.

~~

.."

SUblevel!! ~.

Y//////////;////////////~

"

////////;~' A

Main level F~

~//////////////////////////////////////;/~Fig. 7.24 Orientation via inclined raise by meth-od of plumb-line points

~,

line is aimed 4-5 times precisely on the staff,and each time the readings are taken on thehorizontal circle, after which the mean ofthese readings is calculated.

Upon the completion of the described cycleof observations, the telescopes of both in-struments are reversed and a second cycle ofobservations is made. After sighting the lowertheodolite on the upper one, it is horizontal-ized and the upper theodolite is aimed 4-5times at the staff axis. Mter that, the ob-servations of points D and A are made by theupper and lower theodolites respectively.

If an inclined raise has an intricate con-figuration, it may be recommended to use themethod of plumb-line points. A theodolite is setup on the main level under the point C of asurvey net (Fig. 7.24), and, using the instru-ment, two plumb-lines are suspended inpoints B and K in line with the point C. Apoint E on the plumb line KB is fixed on thesublevel to be oriented, after which a point Dis fixed on the plumb line EB. Since lines DEand CK lie in the same vertical plane, theirdirection angles are equal to each other.Having measured the horizontal angles ACKand KED and using the direction angle of aline AC, it is now possible to calculate the

11-1270

7.8. Measurements of MiningWorkings and Reservesof Mineral in Stocks

Stope faces are measured to plot a sketchof the stoping area (Fig. 7.25), and the pointsare fixed from which the surveys of details arecarried out (position and dimensions of leftpillars of the mineral, fill-in strips, angles ofdip, thickness and structure of a seam, posi-tion and bedding elements of tectonic dis-turbances, seam pinches, etc.).

By the results of survey, the position of thestoping area is plotted on a large-scale planof mining workings on which the meanlength of a face line can be determined fromthe expression:Lm = SlAm

where Am is the mean advance of a face for aspecified period, m and S is the working areadetermined by the formulaS = Spllcos v

where Spl is the working area measuredplanimetrically on the plan and v is the angleof dip of a seam.

With coal seams of an intricate structure, itis essential to determine by measurements thetotal thickness of a seam (from the footwallto the roof) with all interlayers and the totaluseful thickness, i. e. the sum of the thicknes-ses of all coal bands in the seam. Thethickness of mineral seams is measured by alinen tape or telescopic measuring rod per-pendicular to the bedding plane. The resultsof measurements are recorded and sketchedin the field book. The data of field books ofworking measurements are used as the basis

Ch. 7. Surveys of Preparatory and Stope Workings162

for calculating the volume of mineral extrac-ted from a stope face.

The quantity of mineral mined in stopefaces in a specified period can be determinedby the formula:Q = Vy -Lm

where V is the volume of the worked-outspace, m3; y is the density of the mineral inthe rock massif, t/m3; and Lm is the loss of themined mineral. The quantity of useful com-mercial mineral mined in the specified period,Qc, can be determined by the formula:Qc = Vy -Lm + Q'

formula

A -Ak = r.b c.bc Ar.b -Ac

where Ar.b' Ac.b and Ac is respectively the ashcontent of barren rock bands, coal bands andcommercial coal. The moisture coefficient canbe found by the formula:

100 -Wok =m loo -W

where Wo is the moisture content of usefulmineral in the massif and W is that of minedcommercial mineral.

Under particular mining conditions, thedetermination of the quantity of mined coalby measurements of mining workings iscarried out with insufficient accuracy orsometimes is not done at all. In such cases, areliable check is to measure the amount ofmineral in stocks at the end of a month. Thequantity of mineral mined during the monthelapsed is then found by the formula:Q = Ql + Q3 -Q2

orQc = (V'Y -Lm)kckm

where Q' is the quantity of barren rockpresent in the mined mineral, t; kc is thecoefficient of contamination of the usefulmineral with barren rock; and km is themoisture coefficient of the useful mineral.

The coefficient of contamination of coals incoal deposits is usually determined by the


where Ql is the quantity of mineral shippedto consumers or spent at the mining enterpri-se,t; Q2' Q3 is the remainder of useful mineralat the beginning and end of the periodconsidered in stores, bins, and railwaycars, t.

The quantity Ql is determined by weighingat shipping of the mineral or is takenaccording to accounts, whereas Q2 and Q3are found directly by the results of the surveymeasurements of the mineral contained instores, bins and other storage places. Sincethe amount of mineral in stocks at thebeginning or end of a month is usually muchless than the monthly output by the enter-prise, the errors of measurements in stockshave practically no effect on the montWyoutput of the mineral by a mine.

The remaining mass of mineral in stocks(Q, t) is found by multiplying the volume Vofdumps (or of the filled-in portion of bins) bythe density y of the mineral in dumps (bins).The accuracy of determination of the mass ofmineral in stocks depends on the accuracy ofthe volume and density determination, whichin turn depends on the difficulties of measure-ments in stocks. In this respect, it is possibleto distinguish between three categories ofdumps.

Category I includes dumps having an es-sentially regular geometrical shape: cone-sha-ped, pyramidal, prismatic with trapezoida,lcross section (of the type of road embank-ments) and some other shapes typical ofstockyards with trestles.

Category II includes dumps whose shape isa combination of cone-shaped, prismatic,pyramidal, etc. bodies.

Category III includes dumps with a comp-licated shape of the surface typical of bin-scraper and scraper stores.

The volumes of dumps related to the firstand second category (except for second-ca-tegory dump~ of a height more than 5 m) canbe recommended to be determined by tapemeasurements, with approximation of these

dumps to regular geometric bodies whenneeded.

In order to determine the volume of adump or pile, its height, width, length, ba-se diameter, etc. are measured by a tape.Substituting the measured values into suita-ble geometrical formulae (Fig. 7.26), the vol-ume of a dump is calculated with an accqracyto 10% depending on. the shape complexityand dimensions of the dump. The volumes ofdumps (piles) of category III and partially ofcategory II (with the height more than 5 m)are determined on the basis of tacheometric,plane-table or profile survey. In such cases,the terrain area allotted for mineral storage issurveyed topographically to plot a large-scaleplan of the area with horizontals.

The method of profiles is employed mostlyfor surveying of elongated dumps. In thatcase, profile lines are assigned perpendicularto the longitudinal axis of a dump. Theprofile lines are plumbed, and the mostcharacteristic points are fixed by pickets. Thespacing between the profile lines is takenequal to 5-10 m depending on the shapecomplexity of the dump. Surveying by profilelines consists in measuring the distancesbetween the picket (change) points (startingfrom the initial points) and the height diffe-rences between them. Distances are measuredby tapes (twice), and the tape readings arerounded off to decimetres. The height diffe-rence is determined by technical levelling.Theodolite-tacheometers can also be used forprofile line surveying. The measured resultsare recorded in a field book. Using the heightdifference of the base isolines and the points(pickets) on the dump surface, the crosssections of the dump are plotted (Fig. 7.27)and their areas are measured by a planimeter(with double contouring).

The volume of a dump is found by theformula:

S1+S2 S2+S3 8.+8.+1V=-/ +-/ +..0+ /2 1 , 2 , .


(b) $,

/

v=* (SI + S b + 1{S;""";f;:)

(cJ

(e) (f)

--

v=~[( 20-::~)bb +( 2ot + °b)bt]

it

(9)

7

hb b

6(2Ib+I,)v=

Fig. 7.26 Shapes of dumps suitable for tape measuring: (a) trapezoidal profile pile; (b) truncated pyramid;(c) circular cone; (d) truncated circular cone; (e) truncated elliptical cone; (f) spherical segment; (g)truncated trihedral prism; (h) wedge


9"

60-

~:50---

~

40-

30-

20-

a~,

1~3

23.

IIFig. 7.27 Scheme of measuring volume of dumpby method of profiles: l-contour of dump;2-cross-sectional profile of dump; 3-fixed pointsof profile lines and longitudinal axis

where Sl' S2' ..., Sn are the areas of profilesections of the dump and I; are the spacingsbetween two adjacent profiles. This methodcan determine the volume of dumps with anaccuracy to ::t 3.5% .

If the tacheometric or plane-table methodis employed for measuring the volume ofdumps, the tacheometric or respectively pla-ne-table survey is started from the points of asurvey net. The coordinates x, y of surveyingpoints are determined by theodolite traverses,chains of triangles or other figures or of theirintersections. The z coordinate is found bytechnical or trigonometric levelling, The dis-tances from the instrument to staff (picket)points should be not more than 60 m. Staff

points are established in all characteristicplaces of the dump surface, with spacingsbetween them not more than 6 m.

The results of survey are plotted on theplan of the dump (store) on a scale 11200 (or alarger scale), and isolines of the dump surfaceare drawn with height intervals 0.25-0.50 mfor dumps less than 5 m in height and 1.0 mfor those with the mean height more than5 m.

The volume of a dump can be calculatedby the method of vertical sections or that ofhorizontal sections. In the latter case, thedump is cut into layers by horizontal planes,and the areas of the sections are measuredtwice by a planimeter, the mean value of thetwo measurements being taken as the finalresult. The volume of the dump is the sum ofth~ volumes of the layers confined betweenthe horizontal planes drawn in intervals of0.25 m, 0.5 m or 1.0 m. The error of volumemeasurement by tacheometric survey is notmore than 4% .

The measurements of preparatory work-ings are essentially simplified surveys with theuse of simpler instruments (steel and linentapes, suspension semicircle, inclinatorium,etc.). The measurements of preparatory work-ings include the following operations: sketch-ing the working and face in the field book;measuring the length of a working and theamount of advance during the specified pe-riod; measuring the cross section of theworking, its area within the boundaries ofprospected mineral, seam thickness, andbedding elements of the seam.

The amount of advance in workings ismeasured by tapes from fixed survey pointsor other reference points located near theface.

Sketches in the field book should show: thepositions of the initial points and distancesfrom them to the faces according to theprevious and current measurements; the di-mensions of workings for calculating theworked-out area and volume of extracted


1- a -I

Im

aav

a1~-I~!

~/////////////~,02

mineral and rock; thicknesses of the seam inmeasured points .md outlines of structuralelements of the seam (deposit); location andmeasurements of bedding elements of theseam; location of geological disturbances andtheir bedding elements; and some other datathat should be reflected in mine survey plan.

An advance of a working may be de-termined as the advance in coal (Ic)' that ingangue (barren rock), 19' or that in support(lining), Is (Fig. 7.28a). The amoUnt of advan-ce is found as the difference between thecorresponding distances from the initial pointat the beginning and end of the specifiedperiod. Hence, the amount of advance of aworking during the specified period will be:in coal Ic = Ic2 -Ic1; in gangue 19 = 192 -/91'and in support Is = Is2 -Is1. Upon deter-mining the advances of a working, theworking cross section is measured. If theworking is driven partially in the mineral and

partially in barren rock, it is required tomeasure the total cross-sectional area and thearea in mineral (Fig. 7.28b) as the product ofthe seam thickness by the mean width of thecross section in the seam: 8 = amm, where amis the mean length of the face line of theworking in mineral and m is the seamthickness.

The mean cross-sectional area in mineralby the results of several (n) measurements willthen be:

81 + 82 + ...+ 8n8 =m n

The quantity of mineral extracted from theworking during the specified period can becalculated by the formula:Q = IcSmY

where Y is the density of coal, tlm3.

Chapter Eight

Special Surveys in Underground Workings

'conductors', directions are assigned both inthe horizontal and vertical plane.

For assigning the direction to a working inthese planes, the mine surveyor should knowthe spatial coordinates (x, Y, z) of the pointsto be used in calculations and be capable ofsolving such problems as the determinationof direction angles of the projected direction,angle between directions, inclination anglesof lines, inclined length (distance) and itsprojections onto the horizontal or verticalplane, etc.

The solution of some most typical pro-blems encountered in practice will be de-monstrated below.

I. Figure 8.la gives the coordinates of apoint A (x A' Y A' z A) and a point B (XB' YB' ZB).It is required to determine: the directionangle of the direction from a point A to apoint B; the horizontal projection of the linethat connects points A and B; the inclinationangle of a line A-B; and the length (distance)of a line A-B.

The direction angle of the line AB is foundby the formula:

YB -Y Atan a AB =XB -xA

8.1. Assigning Directionsto Underground Workings

One of the most important tasks of minesurveying service in the construction andexploitation of mining enterprises is totransfer correctly the designed location ofunderground workings into nature. In thatconnection, the mine surveyor has to de-terrnine the places of location (intersections)of workings in accordance with the design orcalendar plan of mining work development,to assign, fix and transfer the directions, andto control the driving of workings along theassigned direction with due observance of thedesigned profile and the chart of supports.

The most common job of a mine surveyoris to check the drivingof workings along aspecified direction in the horizontal and verti-cal plane. The method by which directionsare assigned depends on the mining con-ditions and the kind of working, elements ofseam bedding, and some other factors. Inmany cases, the work of direction assignmentis facilitated by the availability of a naturallandmark or element (for instance, thebedding plane of the foot or roof of a seam).In practice, such elements are called 'con-ductors'.

For workings to be driven on dip of aninclined or steeply deeping seam, where theline of dip is a good landmark, directions areassigned only in the horizontal plane. Forworkings to be driven on the strike of aninclined or steeply dipping seam, only thedirections in the vertical plane are assigned.For crosscuts or lateral drifts which have no

or

SAB = J(YB -y Af + (XB -XA)2

168 Ch. 8. Special Surveys in Underground Workings

(a) (cl(bJ

xYO-YA

~

'~B

~ (AB)y (BC) ~rC) PL ~C8)

B

B

y~..:

7 (CG)

x

A4: ~

8~..r G / ',E"

Fig. 8.1 Schematic diagrams: (a) for solving the inverse problem; (b) for measuring the angle betweendirections; (c) for determining the coordinates of intersection point of two straight lines

The inclination angle of the line AB isfound by the formula:

ZB -ZArany=

The coordinates of the point of intersection(a point D) of these lines can be found bysolving the triangle BCD:XD = xB + BDcosaAB' YD = YB + BDsin a AB

where

BD=-

First, we find the direction angle !lCB

YB -Yctan !lCB =XB-

and the length

CB = YB -Yc

sin aBc

where s is the horizontal projection of thelength S between the points A and B (ho-rizontal distance).

The inclined length of the line AB canalso be determined from the expressionS = s/cos v or, for checking, from the expres-slon:

s = J(YB -YA)2 + (XB -XA)2 + (ZB -ZA)2

XB -Xc

COS aBC

2. Figure 8.lb shows two intersecting linesections AB and BC with known directionangles; it is required to find the forward leftand forward right angle of crossing. Tfeseangles can be found by the formulae:13, = aBc -aBA

13, = aBA -aBc

3. In practice, the mine surveyor often hasto determine the coordinates of intersectionpoint of two directions, say, of a point Dwhere lines AE and CG intersect (Fig. 8.lc).The line AE is specified by the coordinates ofa point B (XB and YB) and the direction anglea AB. Similarly, the line CG is given by thecoordinates of a point C (Xc, Yc) and thedirection angle aCG.

The angles O and y can be found as thedifferences of the corresponding directionangles.

The coordinates of the intersection point Dcan also be determined by the combinedsolution of the equations of intersecting lines:

xB tan(1AB -Xctan (1CG -YB + YcxD=

tan (1 AB -tan (1CGYBcotan(1AB -Yccotan(1CG -'- xB + Xc

YD=cotan(1AB -cotan(1CG

The directions to mining workings areassigned by surveying instruments. The

CB sin a

siny

8.1. Assigning Directions to Underground Workings 169

choice of a particular type of instrumentdepends on the kind of problem to be solved,type of working, and required accuracy.

on whether the accuracy of angle assignmentis lower or higher than the accuracy of theinstrument.

In both cases, the working is marked outand the theodolite is set up and centred in theinitial point B (Fig. 8.2a). Since the distancefrom the initial point to the wells of theworking is smaller than the sighting limitof the telescope, a provisional direction isassigned through the telescope of the instru-ment according to the calculated angle ~.This direction i~ fixed by at least two points(Bl, B2); noting the station point of theinstrument, the provisional direction willthus be fixed by three points (B, Bl, and B2).Upon driving the working by 5-10 m in theprovisional direction, the permanent direc-tion is assigned and fixed by three points.

If the required accuracy of laying off ahorizontal angle is lower than the instrumentaccuracy, the permanent direction is assignedin the following order. The theodolite is setup again in the point B, and two points P 1and P2 are marked in the range of thedirections obtained by constructing the angle~ at two different positions of the theodolitetube. The distance Pl-P2 is then halved and asurvey mark is fixed in the mid point (P). Theangle ABP will correspond to the calculatedangle ~. Upon the fixation of the point P, theangle ABP should be measured again. Thediscrepancy between the measured and cal-culated values of the angle ~ must be within

CI C(b) r---,

611 ~S'I.rs"1

I6~1

8.1.1. Assigning the HorizontalDirection to a Working

The horizontal direction to the straightsection of a preparatory working can beassigned by means of a theodolite, compassor gyroscopic instrument by laying out innature the design or calculated angle or byranging the direction directly according tothe known direction angle by means of agyrotheodolite or gyrocompass.

An assigned direction is fixed by surveymarks (clamps) in at least three points at adistance of 1-3 m from one another. Plumbbobs hung above these points form a rangingline to be used by drivers for the orientationof a face. As the face is being advanced, thedirection is continued, and the required checkmeasurements are made. If a working isdesigned so that its direction varies, a newdirection must be assigned in each turningpoint. In cases when a working is to be drivenfrom two ends, it is required that the geomet-rical axis of one of its sections be perfectlycoincident with the continued geometricalaxis of the other section.

The direction to a working in the horizon-tal plane can be assigned by means of atheodolite by one of two methods depending

~ .'I ~«'

A B

Fig. 8.2 Scheme for assigning a direction: (a) with an accuracy less than the instrument accuracy; (b) witha higher accuracy

Ch. 8. Special Surveys in Underground Workings170

r---

Fig. 8.3 Assigning a direction by compass

the permissible limit. If so, two other points,P' and P", are set up by a theodolite alongthe collimating ray RP, at a distance of 1-3 mfrom each other. Thus, the "line passingthrough the points P, P', and P" will be thebeginning of the permanent direction.

In cases when the angle must be constructedwith a higher accuracy (for instance, fordriving a working from two ends), the pro-cedure is as follows. A point Cl is set up inone position of the,elescope (Fig. 8.2b), andthe angle ARCl thus obtained is measuredwith the required accuracy. The measuredangle ~m = ARC 1 is compared with thespecified value ~sP' and the difference 11~ == ~m -~sP is compared with the requiredaccuracy of angle laying. If 11~ is higher thanthe required accuracy, angle ARCl must becorrected. To do this, the distance RC 1 = I ismeasured and a linear correction is calcula-ted by the formulae:

111~"111 = -

p"

orL\l = 1 sin L\j3

The point C 1 is then displaced by thiscorrection (to a point C), which gives thesought-for angle ARC. The theodolite issighted on the point C, and two new points,B' and B", at a distance of 1-3 ill from eachother, are set up and fixed. Thus, the specifieddirection will be given by the line RR" B' .

The directions of auxiliary workings in the

horizontal plane can be assigned by means ofa suspension compass. For this purpose, theplan of a working is oriented along themagnetic meridian, and a straight line isdrawn on the plan from a survey point B atthe beginning of the working in the directionof the projected axis. The miner's compass isthen laid on the plan to measure the magne-tic azimuth of a line. A cord is fixed at thepoint Bin the mine and tensioned roughly inthe specified direction (Fig. 8.3). A suspensioncompass is hung from the cord and the freeend of the latter is moved laterally until thecompass needle points at the specified magne-tic azimuth. The cord is fixed in this position,and two or three plumb bobs are hung fromit. The method is, however, employed onlyrarely.

Points for assigning the direction to aworking in the horizontal plane can belocated more conveniently at a certaindistance (20-30 cm) from the walls of theworking, rather than along the central axis.In that case, plumb bobs hung from the fixedpoints will not obstruct the motion of miningworkers and will be preserved better. Drivers,however, must know the distance from thesepoints to the face walls, which is called a'bracket' and can be found in the followingway.

Suppose that a working must be drivenfrom a point A (Fig. 8.4) in the direction of aline AC which is its axis. Points At and A2near the walls of the working fix a directionthat is parallel to the axis. The width of

8 Assigning Directions to Underground Workings 171

Fig. 8.4 Scheme for calculating 'brackets' when axial direction is transferred closer to working sides

plummet has a cylindrical housing 2 with acover 1, which contains a dry cell. An electriclamp 3 at the bottom end of the housing iscovered with a red or green transparent cap4. At the top of the housing, there are aswitching knob 6 and eyelet 5 for hanging theplummet from a cord.

Light plummets are hung along the spe-cified direction so that the line formed by thelamps is the direction axis in the vertical andhorizontal plane. Light plummets are visibleat a distance of 60- 70 m on the average.

'brackets' Cl and C2 can be determined fromtriangles AA1D1 and A1A2D2. First, we haveto calculate the distances dl and d2 by theformulae:dl = AA1 sin 11 and d2 = A1A2 sin 12

or, since the angles 11 and 12 are small, bythe formulae:

1~ 1;dl = AA1- and d2 = A1A2-

p" p"where 11 = aAA -a AB' 12 = aA B -aA A ,

1 1 1 2and p" = 206265".

As may be seen from Fig. 8.4, Cl = 0.51- dland C2 = 1- (Cl + d2), where I is the clearwidth of a working.

Drivers are usually provided with a sketchof the working which gives the positions ofplumb bobs and the size of a 'bracket'.

Points assigning the direction to a workingare usually fixed in support beams or roof. Inpermanent workings, range points are fixedmore reliably by drilling holes 20 cm in depthin the roof and driving survey markers withhooks for plumb bobs into them. As theworking is advanced, the plumb bobs aretransferred closer to the face. With thetransfer distance up to 15-20 m, new pointscan be marked visually (by sighting along theline of the earlier plumb bobs) and withdistances up to 50 m, by means of atheodolite.

Directions to workings can also be assig-ned by using light plummets (Fig. 8.5). A light

Fig. 8.5 Light plummet: 1- cap; 2- metal hous-ing; 3-electric lamp; 4-coloured acrylic plasticcap; 5 -eyelet; 6 -light-switching screw


instrument, the sighting micrometer screw ofthe laser is turned so as to make coincide thelight beam with the plummet and fix up thespecifi~d direction. For better visibility, abright screen may be placed behind theplummet. It is recommended to use thefocussing ring of the instrument for moreaccurate sighting.

For assigning the direction along theheight, it is required to turn the opticalwedges at the exit of the collimating systemrelative to each other. The design inclination(slope) of the working is set up on the scaleconnected .with the optical wedges. The lightbeam directed onto the face or tunnel shieldforms a bright red spot up to 80 mm indiameter, which is easily seen from a distanceup to 500 m.

Fig. 8.6 Laser indicator: 1 -projector; 2- base incasing; 3- separate power supply unit

Laser instruments are also coming intowide use for direction assignment in un-derground workings. An explosion-proof la-ser indicator is illustrated in Fig. 8.6. It isessentially a light projector with a lasersource, which forms a narrow directed beamof red light to be used for assigning thedirections to underground workings. Theprincipal element of the instrument is theprojector consisting of a light source (lasertube) placed together with a collimating sys-tem into an explosion-proof housing.

For operation with a laser indicator, asurvey point (initial point), above which theinstrument will be set up, is fixed at adistance not more than 40 cm from the wallof a working. A theodolite is set up above thispoint to layoff the calculated direction angle,and the direction thus determined is fixed bytwo temporary marks located at a distance of10-20 m from the initial point. The bracket ofthe laser indicator set is fastened belowthe initial point to the supports of theworking wall. The laser indicator is mountedon the bracket and connected to the powersupply source. The laser beam is directed'roughly ('by hand') onto a plummet that hasbeen hung in advance. Upon fastening the

8.1.2. Assigning Directionsto Curvilinear Sectionsof Workings

Directions to curvilinear sections of under-ground workings can be assigned by themethod of perpendiculars or the method ofradii.

Method of perpendiculars. A circular curveof the curvilinear section of a working on alarge-scale plan (1/20, 1/50) is replaced byinscribed chords according to the precalcula-ted turning angles and lengths. Then thelengths of perpendiculars from a chord to thewall of the working in intervals of 1-2 m aremeasured on the drawing (Fig. 8.7). Thenumerical values of perpendiculars are writtenon the drawing.

Method of radii. In this method, a large-scale (1/20, 1/50) drawing (Fig. 8.8) of thecurvilinear section of a working is used forthe graphical determination of radial distan-ces from a chord to the wall of the working,after which it is possible to calculate thedistances between the axes of adjacent sup-ports by the external (dJ and internal (dl)side of the working. These distances can be

8. Assigning Directions to Underground Workings 173

....!) 0:) .~

~ ~ O

'l C?".~,

..""'.~~ t? ~\:o \:;...,;.~

8 ~'X((.O~~-' ' ; 0 .~ 0 ~0 .6] a

"'1 .~ o:!0 ,- ?,,-,

"3.00~i-

2.55~

1.80

~O~1 ...; .65 .

1.35 ~li Q95 (X=93.30.

~1.'J5 R=18.5m .7

Fig. 8.7 Scheme of direction assigning by methodof perpendiculars

Fig. 8.8 Scheme of direction assigning by methodof radii

are established as the working is beingadvanced.

With inclination angles of workings up to5-6° (i = :J: 0.1), the directions in verticalplanes can be assigned by means of levelinstruments, templates with levels, water levelwith light instruments, inclinometer, etc.

If a level instrument is used for the purpo-se, side bench marks are fixed in the wall at aheight of 1-1.5 m above the design position ofthe working foot or rail head, i. e. in a planeparallel to the design. slope. For instance(Fig. 8.9), a bench mark Rl is fixed in the wallof the working at a height d above the railhead. A point A is then marked on the wall ata distance of 5-6 m from the bench mark,which is the projection of the collimating rayof the level instrument. A staff is set up on thebench mark R1, and the reading a is taken.Upon measuring the distance i between thelevelling staff and the point A, the heightdifference h = ii corresponding to the givenslope i is calculated. The position of thesecond bench mark, R2, is found by laying offvertically the height a + h. The line con-necting the bench marks Rl and R2 gives innature the specified slope. If required, similar

found by the formulae:dl = d + d(s/2R) and dl = d- d(s/2R)

where d is the distance between the supportframes in the straight section of a working(according to the chart of supports); s is theaverage width of a working; and R is theradius of curvature of the curvilinear section.

All dimensions essential for checking areindicated on the drawing of the curvilinearsection.

The method of radii is more convenientand expedient than that of perpendiculars. Inthis method, it is easier to check the di-mensions of a working at both sides of achord and to control a correct placing ofsupport frames along curvature radii.

8.1.3. Assigning the Vertical Directionto a Working

The direction to a working in the verticalplane is assigned according to the designslope which is given as the difference of theelevation marks of the extreme points relatedto the distance between these points. It ismarked by axial or side bench marks which

'-i0.6~0 ~ 40"15"

11.05

-1.8 R=17.5m


A---

,a

R1

Fig. 8.9 Scheme of vertical direction assigning to working by a level and wall marks

diameter of light beam varies depending ondistances and reaches 200 mm.

A level-inclinometer (Fig. 8.11) consistingof a level 1 and wedge-type inclinome-ter attachment 2 can be employed for as-signment and checking of slopes of horizontalworkings and for laying rail tracks in minesand on the surface. It has the followingoperating characteristics:

bench marks may be fixed in the oppositewall of the working.

Directions to workings can also be assig-ned by using laser indicators whose opticalsystem includes a wedge compensator withthe working range :t 2°. The desired slope isset up by means of a special ring arrangedbefore the collimator and graduated inthousandths of gradient.

A laser sight (Fig. 8.10) has many applica-lions, in particular, for direction assignmentand control of cutting of heading machinesand tunnel shields in workings with inclina-lion angles up to 10°. Laser sights of this typecan operate properly at temperatures from+ 30° to -40° and air humidity up to 80% .Their working range is above 200 m and the

::t: 0.008

I 0.048

I 0.0001

I 0.0005

Range of slopes assigned by the

main optical-wedge system, rad .

Ditto, with the use of additional

wedges,rad Division value of slope scale, rad ..

Accuracy of slope assignment, rad .

Mass of inclinometer attachments,

kg. 0.33

4/

\5 2

Fig. 8.11 Level-inclinometer assembled: l-level;2-wedge-type inclinometer attachment; 3~micro-meter screw of inclination scale; 4- inclination-measuring microscope; 5 -clamp screw of inclino-meter attachmentFie. 8.10 Laser sight

traverse sides are measured by a linen tape orby goniometer stadia hairs. If goniometerswith eccentric telescope (types UTG andUT -3) are employed, the inclination angles ofsurvey traverse sides should be measuredtwice, i. e. forward and back. The actualinclination angle is found as the half-sum ofmeasured values.

for linearity by means of engineering theodo-lites or goniometers.

The junction of a goniometer traverse to atheodolite traverse can be effected by meansof a connection triangle. For this, thegoniometer is set up in a point 1 in the entry(see Fig. 7.11) to measure the angle 'Y of theconnection triangle and angle 13. The lengthof the first side a of the goniometer traverse ismeasured. If the first point is chosen so thatthe connection triangle angle 'Y does notexceed 5°, the junction angle <p can becalculated by the formula:<p = 180° -(I + a/c) 'Y

where c is the length of the polygonometrictraverse side.

If a traverse is run in a face with the solepurpose to check the face linearity, its con-nection to the polygonometric traverse is notneeded.

7.4. Surveys of UndergroundChambers and Cavities

As the mineral is being extracted under-ground, there are formed voids and cavitiesof various configuration and size. These cavi-ties may be filled with air, gases, salt water,petroleum, etc. From the standpoint of minesurveying, underground cavities are dividedinto accessible and inaccessible. Undergro-und cavities are regarded to be inaccessible ifobservers have no access to their walls or ifthis is forbidden for some or other reason.Accessible cavities can be surveyed by themethods discussed earlier, whereas the sur-veys of inaccessible cavities have certainspecific features.

In view of a large diversity of miningconditions, it may be distinguished betweenthe following trends in the surveys of under-ground workings of large volume: surveysbased on the tacheometric principle of deter-mination of coordinates of inaccessible spa-ces; surveys based on the photogrammetric

7.3.3. Survey Work in Faceswith Powered MiningComplexes

For the normal exploitation of facesequipped with powered mining complexes, itis essential to ensure survey control of thelinearity of a face and the position of apowered complex in it.

For controlling the position of the comp-lex, pickets are established at intervals of 10m or 20 m in the main entry and ventilationentry. The lines connecting like points inboth entries should be perpendicular to theaxes of entries. The position of the complex iscontrolled by measuring the distances fromits ends to the like pickets in the entries. Withhorizontal and gently dipping seams, thesedistances should be equal, i. e. the complexshould be located perpendicular to the axesof the entries. For dipping seams (with theangle of dip 15-25°), these distances shouldnot be equal, since in that case the anglebetween the face conveyer and the axis ofhauling (conveyer) entry must be equal to91-93°. Thus, the hauling (conveyer) facemust be advanced to some or other extentdepending on the type of complex, lengthof face, and mining and geological condi-tions.

The linearity of a face with a poweredmining complex must be checked at leastonce a month. The check for the linearity of aface ofa small length (60-100 m) can be donevisually or by taping from change points ortheodolite traverse points. The faces of alarge extension (above loo m) are controlled


coincide with a mark 5 when the longer bar isperfectly horizontal; and wooden blocks 4and 6 of different height (H I and H 2) whichdefine the specified slope. The slope is de-termined by the ratio (HI -H2)!1 which isconstant for a given instrument. For instance,with H I = 0.04 m, H 2 = 0.02 m, and 1 = 2 m,the slope is:

.HI -H2 0.021 = = -= 0.01

1 2.0

When checking the profile of a working,the instrument is set onto a rail or a boardplaced on the smoothened foot surface of theworking so that the smaller block is 'on therise'. If the plumb bob is against the mark 5,the slope is correct. If otherwise, the foot soilmust be cut off or respectively more groundmust be added.

A more convenient and perfect instrumentfor laying railway tracks of a specified gra-dient and for assigning directions to work-ings is a mining track gauge (Fig. 8.14). Itconsists of a tubular rod 3, two fixed blocks 6and 8, a movable block 5 with an extendablestop 4, spring clamp 7, two hinged sightingstands 9, a transporting handle 2, quadrant10 graduated in degrees, and a spirit level 1.

For operation, the gauge is placed with

Fig. 8.13 Water level with plumb bob

direction of the working in the vertical plane.With the known vertical distance from thetop of a plumb bob to the head of a rail(which is equal to Ht -ht for the initialpoint), it is then possible to check the gra-dient of the rail track.

It should be noted that the plumb bobsdescribed can be used for assigning thedirection to a working in the horizontalplane.

The specified slope during driving of aworking can also be checked by means of awater level with plumb bob (Fig. 8.13). Theinstrument consists of two mutually perpen-dicular wooden bars: a long bar 1 (up to 2 m)and a short one 2, which are fastenedtogether; a plumb bob 3 whose point must

Fig. 8.14 Mining track gauge


Fig. 8.15 Track-measuring complex

blocks 8 and 5 on a rail so that the block 5 ison the rise, and fastened by the spring clamps7. The required slope of the track is set up onthe spirit level. Mter that the forward end ofthe rail is moved vertically until the levelbubble is in the centre, and the rail is fixed inthat position.

A check of the specified gradient of aworking is done by means of geometricallevelling along the rail track laid in theworking in accordance with the recommen-dations on vertical surveying of rail tracks asgiven in Ch. 5.

Automatic levelling of haulage tracks canbe carried out by using a track-measuringcomplex, such as shown in Fig. 8.15. Itmeasures and records on a chart strip threemain parameters of a surveyed rail track: alongitudinal profile 2 (Fig. 8.16), elevation 3of one rail above the other, and discrepancy 1of the track gauge against the specified value.

The complex consists of a carriage 1 with astandard track gauge (900 mm or 1520 mm),an explosion-proof casing 2, power supplyunit 3, and a box for spare parts 4. The casingcontains sensors for measuring the specifiedparameters and a recorder and has a window6 where the measured parameters are dis-played. The main operating characteristics ofthe complex are as follows:

Before using the complex for measure-ments, the zero points of all its sensors areadjusted, the chart paper is charged into therecorder, and the dimensions of picket distan-ces are set up on the scheme, which will befixed on the chart by a lever 5. The complexis placed at a distance of 5- 7 m from theinitial picket point and is started by switchingon the power supply. The speed of thecomplex is increased gradually so as to attainthe optimum speed (roughly 3-4 km/h)beginning from the first picket. The operatorpasses on the lever 5 at all specified picketsand track switches, and the measured trackparameters are thus recorded on the chartstrip. As a rule, a track section is measuredtwice (when travelling forward and back).

At the end of a measuring run, the chartstrip is taken off from the recorder andprocessed. The day of survey, number of run,track section, and record scale are written atthe top of the chart. All picket and othercharacteristic points are numbered on thechart. Then the elevations of all pickets aredetermined in a conventional system of co-ordinates relative to the elevation of the firstpicket, and the gradients of the track arecalculated. For instance, the gradient of thetrack section between the picket points Nos.15 and 25 (see curve 2 in Fig. 8.16) isdetermined in the following way. The heightdifference is found by subtraction: 55.2 -

Error of recorded longitudinal slopeat a travel length of 500 m, rad .. up to

:t 0.0005

2.5

.5

'200

Root-mean square error of measured

relative rail elevation, mm Root-mean square error of measured

trackgauge,mm Relative error of recorded travel

length. Limits of measurement of rail track

gradient, rad Travelling speed, m/s Temperature limits, degrees . :f:0.050.9-1.2

-10° to

+ 40°C

55

2

Mass of set, kg. ...Number of operators

12-1270


~ ooooooo 000100 : -ii'". ' F-.'.'i'Y -

2mmt t==M.:

5mm

'II

11mrr

01

0)"0la

I~

:1@

80

60

~2!!!!!i

40I~ ~\~.r=

...C)"Q;:E=--of

3

~20

...~~Q)

...0:

.0:"'

".~:c

,CI:0

o alo O O O O O O O O O O O O O O

Picket 15 Picket25

Fig.8.16 Chart strip with recorded data: }-curve of track gauge variation (::t2mrn); 2-curve ofrecorded longitudinal profile; 3 -curve of recorded discrepancies between the heights of rails

number of divisions by the width of onedivision on a scale 1/1, i. e. 5.5 x 2 = II mm.

By the results of these measurements, it ispossible to judge on the condition of the railtrack and the necessity of repairs.

In mining practice, it is essentiar to controlthat underground workings are cut to thedesign cross-sectional area. This is especiallyimportant for opening and developmentworkings, air ways, and haulage ways. Withreduced cross sections of workings, theclearance for the rolling stock or conveyertrains will decrease below the permissiblelimits and may be the cause of accidents and

-52.8 = 2.4 mm on the chart and, con-sidering that the chart scale is 1/50, the actualheight difference will be 120 mm. Dividingthis height difference by the distance betweenthe chosen picket points, we obtain thegradient 120/103, or 12.

The elevation of one rail above the other,say, in a point H (see curve 3 in Fig. 8.16) isfound by multiplying the distance from thepoint H to the zero line by the scale base, i. e.2x3x5=30mm.

The deviation of the track gauge from thestandard size, say in a point p (curve 1 inFig. 8.16) is determined by multiplying the


A1---

.v/

injuries. Further, reduced cross sections canworsen the conditions of ventilation of stopesand be the restricting factor in the extractionof the mineral.

Surveying practice employs several me-thods for checking the cross section of work-ings, depending on the cross-sectional shape:the method of measurement by commonstaffs and plumb bobs moved on a cord alongthe walls; the polar method; the method oflinear intersections; method of direct measu-rements of the width and height of workings;etc.

The method of direct measurements is one ofthe simplest and is resorted to when workingshave a trapezoidal or rectangular cross sec-tion. By this method, one can determine thetotal cross-sectional area of a working (asformed in the rock) and the clear cross-sectional area. For this, it is required tomeasure the total height ho of the workingbetween the roof and foot and the clearheight hi (between the top beam and railhead); the total width A and clear width a atthe level of the top beam; the total width Cand clear width c at the level of the top of acarriage; and the total width B and clearwidth b at the foot of the working (Fig. 8.17).It is also essential to measure the clearancesbetween the supports and the top of thecarriage, between the rail head level and thecontact wire, etc. The measured parametersare oriented correspondingly relative to theassigned direction of the working. The resultsof measurements and a sketch of the workingare written in a standard field book.

The method of measurement of cross sec-tions by means of two staffs (Fig. 8.18) ismainly employed in workings with temporaryrailway tracks. Picket points are arranged ina working at intervals of 1-5 m, and the axisof the working at the foot level is marked atthese points. Then the distances from this axisto the rail heaQs, a and b, are measured. Staffswith decimetre divisions are set up verticallyon the rail heads, and a rod with centimetre

~.P..

I-~.-,

Fig. 8.17 Measuring cross section of trapezoidalworking

B

divisions is applied transversely to them atintervals of 0.3-0.5 m to measure distances /1and /2 from the left and right rail to therespective walls of the working. The results ofmeasurements are marked on the sketches ofcross sections in the field book, after which

Fig. 8.18 Measuring working cross section bytwo staffs


template placed onto the head of rails. Theprocedure consists in measuring the distancesfrom the protractor centre to the contourpoints of a working and the angles of thesedistances which are read on the protractor.

The cross sections of workings 2-4 m highcan be measured by telescopic (sliding) staffssuch as those illustrated in Fig. 8.21.

The staff shown in Fig. 8.210 consists of ametallic (light alloy) tube 1 3-5 cm in diame-ter and 2110 cm long in which a wooden rod2 of the same length can slide freely. Two pins3 are screwed into the wooden rod at thebottom end and roughly in the mid of itslength. The heads of pins move in a 5-mmwide slot made longitudinally in the tube.The tube length at the slot is graduated in

(b)

Fig. 8.19 Measuring working cross section bymethod of linear intersections

2.2

~

~"33.5

Fig. 8.20 Measuring working cross section byprotractor and rule

3.0. 33I

0

2.5

m..

2.0 .. jfJ:42.0

,

30

Fig. 8.21 Measuring rods: (a) tubular (l-tube;2- extractable rod; 3- pins; 4- bar with hole for

plummet); (b) staff-type (l-graduated staff; 2-extractable rod; 3- pins; 4- guide cleats)

these cross sections are drawn on a suitablescale.

The working cross sections having a curvi-linear or irregular shape are measured bymeans of templates, by the method of linearintersections or by the polar method.

The method of linear intersections consistsin measuring distances 11 and 12 from benchmarks R1 and R2 to the typical points of thecontour of a working (Fig. 8.19).

In the polar method, measurements aredone by means of a protractor arranged onan extendable stand (Fig. 8.20) or on a

1818.2. Surveying of Workings Driven from Two Ends

8.2. Surveying of Workings Drivenfrom Two Ends

decimetres with numbering in every 0.5 m. Adifferent length of the staff can be chosenwhen needed.

The staff illustrated in Fig. 8.21b consistsof a wooden rod 1 with guide cleats 4 forretaining a sliding rod 2 with pins 3. Thestationary rod has decimetre divisions num-bered in 0.5-m intervals. The cleats andsliding rod are bevelled longitudinally at anangle of 75°.

The cross sections of workings are measu-red with a sliding staff in the following way(Fig. 8.22). A plumb bob is hung in thedesired cross section onto the direction linegiven by a surveyor. A linen tape is stretchedand fixed perpendicular to that line; it alsoserves to fix the position of the plumb bob.The sliding staff is applied to the tape atdefinite intervals to measure the heights ofthe working contour. Before every measure-ment, the staff is checked for verticality by aplumb bob attached to it. The intervals atwhich staff measurements are done dependon the complexity of the working contourshape. The results of measurements are indi-cated at sketches in the field book.

For successful connection of faces in work-ings driven from two ends, it is essential tosolve properly and correctly the whole comp-lex of surveying tasks, the principal onesamong them being: examination of the en-gineering purpose of a working and of itsdesign data (cross section, slope, method ofdriving, etc.); determination of the place (point)of connection of faces; determination ofthe permissible deviation of faces in theconnection point; compilation of the schemeof mining workings which connect the ap-proaching faces; compilation of the project ofmine surveying work and selection of suitablemethods and instruments; preliminary cal-culation of the ultimate error of connectionof approaching faces; determination of theexpected ultimate error which is found bypreliminary calculation for the establishedultimate deviation of the faces; survey workand calculations for determining the connec-tion parameters (angles, direction of con-nection axis, axis length, elevation marks,gradients, inclination angles, etc.); assignmentand fixation of the connection axis in nature;and systematic survey control of the drivingof a working in the assigned direction anddetermination of the actual connection errorof approaching faces by making horizontaland vertical connection surveys for com-paring the actual discrepancies with the per-missible and precalculated ones.

In the preliminary calculations, it is essen-tial to consider three principal directions:along the connection axis, y'; perpendicularto that axis, x'; and in the vertical plane, z.Depending on the availability of a 'con-ductor', it is distinguished between criticaland less critical (free) directions. The formerare those whose errors can ,influence thetechnology of mining work.

The choice of surveying methods and theiraccuracy for developing the planimetric and

Fig. 8.22 Measuring working cross section up to4 m high by means of telescopic staff, tape and

plummet


(a)

Fig. 8.23 Scheme of assigning direction to cross-cut driven from two ends: (a) plan view; (b) sectionalong the axis of projected crosscut

height control of workings driven from twoends depend on the particular mining pro-duction conditions and requirements. Theprincipal factor that determines the accuracyof connection of mining workings is the kindof mining transport. For instance, for electrichaulage trains, the permissible deviation offaces is up to 0.5 m in plan and 0.3 mvertically. In every particular case, minesurveyors must be informed on the permis-sible connection error by the engineeringmanagement of the mine.

Main kinds of face connection. For work-ings driven simultaneously from two ends, itmay be distinguished between the followingkinds of connection:

(a) a working is driven from two ends bytwo approaching faces;

(b) faces in a working are advanced in thesame direction and follow each other; and

(c) a working is driven from one end (face)towards another face in which no miningwork is being done.

All these cases of face connection may bedivided into three principal types: (a) con-nections carried out within the limits of asingle mine, (b) connections between differentmines, and (c) connections of vertical work-ings. Accordingly, let us consider threeexamples of face connection.

points A and B, which are the initial ones forassigning the direction to a crosscut AB, intothe seams 14 and 15. For this purpose,approach points 1 and 2 are established inthe entries by running theodolite traversesfrom permanent bench marks I, II, III to thepoints A and B. The measured angles andside lengths are used for calculating directionangles al-l and aIlI-2 and the coordinates ofpoints 1 and 2 (XI' YI; X2' Y2). To establishthe points A and B in nature, it is required tocalculate angles !31 and !32 and side lengthsS2A and SIB. Besides, for assigning the direc-tion to the crosscut, it is essential to knowangles !3 A and !3B and a side length s AB. Forthis, the direction angles and horizontaldistances SIB and S2A are calculated by theformulae of inverse geodetic problem. Mterthat, it is possible to calculate the angles:

8.2.1. Connection of a Working Driven

Within the Limits of a Single

Mine

This case may be exemplified by driving acrosscut AB simultaneously from points Aand B (Fig. 8.23).

In the crosscut No.2, which has beendriven in the rock between the entries ofseams 14 and 15' there are three fixed per-manent bench marks I, II, and III. We drawon the plan the axis of the projected crosscutNo.3 and de'termine the coordinates of the.points A and B (XA' Y A' XB' and YB).

The matter consists in transferring the

8.2. Surveying of Workings Driven from Two Ends 183

~l = alB -all, ~l = alA -alIIl, ~A = a AB --aAl' and ~B = aBA -aBl.

Theodolites are then set up under the fixedpoints A and B, and the horizontal directionto the crosscut is assigned by setting theangles ~A and ~B on the limb.

In order to determine the direction of thecrosscut in the vertical plane, a line of levelsis run through the workings between thepoints A and B, and the height differense ofthe point A above the point B is measured(L\z). As may be seen in the vertical section inFig. 8.23b, the crosscut must be driven in thedirection from B to A with a gradient i = tan v(v is the angle of inclination of the crosscutfoot), which can be found by the formula:

L\z

s AB -(a + b)

where s AB is the horizontal distance betweenthe points A and B, which can be calculatedby the foimula:

YB -Y A XB -xAsAB = .=smaAB cosaAB

where a and b are the distances from thepoints A and B to the corresponding sides ofentries, which can be measured by a tape.

Fig. 8.24 Scheme of (a) elevation and (b) plani-metric control for driving crosscut between twoshafts

the collars of both shafts, R3 in the pitbottom of a mine No. I, and R4 in the wall ofa shaft No.2 (near the face). Then a closedgeometric levelling run is laid off between thebench marks Rl and R2 in order to deter-mine the coordinate z of these bench marksand to transfer this coordinate to benchmarks R3 and R4. After that the designelevation of the pit bottom of the mine No.2is determined, for which purpose the eleva-tion of the bench mark R3 (z;) is transferredonto the pit bottom, and the design length ofa crosscut, L, is then determined. Now thatwe know the elevation of the pit bottom inthe mine No. I, the design length of thecrosscut, and the design gradient, it is pos-sible to determine the elevation of the pitbottom in the mine No.2 by the formula:z' 5 = z; + iL. The difference between the ele-vation of the bench mark R4 and the designelevation of the pit bottom of the mine No.2

8.2.2. Connection of Workings inNon-Communicating Mines

As an example of this type of connection,let us consider the complex of surveyingoperations for driving a crosscut between twovertical shafts by approaching faces. One ofthe shafts is sunk to the projected level andhas a pit bottom, while the other is in thestage of driving (Fig. 8.24).

The survey work in the case consideredmay be performed in the following sequence.

First, it is required to determine the designelevations of the inset of pit bottom and therequired deepening of the shaft of a mineNo.2. For this, four bench marks are estab-lished: Rl and R2 on the ground surface at

Ch. 8. Special Surveys in Underground Workings

Level +50 m

Fig. 8.25 Scheme of connection of vertical mineshafts (axonometric projection)

(z~) permits us to find the required deepeningh ~ ,

-Z4 -ZS.Upon deepening the shaft of the mine

No.2 to the design level z's and making theinset in the pit bottom, both mines areoriented, and the elevation mark is transfer-red onto the bench mark Rs. For this pur-pose, two approach points are established onthe surface near each shaft and three per-manent points, in the pit bottom of eachmine. A closed theodolite traverse is runbetween the approach points, I, II of the mineNo. 1 and III, IV of the mine No.2, which isgiven, where possible, a shape stretched in thedirection of a connection axis. The angles andside lengths of the traverse are measured. Forproper checking, the orientation is done atleast twice for each shaft. The results oforientation are used for determining thecoordinates x, y of points V, VI, and VII inthe mine No. 1 and of points VIII, IX and Xin the mine No.2.

The coordinates of the points VII and Xare used to calculate the direction angle ofthe connection axis avIl- x. The directionangles 131 and 132 are determined by thedifference of the direction angles of initialsides VI-VII and IX-X and the connectionaxis, i. e. 131 = aVII-X -aVII-VI' 132 == ax -VII -ax -IX .

The calculated gngles 131 and 132 are laid offin nature in the points VII and X, and threepoints are fixed at each angle side, whichdefine the direction of the axis of approach-ing faces in the crosscut.

Surveying work required for this connec-tion consists in finding a point at the level+ 50 m, which lies on the same vertical linewith the centre of the shaft No.2 at the level+ 150 m. For this, it is required (a) to deter-mine the coordinates of the centre and thedirection angle of the axis of the shaft No.2at the level + 150 m; (b) to run a theodolitetraverse from the shaft No.2 to the shaftNo. 1 at the level + 150 m; (c) to perform theorientation of mine surveying at the level+50 m from the level + 150 m through theshaft No. I; (d) to run a theodolite traverse atthe level + 50 m from the shaft No. 1 beneaththe shaft No.2; and (e) to determine thecentre of the shaft No.2 at the level + 50 mand arrange the axes.

The coordinates of the centre and thedirection angle of the shaft axis are deter-mined by a special technique or according tothe recommendations of specifications onmine surveying. The theodolite traverse fromthe shaft No.2 to the shaft No. 1 at the level+ 150 m is run from the points for which thecoordinates of the centre and the directionangle of the shaft No.2 are determined. Theorientation of surveying work at the level

8.2.3. Connection of VerticalWorkings

Let the shaft of the mine No. 1 (Fig. 8.25)open the levels + 150 ill and + 50 ill andthe shaft No.2 be sunk to the workinglevel + 150 ill. At the level +50 ill, miningoperations are advanced under the shaft ofthe mine No.2, which should be deepenedfroill the bottoill upwards.

8.3. Preliminary Estimation of Face Connection Accuracy 185

+ 50 m from the level + 150 m should bedone at least twice.

When the coordinates of the shaft centre atthe level + 150 m, the coordinates of a point61, and the direction angle of a side 60-61 atthe level + 50 m are found, the centre of theshaft is transferred onto the lower level. Forthis, it is needed to calculate the angle 13 ofthe direction from the point 61 onto the point62 (shaft centre) and the distance d from thepoint 61 to the point 62.

8.3. Preliminary Estimationof Accuracy ofFace Connection

For driving a working from two ends, it isessential to estimate preliminarily the ex-pected accuracy of face connection in eachcritical direction.

For this purpose, a project of surveyingwork with explanatory notes is compiled,which specifies the proposed method ofsurveying and the list of instruments to beused. When compiling the project, the sur-veyor must consult with the management ofthe mining enterprise on the permissiblediscrepancies of workings in the critical di-rections. Upon compiling the project, it isrequired to calculate the expected error in thedetermination of the point of connection ofapproaching faces (M exp).

If the calculated expected error is greaterthan the permissible value, it is required tofind out which of the measurements asso-ciated with the determination of the connec-tion point is most responsible for the errorMexp. This measurement should then be doneby a more perfect method or more accurateinstruments. For higher accuracy of faceconnection, it is recommended to make addi-tional measurements of direction angles bygyroscopic instruments.

In the final result, the expected error mustbe smaller than or, in exceptional cases, equalto the permissible error (M exD ~ M D).

Fig. 8.26 Scheme for preliminal'Y calculation oferror of face connection


the angles and sides in the polygon A-E-III-II-D-C-B in Fig. 8.26. Let a point k be theexpected point of face connection. We candraw two axes through this point: y' alongthe axis of a working and x' perpendicular tothat axis. We are interested in the deviationof the axes of faces in the direction perpendi-cular to the axis x' and in the direction of theaxis z' (vertically).

The mean error of face connection due tothe errors of angular measurements in hang-ing polygonometric traverses run twice canbe determined by the formula:

-.!!!!!-~m = I~R;. (8.1)Xp p"j2v .

where mIl is the mean square error of angularmeasurements, s; Ry. are the projections ofthe distances from the connection point tothe corners of a polygon onto the y'-axis, m(the values of Ry are found graphically on theplan, see Ch. 4); and p" = 206265".

The mean error of face connection depen-ding on the accuracy of measurement of sidelengths in polygonometric traverses run twicecan be determined by the formula:

~ ~ "' (8.2)JI.12~SiCOS2 a, 2 2mx = + A.L cas I, 2

where 1.1 is a coefficient which accounts for theinfluence of random errors per unit of mea-sured length; I.. is a coefficient of the influenceof systematic errors per unit length; Si is thelength of the side of a theodolite traverse, m;L is the projection of the closing side of atraverse onto the x'-axis (the distance be-tween the initial poirits of a polygonometrictraverse in a mine); ai is the angle between theside of a polygonometric traverse and thecritical direction (to be found graphically onthe plan); y is the angle between the closingside of a traverse and the critical direction (tobe found graphically on the plan); the termSi COS2 ai can be found graphically by doubleprojection on the plan (see Ch. 4).

M z = ~; , + m;, + mfl + 2m;' (8.5)

In preliminary calculation of the error offace connection in vertical shafts (see Fig.8.24) the following errors must be deterrni-ned:

(I) errors of angular measurements intheodolite traverses run at the upper andlower levels of a mine:

m"M = --.!!. rr:iii{1 "V~~i

p

where m{1 is the root-mean square error ofangular measurement and Ri is the distancefrom the centre of connected shafts to thecorners of a theodolite traverse;

The total mean error of face connection inthe horizontal plane in the critical directionx' is found from the formula:

Mx = Jm~. + m~ (8.3)p ,

The mean error of face connection alongthe height can be calculated by the formula:

Mz = Jm;l + mll (8.4)

where mgl is the root-mean square error ofgeometric levelling in the mine and mtl is themean error of trigonometric levelling in thenune.

In cases when it is needed to determine themean error of connection of approachingfaces along the height considering the error ofheight transfer through the mine shafts, it isessential to take into account the followingprobable sources of errors:

(a) error of geometric levelling on thesurface mz;

(b) erro~ of geometric levelling in the mine,

mgl;~ (c) error of trigonometric levelling in the

mine, mtl; and(d) error of height mark transfer through a

vertical shaft, mz (see Ch. 4).The expected total error of face connection

along the height can be found by the formula:

8.3. Preliminary Estimation of Face Connection Accuracy 187

the lower level being connected ( + 50 m):

marMar = -Rop

where mar is the mean error of orientationand Ro is the distance between the centres ofshafts.

(2) errors of measurements of side lengthsin theodolite traverses run at the upper( + 150 m) and lower ( + 50 m) levels:

M s = ft;;;:;

where ms is the mean error of length mea-surement~; and

(3) errors of the orientation of surveys at

Chapter Nine

Surveying in Mine Construction

rections, gradients and cross-sectional di-mensions of driven workings;

(g) measurements for determining the de-formations of buildings and structures; and

(h) revision surveys of construction objectsand driven workings for depicting them inmaps, plans, sections, etc.

The layout of buildings and structures andassignment of directions to undergroundworkings are carried out according to thedesign drawings. For the construction ofmine objects, the following technical anddesign documentation should be available: anengineering report on the topographic andsurvey work on the site; the general layoutwhich is of prime importance, since it giveshorizontal distances of all permanent andtemporary structures, etc. from the axes of ashaft and their elevations; the design plan ofarrangement of heading equipment on themine surface; the design plans and verticallayout of earth-moving work with distribu-tion of soil masses; the general plan ofpermanent and temporary underground ser-vice lines; the topographic plan Qf the terri-tory allotted for construction; drawings offoundations; and design documentation re-lating to mine shafts and other mine objects.

The instrumental layout of constructionobjects is carried out from the points of amine survey reference net, points located onthe axial lines of mine shafts, and the pointsof a layout net. The layout work under-ground is done from the points of under-ground polygonometric nets and survey nets'of the first or second order.

9.1. General

Survey work in mine construction is animportant part of mine surveying. It consistsspecifically in that the angular and linearmeasurements which determine the designdimensions of underground workings andmine head-gears are transferred into natureand fixed properly. Further, modern minesare characterized by intricate undergroundcomplexes with hoisting vessels a few tenscubic metres in capacity and high liftingspeeds, which sets forth especially rigorousrequirements to the accuracy of their assemb-ly. These circumstances make the surveywork in mine construction the most comp-licated and critical part of mine surveyingservIce.

The principal problems to be solved bymine surveying in mine construction are asfollows:

(a) construction of reference nets on thesurface for making the layout work;

(b) determination of the scope of the earth-moving work;

(c) instrumental layout of the axes of amine hoist on the surface and transferring thegeometrical elements of buildings, structures,etc. into nature;

(d) special measurements and surveysduring sinking and equipment of mine shafts;

(e) control of the relation between thegeometrical elements of mine hoists duringconstruction;

(I) assigning directions to undergroundworkings and surveying control of the di-

9.1. General 189

v 'CIj'-II

I[] --1

2:

The layout control work is understood asthe work of transferring the project of astructure into nature. The principal layoutcontrol operations consist in the constructionon the terrain of the main axes of a con-structed site (mine camp), such as the axes ofmine shafts or the sides of a layout controlnet.

The axes of a vertical mine shaft areessentially two horizontal lines one of thembeing parallel and the other, perpendicular tothe main buntons (dividers) of that shaft. Thepoint of their intersection is called the centreof the shaft. Detailed layout control is per-formed by mine surveyors and consists in theconstruction of the main axes of buildings,structures, machine foundations, and hoistaxes.

9.1.1. Layout Control Net of MineCamp

Detailed layout work at the constructionsite of a mine head-gear (mine camp) isfacilitated by constructing a layout controlnet of reference points. Its construction isbased on the results of topographic and minesurveys carried out on the territory of mineconstruction.

In cases when the objects of a surfacecomplex are distributed all over the minecamp, layout control can be reduced to theconstruction of a layout net consisting ofpoints located on the axes of the main andauxiliary shaft. At large mines, all mainbuildings of the surface complex are Jlsuallycombined into three blocks: main shaft block,auxiliary shaft block, and office and accom-modation block. In such cases, the points onthe axes of shafts do not form a common netand thus cannot always ensure the requiredaccuracy of layout work. Besides, if theobjects of a large extension are to be built inthe central portion of a mine camp, mostpoints on the shaft axes will be inevitablylost. In such caSes, it is required to constructpreliminarily (before construction) a special

il i E3J! n ~ FIB f +-~--- I"---tl-~ ~

I I I ,Main shaft I II I :11 IAu~iliaryr : .

~--- +- --~~h.:~- + I I.II I O ,

A0..: t! ~ O J OH G

Fig. 9.1 Layout control net

layout control net covering all the territory ofthe mine camp.

In modem mine construction, a layoutcontrol net is formed as a system of rectan-gles with vertexes in spaces between thesurface structures and with sides orientedparallel to the axes of a shaft (Fig. 9: I ). Alayout control net should be formed alongthe following recommendations:

(a) the main points of a net should bearranged at the vertexes of rectangles and theauxiliary ones, on lines connecting the mainpoints;

(b) the sides of rectangles between themain points should be 80-350 m long;

(c) the main points should be establishedin places where their long preservance can beguaranteed; and

(d) the coordinates of points should bedetermined analytically in a conventionalsystem of coordinates whose axes are di-rected along the axes of a shaft.

The construction of a layout control net iscarried out in the following order:

(a) the main points of a net are transferredinto nature and fixed by permanent benchmarks;

(b) a polygonometric traverse is runthrough these points;

(c) the results of measurements are pro-cessed for the reduction of the system ofpolygonometric traverses;

(d) the points are reduced, and checkmeasurements are carried out;

D

r-:::

E---y ~-I

I~ ,.,

Ch. 9. Surveying in Mine Consl190

Fig. 9.2 Transfe )f horizontal angle into nature

(e) auxiliary points are established on linesbetween the main points; and

(1) the elevations of these points are de-termined by levelling.

The accuracy of construction of a layoutcontrol net must satisfy the following re-

quirements:(a) an error in the position of the first

established point of a layout net relative tothe points of a reference net (national geo-detic net or densification net) must not ex-ceed 0.1 m;

(b) the direction angle of the first side of alayout net must differ from the design valueby not more than 20";

(c) the non-perpendicularity of the sides ofa layout net must not exceed 20";

(d) the root-mean square errors of angularmeasurements must be not more than 10";and

(e) linear measurements must be done witha relative error not worse than 1/15000.

The axes of mine shafts are establishedfrom the points of a layout control net andeach semi-axis is fixed by at least two points;in that case, the errors of angular measure-ments must be not more than 40" and thoseof linear measurements, not more than1/3000.

9.1 .2. The Concept of Layouts

Layout control is carried out in horizontaland verti'tal planes and contains a number ofgeodetic operations, such as transferring apoint, design distance, design horizontal an-gle, elevation mark, axes, etc. into nature.

Transfer of a horizontal angle into nature.This operation reduces to finding the secondside of that angle on the terrain. For thispurpose, the theodolite is set up at the vertexof the angle (a point B in Fig. 9.2a). Thespecified angle is laid off from the initialdirection at two positions of the telescope(FR and FL). If points C' and c" determinedat the two positions of the telescope (FR and

FL) do not coincide, i. e. there is a collima-tion error, the section between these points ishalved, and the point C is found in the mid,which determines an angle 13. For checking,the angle 13 is measured and compared withthe design value. If the difference between thespecified and measured angles is greater thanthe permissible error of angle measurement,this difference is used to calculate the linearcorrection by which the second side of theangle should be transferred (a point Cl inFig. 9.2b). This correction can be calculatedby the formula:AI = IA13"/p"

where 1 is the horizontal distance between thetheodolite and the point C; A13 is the differ-ence between the specified and measuredangles; and p" = 206265".

Transfer of a specified horizontal distanceinto nature. The method of transferring thespecified horizontal distances into nature ischosen depending on the terrain relief, re-quired accuracy, length of lines, etc. Thefollowing main cases may be encountered inmine surveying practice.

If the terrain is flat, the inclination angledoes not exceed 3°, and the length of a line isnot more than 50 m, the design distance islaid off on the terrain by taping along thespecified direction and is fixed by a point. Ifthe terrain is an even slope and the linelength does not exceed 50 m, the inclinationangle of the specified direction is first meas-ured by a theodolite, after which the design

9.1. General

On a rough terrain and with a large designdistance, the layout work is started by settingup a theodolite in a point A (Fig. 9.4). Thepoint Bo near the future point B is estab-lished on the specified direction by means ofa range finder. Then, the line AB is ranged inthat direction and the points where the slopeis measured are fixed by stakes. The lengthsand angles in each inclined section Si aremeasured. After calculating the horizontaldistances Si' their sum (~sJ is found andcompared with the design horizontal dis-tance. This gives the length of a line sectionL\s = ~s. -s,

for determining the position of the designpoint B.

Transfer of design points into nature. Thetransfer of design points during layout can beperformed by several methods.

I. Polar method. It is essential to have twopoints with known coordinates on the terrain(A and B in Fig. 9.5a). The design angle ~ andlength s are laid off from the direction AB,which gives the position of a point C. Thepolar method is the most popular one fortransferring points into nature. The root-mean square error of the position of a pointcan be found by the formula:

~ (smpf

mp= ms +~

p

Fig. 9.3 Transfer of specified horizontal distanceinto nature on terrain of intricate relief

horizontal distance is laid off. With the anglev being known. the inclined length S iscalculated by the formula:S = s/cos v

This length is laid off by a tape along thespecified direction. On the terrain of anintricate relief. an auxiliary point Eo is firstestablished on the specified direction near thesought-for point E (Fig. 9.3). The inclinationangle v is measured by a theodolite and theinclined length AHo. by a tape. The hori-zontal distance is calculated by the formula:Sf = AEocosv

Then the difference between s' and thedesign horizontal distance s is determined

As=S-Sf

which is laid off from the point Eo. and at lastthe point E is fixed. where ms and mp are the rrns errors of

Fig. 9.4 Transfer of specified horizontal distance into nature on rough terrain

192 Ch. 9. Surveying in Mine Construction

c

A 8

An(c) (d)

'c -,-!

Oc

RI =AC / , R =BC/ ,2

/ ,

// ,o O -OA B O B

Fig. 9.5 Layout of points: (a) polar method;(b) method of angular intersection; (c) method of linearintersection; (d) method of rectangular coordinates

point C (xc, Yc) are known, they can be foundby solving the inverse geodetic problem. Thedirection angle of a line EC can be deter-mined by the formula:

Yc -YBtan IlBC =Xc -XB

With the known direction angle of a lineEA and the calculated direction EC, we canfind the angle 13 = IlBC -IlBA. The length ofthe section EC will then be found from theexpression:EC = .~ = Yc -YB J ~ -!..!!.'l---

sin aBC COS aBC

2. Method of angular intersection. The po-sition of a point C can be detennined by thepoint of intersection of two directions drawnat angles ~ A and ~B from points A and B of aknown side (Fig. 9.5b).

If the angles ~ A and ~B are not specified,they can be calculated from the knowncoordinates of points A, B, and C by thefonnulae:~A=aAB-aAC' ~B=aBC ' .

Yc -y A

-a BA

Yc -YBtan aAC = , tan aBC =

Xc -XA Xc -XB

The method of angular intersection is usedin cases when the points A and B are at largedistances from the point C and linear meas-urements would involye difficulties.

3. M ethod of linear intersection. In thismethod, the arcs of radii AC and BC aredrawn on the ground from the centres inknown points A and B (Fig. 9.5c), and theirintersection gives the sought-for point C.

4. M ethod of rectangular coordinates. Thisis employed in cases when the points to belaid out on the ground are essentially close toa reference (layout) net. The coordinates xand y of a point C relative to a reference netare determined on the plan and then laid offand fixed on the ground (Fig. 9.5d). Thelayout work is checked by measuring thedistances between the points established on

measurement of lengths and angles respect-ively and s is the distance from the knownpoint to that to be established. Assuming thatthe accuracy in detailed layout work is up to1/3000 for linear measurements and up to I'for angular measurements and the error inthe determination of the positions of cornerand axial points of building foundations isnot more than 0.01 m, the maximum distancefrom a point of the net to the contour beinglaid out should be not more than:

I~-=Imax

0.012

Jr moo~

-~22m

., , (~)2

Thus, the points of layout control andreference nets in the layout work should belocated at distances not more than 25 m fromthe contour being laid out.

If the angle 13 and length s (Fig. 9.5a) arenot specified, but only the coordinates of a

9.2. Surveying at Mine Camp 193

fomlula:

b=IH-HB

If the design elevation is transferred ontothe well of a working or another object abovethe ground, the staff set up in the respectivepoint should be lowered or lifted until thereading on it is equal to the design value. Aline drawn at the staff foot will then give thedesign elevation mark.

If the design elevation mark is to betransferred onto the top of a peg, the lattershould be hammered down until the readingon the staff set up onto it will be equal to b.

9.2. Surveying at Mine ,Camp

The main axes of all buildings and struc-tures should be laid out in nature and fIXed ata mine camp before starting the earth-movingwork. The distances from the net being laidout to the points determining the axes ofstructures should not exceed 25 m. The di-rections onto the points to be establishedshould be assigned with an accuracy notworse than I' and the distances to thesepoints, with an accuracy not worse than10 mm. The main axes of buildings andfoundations should be laid out so as to bepreserved fully for the entire period of con-struction. Linear measurements of distancesbetween the layout axes of buildings, struc-tures, foundations and machinery, betweenthe axes of columns, and between the layoutaxes and the axes of support structures,embedded parts, anchor bolts, axes of precast

the ground. In mine construction, a versionof this method is popular with one of therectangular (layout) axes being fixed bymeans of a stretched wire. A plumb bob issuspended from the wire, and the requireddistance is laid off from it perpendicularly.Instead of plumb bobs, other means can alsobe used for the fixation of points on the wire.

5. M ethod of ranging measurements. In or-der to transfer into nature design points, say,A and B, which lie on the line between points1 and 2 of a layout net, the theodolite is setup, say, in the point 2. The instrument issighted at the point I, and the design distan-ces S2A and S2B are laid off by means of a tapefrom the point2; the points A and B found inthis way are t~en fixed.

In the construction of structures and otherconstruction jobs it is often needed to trans-fer points with design elevations into nature.Such points can be transferred by geometriclevelling with two staffs or by means of aninstrument horizon. For this purpose, thelevel instrument is set up midway betweenthe bench mark A with the known elevationH A and the point B to be established, whoseelevation HB is specified in the project(Fig. 9.6).

The staff is set up onto the bench mark A,the reading a is taken on it, and the instru-ment horizon is calculated by the formula:

IH=HA+a

Mter that, the reading of the staff set up inthe point B, at which the staff foot will be atthe design elevation, is calculated by the

13-1270

Ch. 9. Surveying in Mine Construction

mine camp. The plan position of each struc-ture is determined by the distances from itscharacteristic points to the axial points of themine shaft or points of the layout net.

When laying out the foundation of abuilding, its characteristic points (A and B inFig. 9.7) are established by the predeter-mined angular and linear elements, and theaxes 1-1, 11-11 and 111-111 of the building aremarked in nature. Using these axes, it is thenpossible to layout the axes of the walls(mostly by the method of perpendiculars orpolar method). The main axes of the buildingare fixed by axial points and the axes of thefoundation are transferred onto and fixed onbatter boards fastened on poles- (Fig. 9.7).The batter boards should be arranged at acertain distance (not less than 3 m) from theexterior walls of the building. Wires stretched

reinforced concrete and steel structures, andmounting axes of process equipment andmechanisms are made by standardized tapes.

All measurements are fixed in a layoutbook together with the date of the layoutwork, coordinates of initial points, numbersof design drawings, distances and measure-ments used for layout, and the orientation ofobjects relative to the axes of the site.

The layout work at a mine camp is startedfrom the centre and axes of a shaft. The axesare laid out and fixed according to thecoordinates x, y of the shaft centre and thedirection angles of the shaft axes, proceedingfrom survey net points located at a distancenot more than 300 m from the shaft. Thecentre of the shaft is established indepen-dently twice; the discrepancy between the twomeasurements should not exceed 0.5 m. Theangular error of the layout of the main axis ofthe shaft relative to points of the surveyreference net should not exceed 31. If thecentre and main axes are established for ashaft associated with an operating miningcomplex, the errors should not exceed respec-tively 0.1 m and 1'30". The error of the layoutof a perpendicular axis relative to the mainone should be not more than 45".

At least six points should be establishedand fixed at each axial line of a shaft. Thesepoints should be arranged so that they can beused for the construction of buildings andstructures at the site. At least two pointsshQl.11d be established beyond the limits of themine camp. The distances between adjacentpoints must be not less than 50 m. The layoutof the centre of a shaft can be done by themethod of perpendiculars or polar method.

Upon finishing the layout work, a second-order polygonometric traverse is run throughthe shaft centre, axial points and points of thesurvey reference net, and the coordinates ofthe axial points are calculated.

Before starting the earth-moving work, themain axes of buildings and structures shouldbe transferred into nature and fixed at the

9.3. Surveying in Construction of Mine Hoists 195

between the axial points of opposite batterboards determine the directions of the buil-ding axes, and their intersections define cor-ner points. In the construction of large blocksof industrial buildings (of a length more than80 m), batter boards and wires are also usedfor the fixation of the axes of exterior walls;plumb bobs 1,2,3,4 are suspended from thepoints of wire intersection (Fig. 9.8).

The vertical layout of foundations is car-ried out by means of a level instrument andstaff, starting fr.om bench marks usually fixedon the piles of batter boards. ..

Buildings and structures in mine construc-tion may have cast in-situ, strip, pile foun-dations, etc. The layout work for strip foun-dations consists in checking that the foun-dation pit has been dug properly, arrange-ment of a shuttering (formwork), and trans-ferring the design elevation marks of thefoundation top onto the formwork. The po-sition of the formwork in plan is checked bymeans of plumb bobs suspended from thepoints of foundation axes marked on batterboards. The deviations of the foundation axesfrom the design values should be not morethan 2 cm and the deviations of the axes ofwells, columns, beams and girders, not morethan 1 cm. A decrease of the cross-sectionalsize of a foundation against the design valueis inadmissible; an increase by not more than

5 mm is allowed. The vertical position of aformwock is checked by a plumb bob; thepermissible error is 2 mm per metre of thefoundation height.

After concreting a foundation, it is cont-rolled by planimetric and height surveying.The discrepancy, between the actual anddesign elevation marks of the foundation topmust be not more than 20 mm.

The mine survey servicing of precast foun-dations means the fixation of their exteriorand interior faces by cords or wires stretchedbetween batter boards. The design position ofa foundation is marked initially, after whichthe foundation is laid in place. For thispurpose, the foundation guide blocks are firstlaid in place in every 20-25 m, cords arestretched between them, and intermediateblocks are then laid.

In the construction of deep foundations,the axes of the exterior rows of piles or theaxes of pits are first marked in the foundationpit, and the contour of the cutting shoe of acaisson ring is established. After pile driving,levelling is carried out to check that all pileheads are in the same horizontal plane.

Plane foundations are the most populartype of foundation for reinforced-concretecolumns. In laying, the foundation plates arechecked by a theodolite or level instrument.The deviations of the axes of a foundationfrom the design values should not exceed5 mm and those of the support surfaces fromthe design elevation marks, 3 mm. Anchorbolts for fastening metal columns must not bedisplaced from the design position by morethan 5 mm in the horizontal plane and bymore than 20 mm, vertically.

9.3. Surveying in Constructionof Mine Hoists

9.3.1. Brief Data on HoistingComplexes of Vertical Shafts

Modern hoisting complexes employed inmining can be characterized by ever increas-


ing hoisting depths, increased speeds ofhoisting vessels, and larger mass of cargoes.In addition, the construction of mine comp-lexes is often oriented at industrial methods.These circumstances set forth new compli-cated problems before mine surveyors. Inparticular, they must ensure the proper ac-curacy of mounting the process equipmentand safe operation of mine hoists. The minesurveyor has to take part in all stages of theconstruction and operation of mine hoists.He is directly engaged in the constructionand installation work, plays an essential rolein the acceptance of a mine hoist, andperforms control during the hoist operation.

A mine hoist has the following main com-ponents: (I) hoisting plant, (2) shaft equip-ment, and ,(3) auxiliary hoisting equipment.The hoisting plant of a mine includes ahoisting machine, head-gear (head-frame),hoisting (driving) pulleys, hoisting ropes, andhoisting vessels.

According to the kind of hoisting vessel,hoisting plants can be divided into skiphoists, cage hoists, skip-cage hoists, andbucket hoists. They may be of the single- ormulti-rope type depending on the number ofhoisting ropes. Further, by the method ofrope winding, it is distinguished betweenhoisting plants with a constant windingradius and those with a variable radius.

Depending on the kind of guides, theequipment of a shaft may be either rigid orconsist of ropes. Combined equipment is alsoemployed, in which rigid conductors are usedfor hoisting vessels and rope guides, forcounter-weights.

The auxiliary equipment of a mine hoistincludes load-handling facilities and landingstages.

Hoisting machines, which are the principalpart of mine hoists, may be provided witheither rope-winding drums or friction typepulleys (Koepe sheaves). Druni-type hoistingmachines may be with a constant or variablewinding radius. Those with Koepe sheaves

may be of the single- or multi-rope type.Hoisting plants of vertical shafts are equip-ped with medium-sized or large-sized drum-type machines. The former have a windingdrum 2.5 m. 3 m or 3.5 m in diameter andensure a hoisting speed of 7-10 m/s. Large-sized hoisting machines have drums 4-9 m indiameter and up to 1560 m in coiling length.The hoisting speed of these machines attains16 m/s.

Multi-rope hoisting machines have severalropes which are driven from a hoisting pulleyowing to the friction between the pulleylining and ropes. Each of the ropes is fastenedto both hoisting vessels. Multi-rope hoistingmachines are mainly employed in tower-typehead-gears. Multi-rope machines manufac-tured in this country have four. six or eightropes. a load-carrying capacity from 3 t to50 t and driving pulleys 2.1-5 m in diameter.

A head-frame is a structure above a shaftwhich carries guide pulleys. conductors. cagerests. unloading curves. etc. There are twomain types of head-frame: jib head-framesand tower head-frames.

A jib-type head1rame (Fig. 9.9) consists ofa vertical frame 1. a jib 2 which serves as astrut for the vertical frame and absorbs thetilting force developed by a hoisting rope.and a pulley (landing) stage 3 for guidepulleys. Jib-type head-frames are mostlymade of metal and much rarely of wood andmay be classified as A-shaped. four-stand-type and tent-type.

A tower-type head1rame carries the entirehoisting complex. including the hoisting ma-chine. Tower-type head-frames may have ametal framework or reinforced-concrete(cast-in-situ or precast) carrying walls (Fig.9.10). The walls of a head-frame form aninterior shell of a rectangular cross sectionwhich serves as a support. and an exteriorshell of a circular or rectangular cross sec-tion.

Hoisting pulleys are mounted on the pulleystage of a head-frame. They hold the ropes

1979.3. Surveying in Construction of Mine Hoists

(b)

Fig. 9.9 Steel jib-type head-frames: (a) A-shaped; (I2-jib; 3 -pu1ley (landing) stage

and direct them from the hoisting machineinto the mine shaft.

Hoisting pulleys may be without lining orwith a lining made of soft metals, wood,rubber, etc. The diameter of a pulley dependson the diameter (thickness) of a hoisting rope.For tight contact of a rope on a pulley, thediameter of the latter must be not less than 80rope diameters. Non-lined pulleys are madeof high-strength cast iron (with the diameterup to 3 m) or stamped of steel (with thediameter more than 3 m).

Hoisting ropes. Only steel-wire ropes areemployed in hoisting plants. Round-strandright- or left-hand twisted ropes and flattened-strand ropes are used in hoists of a small ormoderate hoisting height. With a large hois-ting height, use is preferably made of cross-twisted round-strand ropes and self-tighten-ing sheathed ropes, as well as of self-tighten-ing multi-layer ropes. Hoisting machines withKoepe sheaves are equipped with flattened-strand and sheathed ropes.

Hoisting vessels. Buckets, cages, skips andcombined types (such as skip-cage) areemployed as hoisting vessels. Cages may beof the non-tilting (common) or tilting typeand are divided by the type of load intoman-cargo and man (passenger) cages. Sin-gle- and double-stage non-tilting cages arethe most popular types. Skips 7-15 m3 incapacity are employed in single-rope hoists

II) with four stands; (c) tent type; 1-vertical frame;

and those 9.5-35 m3 in capacity, in multi-rope hoists.

Suspensions of hoisting vessels. Suspensions(bails) are devices by which hoisting vesselsare connected to ropes. According to safetyregulations, cage bails have a double inde-pendent suspension with l3-fold safety mar-gin and skip bails, a single suspension withlO-fold safety margin.

Loading-unloading devices (stations). Load-ing and unloading of hoisting vessels are themost critical operations of hoisting. Skips areloaded in a shaft by means of a loadingdevice which includes an underground bun-ker, chutes, and gates with drive mechanisms.Skips and tilting cages are unloaded on thesurface by means of unloading curves moun-ted in the head-frame.

A cage hoist has landing stages in the shaftand on the surface, which are provided withlanding chairs to support the cages duringloading and unloading; they also have arrange-ments for moving carriages into and fromcages and safety devices. Landing dogs arethe most popular type of landing chairs.

Equipment of vertical shafts. The equip-ment of shafts is understood as a complex ofelements which ensure the directed motion ofhoisting vessels under the specified operatingconditions of a hoist. The shaft equipmentmay be either rigid or of the rope type.

A rigid equipment consists of conductors


and buntons (dividers) which carry the for-mer. The conductors serve to direct themoving hoisting vessels. They are made ofrectangular wooden bars, steel rails or rolledU-shaped steel sections in the form of con-tinuous cage structures which are arrangedvertically in a shaft. The conductors arefastened to buntons (dividers) which are es-sentially horizontal beams built in by one orboth ends in the shaft lining. The buntons aremade of wood or various rolled steel sections.

A rope equipment can be employed inshafts where one or two hoists are arrangedin parallel and the path of hoisting vessels isnot curved. A rope equipment (Fig. 9.11)includes rope guides 1, balance ropes 2, ropeclips 3, rope-tensionirig weights 4, a ten-sioning frame 5, guides for hoisting vessels 6,and devices for the fixation of hoisting vesselsat the loading and unloading stages, 7 and 8.

The rope guides are usually made fromsheathed ropes. Four rope guides are usuallyprovided for a hoisting vessel, which arearranged either at the corners or pairwisealong the larger side of a cage. In shafts withtwo hoists, the balance ropes are stretchedbetween the vessels in order to prevent theircollisions. The ropes are tensioned by meansof weights arranged in a sump or by means ofa hydraulic device mounted on a head-frame.

The equipment of a shaft can be mountedeither after driving the shaft or at the sametime. In the former case, all operations can becarried out by a consecutive, parallel orcombined scheme. With the consecutive sche-me, buntons are mounted from a suspendedstage, beginning from the top of a shaft, andafter that, conductors are fastened to themfrom a cradle, beginning from the bottom.With the parallel scheme, conductors aremounted at the same time with buntons, butthe latter are mounted from a sinking plat-form and the former, from a cradle thatmoves behind the platform. With the com-bined scheme of arrangement of the shaft

Fig. 9.10 Reinforced-concrete tower-type head-frame: 1 -machine rooms; 2 -level of guide pulleys;3- metal stand; 4- floors; 5- foundation


equipment, buntons and conductors aremounted simultaneously.

In cases when the shaft equipment ismounted simultaneously with shaft driving, asection of shaft lining is first fastened in theshaft, after which buntons and conductorsare mounted on it from a sinking platform.

arrangement of metal structures, to make theprofile survey of the head-frame structure,and to transfer the layout axes of a pulleystage, guide pulleys, and unloading curves.

For mounting a jib-type head-frame, asupporting frame is made around the collarof the shaft and foundations for a jib arebuilt. The correct position of the supportingframe is checked relative to the axial pointsfixed in the permanent lining of the shaftcollar. The errors in the position of thesupporting frame should be not more than5 mm in the horizontal plane and 30 mm inthe vertical plane, and the difference betweenthe elevation marks of the frame cornersshould be not more than 5 mm.

The layout of the foundations of a jib isdone according to a working drawing andthe plan of arrangement of foundations rela-tive to the shaft axes. Upon the constructionof the foundation, the mine surveyor checksthe depth of the foundation pit, the hori-zontality of the foundation pad, and thecorrect mounting of a shuttering. Since thefaces of the foundation are represented in theworking drawing with distortions of theirdimensions, it is essential to determine theiractual dimensions for the manufacture ofshuttering panels.

For the arrangement of the shutteringalong the axes of a head-frame foot(Fig. 9.12), these axes are first transferredonto side piles, and cords are stretchedbetween the piles. After that, corner points A,B, C and D are marked on the foundationpad by means of plumb bobs sunk from thecords. The correct arrangement of the shut-tering is checked at its top, by using points a,b, c, and d. A shuttered foundation foot isconcreted partially, anchor bolts are set up,and concreting is finished.

Metallic jib-type head-frames can be mount-ed by two methods: (a) the head-frame ispreassembled on an assembling stage andthen lifted and mounted on a supportingframe or (b) the sectiQfis of a head-frame are

9.3.2. Survey Control DuringMounting of MetallicJib-Type Head-Frames

During mounting a jib-type steel head-fra-me, the mine surveyor has to layout the axesof the supporting frame and foundations forthe head-frame jib, to check the correct


~"~\, ,0/.

"1!11\ \

~1\\II \ I\.I~i'!'Y

\ 1\1 , I

A l\ \

D

Fig. 9.12 Arrangement of shuttering of head-frame jib foundation

mounted successively on a supporting frame.Before lifting an assembled head-frame, the

design positions of the shaft axes should bemarked on the pulley stage and the hori-zontal ties of the jib. The axes are fixed finallyafter they have been transferred onto thepulley stage of the erected head-frame. In thatcase, the deviations of the axes of the pulleystage from the design positions must be notmore than 25 mm in directions perpendicularto the hoisting axis and not more than50 mm in the direction parallel to thehoisting axis.

In cases when a head-frame is erected bymounting individual sections one on top theother, the survey work consists essentially inchecking that each section has been mountedcorrectly.

For mounting unloading curves, it is re-quired to transfer their layout axes. An errorof arrangement of unloading curves in planrelative to conductors should not exceed10 mm; the planes of the plates to which theunloading curves are fastened should beperpendicular to the plane passing through

the conductors (the permissible deviation isnot more than 10 mm); the correspondingpoints of external and internal curves shouldnot deviate from the same level by more than10mm.

A check of the correct arrangement ofguide pulleys is done after the final fixation ofthe jib and head-frame foundation. For thispurpose, the layout axes of the shaft andhoist are transferred onto the landing stage.The distance from the pulley rim to thelayout axis (hoisting axis) should not differfrom the design value by more than 10 mmfor pulleys up to 6 m in diameter and bymore than 15 mm for those above 6 m indiameter. If it turns out that these distancesexceed the specified values, the pulley mustbe readjusted. A check should then be madethat the axis of the pulley is perfectly hori-zontal (the permissible discrepancy betweenthe elevations of the shaft ends is 1 mm).

A check of the arrangement of a pulley ona landing stage is done by the mine surveyorin the following sequence.

A cord is stretched along the hoisting axis


The horizontality of the shaft of a head-frame pulley can be controlled by a framelevel with a division value not worse than20", hydrostatic level, or level with a com-pensator, which permit the measurements ofthe elevations of shaft ends with an accuracyup to 1 mm. The permissible deviations ofthe pulley axis from the horizontal are estab-lished by specifications on assembling parti-cular hoists.

(Fig. 9.13), from which horizontal distancesto the pulley rim are measured (/1' /1,4 and/2). These measurements are then repeatedafter turning the pulley through 180°. Thefinal results are found as their mean values,i. e.:

11+/1 12+/2a1=- a2=-

2 2

If the distances a1 and a2 are not equal toeach other, it is then required to calculate the

a -aangle'Y = 1- 2 n thrO1lgh whicJ, thp n1111p\Tr 0-- , .,'~ t'.."~J

Dp

must be turned (here D p is the diameter of thepulley). The position of the axis of the pulleyshaft is determined by measuring the distan-ces Si and S2 from the shaft axis to the plumbbobs hung from wires which fix the shaft axison the landing stage.

9.3.3. Survey Control In Constructionof Tower Head-Frames

The layout work for the construction ofsteel tower head-frames consists mainly inlaying out the axes of columns of the first andupper stages of the frame structure.

Before mounting steel structures on the


Upon erecting the walls to a height of 2 m,the shaft axes are fixed by brackets from theexternal and internal side of the head-frame.Later in the course of the erection of thehead-frame, the position of the slip form iscontrolled by means of a vertical sightingdevice, preferably by an automatic zenith-telescope (Fig. 9.15). The instrument is inten-ded for vertical projection of a point from thebottom upwards; it gives an error not .morethan I mm per 100 m of vertical distance.

The zenith-telescope or another similarinstrument is sighted at sighting marks(Fig. 9.16) which are fastened on slip forms.Each sighting mark is essentially a squarenetwork drawn or printed on a transparentmaterial (such as triacetate film). Sightingmarks are fastened to wooden bars thatsupport the working floor of the slip forms.

foundation, a mounting network is markedwhose points should be principally coinci-dent with the centres of columns. For con-venience, however, the reference points areshifted somewhat aside, which makes it pos-sible to use them during the entire period ofmounting work. The spacings between adja-cent sides of the network should not differfrom the design values by more than 5 rnrn.

The upright position of columns is checkedby the method of vertical plane with the useof two theodolites which are set up on twomutually perpendicular axes of columns oron axes of the mounting network. At eachtheodolite station and with two differentpositions of a telescope, the upper axialmarks of a column are projected onto thecolumn base. The displacement of the uppercentre relative to the lower one is measuredby a millimetre-graded staff; the permissibledeviation is up to 15 rnrn for columns up to15 m high and 0.001 of the column height(but not more than 35 mm) for highercolumns.

Mter mounting each stage of the framestructure, the schemes of column rows aredrawn in the vertical projection in planesparallel to the two axes of the shaft(Fig. 9.14). As the frame structure is beingerected, the shaft axes are laid out on eachplatform; upon the construction of reinforcedconcrete stage floors and arrangement ofwall panels, these axes are transferred ontobrackets.

In the construction of cast-in-situ concretetower head-frames in slip forms, the surveywork consists in the following.

The mine surveyor checks the dimensions,shape and position of the slip form which isassembled on the head-frame foundation. Inthe first place, he makes a check by mea-suring the distances from the shaft axestransferred onto the slip form to the plane ofeach panel that divides the slip form intosections; he also makes the levelling of theworking floor in the corners of sections.


Fig. 9.15 Zenith-telescope PZL (GDR): I-pro-tective glass; 2- housing; 3 ~ telescope eyepiece;

4- focussing screw; 5- reading-olT microscope;6- pivoting mirror; 7- clamp screw; 8- sighting

screw; 9-base; JO-tripod

The zenith-telescope is set up successivelyunder each sighting mark, which makes itpossible to control the verticality of thetower, hoisting compartments, and exteriorwalls. The arrangement of sighting marksdepends on the shape of slip forms. Theprincipal diagram of the arrangement ofsighting marks for the construction of atower head-frame of rectangular cross sectionis shown in Fig. 9.17.

In order to determine the height of theworking floor of the slip forms, control staffsare fastened at the corners of the shaftportion and external portion of a towerhead-frame. These staffs are extended period-ically as the slip forms are lifted. In addition,as the slip forms are advanced through every20 m, the mine surveyor measures the heightof the working floor relative to a bench markconcreted in the bottom portion of the head-frame. If the heights of the working floordetermined by the check measurements differfrom the readings of the staffs on the slipforms by more than 20 mm, the staff readingsare corrected.

The results of control of the position of slipforms are presented as a scheme of matched

L

l

Fig. 9.17 Principal diagram of arrangement ofsighting marks for construction of head-frames ofrectangular cross section: I-sighting mark; LandS -increasing numbers of larger and smaller scale;x. y-coordinate axes

Fig. 9.16 Sighting mark: 5, 10, 15, 20, 25-num.bering of smaller scale; 55, 60; 65, 70, 75-num.bering of larger scale


sections of the headframe constructed inintervals of 2-4 ill, which makes it possible tocheck the positions of the headframe wallsand thus to take measures for preventingfurther deformations and deviations of theslip forms.

The total hoisting height H is the verticaldistance from the lowermost point of ahoisting vessel when this is in the lowermostposition to the same point of the vessel in theuppermost position at the end of unloading(Fig. 9.18): H = h + ht + hb, where h is thedepth of the shaft; ht is the distance from thezero stage to the lowermost point of thehoisting vessel at the moment of unloading;and hb is the maximum sinking of the hoist-ing vessel below the pit-bottom level duringloading.

The height of a head-frame Hhf is thevertical distance between the axis of rotationof the guide pulley and the zero stage:Hhf = ht + hv + hp + hz + O.75Rp

9.3.4. Geometrical Elementsof a Mine Hoist

For efficient and safe operation of a minehoist, its individual elements should have thespecified geometrical relationships.

Geometrical elements of a single-rope hoist.The principal geometrical elements of a sin-gle-rope hoist are as follows.

5000 dia---

--~

ii;,,; ,

~

~ :" '.

, ,,"" ,

~."',

~Receiving stage level

,"

">

~

5000 dia

~\,

~

~r~or level

~~+

~

30000 17500

Fig. 9.18 Geometrical elements of single-rope mine hoist

5000 dia/

"/'~

~~ '~ ,Level of discharae curves

Rp

11'-",

by the formulae:<PI = <P + A<p,; <Pu = <P -A<pu

where <PI is the inclination angle of the lowerstring; <Pu is the inclination angle of the upper

, Lu string; A<p, and A<pu are the inclination angles~'a, of the lower and upper strings relative to the

" L~ , " line that connects the rotation axes of the~ L R 17' Rdr drum and pulley; <p is the inclination angle of

p the straight line connecting the axes of the

~~/&'/~~~ "'-' ./ ~ pulley and drum of the hoisting machine,~ ~ which can be found by the formula:

H-HFig. 9.19 Inclination angles of hoisting ropes tan <p -p d..

!.0.0" rL

where H p is the height of the pulley axisabove the zero stage; Hdr is the height of thedrum axis above that stage; and L is thehorizontal projection of the line connectingthe axes of the pulley and drum.

The terms A<p, and A<pu can be found bythe formulae:

Rdr + Rp Rdr -Rptan A(D.. -tan A(D -ILoc ' Loc

where Rdr and Rp are respectively the radii ofthe drum and pulley of the hoisting machineand Loc is the distance between the centres ofthe drum and pulley (0 and C).

The length of a rope string is the distancebetween the point of run-off of the rope fromthe drum and the point of run-on of the ropeon the guide pulley. It is distinguished be-tween the string of an upper rope, Lu, andthat of a lower one, L (see Fig. 9.19).

Among various types of hoisting machines,those with cylindrical drums are the mostpopular, that is why the characteristics ofrope coiling will be discussed for this type ofmachine.

The distance between the internal faces ofthe rims of a drum is called the constructionwidth and denoted Ldr. Various portions ofthe construction width of a drum servedifferent purposes and accordingly the fol-lowing zones are distinguished (Fig. 9.20).

where hv is the height of a hoisting vessel; hiis the height of overlifting; hp is the elevationof the top pulley axis over the bottom pulleyaxis; and Rp is the pulley radius.

The hoisting axis of a vertical shaft is thestraight line that passes through the pointmidway between the two vertical hoistingropes perpendicular to the axis of the mainshaft of a hoisting machine.

The hoisting centre of a single-rope hoist isthe point that <;:oincides with the projection ofthe rope axis onto the horizontal plane; for adouble-rope hoist, this is the point of inter-section of the hoisting axis with the straightline passing through the axes of the twovertical hoisting ropes.

The centre of the shaft of a hoisting machineis a point on the axis of the main shaftmidway between the internal edges of therims of a drum (for single-drum machines) ormidway between the internal edges of therims of drums (for two-drum machines).

The axial plane of a guide pulley is thestraight line that passes perpendicular to theaxis of a pulley shaft midway between theinternal faces of pulley rims.

The inclination angles of hoisting ropes arethe angles <P, and <Pu made by the rope axeswith a horizontal plane when there is no ropesagging (Fig. 9.19); they can be determined


cated:

(H+ 30 )~ + n (dhemp = Ldre)

The zone of working coils of a width hwwhich depends on the total hoisting heightand can be determined by the formula:

Hc w (d + e)

1tD dr

where H is the total hoisting height; d is therope diameter; D dr is the drum diameter; ande is the spacing between the adjacent coils ofa rope.

The zone of reserve coils, br, which isneeded to take on the additional length of arope. Its width can be found by the formula:

30

h=-

where a is the distance from the hoisting axisto the pulley plane at the pulley axis; bl andb2 are the distances from the hoisting axisrespectively to the farther and closer end ofthe working portion of a drum; and L is thevertical distance between the centre lines ofthe drum and pulley of the hoisting machine.

In order to make the fleet angles on apulley equal to each other (131 = 13u)' the axialplane of the pulley is oriented onto the centreof the working portion of the hoist drum. Incases when the axial plane of a pulley isarranged parallel to the axis of a mine shaft,the fleet angles of the rope on a pulley anddrum ar~ equal to each other (al = 131,au = 13u). If the axial plane of a pulley is notparallel to the hoisting axis, the fleet angles

b. = -=--(d + e)1tl} dr

where 30 is the additional length of a rope, ill,required for strength tests.

The zone of friction coils, h fr , which isprovided for stronger holding of the rope onthe drum. This width is usually determinedby three or five rope coils, i. e.hfr = n(d + e)

where n = 3-5.The empty portion of a drum, hemp, is the

difference between the construction width ofa drum Ldr and the SUm of the zones indi-

takes place when

a,-au1'=

2 cos q>

Substituting the expressions for a, and auinto this formula, we obtain the conditionthat makes it possible to find in each parti-cular case the magnitude a2 -al , i. e. themagnitude by which a pulley should beturned so that its axial plane will be orientedonto the centre of the working portion of adrum:

2aD,

+b2 -

2Lcos , 13u = au + ycos 

where y = [(at -a2)/Dp] p' is the horizontalangle of the turn of a pulley relative to thehoisting axis; at and a2 are the distances fromthe hoisting axis to the pulley plane at theends of the horizontal diameter of a pulley; is the angle of inclination of a hoisting rope;and D p is the pulley diameter.

For normal operation of pulleys, whichprevents one-sided wear, the fleet angles on apulley must be equal to each other, which

Geometrical elements of a multi-rope hoist.The scheme of the most popular four-ropehoist with pulleys which deflect one system ofropes is shown in Fig. 9.22. The main geo-metrical elements of this hoist are as follows:the axes of hoisting ropes of a non-deflectedrope system (2); the axes of intermediate ropestrings between the drive pulleys and guidepulleys (9); the axes of hoisting ropes of adeflected rope system (6); the mean points ofsuspension devices (4, 5); the mean point ofrope run-off from guide pulleys (3); the meanpoint of rope run-off from drive pulleys (1);the axis of the non-deflected rope system (8)which is a straight line connecting the meanrun-off point and the mean point of a sus-pended balancing device; the axis of thedeflected rope system (7) -a straight lineconnecting the mean run-off points and themean point of a suspended non-balanceddevice; the hoisting axis v-v which is ahorizontal line passing perpendicular to themain shaft axis through the mean run-offpoint on drive pulleys; the vertical axes of thehoisting compartments of a tower head-fra-me; and the angles of bending of hoistingropes by guide pulleys.

In multi-rope hoisting machines, it is dis-tinguished between the following fleet angles:(a) the fleet angles of descending ropes on

(c)10

\

3

9

I~-

J1~L.u ~- -j -/-10 ~ 11

Fig. 9.23 Geometrical elements and parameters of multi-rope hoisting plant: (a) and (6) verticalprojections; (c) plan view; 1-drum of drive pulleys; 2, 3-mean run-off points of ropes on drive and guidepulleys; 4- guide pulleys; 5 -level of guide pulleys; 6- numbers of ropes; 7- bunton; 8- hoisting vessel clip;9-conductor; 10-mean point of suspension device (clip); 11- hoisting vessel; l-length of intermediaterope string; h-elevation of main shaft axis above guide pulley shaft axis; hi, hl -elevation of main shaftaxis and guide pulley shaft axis above guide pulley stage level; h3' h4 -elevation of main shaft axis andguide pulley shaft axis above mean points of suspension devices; R"p. Rgp- radii of drive and guide pulleys

14-1270

Ch. 9. Surveying in Mine Construction210

drive pulleys, ai, Fig. 9.23 (an angle formedby the axis of a rope with the plane of a drivepulley); (b) the fleet angles of descendingropes on guide pulleys, Pi (an angle betweenthe axis of a descending rope and the plane ofa guide pulley); and (c) the fleet angles ofintermediate rope strings on drive pulleys (~Jand guide pulleys ('1'J. In addition to fleetangles, of essential importance are also theangles of deviation from the vertical axis ofsymmetry of the system of ropes and theangle of contact (wrapping angle) of a ropeon a guide pulley, 11 (see Fig. 9.23).

The elevated fleet angles of ropes are themain cause of quick wear of a pulley lining,while the deviation of a rope system from thevertical may cause increased horizontal loadsexerted by hoisting vessels on the shaft equip-ment.

The fleet angles of ropes on drive andguide pulleys of multi-rope hoisting machinesmust not exceed 30-40'.

The control of the relation between themain geometrical elements of hoisting ma-chines of this type consists essentially inobserving the following requirements: (a) theaxes of the main shaft and guide pulley shaftshould be horizontal and parallel to one'another; (b) the axes of main hoisting ropesshould be perfectly vertical; (c) the drive andguide pulleys of a rope string should lie in thesame vertical plane; (d) the straight lineconnecting the mean run-off point of a ropeand the mean point of a suspension deviceshould lie on the vertical axis of a hoistingcompartment; (e) drive and guide pulleysshould have the same diameters correspond-ing to the design specifications; and (1) theangles of deflection of ropes by guide pulleysshould be within the limits of 8-15°.

The experience of operation of multi-ropehoists has demonstrated that the design di-mensions of these machines should be obser-ved with a high degree of accuracy, sincetheir deviations may influence substantiallythe operating conditions of a hoisting ma-

chine, lead to uneven wear of a pulleylining, and cause uneven loads on ropes andelevated forces acting .on conductors. Themain causes which may lead to the dis-tortions in the relation between the geomet-rical elements and deviations of main ropesfrom the vertical are as follows: (a) inaccu-rate assembly of a hoisting machine andequipment; (b) wear of a pulley lining, and(c) displacement of a hoisting machine orequipment due to underworking a towerhead-frame or mine shaft.

9.3.5. Survey Work During Mountingof Hoisting Plants

Survey work for mounting a hoisting plantconsists in transferring the hoisting axis andthe main shaft axis into the hoisting plantbuilding and laying out the foundation forthe hoisting machine and its elements. Thelayout work is started by transferring intonature the point of intersection of the axis ofthe main shaft and the axis of the hoist shaft.

Upon erecting the walls of the hoistingmachine room to a height of 1-1.5 m abovethe ground, the axis of the main shaft and theaxis of the hoisting machine shaft are trans-ferred by means of a theodolite inside thebuilding and fixed by brackets on the innerwalls. Mter erecting the building walls to thefull height, a second row of brackets (mount-ing brackets) is built in at a height somewhatbelow the ceiling floor level. The axial pointsare transferred onto these brackets from thelower ones by a theodolite or plumb bobs.

The hoisting axis and the machine shaftaxis are laid out twice. The mean directionangle of the main shaft should differ from thedesign value by not more than 2', and theangle between the two fixed perpendicularaxes should differ from a right angle by notmore than 1 '. The distance from the centre ofthe mine shaft to the machine shaft shoulddiffer from the design value by not more than100 mm, and the side displacement of the


point of intersection of the hoisting axis andmachine shaft axis, by not more than 50 mill.The permissible deviation of the machineshaft axis from the horizontal position isestablished by the specifications for hoistingmachine assembly.

Mter laying the supporting frame of a hoistinto its place, it is checked for horizontalityand correct position relative to the hoistingaxis and the main shaft axis of the machine.The position of the frame along the height ischecked by levelling the corner points of theframe in plan relative to the axes by means ofplumb bobs. The deviation of the frame fromits design position should not exceed 10 millin plan and 100 mill vertically. The highestdifference of elevations of the corner points ofthe frame should be not more than 15 mm.

The arrangement of the main shaft bear-ings is checked along the height by levellingthe lower points of their internal surface andin the horizontal plane, by means of plumbbobs hung from a cord stretched between theaxial brackets of the main shaft of thehoisting machine. The deviations of bearingsin plan and vertically should not exceed1-2 mill. The actual position of the shaft ofthe hoisting machine is checked by the samemethod as the position of bearings.

Mter the completion of the machine as-sembly, the position of the drum relative tothe hoisting axis is checked by hanging twoplumb bobs and measuring the distancesfrom the plumb bob lines to the drum rims.

+x

'~~

""\

~~,

~~ /. 2

SItB

9.3.6. Survey Work for Checkingthe Geometrical Elementsof a Single- Rope Hoisting Plant

After the assembly of a hoisting plant, it isrequired to check the horizontality of theaxes of machine shafts and drive pulleys, thepositions of the axes of hoisting ropes relativeto conductors at the level of the zero stage,and the fleet angles of hoisting ropes on drumsand pulleys. For this purpose, a theodolite

14.

/

Fig. 9.24 Theodolite traverse for checking of re-lation between geometrical elements of hoisting

plant

traverse A-I-2-3 (Fig. 9.24) is run from thelayout axis of the main shaft which is takenas the initial direction. The point 4 of atraverse is fixed approximately on the hoist-ing axis near the zero stage. The angle 2-3-1is laid up at a point 3 (from the side 3-2),which is calculated so that the direction 3-1 isperpendicular to the axis of the machineshaft. This direction is transferred onto thepulley stage and fixed by a wire I-II. At thepulley stage, the distances a1, a'1' a2 and a~from the wire I-II to the external edges ofpulley rims at the ends of a horizontaldiameter are then measured. The distance 1between the external faces of the pulley rimsis also measured. In the machine room build-ing, there are measured the distance betweenthe internal faces of drum rims ho, the widthof empty portion of the drum h and h', thewidth of the working portion hw and h;., the

I

~

total width of the zone of friction coils andreserve coils (bfr + br) and (bfr + b~) for two-drum machines; for single-drum and bicy-lindrical machines, it is required to measurethe total width of the empty portion and ofthe zones of friction coils and reserve coils(b + b fr + br) and (b' + bfr + b~) and the to-tal width of the drum, B.

Taking the system of coordinates with theaxis of machine shaft being the y-axis and theaxis of symmetry of the machine, the x-axis, itis now possible to calculate the coordinatesof theodolite traverse points and of the axesof ropes and conductors. For each rope, thereare determined the maximum exterior (a.x)and interior (ain) fleet angles on the drum ofthe hoisting machine:

(a) for a hoisting plant with two cylindricaldrums and pulleys:

b.x -a, a -bin ,a.x= p, ain=-pL L

(b) for a hoist with one cylindrical orbicylindrical drum:

b.x -a, bin + a ,.p -:--pUin =u"x =

1L

Dpangle of inclination of the hoisting ropestring, which can be found, with an accuracyto 10, from the formula

tan <p = L\h/ L

where p' = 3440'; hex and hin are the distancesfrom the axis Ox to the rope on the drum inits extreme (exterior or interior) positions; a isthe distance from the axis Ox to the axialplane of the pulley; and L is the inclineddistance between the axes of the machineshaft and pulley, which should be determinedwith an accuracy to 1 m.

The terms hex and hin can be found by thefollowing formulae:

for two-drum machines (see Fig. 9.21a):hex = 0.5ho + h + hw + hror hex = B- hfr + 0.5ho, hin = 0.5ho + h

for single-drum and cylindrical machines(see Fig. 9.21h and c)hex = O.5B -hfr

h,- = 0.5B -(h' + h: + h'..-)

The distances a and a' for hoisting ma-chines of the first and second type are foundby the formulae:a = 0.5(a1 + a2) + 0.5/ :t c

a' = 0.5(a'1 + a~) + 0.5/ :t c

where c is the distance between the transfer-red I-II direction and Ox axis, which is equalto the ordinate of point I.

For hoisting machines of the third type, thedistances a and a' are determined by theformulae:

a =10.5(a1+a2)+0.5/-cla' = 10.5(d1 + a~) + 0.5/- c I

The inclined distance L (of a rope string)can be found from the expression

L=~where Lo = x.. -D J2 (here x.. is the abscissaof a rope in the adopted system of coordi-nates and D p is the pulley diameter); Ah is theheight difference of the pulley axis above thatof the machine shaft.

Since the axis of a pulley may turn out tobe unparallel to the machine shaft axis, thefleet angles on the pulley may respectivelydiffer from those on the drum. For pulleys,we determine the two maximum fleet anglesof ropes: an exterior angle ~ex and interiorangle ~in' by the formulae:~ex = a ex -'Y cos <p, ~in = ain + 'Y COS <p

where 'Y is the horizontal angle of turning ofthe pulley plane relative to the axis Ox(h ... ) a2 -at , d .

holstlng axis , y = ~ p an <p lS t e

9.3.7. Survey Work for Checkingthe Relation Betweenthe Geometrical Elementsof a Multi-Rope Hoisting Plant

Surveying a multi-rope hoisting plant iscarried out in order to determine the anglesof deviation of the axes of rope systems fromthe vertical in projections onto the axes x andy (ex, ey, mx' and my), fleet angles of the mainand intermediate ropes on drive and guidepulleys (a, ~, <p, and 'I'), angle of deflection ofthe rope by a guide pulley (11), angles ofinclination of the axes of the main shaft andguide pulleys (0, 0'), and the angle of turn ofthe axes of guide pulleys relative to the mainshaft axis (I:).

The sequence of survey work for checkinga four-rope hoisting plant is as follows.

Determination of radii of drive pulleys. Theradii of drive pulleys should be determined toobtain the abscissae of the rope axes inrun-off points, which, with the hoistingvessels in the lowermost position, are con-sidered practically coincident. Because of thisthe run-off points are ,projected onto themeasuring levels.

Fig. 9.25 Determining radii of drive pulleys

One of the probable methods for deter-mining the radii of drive pulleys consists inthe following. A line parallel to the main shaftaxis is fixed in the machine room, after whichthe distances from that line to hoisting ropesare measured.

The point A is fixed on the floor of themachine room (Fig. 9.25). A theodolite is setup on that point and sighted roughly alongthe rope line (direction AaIl). The readings aIand all are taken on two staffs set up in pointsI and II horizontally and tangentially to themachine shaft. The distances SI and SII fromthe point A to staffs I and II are thenmeasured. The shaft is measured circum-ferentially in the points I and II (CI and CII)and its radii are calculated by the formulaerI = cJ21t and rIl = cIJ21t

These radii and the measured values aI andall make it possible to take readings on thestaffs with the theodolite telescope sightedparallel to the main shaft axis:

sIlaI -sI(aIl + rIl -rJbI=

SII -SI


SIl(aI + rI -rIJ -sIallbll=

SII- SI

The vertical hair of the telescope is sightedat the reading bll of a staff, provided that thesighting line passes through the reading bI.1fit turns out that (bll + rll) -(bI + rJ is lessthan 0.5 mm, the direction parallel to themain shaft axis is fixed on a bracket or plate(point B) concreted in the wall of the machineroom. Mter that, the telescope is sighted atthe point B and the readings 15, 16, 17, and 18are taken, with an accuracy to 1 mm, on ahorizontal staff set successively to ropes 5, 6,7, and 8 in points of their run-off frompulleys. The radii of drive pulleys are calcu-lated by the formulae:R5 = bll + rll -(b5 + rr)

R6 = bll + rll -(b6 + rr)

R7 = bll + rll -(b7 + r r)

R8 = bll + rll -(b8 + rr)

where r r is the radius of the rope.Fixation of auxiliary axes on the measuring

level and determination of coordinates of ref-erence points. The points which fix auxiliaryaxes are called reference points. They are laidoff on a cross-piece below the machine roomwhere the ropes descending into the mineshaft are easily accessible.

The hoisting vessel is sunk into the lower-most position, and a staff is laid on them~asuring level to the non-deflected ropes (5,6, 7, 8, see Fig. 9.26). The shortest distancesfrom the staff to plumb bobs 5 and 8 are thenmeasured. Then, using the calculated radii ofdrive pulleys, the distances from the mainshaft axis to the staff axis are calculated. Thestaff is then placed in a position so that itsaxis can be parallel to the main shaft axis,and this direction is fixed by points C and D.Using the method of corner sections, pointsA and B are marked from these points. Theydetermine the direction parallel to the line ofdeflected ropes (I, 2, 3 4). Non-parallelity

between AB and CD should be not more than10'.

The coordinates of points A, B, C, and Dare determined by ordinate surveying ofnon-deflected ropes, with the hoisting vesselin the lowermost position, and by measuringthe sides and diagonals of rectangleABCD.

The distances from the rope axes to thestaff axis and the staff readings correspondingto the projections of the rope axes onto thestaff are determined in the following manner.The staff is fixed on points C and D. After anextreme rope, say 5, has dampened, an angleis placed to it (Fig. 9.27a), and an ordinato-meter is placed to the staff and moved to theangle. The reading /51 is taken by means of arule against the edge of the angle and thereading! 51 is taken on the staff against theordinatometer edge. The angle is turned intoanother position (Fig. 9.27b) and new read-ings 15II and !5II are taken. Similarly, thereadings 151II, 15IV'!51II' and!5lV are taken in athird and fourth position of the angle(Fig. 9.27c and d). The positions of otherropes are determined in a similar way.

The readings are reduced to the staff axis

and rope axes by the formulae:

liI + lill + 2d -lillI -liIv'=k+

4

J;I + J;II +J;III + J;IV

If aCD ::!: 90° < 10', then Xc = Xr5 and YC == v -f 5' where v is the staff reading corres-ponding to the centre of a hole for thefixation of the staff in the point C (seeFig. 9.27).1; = 4 The angles of rectangle ABCD are found

by solving the triangles into which thewhere i is the number of a rope; k is the rectangle is divided by diagonals AD and CB.distance from the staff axis to the beginning Taking the coordinates of the point C as theof the ordinatometer scale; and d is the length initial ones and knowing the direction angleof the ordinatometer scale. aCD' it is possible to determine the coordi-

The values of abscissae on the staff can be nates of points A, B, and D.found from the expressions: Determination of the angle of turning ofx = -R + 1 x = -R + 1 guide pulley shaft axis relative to the mainr5 5 5' r6 6 6 ..

--R + 1 --R + 1 shaft axis. In order to determIne the angle &,aXr7 -7 7' Xr8 -8 8 staff is fixed on points A and B laid up

where R is the radius of a drive pulley. parallel to the line of deflected ropes (Fig.The direction angle ofa side CD (staff axis) 9.28). Two plumb bobs 01 and O2 are hung

can be found by the formula: at one end of the shaft in a point IV, and a(x -x) metal rule is laid below them perpendicular

r5 r8 p' to a staff AB. A series of readings n1, n2' n3'

n4' etc., and m1, m2, m3, m4, etc. are takenunder the centres of plumb bobs, and theirmean values are found (n and m). The dis-tance CIV from the metal rule to the axis of thestaff AB is measured, after which the distancefrom the shaft axis to the staff axis AB is

aCD = 90° + .

f8 -f5

The coordinates x, y of a point C are

calculated by the formulae:

Xc = Xr5 + (V -f5)tan(aCD -90°)

Yc = v -f5 + 15tan(acD -90°)


Staff

Fig. 9.28 Determining angle of turning of guide pulley shaft axis relative to main shaft axis

AHI-II + Arl-ll°II- p'

SI

The rule is displaced through several cen-timetres, and a new distance d;v is deter-mined, which should differ from the fornlerby not more than 2 mill. Similarly, twodistances from the end III of the shaft ofguide pulleys to the staff axis AB are deter-mined (dIll and d{lI).

The turning angle E is calculated by theformula:

(dIv + d;v) -(dIll + d;lI)0' + (a.D -900)

Determination of the angles of inclination ofthe axes of the main shaft and guide puUeyshaft. These angles can be determined withthe aid of hydrostatic levels by measuring theheight difference L1H between the end points ofthe axis of a shaft. The inclination angle of themain shaft axis is calculated by the formula:

E=2s

where s is the distance between points III and

IV.

where Arl-Il is the difference of radii of theshaft in the measured sections (in points Iand II) and SI -II is the distance betweenpoints I and II.

The angle of inclination of the axis of guidepulley shaft, OIV -III is determined by a similarformula.

Determination of the coordinates of ropeaxes on the measuring level. The coordinatesof ropes in two extreme (upper- and lower-most) positions of hoisting vessels are neededfor determining the angles of their deviation.The coordinates of plumb bobs are deter-mined from reference points CD and AB onthe measuring level (see Fig. 9,26) by meansof a staff-type coordinatometer.

With the hoisting vessel in the lowermostposition, we determine the coordinates of theaxes of non-deflected ropes (Xi' Y;) and thoseof deflected ropes (xr, Yr). Similar measure-ments are made with the hoisting vessel inthe uppermost position (respectively x;, Y;


measurements; Yr and Y~ are the ordinates ofthe axes of deflected ropes respectively in thelowermost and uppermost positions of ahoisting vessel; Xr and X~ are the abscissae ofthe axes of these ropes; h2 is the elevation ofthe axis of the guide pulley shaft above themeasuring level; h4 is the elevation of the axisof the guide pulley shaft above the adjacentpoint of a suspension device; and R9,d and Rgis the design radius and actual radius of guidepulleys at measurements.

Thefleet angles ofmain ropes can be foundby the formulae:

on drive pulleys:a = e + 8 + A.y ,

on guide pulleys:~ = my + 8' + Ar

where 8 and 8' are the inclination angles ofthe main shaft axis and guide pulley axis andAi and Ar are the corrections for the positionof balancing devices, which can be deter-mined by the formula:

s -s.A=---2

hwhere s is the distance from the system axisto the axis of a rope at the level of balancingdevices; Si is the distance from the system axisto the axis of a rope in a run-off point; and his taken equal to h3 for determining Ai andequal to h4 for determining Ar.

The fleet angles of intermediate rope stringscan be found by the formulae:

on drive pulleys:

t1.y" .where n is the number of ropes in a system; Yiand Y; are the ordinates of the axes ofnon-deflected ropes respectively in the lower-most and uppermost positions of a hoistingvessel; hi is the elevation of the main shaftaxis above the measuring level; xi and x; arethe abscissae of the axes of these ropes; h3 isthe elevation of the main shaft axis above themid point of a suspension device; Rdr,d is thedesign radius of a drive pulley; Rdr isthe actual radius of a drive pulley at

dimensions of the shaft, the arrangement ofequipment and hoisting vessels, the line ofvertical section along which records are beingmade, and conventional symbols of rocksand lining materials. The second page con-tains data on the course of shaft sinking. Onthe third and subsequent pages, a verticalsection of the shaft on a scale 1/100 andsketches of shaft elements are drawn. Minesurveying work during the sinking of a shaftcan be divided into two periods: (I) initialperiod during which the shaft is providedwith mining (heading) equipment and theshaft collar is constructed and (2) shaft sin-king proper.

11 is the wrapping angle of a rope on a guidepulley; E is the angle of turning of the axis ofthe guide pulley shaft relative to the mainshaft axis; ° and 0' are the angles of inclina-tion of the axes of the main shaft and guidepulley shaft; and 1 is the length of an inter-mediate rope string:1 = [h -(Rg + xr) tan 11]

where h is the height difference between theaxis of the main shaft and that of the guidepulley shaft and Xr is the abscissa of the axisof a deflected rope. The permissible values forthe indicated angles are as follows: Ox, Oy, roxand roy not more than 0°15'; angle of incli-nation of the main shaft axis, 0, not morethan 0°05'; angle of inclination of the axis ofthe guide pulley shaft relative to the directionof the main shaft axis, not more than 0°45';fleet angles a and ~, not more than 1030' andthose for intermediate strings ( <p, '11), not morethan 0°30'.

9.4. Survey Work During Sinkingof Vertical Shafts

The construction of mine shafts include.ssinking a shaft and the arrangement of alining and equipment. The main object ofmine surveying service in the construction ofmine shafts is to ensure the design position ofthe shaft and its elements. To achieve this, themine surveyor has to perform the followingprocedures: to transfer the axes of hoistingplants into the driven shaft; to assign thedesign direction to shaft sinking; to transferand mark the layout net for the assembly ofhoisting machines; to make check measure-ments in the shaft; and to layout shaftworkings and chambers.

All mine surveying measurements are re-corded in a register which is the main docu-ment reflecting the actual state of the const-ruction of a shaft (Fig. 9.29). The first page ofthe register gives the design section of theshaft on a scale 1/50 and the principal

9.4.1 .Survey Work During theInitial Period of ShaftSinking

The survey work at this stage consists intransferring the axes of temporary buildingsand structures into nature, which is requiredfor arranging a layout network and markingthe axes of a shaft according to the dimen-sions indicated on the general layout and onthe drawings of the arrangement of miningequipment. During the mounting of hoistingmachines, special attention should be givento checking the arrangement of the hoistframe relative to the predetermined hoistingaxis and machine shaft (drum) axis, as wen asto correct arrangement of the shaft of themine hoist. The deviation of the hoist framefrom the hoisting axis should not exceed50 mm; the deviation of the elevation marksof frame corners from the design level shouldbe not more than 300 mm, and the elevationmarks of corners should differ from oneanother by not more than 15 mm. The de-viation of the hoist shaft axis from the axis ofa layout network should be not more than 2',the height difference on one end of the shaftabove the other being not more than 0.001 ofthe shaft length.

The sinking frame should be mounted

properly relative to the shaft axis; the displa-

cement of the pulley

stage in the horizontalplane from

the design position should be not

more than

60 mm

.T

he layout of the pit

for the shaft collar,

construction of a cap, and the arrangem

ent of

9.4. S

urvey W

ork D

uring S

inking of

Vertical

Shafts

a zero frame are carried

out relative to the

axial lines of the shaft. The displacem

ent ofthe zero

frame

axes relative to

the design

position should not exceed 5 m

m, the devia-

tion of the elevation marks of the fram

e fromthe design position should not exceed 50 m

m,

Intermediate

shoe at

-25.5 m

219


Fig. 9.30 Main heading frame: l-opening forbucket; 2- rescue ladder; 3- ventilation column;4- concrete pipeline passage; 5- compressed aircolumn; 6-central plumb bob

are not allowed. The centre of the shaft istransferred instrumentally from the axialpoints onto the heading frame, and the guidepulley of the central plumb bob is fixed sothat the plumb bob line is not displaced fromthe shaft centre by more than 5 mm. Thesurvey control of shaft sinking is performedfrom the central plumb bob and side plumbbobs suspended from the main headingframe.

and the difference of elevation marks of thesupport points of the unloading bedframeshould not exceed 5 mm. Since the zeroframe defines in nature the contour of theshaft cross section, its dimensions and shapeshould correspond strictly to the design crosssection of the shaft. The centre of the shaft isfixed on the zero frame, and the directions ofthe shaft axes are indicated by marks. Thepositions of the shaft centre and axial marksare determined twice by independent meas-urements; the discrepancy between themeasurements should be not more than5mm.

The directions of the shaft axes are thentransferred from the zero frame into the shaftmouth and fIXed by marks on brackets builtin at a distance of 50-100 mm from the wallsof the shaft lining. Elevation marks aretransferred onto the axial brackets. The dis-placement of the marks from the axial lineshould not exceed 2 mm.

If upon sinking the shaft mouth to thedesign level it turns out tpat the actualgeological section corresponds well to thatdesigned, permission is given to make thefirst circular cut for a foundation CUl;b.Otherwise, the problem should be coordinatedwith the designer.

Upon sinking the shaft to the first founda-tion curb, the position of the shaft along thedepth and in the horizontal plane is checkedby taping the vertical distances and thedistances from the zero frame to the cut floor.The position of the shuttering for the foun-dation curb is checked in the vertical andhorizontal plane by measuring the radii froma temporary central plumb bob to the exte-rior surface of the shuttering, and the distan-ces from the frame to curve pieces.

Upon the construction of the shaft lining,the zero frame is replaced by the mainheading frame which is placed .onto the per-manent lining of the shaft mouth and orien-ted properly relative to the centre and axes ofthe shaft (Fig. 9.30). Deviations above 20 mm

9.4.2. Survey Work DuringSinking a M ine Shaft

In shaft sinking by the conventional dril-ling-and-blasting method, the survey workconsists in checking the positions of verticaldirections, determining the scope of the mi-ning work performed, locating the places anddimensions of rock inrush and backfillingbehind the lining, and checking the positionof travelling forms and the dimensions of theshaft section and vertical walls of a lining.

For the horizontal and vertical control ofshaft sinking, there is formed a geometricalbasis as a system of plumb bobs, light

5. Survey Work for Arranging of Shaft Equipment 221

at least in eight points around the peripheryof the forms. The vertical axis of the formsshould not deviate from the mean position ofthe plumb bob by more than 20 mm. Thevertical position of the forms is checked byhydrostatic level with an accuracy not worsethan 10 mm. The errors of measurement ofdistances from the central plumb bob to theforms of a shaft lining should not exceed10 mm. For cast-in-situ concrete and rein-forced-concrete linings, the deviations ofradial distances from the centre should be notmore than 50 mm.

A concrete-tubbing lining is built from thetop downwards, support tubbings (crib seats)being placed after every 20-24 m. They areplaced in the presence of the mine surveyorwho checks that the distances from thecentral plumb bob to the internal faces oftubbings differ by not more than 10 mm fromthe design value.

All placed tubbing crib seats and eachtenth ordinary tubbing should be controlledby mine surveying. The plan position of atubbing ring is controlled by measuring thedistances from the central plumb bob toselected points at tubbing joirits. Verticalcontrol is effected upon mounting 6-8 rings. Ifit turns out that the deviation of a tubbingcolumn from the vertical is more tban 30 mm,the lining should be corrected.

9.5. Survey Work for Arrangingof Shaft Equipment

The main task of the mine surveyor duringthe arrangement of shaft equipment is tocontrol that buntons and conductors aremounted strictly in their design positions.

The equipment of a mine shaft is acomplex of structures and elements whichensure correct motion of hoisting vessels. Themain elements of equipment are conductorsand buntons; the latter are divided into themain and auxiliary ones depending on theirposition in the shaft. The main buntons are

indicators or projection meters. Plumb bobsare mostly employed for the purpose. Theirnumber and arrangement depend on thecross-sectional shape of the shaft and thearrangement of mining and hoisting equip-ment in it. For instance, a single centralplumb bob is employed in shafts of a circularcross section, four plumb bobs hung at adistane of 20-30 cm from the shaft walls, inshafts of a rectangular cross section. In shaftsof an oval cross section, two plumb bobs aresuspended near the walls at each axis of anellipse. The positions of plumb bobs duringsinking a shaft should be checked at leastonce a month.

The deviations of vertical directions fromthe design values are checked by makingmeasurements from the axial points fixed inthe shaft mouth or on the main headingframe. These measurements can be made byusing plumb bobs, light indicators or projec-tion meters. In order to minimize errors, thecables of projection meters should be fixed inevery 300 or 400 m. The error in the positionof fixation points of light indicators relativeto the previous level should not exceed15 mill.

The state of shaft walls is controlled bymeasuring the radii from the central plumbbob to walls in vertical intervals of 3-4 m.The measured results are used to calculatethe actual cross-sectional area of the shaftwhich should not differ from the design valueby more than 4-10% for shafts up to 20 m2 incross-sectional area, by 3-8% for those20-40 m2 in area, and by 2-5% for thoseabove 40 m2 in area.

The permanent lining of vertical shafts isconstructed by means of travelling formswhich are placed into the working positionsrelative to the central plumb bob. The posi-tion of the travelling forms and shaft wallsshould be checked by the mine surveyor atleast after every three or four travel cycles.The correct position of the travelling formsrelative to the central plumb bob is checked


The survey work during the arrangementof the equipment of a vertical shaft includesthree stages: (I) the control of preparatorywork and the arrangement of hoisting andmining equipment; (2) the control of thearrangement of buntons and suspension ofconductors; and (3) the final control of theaccuracy of mounting the equipment bymaking the profile survey of conductors andbuntons.

At the first stage, the profiles of the shaftand drawings of cross sections at variouslevels are prepared, and it is checked that thedimensions of buntons, points of connectionof buntons, etc. correspond to the designspecifications. Upon sinking the shaft, theprofiling of the shaft walls (control survey) iscarried out in order to determine the minimalgaps between the shaft lining and the mostprotruding portions of hoisting vessels. The

built in into the shaft lining at both ends,whereas the auxiliary ones are either fastenedbetween the main buntons or attached at oneend to a main bunton and built in at theother end into the lining. The main buntonarranged in the centre of a shaft or near it iscalled the central bunton. The combination ofmain and auxiliary buntons located in thesame horizontal plane is called a buntonstage. The distance between adjacent buntonstages is called the pitch of equipment.Conductors (of the rigid or rope type) arefastened to buntons.

The arrangement of equipment in a shaftmay be done by a consecutive or combinedscheme. In the former case, first all buntonsare mounted to the entire depth of the shaft,after which conductors are fastened to them.In the latter case, conductors are suspendedupon mounting three or four bunton stages.

(a) Geological section ~Deptli- from

Mouth level surface,+193.5 m m

(b) Sections through shaft walls

II III IV

O

5

Soil

10

15

20

25

30

35

40

45

Clay

0

0

-10

0

0

0

0

-10

-10

-40

~,

Sand

~--

Floatingearth

Clay shale

~50

55

60

65

70

Sandstone

~Shale

Coal

Fig. 9.31 Profiling of walls ofvertical mine shaft: (a) arrangementof plumb bobs; (b) profiles of walls

;[;1 Sandstone~

,i~\;~(i~

0

+30 mm

+10

-10

+10

+20

+10

+10

0

0

~

2239.5. Survey Work for Arranging of Shaft Equipment

Fig. 9.32 Schemes of plumb bobs for arrangementof shaft equipment

results of profiling are used for revealing thelining defects and making decisions on chan-ging the scheme of equipment or eliminatingthe detected curvatures of the shaft. Theprofiling survey is done by measuring thedistances from plumb bobs to shaft walls.The number and arrangement of plumb bobsare determined by the cross-sectional shapeof the shaft and the arrangement of hoistingvessels in it (Fig. 9.31a). The measuringinterval is usually taken equal to the pitch ofequipment. The results of profiling are usedfor plotting the vertical profile of the shaftwall. The profile is drawn on a vertical scale(along the plumb bob line) of 1/100-1/200and horizontal scale 1/10-1/20 (Fig. 9.31b). Atthe preparatory stage, the mine surveyorshould also compile the scheme of arrange-ment and fastening of plumb bobs in theshaft, work out templates for the arrange-ment of buntons, and control the correctpositioning of winches, pulleys, buckets andother mining and hoisting devices. At thesecond stage, the mine surveyor controls thedesign dimensions of the first bunton stageand then checks with especial care that thefirst bunton stage is mounted properly in itsplace, since plumb bobs will be later hungfrom it to control the positions of subsequentbunton stages. The correct mounting of thefirst bunton stage is controlled by measuringthe distances from the shaft axes to the endsof each bunton, sleepers, and the points ofconnection of buntons and by levelling theends of each bunton by a striding level. Thedisplacement of the axes of buntons in thehorizontal plane should not exceed 3 mmand the difference of the elevation marks ofbunton ends, 5 mm.

The number and arrangement of plumbbobs in a shaft depend on the scheme ofequipment and arrangement of buntons.With the consecutive scheme of arrangementof equipment, plumb bobs are arranged aga-inst sleepers; with the combined scheme, theyare arranged so as not to obstruct the placing

of conductors. The distances from the sus-pension points of plumb bobs tobuntons andside faces of conductors should not exceed200 mm. A scheme of suspension of plumbbobs 1-6 for arranging the rigid equipment ofa shaft of a unified cross section is shown inFig. 9.32.

The survey work for controlling the pla-cing of buntons and suspension of conduc-tors consists in checking the vertical distancesbetween bunton stages, the positions of con-ductors and buntons relative to the horizon-tal axes of a shaft, the points of junction ofbuntons in a stage, and the positions of


3~ p:C9 51

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6

A-A

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~ 88:z.tzA

Fig.9.33 Templates for arrangement of shaft equipment: I. 2. 3-spacing templates; 4. 5-verticaltemplates for marking holes for buntons; 6. 7- horizontal templates; 8- templates for correct placing of

buntons relative to plumb bobs

plumb bobs proper. Since the positions of thecharacteristic points of the shaft equipmentare repeated from one bunton stage to another,it is possible to employ templates for thecontrol of mounting operations. The numberand design of templates are chosen depen-ding on the arrangement of buntons andplumb bobs and the technology of arrange-ment of the equipment. The templates are

usually made from steel sheets, angles ortubes.

According to their application, templatescan be divided into the following groups: (1)templates for marking the lengths of buntonsand places of location of sleepers or moun-ting holes; (2) templates for placing the bun-tons at specified vertical distances from oneanother (spacing templates); (3) templates for


marking holes for buntons; (4) templates forcoordinated arrangement of buntons in astage (horizontal templates); and (5) templa-tes for correct placing of buntons relative toplumb bobs. Some types of templates forthese purposes are illustrated in Fig. 9.33.

After mounting the equipment of a verticalshaft, the surveying of conductors is carriedout in order to compile the profiles of con-ductors, buntons, and shaft walls. In thiscountry, vertical shafts are surveyed bymeans of a complex for automatic control ofthe parameters of the equipment and lining.The complex comprises stations for theprofile surveying of conductors, apparatus forthe surveying of shaft walls, an instrument formeasuring the safe spacings in mine shafts,apparatus for measuring the wear of conduc-tors, and straightening instruments for thecontrol of conductors.

The stations are provided with instrumentsfor measuring the angles of deviation ofconductors from the vertical and distancesbetween conductors and for checking themutual arrangement of conductors in theshaft. Two instruments for measuring thevertical deviation angles are arranged at anangle of 90° to each other and mounted oncarriages (Fig. 9.34) which are run alongconductors. In this way, the angles of devia-tion of conductors in two mutually perpen-dicular planes are recorded. Records aremade on 35-mm perforated photographicfilm together with the base line and eleva-tions of buntons. The accuracy of measure-ments is 30" and the measuring range, :t20'.

The instrument for measuring the distancesbetween conductors is essentially a mecha-nical recorder fastened on one of the sectionsof the carriage. Records are made on aparaffin-impregnated tape on which one sty-lus draws the curve of deviations of the actualdistances between conductors from the ratedmeasure, whereas another stylus draws thebase line. The elevations of buntons are alsomarked on the tape. The horizontal scale of

15~1270

Fig. 9.34 Carriage: 1- box frame; 2 -detachablecovers; 3- springs; 4- telescopic rod; 5- clamp;6- supports; 7- auxiliary safety rollers; 8- manualwinding mechanism; 9-axles; 10-shackles

records of distances is 1 I 1 and the verticalscale, 1/500; the measuring accuracy is:to.5 mm, the range of deviations of con-ductor spacings from the rated value is:t40 mm, and the range of measured dis-tances, 350-3000 mm. The speed of motion ofthe carriage on conductors is up to 0.8 mlsand the largest depth of shafts which can beprofiled by this complex is 1700 m. Thesurvey of conductors of a single compartmentof a shaft 500-800 m deep requires only 0.5-1hour.

The photograms of deviation angles ob-tained in this way are processed in the officeto construct the profiles of conductors. Thisis done by means of a semiautomatic integra-


Fig. 9.35 Integrator

Fig. 9.36 Aligning inclinometer


",1 partment, etc. The measuring range is from 0to 500 mill and the accuracy of measure-ments is I5 mill.

The apparatus illustrated in Fig. 9.38 isdesigned for continuous measurements of thewear of conductors and spacings betweenconductors. It contains two mechanical re-corders which simultaneously register thedegree of wear of two conductors separatelyat each side of each of them and the spacingsbetween the conductors. The apparatus canbe used for measurements of conductors incombination with a station. In that case, theapparatus is connected to a carriage on whichthe instruments of the station are mounted.

Fig. 9.37 Profiling instrument: I-photographiccamera cap; 2-measuring drum; 3-lock screw;4- wide-angle objective; 5- handle; 6- illuminator

marked on 35-mm photographic film. Thedistance range of the instrument is from 0 to3000 mm; the scale of recorded distances tothe shaft walls is 1/25 or 1/50; and theroot-mean square error of measured distan-ces is I 5 mm in the range from 0 to 500 mmand I 10 mm in the range from 500 mm to3000 mm.

The instrument for measuring the gapsbetween the protruding portions of hoistingvessels and elements of shaft equipment isbased on the same principle as the instrumentfor profile surveying, but has substantiallysmaller dimensions and mass. It is mountedon the top of a hoisting vessel or in a cage.The instrument can be set up for measuringthe gaps between the guide paws of a hoistingvessel and equipment elements; the distancesto the lining, tube stand, cables, ladder com-

15.

Fig. 9.38 Apparatus for continuous measure-ments of wear of conductors and spacings betweenconductors


ordinates. The design positions of hoist clipsand jacks are denoted by axial marks opsupporting surfaces.

Rope conductors are fixed in the verticalposition by using a projection meter; for thispurpose, the vertical sensor of the projectionmeter is fastened on a rope conductor abovethe tensioning frame.

The final surveying of rope conductors iscarried out after mounting the hoist clips andfastening the guide sleeves and consists inmeasuring the linear distances from thelayout axes. The results of measurements areprocessed to compile a scheme of fastening ofrope conductors on a head-frame ceiling andtensioning frame. The actual distances be-tween the axes of ropes (devices) and layoutaxes should differ from the design values bynot more than 7 mm.

When used individually, the apparatus isfastened to a hoisting vessel or to the hoistingcable of a mine hoist. The measuring accu-racy is:!: 1 mm, the scale of recording 1/1,and the working speed of lifting or loweringin a shaft, 1-2 m/s.

The survey work during mounting of arope equipment consists in transferring thelayout axes onto the mounting levels; check-ing the tensioning frame; control of arrange-ment of suspension clips, guide and ten-sioning devices; control measurements duringmounting of auxiliary conductors; checkingthe track gauge of guides for hoisting vessels;and final surveying of shaft portions withhoisting and mining equipment.

The layout axes of tower head-frames aretransferred onto the mounting levels (head-frame ceilings) by using the layout axes of amulti-rope hoisting machine. For jib-typehead-frames, the axes are transferred onto themounting level from the axial points bymeans of a theodolite and plumb bobs hungfrom a pulley stage. The axes of a shaft aretransferred onto the fixation levels of guideropes by means of plumb bobs at an earlierstage (during sinking a shaft). The discrepan-cies between the positions of axial marksobtained in two measurements should notexceed 20 mm on a suspension level and50 mm on a fixation level.

The arrangement of a tensioning frame andauxiliary conductors at loading levels is cont-rolle.d relative to the layout axes of thefixation level of rope conductors and theaxial points set up in the lining near the shaftbottom. The displacements of axes of bun-tons on a particular level should be not morethan 3 mm in the horizontal plane, and thedifference of elevations of the ends of buntonsshould not exceed 5 mm.

The mounting of hoist clips and jacks on asuspension level is controlled relative to theaxes of a shaft or multi-rope hoisting machi-ne which are fixed on that level. The axes ofthese devices are laid out by the method of

9.6. Survey Work During Drivingof Shaft Workings

The survey work during driving of un-derground workings near a shaft may involvecertain difficulties, since such workings oftenhave a rather intricate configuration withmany joints, curvatures and with variablecross sections, combinations of straight andcurvilinear sections, an intricate profile ofhaulage tracks, and contain large-sized sta-tionary equipment units.

Before constructing the shaft bottom, adesign polygon on a scale of 1/200 or 1/500 isdrawn (Fig. 9.39) which serves for checkingwhether the dimensions of underground work-ings are correct and for obtaining the initialdata for the instrumental transfer of the axesof designed workings into nature.

The drawing of such a polygon containsnumerical data on the dimensions of straightand curved sections of workings, angles ofturn of circular curves, elevations of parti-cular pqints, etc.

The axes of curved sections are replaced bychords whose number is chosen so that the

9.7. Survey Work by Special Methods 229

~

Fig. 9.39 Design polygon of shaft workings

chords do not touch the lines of the walls ofworkings.

Check calculations determine the designangles of a closed polygon and the coordinateincreases at all its vertexes. The check calcu-lations are done by the formulae:~13 -180° (n -2) = 0, ~Ax = ~Ay = °

where n is the number of vertexes of apolygon.

If the conditions described by these for-mulae are not fulfilled, the polygon should beredesigned. Mter the plan adjustment of thepolygon, a design profile is drawn, whosecharacteristic points are those where theworkings intersect one another or the anglesof their inclination change.

The insets of conjunctions of workings andvertical shafts are determined after transfer-ring the elevation mark from the groundsurface onto the bench marks concreted inthe walls of the shaft. These bench marks areusually set up somewhat above a conjunctionso as to enable a convenient transfer of theelevation mark onto the roof (bottom) of anadjacent working or onto the head of a trackrail. Conjunction axes are usually transferredfrom two plumb bobs sunk from the surface,which define the axis of the shaft. This axis isfixed by means of two or three bracketsdriven into the shaft walls somewhat abovethe level of the projected conjunction.

The direction of inset for a conjunctionbetween the mine shaft and a working is

assigned from two side plumb bobs sunk intothe shaft. The mining work for insetting aworking is permitted at a distance not morethan 40 m from a plumb bob sunk into theshaft. The working can then be driven furtheronly after the points and bench marks of anunderground survey reference net have beenfixed on its level.

As the face is advanced in a working, themine surveyor checks all parameters of theworking being driven, marks the actual di-mensions of the working on a survey plateand compares them with the design dimen-sions, and determines the actual discrepan-cies. The discrepancies of the cross-sectionalarea of a roughly driven working should benot more than 5-12% for a cross-sectionalarea up to 8 m2, 5-10% for an area up to15 m2, and 3-7% for an area above 15 m2.

All cases of rock inrush and caving thattook place during driving of a working arerecorded in the mine surveyor's documentswhere their locations and main dimensionsare indicated. The voids left in the rockmassif due to inrushes and cavings should besupported reliably and backfilled with non-combustible rocks in order to prevent furtherrock displacement and the possible harmfuleffects on the shaft lining.

Directions are assigned to workings bymeans of a theodolite and fixed by at leastthree plumb bobs hung at a distance not lessthan 3-5 m from one another. Miners engagedin the driving work can use the direction linedefined by the plumb bobs on advancing to adistance not more than 40 m from the lastplumb bob. With a larger distance, instru-mental surveying is needed to set up newplumb bobs in the face.

'

9.7. Survey Work During Driving

of Vertical Shaftsby Special Methods

Geological and hydrogeological conditionsof mineral deposits are not always quite


suitable for the construction of vertical shaftsby conventional methods. In such cases,special methods are resorted to, in whichmeasures are taken for strengthening therock massif, ground water lowering, pluggingand soil freezing, which can facilitate thedriving of mine shafts. Under complicatedconditions, vertical shafts can also be drivenby drilling. In mine shafts driven by thesespecial methods, the mine surv~yor has tosolve certain specific survey problems.

9.7.1 Survey Work During Drivingof Vertical Shaftswith Artificial Rock Freezing

During driving of a mine shaft with artifi-cial freezing of the rock, the mine surveyorsperform the following operations: the layoutof the centre of a shaft and the mouths offreezing and monitor holes; checking theconstruction of a drilling site, assembly and

~

5' 3

Fig. 9.40 lnclinometric station: 1- automobile with logging hoist; 2- inclinometer; 3- tripod; 4- striding

level; 5- counterweight block

position of drilling equipment, and the verti-cality of surface casings; surveying drill holesduring drilling; and the compilation of levelplans of ice-rock enclosure.

The centre and axes of a shaft are trans-ferred into nature by the method described inSec. 9.2. The most popular method of layoutof holes in the terrain consists in the fol-lowing. A theodolite is set up at the centre ofthe shaft and oriented along one of the shaftaxes, after which the required angle is laid offand distances to each drill hole are measuredby a tape according to the design data. Theaccuracy of laying out of holes should be notworse than :J: 50 mm. The mouth of eachhole is marked by pegs.

Before drilling the holes, a geometricalcheck is made (for verticality, centring abovethe hole mouth, linearity of the kelly, etc.) inaccordance with the direction assigned by themine surveyor, and the hole mouth is drilledfor the surface casing. The length of the latter

,Jf


depends on the thickness of alluvium andupper caving rock and is usually of an orderof 20 m.

Before mounting a drilling rig, the rings ofa drilling site are checked for horizontality bygeometrical levelling at the top edge of therings with an interval of 1 m. The. differenceof height marks should not exceed 10 mm.

A drilling rig is regarded to be ready foroperation provided that the difference ofelevations of the corner points of a platformdoes not exceed 5 mm; the error of centringof a rotary table above the hole mouth is notmore than 10 mm; the difference between theheight marks of the axial points of a rotarytable is not more than 2 mm; and the devia-tion of the kelly in a rotary table from thevertical is not more than 0.001 of the kellylength.

Deep vertical freezing and monitor holescan be surveyed by means of gyroscopicinclinometers which measure zenith angles inthe range from 0° to 4-6° with an accuracy of1.5-2' and direction angles, with an accuracyof 3-6°, The interval for measuring zenith anddirection angles is not more than 30 m.

Figure 9.40 shows an inclinometric stationfor measuring drill holes up to 1000 m indepth with a casing string and drill string of96-127 mm in diameter. The station is moun-ted on a truck chassis,

The main instrument of the station is aninclinometer (Fig. 9.41) with a gyroscopicdirection stabilizer and zenith attachment forthe orientation of the inclinometer from thesurface. The measuring portion of the incli-nometer consists of an azimuthal gyrostabi-lizer unit and zenith angle measuring unit.The latter has two penduli which make itpossible to determine the zenith angle of theaxis of a drill hole. The measured values ofzenith angles are transmitted onto the sur-face.

Fig. 9.41 Inclinometer with gyroscopic directionstabilizer


The inclinometer consists of a housing 2,measuring portion 8, and guide rollers 1.

The measuring portion includes the unit ofazimuthal gyrostabilizer and unit for deter-mining the zenith angle. The gyrostabilizerhas a sensitive element 5, semiconductoramplifier 4, actuating motor with a reducer 3,and a m9tor with a rocker 7.

When the inclinometer moves in a hole,there appears an external moment whichrotates the housing 2 on the longitudinal axisof the instrument. This moment is transferredonto the measuring portion 8 and tends toturn the latter. Under this action, a gyro-motor together with an angle sensor frame 6deviates from the neutral position, and thesensor pulse is transmitted to the actuatingmotor 3. The motor develops (through thereducer) a compensating moment which re-tains the measuring portion of the instrument

in the given direction, so that its orientationis not changed.

The unit for zenith angle measurementshas two measuring elements which determinethe zenith angles in two mutually pocpen-dicular planes. Each element has a flat pen-dulum 9 contained in a h()rmetically closedcylinder which is filled with a viscous liquid.Each pendulum carries the frame of aninduction sensor;

Surveying a drill hole is started fromcentring the inclinometer on a tripod abovethe hole mouth, after which the first orien-tation is carried out by means of an orien-tation attachment fastened on the inclino-meter housing. For this purpose, a distinctobject is chosen on the terrain at a distancenot less than 30 m from the inclinometer, andthe direction angle of this object relative to aline OlHl is measured (Fig. 9.42). The incli-

~~Field sheet No.5

Shaft No.1 Hole No.3

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the lines HlOl and 02H2. The angularcorrection is then introduced into the twoorientation directions obtained during sin-king and lifting of the inclinometer. Thecorrected directions are brought to coinci-dence in the points of the hole mouth, whichgives two positions of the inclinogram.

The results of surveying of freezing holesare used for plotting the level plans of anice-rock enclosure (Fig. 9.43), which make itpossible to estimate the thickness of theenclosure and determine the boundaries offrozen rock (to the centre and to the rockmassif). The radii of ice-rock cylinders can becalculated by the formula:

r = J(I/2 + af + k

where 1 is the spacing between freezingholes; a is the deviation of a hole from thevertical; k is a coefficient depending on thethickness of an ice-rock enclosure; it is takenequal to 0.6L for the inner boundary and0.4L for the outer one (L is the thickness ofthe ice-rock enclosure as specified in theproject). The permissible deviation of freezingholes from the vertical is 0.5 + 0.002 H,where H is the depth of a shaft, m; in allcases, the maximum deviation of freezingholes from the vertical to the shaft centreshould not exceed 0.6 m.

,If,f~I

/

s

Fig. 9.43 Level plan of ice-rock enclosure

nometer is then unclamped and sunk into thedrill hole. As the instrument is being sunk,the planigraph records an inclinogram withelevation marks of depth intervals. Uponreaching the face of the drill hole, theorientation (inclination) of the inclinometeraxis 0191 is recorded, and the gyrostabilizeris turned through 180° to record a neworientation of the inclinometer axis, 0292.Mter that, the inclinometer is lifted in thehole to make measurements from the bottomupwards. As the inclinometer appears on thesurface, it is again oriented, and thedirection angle of a line H2O2 is measured.The lines 0 1 H 1 and H 2 0 2 are shifted parallelto themselves until points 0 1 and H 2 coin-cide. The angle 'Y formed by these lines (andcalled the angular correction) is determinedgraphically. A similar procedure is done for

9.7.2. Survey Work During Drillingof Vertical Shafts

The drilling method is used widely fordriving of mine shafts. It allows one tomechanize completely the operations of rockdisintegration and rock lifting onto the sur-face and eliminates the dangerous and hardwork of underground miners. The method ismainly employed for shaft driving in softwater-bearing rocks (drift sand, water-bea-ring sands, chalk, clays, etc.); in coarse-grai-ned sands, the method is not quite efficient inview of large losses of a clay drilling mud.

Mine shafts are drilled by drilling rigs

3~ -;,~, 3

\ 4\\

\ I--,


drilling tool, which is done by the optical orgeometrical method. With the optical meth-od, the surveyor observes a light signalprojected through a drill string; with thegeometrical method, a cable is stretchedthrough the drill string from the shaft mouthto the drilling tool, and its deviation ismeasured. In the former method, which isapplicable at depths up to 200-250 m, use ismade of instruments of the type of directionprojectors. In the latter method, the de-viations of the cable from the vertical can bemeasured at any desired depth with anaccuracy to 20" by means of a projectionmeter. The error in the position of the cablerelative to the drill string axis does notexceed 20 mm.

Shaft walls are surveyed during drilling bymeans of ultrasonic locators which make itpossible to take measurements in mud-filledshafts with an error up to 2% along theradius and 3%, in the orientation of ameasured radius.

permitting the drilling out of the rock alloverthe face.

Drilling a shaft is started from drilling apilot hole of a depth exceeding by 5-10 m thedesign depth of the shaft and of a diameter of0.5-1.2 m. The pilot hole serves for guidingthe drilling tool in subsequent widening ofthe shaft. Upon drilling, the shaft lining isconstructed by the float-on or sectionalmethod.

With the float-on method, a number oflining rings are mounted on one another on areinforced concrete bottom plate. The cyl-inder thus formed is sunk into the fore shaftfilled with washing fluid and floats, as it were,in the latter. New ring sections 4-6 m highare then put on top of the floating cylinder.After placing a ring section on the cylin-der, ballast fluid is pumped in to ensuresinking the cylinder to a certain depth. Afterbuilding the lining to the entire height of theshaft, the space between the lining and rock isplugged with a cement mortar.

With the sectional method, a fixing sectionof the lining is first sunk onto a concrete padprepared on the shaft bottom. Upon check-ing whether the section is placed correctly, itis fixed by a cement mortar poured into thespace behind the lining. Mter that, the liningsections 15-20 m high are placed successivelyonto the fixing section and secured by plug-gmg.

Mine survey servicing during drilling ofmin� shafts consists in checking the vertica-lity of the shaft axis and observing that thelining is errected properly. The deviations ofthe shaft axis from the design (vertical) posi-tion should not exceed the spacing betweenthe outer surface of the lining and the surfaceof the rock, which is taken equal to 200-350 mm. The control of verticality of a shaftaxis is complicated by the fact that the shaftis filled by clay drilling liquid during drilling.

In shaft drilling without lifting the drillingtool onto the surface, the verticality is con-trolled by the position of the centre of the

9.8. Survey Work DuringDeepening of Vertical Shafts

Deepening vertical shafts can be performedfrom the top downwards or vice versa. In theformer case, the survey work is essentially thesame as that during sinking of a shaft fromthe surface, though some specifics relate tothe restoration and fixation of the centre andaxes of the shaft in the deepened portion.Deepening a shaft from the top downwardscan be done by one of three probableschemes: (I) under a platform constructedbelow the floor level of the working connec-ted to the shaft bottom; (2) by means of aspecial passageway driven in the shaft por-tion to be deepened; and (3) through auxiliaryworkings driven sideways of the shaft.

In deepening by the first scheme, thesurvey work consists in determining thecentre and axes of the shaft in its sectionadjacent to the conjunction between the shaft

9.8. Survey Work During Deepening of Vertical Shafts 235

/

l..vI"0

I:o'~

ALA-A-r--

b~~n l2

-=

t.k~~

11A

W//////&Fig. 9.44 Restoration of centre and axes indeepened portion of shaft through sinking pas-sageway by means of plumb bobs and theodolite

and pit bottom, after which the restored axesare fixed by brackets below the futureplatform. In that case, the centre of the shaftis determined by the point of intersection ofwires stretched between the brackets that fixthe shaft axes.

With the second scheme of shaft deepening(Fig. 9.44), the survey work is started fromdetermining the centre and axes of the shaftin the bottom portion, by using the points ofan underground survey reference net.

The centre and axes are transferred undera pillar by means of plumb bobs 01 and O2

(see Fig. 9.44) whose coordinates aredetermined from the points of the referencenet of the workings near the shaft bottom.Mter cutting a chamber under the pillar, thecentre and axes of the shaft are laid out bymeans of plumb bobs 01 and O2. For thispu~ose, the theodolite is set up in a point Awhich is chosen so that the shape of aconnection triangle A01O2 can be convenientfor solving the junction problem. Thetheodolite is sighted at points 01 and O2, andpoints a and b are marked on the shaft walls.Solving the connection triangle A01O2, it isthen possible to determine the coordinates ofthe point A and the direction angles of linesA01 (Aa) and A02 (Ab). The coordinates ofthe shaft centre determined at the level ofshaft workings and the coordinates of thepoint A just found are used for solving theinverse geodetic problem of determining thelayout angle aAC and the distance AC. Byconstructing the angle aAC and distance ACin nature, we then determine the position of apoint C, the centre of the shaft, which is thentransferred and fixed in the safety pillar. Withthe known direction angles of the shaftaxis and of direction CA, we can now cal-culate an angle ~ and lay it off from thedirection CA by means of a theodolite set upin the shaft centre point. The direction of theshaft axis determined in this way is fixed bybrackets on the shaft walls.

The transfer of the centre and axes of theshaft under the safety pillar is performedtwice. The discrepancies between the tworesults should be not more than 5' in axialdirections and not more than 20 mm for theposition of the shaft centre.

If a shaft is to be deepened throughauxiliary workings driven beyond its limits(winzes, blind pits, inclined workings, etc.),the coordinates of the shaft centre and thedirection angle of one of the shaft axes aredetermined on the desired level from thepoints of an underground reference net(H and D in Fig. 9.45). A polygonometric


A-A

p

Fig. 9.45 Transferring centre and axes in deepened portion of shaft through winze

level, it is possible to solve an inverse geode-tic problem and calculate the layout angleARC = 13 and layout length RC = I, whichare laid off in nature and determine theposition of the shaft centre. Then, as in theprevious case, the direction of one of the shaftaxes is assigned and fixed by points F and G.

For a shaft to be deepened from thebottom upwards, the coordinates of the shaftcentre and the direction angle of the shaftaxis are determined before starting the layoutwork. The survey work in the workings on

traverse is then run from these points to theauxiliary working. In the case illustrated inFig. 9.45, the auxiliary working is oriented bymeans of plumb bobs 01 and O2. Thisorientation makes it possible to find thedirection angle of a certain direction fixed bypoints A and B on the level to which dee-pening should be done. The coordinates x, yof these points are also determined.

With the known coordinates of the shaftcentre and the coordinates of the point B ofthe polygonometric traverse on the lower

9.8. Survey Work During Deepening of Vertical Shafts 237

the level of deepening is also carried out. Allmeasurements essential for laying out thecentre and axes of the shaft on the level ofdeepening are carried out. The centre of ashaft on the lower level is usually fixed in thefoot of a working, and the shaft axes are fiXedby brackets in the walls or roof of theworking. The verticality and cross-sectionalarea of the shaft are checked by means ofplumb bobs hung under the sinking platformfrom brackets in the temporary lining. The

positions of the plumb bobs are checked bymeasuring the distance between them and thecentre of the shaft. The centre of the shaft inthe face is found by means of templatesor measurements from temporary plumbbobs which are centred above the permanentplumb bobs. The shaft should be checked forverticality in every 3 m of face advance, andthe shaft axes should be transferred onto thebrackets of permanent plumb bobs afterevery 10 m of shaft advancement.

Chapter Ten

Surveying in Quarries

10.1. General

The principal aims of the mine-surveyingservice in open-cast mining are as follows: theprovision of the geometric basis for thesurveying work in the form of a reference net;surveying of mining workings and land sur-face; compilation of graphical documents forthe normal operation of a mining enterprise;participation in the planning of drilling andblasting; control of the specified parametersof working systems and the dimensions ofstructures; calculation of the output of amineral, volume of burden rock, dynamicsof losses and the dilution of a mineral;observations on the motions of quarry flanksand development of measures for theirprevention.

The results of mine surveying are used forcompiling calendar plans of mining workdevelopment, investigations of the geolo-gical structure of deposits, solution of vari-ous problems associated with the activity ofproduction sections, etc.

The objects of surveying in quarries in-clude the following main groups:

(a) exploratory, draining and drilling-blasting workings, crests, access tracks, work-ing trenches, catchwater ditches, etc.;

(b) tectonic disturbances, contacts of thelying and hanging wall with the mineral,boundaries of sections with different gradesof ore or different ash content of coal, as-saying points, boundaries of landslides, etc.;

(c) haulage lines in a quarry, pay-ore area

structures, hoists, trestles, power transmissionlines, pulp pipelines, etc.;

(d) flooded workings, cavities left afterunderground mining work, fire zones, etc.

10.2. Reference and Survey Nets

and Surveying Work

10.2.1 Mine-Surveying ReferenceNets

Mine-surveying reference nets on depositsextracted by open-cast methods are de-veloped in accordance with the requirementsset forth to reference nets on the land surfacefor the territories of economic interest ofmining enterprises. They may include tri-angulation points, trilateration points, andpolygonometric points. Levelling benchmarks can be used as the reference basis forsurveying nets in quarries.

Modem organization of mine surveying inopen-cast mining of deposits is character-ized by that the work proceeds successively'from the general to particular', with mea-surements at each stage of the work beingmade with the specified accuracy. On theland surface of a mining enterprise, a ref-erence net beyond the limit of the designcontour of a quarry is formed initially. Afterthat, as the mining work is developed on thequarry flanks, and sometimes inside aquarry, reference points are set up in theseplaces, which are called approach points andserve for the formation of a surveying net.

10.2. Reference and Survey Nets and Surveying Work 239

A , I"

'>f'

~2' "1'~.J )~ 6

6 .~-

B

Fig. 10.3 Construction of reference net by poly.gonometry

I 2 3

/-~,

\\B

-, ,

~~

--~c

Fig. 10.1 Insertion of point into rigid angle fordevelopment of reference net

Depending on the configuration of a quarry,local conditiQns, methods of strippingand provision of technical facilities, the ap-proach points can be determined by themethods of triangulation or polygonometry.

The method of triangulation is employed incases when approach points are readily vi-sible from reference points. In such cases, useis most often made of the insertion of one(Fig. 10.1) or several points into a rigid angle,construction of a chain pf triangles betweentwo fixed points (Fig. 10.2) or the construc-tion of a geodetic quadrangle. In trianglechains, the number of figures should be notmore than five. The angles of triangles should

1 2/"7 JA 13 \ """

'/134 fi5yI 1'10 RM N

~L~4

1"12

3

Fig. 10.2 Construction of chain of triangles be-tween two reference points

be not less than 30° in chains or 20° ingeodetic quadrangles.

The method of polygonometry is resorted toin cases when there is no visibility betweenthe reference points and the points to bedetermined (approach points), but the landsurface is quite convenient for linear meas-urements to determine the approach points.The polygonometry can also be used withsuccess on a rough terrain if it is possible toemploy light or radio range finders. Polygo-nometric traverses are commonly run be-tween the points of a mine-surveying referencenet (for instance, points A, B, and C inFig. 10.3).

10.2.2. Surveying Nets

Surveying nets are constructed on the basisof points of a reference net. In surveying theland surface, waste dumps and quarries,surveying nets are constructed according tothe following requirements: the main pointsof a surveying net should cover evenly thesurvey surface area; their density is determi-ned so as to have four points per km2 insurveyings on a scale 1/5000, 10 points perkm2 on a scale 1/2000, or 16 points per km2on a scale 1/1000; each surveying plate madeon a scale 1/5000 should have at least threemain points fixed by permanent centres; twosuch points are sufficient on plates on a scale

240 Ch. 10. Surveying in Quarries

of 1/2000 and one such point, on those on ascale 1/1000.

Depending on the terrain relief, shape of aquarry in plan, mining technology and someother factors, surveying nets can be con-structed by the following methods: method ofgeodetic intersections; method of analyticalnets; method of theodolite traverses; methodof range lines; polar method; and method of arectangular network.

Since a survey control net has to exist onlyfor a relatively short time, it can be fixed bypermanent or temporary points in the formof wooden page or metal rods driven into thesoil. In hard rocks, temporary points areusually fixed by cross marks made on theprotruding portions of the rock. Surveypoints are usually located on the lowerplatform of each working bench at distancesnot more than 400 m from one another.

Method of geodetic intersections is em-'ployed in cases when the points of a survey-ing net are located at appreciable distancesfrom those of a reference net. Right and sideintersections and reverse intersections (resec-tions) are usually employed.

Right and side intersections are drawn fromat least three initial points. A resection isdrawn from four points, provided that thepoint to be determined lies near the circlepassing through three of the four initialpoints.

The coordinates of the points determinedby r.ight or side intersections are calculatedfrom two triangles; in the method ofresections, they are found from two versions.In all cases, the final coordinates are taken asthe arithmetic means from two measure-ments. The maximum discrepancy should notexceed 0.8 m.

Method of analytical nets is employed inquarries where both flanks are working(moving). Analytical nets are constructed aschains of triangles or other figures (geodeticquadrangles, a central system, etc.) which aresupported by sides and points of a reference

net. Triangle chains and central figures areused most often. The latter are employed forconstructing a surveying net on the lowerlevels of quarries of a small area or of someportions of a quarry, whereas trianglechains are preferred in the quarries of anelongated shape and appreciable depth. Thenumber of points detennined by an indi-vidual triangle chain or figure should be notmore than seven. Triangles should have ashape close to equilateral. The angles at thepoints being determined should be not largerthan 120° or smaller than 30° and the sidelengths, not smaller than 300 m or greaterthan 1000 m.

Angular measurements are commonlymade by means of theodolites. The permis-sible angular discrepancy in triangles withthe side length up to 1000 m is l' and in thosewith the side length more than 1000 m, 40".

Method of theodolite traverses is employedin quarries having a large extention of thefront of mining and stripping work andbenches of a form convenient for linearmeasurements. Theodolite traverses are runbetween two known points A and B (pointsof a reference net) or between closed poly-gons. At junctions of theodolite traverses tothe initial points, there are measured theangles between the junction side of a theo-dolite traverse and two directions onto thepoints of a reference net (Fig. 10.4).

The distances between the points of theo-dolite trayerses should not exceed 400 m and,as a rule, should be less than loo m. Thelength of a traverse should be not more than2.5 km.

The angles in theodolite traverses aremeasured by theodolites. An angular dis-crepancy should not exceed f fJ = 30" J~ ,where n is the number of measured angles.The three-stand scheme can be recommendedfor angular measurements. The theodolitesshould be centred with an accuracy not worsethan 2-3 mm.

The length measurements in theodolite


Fig. 10.4 Providing survey control by means of theodolite traverses

available, it is possible to measure the lines ofa theodolite traverse by the indirect method ofgeodetic intersections which is essentially asfollows. A theodolite traverse is run on theworking platform of a bench and connectedat the ends to the points of a reference net (I,II, Fig. 10.5). Auxiliary points A, B, and C arechosen at certain distances away from thetheodolite traverse line. Angles ~1' ~2' ~3' ...,~17 are measured from the points of thetheodolite traverse line and lines I-I and 6-1I,which are the refere~ bases, are measuredby a tape. The side l-A of a triangle IAl iscalculated by the sine theorem:

traverses can be made by means of steel orcloth tapes or range finders. In some cases,the lengths of traverse sides can be determinedby indirect methods, but in all cases all mea-surements should be done in the forward andreverse direction, and the relative differencebetween two independent measurementsshould be not more than 1/1000. The lineardiscrepancies in theodolite traverses shouldbe not more than 1/3000 of the traverselength. The corrections for temperature, tapestandardization, and horizontalization oflines should be introduced into the measuredlengths. A temperature correction is intro-duced in cases when the temperature atmeasurements differs by more than 5 deg. Cfrom that at which the tapes have beenstandardized. A correction for horizontaliza-tion is introduced when the inclination angleis larger than 10.

Linear measurements can also be carriedout by the optical method with the use ofoptical range finders and range finder attach-ments and a base-measuring (subtense) bar.In some cases when the form of benches isinconvenient for length measurements on theground and optical range finders are not

16-1270

A-l1-2= sma2

sin P4

In a similar way, the side 2-3 is calculated,which is the connecting side for solving thetriangles constructed from the point B. Thecalculations of the next series of triangles give

I!

\

~I

C

~~ I' \ ): ~17

a-,'l: 8 m

B

/~,

l~n ~ 6(15

i "\\\

\ {,

A

~,

I,

"

IPel

Fig. 10.5 Indirect measuring of sides of theodolite traverse

a side 4-5 which is the basis for solving thelast series of triangles constructed from thepoint C. A check is done in this method bycomparing the calculated length of the lastline of a theodolite traverse, 6-11, with itslength measured in the field.

Method of range lines is employed inquarries where the working front is advancedin one direction only, so that the referencepoints fixed on the non-mining flank can beeasily observed from the working benches.This method is especially convenient in caseswhen the platforms of working benches havea certain elevation above the ground surfaceof the opposite flank of a quarry (Fig. 10.6).

For laying out a range line, a second-order .polygonometric traverse is first run (A,B, C, ..., G). With the known directionangles of range lines, it is possible to calculatethe angles 'I' and <p according to which thedirection of a range line is assigned and fixedby points A-l, B-2, C-2, ..., G-7. The pointsof profile lines are laid off as follows. A point(say, p J is first fixed on a range line. Thetheodolite is set up on that point and anglesa and 13 are measured. With these anglesbeing measured and the angles 'I' and <p anddistances CD and DE being known, two sideintersections are calculated and the coordi-

nates of the point p 1 are found, In order tohave an optimal shape of triangles, it isessential that the angles a and 13 be notsmaller than 30°, If however these angles aresmaller than 30°, it is possible to sight theinstrument at reference points located onadjacent range lines (for instance, a point p 2and sighting at points B and F).

Polar method of providing survey controlhas become popular with the appearance of

123 456 7

y ~ ~ ~ I ~ ~III 111 IV v VI VIII I I I I IA B C D F G~~~

~

-7

Oj:l=.: JJI.::.--I ~ -:::.

1--

;:J~P2

Fig. 10.6 Providing survey control by method ofrange lines

eA< I oB, (

[3

Aa<

~

4

\{5l5 \ I

b\

.2

I

~

~

~2~

DO .j ~c

Fig. 10.8 Providing survey control by method ofrectangular network

geodetic light range finders. For successfulapplication of this method, a greater por-tion of a quarry must be readily visible froma few number of points ofa reference net. Forthe construction of a surveying net, a lightrange finder i.s set up on a point (A) of thereference net, and light reflectors are set(Fig. 10.7) up on surveying net points 1, 2, 3,...which are to be determined. Uponmeasuring the distances, the light rangefinder is replaced by a theodolite to measurepolar angles ~l' ~2' ~3' etc.

Method of a rectangular network for theconstruction of surveying nets is applicable inquarries of a shallow depth and with a flatrelief of the surrounding land. A network ofrectangles is laid out on the territory ofdeposit, and survey points are fixed in theircorners (Fig. 10.8). It is a common practice tolayout two systems of rectangles: the mainnetwork with the side length d equal to 50 m,loo m or 200 m and the densifying networkof rectangles with the side length dl equal to5-40 m, which is used directly for surveying.

The orientation of the sides of a network is

chosen parallel (perpendicular) to the mainmining front or coincident with the orienta-tion of a coordinate network.

For laying out a rectangular network, aplan of the surface is compiled, which givesthe technical boundary of a quarry and anumber of reference net points (1, 2,3,4, 5)near it. Then the directions of the axes of arectangular survey net are chosen, the rectan-gular network is laid out, and the coordinatesof its corners are calculated on the plan. Afterthat, a project of the densification of thereference net is designed so that its points canbe as close as possible to the corners of therectangular network; the densification net-work is transferred into nature and fixed onthe ground. The corners of the network canbe fixed by laying off the distance anddirection angle from the closest referencepoint or by the method of angular intersec-tions with the use of one or two theodolites(see Fig. 10.8).

For the transfer of surveying net pointsonto the lower levels of a quarry or therestoration of annihilated points, use is most


(a) (b)

r--r- :J= --r-! L--L. ' .+-~

, ~ ' ,

.(, ~-+ --1L 1 !

Fig. 10.9 Transfer (restoration) of surveying net points: (a) by method of range lines; (b) by method ofangular intersection

often made of the method of range lines inwhich two theodolites are set up on twoclosest existing points (Fig. 10.9a), and a newpoint is fixed at the intersection of theircollimation lines. It is also possible to use themethod of direct angular intersection. In thatcase the position of a point of the referencenet is determined on the ground by laying offtwo horizontal angles ~1 and ~2 by means oftwo theodolites (Fig. 10.9b); the sought-forpoint is then found at the intersection of thecollimation lines of the two instruments.

10.2.3. Elevation Control of Quarries

Elevation control is required for determi-ning the heights of the points in a quarry.The heights of the points of a surveying netare measured by geometric or trigonometrictechnical levelling.

Geometric levelling is usually employed inquarries with railway transport. Technicallevels and levelling staffs of any type aresuitable for the purpose. Technical levellingbetween the points of a reference net may bedone in one direction only; hanging lines arepermitted, provided that they are run in theforward and reverse direction.

The readings in levelling are taken onlyrelative to a single line. The difference ofelevations determined on the black and redface of staffs should not exceed 10 mm. Thepermissible discrepancy of level lines is

50JL mm, where Lis the length of the levelline, km.

Trigonometric levelling has found use inquarries with railless transport and in caseswhen a surveying net is formed by themethod of geodetic intersections. When de-t.ermining the elevations of points by trigo-nometric levelling, vertical angles are mea-sured by means of theodolites at the same timewith measuring the horizontal angles; theaccuracy of reading-off devices of the verticalcircle of the instruments should be not worsethan 30". The heights of an instrument andsighting target should be measured with anaccuracy to 1 cm. The measurements of ver-tical angles can be controlled by the constantplace of the zero point of the vertical circle.The deviations of the zero point should benot greater than thrice the reading-off erroron the vertical circle.

Trigonometric levelling lines should beconnected to the points whose elevationshave been determined by geometric level-ling. Their length should not exceed 2.5 km.The permissible discrepancy between a for-ward and reverse elevation is not more than0.041 cm where I is the length of a line, m. Thediscrepancy of a levelling line, cm, should benot more than

mh = 0.04[1]/J~

where [I] is the length of the levelling line, m,and n is the number of levelling lines.


If the points of a surveying net are deter-mined by the polar method or method ofgeodetic intersections, the elevations betweenthe points are found by trigonometric level-ling in the forward and back direction or in asingle direction only, but from at least twopoints. In such cases, elevation discrepancies(in centimetres) should be not more than0.031 for distances up to 1 km or 0.021 for dis-tances above 1 km (where 1 is the length ofthe lines, m). If a side in one-sided levellingexceeds 700 m, a correction for the Earthcurvature and refraction should be intro-duced into the measured elevation.

10.2.4. Surveying in Quarries

The surveys of quarries and complemen-tary surveys of benches can be carried out bythe following methods: tacheometry, methodof perpendiculars, plane-table survey, stereo-photogrammetry, and their combinations.

For the compilation and complementationof mining working plans, it is advisable,where possible, to perform aerial and groundstereophotogrammetric surveys.

Tacheometric survey is employed for:(a) surveying of quarries where the mining

technology is such that the volume of ex-tracted burden rock and that of the mineralin the pillar can be determined directly fromthe results of bench surveying;

(b) for surveying of quarries of a relativelylow capacity;

(c) for surveying of'dead' spaces obtainedin ground stereophotogrammetry; and

(d) for check surveying of mining workingsin the selective control of their plan posi-tions and for surveys in cases where stereo-photogrammetric methods are inefficientor inapplicable.

Plane-table survey has found no wide ap-plication. It is mainly used for single surveysof small quarries or their portions when ageneral plan of mining workings is to becompiled.

The periodicity and sequence of surveys inquarries are as follows: surveys of contours ofbench crests and blast holes are made only inplaces where blasting work is to be perfor-med. All other objects except for mineralstores are surveyed only when a need arises.Mineral stores are surveyed every ten days oronce a month depending on the methodadopted for calculating the amount of theextracted mineral.

Surveys in quarries are made from thepoints of a survey net. The distances betweenthese points on a bench should not exceed300 m for a scale 1/1000 or 400 m for a scale1/2000. It is permissible when needed todetermine the additional points of a survey-ing net by running a single-sided hangingtheodolite traverse. The length of sidesshould be not more than 300 m in surveys ona scale 1/1000 or 400 m on a scale 1/2000.

The staff is set up on all characteristicpoints of the contours and surfaces beingsurveyed. In surveys on a scale 1/1000, thedistances between the staff points should notexceed 20 m for the bench crests of intricateshape or 30 m for the extended crests. Insurveys on a scale 1/2000 the respectivedistances are 30 m and 40 m.

In the surveys of the surface of blasted rockthe distances between the staff points shouldnot exceed 10 m for a scale 1/1000 or 20 m,for a scale 1/2000.

A sketch of bench contours is drawn ateach survey station (Fig. 10.10a).

A sma[[-sized geo[ogica[ a[timeter(Fig. 10.11) has been developed in this coun-try for the geological documentation ofquarry benches. The instrument is intendedfor the remote measurements of vertical thick-ness and dip angles of visible seams. It canalso determine the relative elevations of theposition of geological elements and otherobjects.

The altimeter is essentially an optico-mechanical goniometer provided with a di-rect-image telescope and self-adjusting verti-


(a)

~

~

c.;c-.

(b)

~ : 10 --:~-- :~("I cpi "' LO

("II ("I.(I)

39.71-

0:~

~ ;15 -:.~,;~5~~

~ 3 \

~I-- --'0

o-~~~~-,I.:Lg--- -13

~ v.:.-~ --

ir::::njt1r~

Fig. 10.10 Sketch of bench contours: (a) by tacheometric method; (b) by method of perpendiculars

(b) eliminates the need in staff men and thusincreases the safety of work;

(c) provides a large choice of points incompiling plans by photographs and thusbetter characterizes the section surveyed; and

(d) involves all visible objects includingthose which are inaccessible for tacheometry.

Fig. 10.11 Geological altimeter: l-eye-piece;2-housing; 3-adjusting level; 4-reading-otTmagnifying glass; 5- horizontal circle; 6- base;7-levelling wedges; 8-handle; 9-horizontal sight-ing screw; 10-vertical sighting screw; ll-tele-scope; 12-focussing device

cal circle with scales of elevations andvertical angles. The working portions ofmeasuring scales are visible directly in thetelescope.

The range of measured elevations is:t 10 m for a sighting length up to 10 m or:t 20 m for a sighting length of 20-40 m. Therange of measured visible dip angles is :t 90°.The error in the measurements of the verticalthickness of seams is not more than 5 cm andthat of the visible dip angles of seams, 1°. Themass of the instrument is 1.5 kg.

Method of perpendiculars can be employedefficiently for the surveys of bench crests withsimple contours when the required number ofstaff points is not large (Fig. 10.10b).

The surveying net for the method ofperpendiculars is constructed in the form oftheodolite traverses or as a rectangular net-work. The length of ordinates, as a rule,should not exceed 30 m. For a length morethan 15 m, they should be set up by means ofa right-angle mirror. Lengths are measuredby tapes and rounded off to decimetres. Thedistances between the staff points are chosenaccording to the recommendations given fortacheometric surveys.

Stereophotogrammetric surveying of quar-ries. In recent time, stereophotogrammetryhas come into use in many quarries in placeof tacheometric surveying, which offers thefollowing advantages:

(a) increases the labour productivity of thefield work;


A

c

I

'I

s -1J / B~h ~S'y- ,11\ 2f!i!f:1 / ~ ~

~ a J a.,C1 I C2

Fig. 10.12 Elements of stereoscopic pair

(10) the focal distances of photographs!1 = 8101 and!2 = 8202.

In stereophotogrammetry, the'position of apoint on the land is determined by a directspatial intersection which is formed by theprojecting beams passing through tq~ left-and right-hand point of the base. For in-stance, the position of a point C (seeFig. 10.12) can be determined if the directionsof projecting beams c181 C and c282C areknown. The surface formed by the pluralityof the points of intersection of correspondingprojecting beams is called the geometricalmodel, or simply model.

Photographic cameras for making stereo-photographs are provided with devices whichensure their definite and fixed positionduring exposure. A photographic camera canalso be combined with a theodolite, and thecombination is called a photo theodolite.

The stereophotogrammetry of quarries canbe performed from a fixed base on the

Ground and aerial stereophotogrammetrycan be employed.

Ground stereophotogrammetry can be usedeither independently or in combination withtacheometric surveying.

Stereophotogrammetry can determine andrepresent graphically the shape, dimensions,and spatial positions of objects and relief ofthe Earth's surface. It is especially efficient inlarge quarries. To compile a plan of a quarrysection, this section is photographed stereo-scopically from two points at the ends of abase S1S2 (Fig. 10.12). The two photographsof the same portion of land, when viewedthrough a stereoscopic device, produce athree-dimensional effect. When made fromtwo ends of a base line they represent astereoscopic pair whose principal elementsare as follows:

(1) the left-pand (PJ and right-hand pho-tograph (P 2);

t2) the centres of projection of the left-handand right-hand photograph, SI and S2' or therear optical centres of the two objectives ofstereophotogrammetric camera;

(3) the photographic base Bph = S1S2which is also equal to the distance betweenthe centres of projection of the photo-graphs;

(4) beam bundles alSlA, ~ISIC, a2S2A,C2S2C, etc., i. e. the combination of projectingbeams which form images on the photo-graphs;

(5) the main beams S101 and S202 whichare perpendicular to the planes of photo-graphs;

(6) the main points 01 and O2, i. e. thepoints of intersection of the main beams withthe planes of photographs;

(7) identical points a1 and a2' c1 and C2'etc.;

(8) the images of the same point on theland on the photographs of a stereoscopicpaIr;

(9) corresponding beams Slal' S2a2' etc.;and

248 Ch. 10. Surveying in auarries

ground or from a flying object (aeroplane). Itis distinguished between two principal casesof ground photogrammetry: with a hori-zontal position of the optical axis of aphotographic camera (horizontal stereo-photogrammetry) and with the optical axisinclined substantially relative to the hori-zontal (oblique, or perspective, stereophoto-grammetry).

Horizontal stereophotogrammetry is easierto make and has an essential advantage overthe oblique method, since the latter requiresmore intricate techniques of photoreading.

Horizontal stereophotogrammetry is usu-ally done as a combination of three cases:with the optical axis of a photographic ca-mera directed perpendicular to the base anddeviated by 30-35° to the left and right fromthis position (Fig. 10.13).

The coordinates of points on photographsare determined in a rectangular system ofcoordinates (x'x' and z'z' in Fig. 10.14). Thepoint of intersection of coordinate axes, 0', isthe origin of coordinates. The coordinates ofa parti<;ular point a, as measured on aphotograph, are commonly called the pho-tocoordinates (xa, Za).

Coordinate marks are fixed so that thepoint 0' which is the origin of coordinates,and the main point 0 of a photograph, areperfectly coincident. In that case, the coor-

Fig. 10.14 Coordinate system of photographFig. 10.13 Horizontalsurvey

s tereop h o togrammetri c

dinates of the main point, Xo and Zo, areequal to zero.

The coordinates of points on the land aredetermined in the coordinate system adoptedfor a quarry. In contradistinction to photo-coordinates, they are designated by capitalletters xYZ.

The coordinates of points on the land aredetermined on photographs according to thepositions of the bundles of projecting beamsat the instant of exposure. The characteristicsthat determine the positions of beam bundlesare called the elements of the orientation of aphotograph (which are subdivided intoexternal and internal).

The elements of internal orientation in-clude the focal distance (focal length) of acamera and the coordinates of the main pointXo, Zo. Among the elements of externalorientation (Fig. 10.15) are the coordinates ofthe left-hand end of a photographic base,Xs , ys and Zs ; the angle of inclination ofthelmaih beam 6f the left-hand photograph,(J)1; the angle of turn of the left-hand photo-graph in its plane, "1; the oblique angle of theleft-hand photograph <Pl which is equal tothe angle between the projection of the mainbeam of that photograph onto a horizontalplane and the perpendicular to the projectionof the photographic base onto the sameplane; the direction angle of the photographic

10.2. Reference and Survey Nets and Surveying Work

xph

249

<pYph

~ :..' / /

// ///

/ZPh

/1112

(111

~ c /

/ --\-"' ff 2

x /.//

~ 8 190, Xph

BaseB ,

z 2~ .11 x / / Horizontal

02 X X2

1

/ ~ S1 HoLta, x ,.../ i/ I 01 xI I

ys z X ,.ls,---1 I

,I/

I':// Xs/ 1

Fig. 10.15 Element of external orientation of stereoscopic pair

base QB; the projection of the photographicbase onto a horizontal plane; the heightdifference of the right-hand- end of thephotographic base above the left-hand end,Az; the angle 'of inclination of the main beamon the right-hand photograph, m2; the angleof the turn of the right-hand photograph inits plane, "2; and the angle made by the mainbeam projections of the photographs onto ahorizontal plane, y (Figc 10.16). With a posi-tive angle y, the main beams are convergent,and the angle y formed by them is caned theangle of convergence; with a negative y, themain beams are divergent, and y is called theangle of divergence.

The coordinates Xs , ys , and Zs , thephotographic base Bp~, arid its dirbctionangle QB are determined by geodetic methods.The oblique angles of photographs are set upby the orientation device of a phototheo-dolite. The inclinatio~ angles of the mainbeams of photographs, m, and the angles ofthe turn of photographs, ", are reduced to

nearly zero values by means of spirit levelsmounted on the camera.

The mine-surveying plans of land surfaceand mining workings art: usually constructedin a left-hand system of coordinates, whereasstereophotogrammetry employs a right-handcoordinate system. In both cases, however,the z-axis is arranged vertically.

Let us analyse a case of normal stereo-photogrammetric survey (see Fig. 10.16) inwhich the optical axes of the photographiccameras set up in points SI and S2 areparallel to each other and perpendicular tothe photographic base Bph. It is assumed inthis example that:

(a) axis Xph coincides with the direction ofthe photographic base;

(b).axis yph coincides with the direction ofthe optical axis of the photographic cameraset up in the point SI (the left-hand end pointof the base); and

(c) axis Zph has a direction perpendicular tothe plane formed by the two other axes.

Ch. 10. Surveying in Quarries250

-:4

<

"-

~..A'

Fig. 10.16 Normal stereophotogrammetric survey

From the similarity of triangles SlOKand Slojkj, it may be written:

Xph/Yph = Xj/!c or Xph = (Xj/!c)Yph

Substituting for Yph' we get:Xph = BphX,/P (10;2)

Similarly:Zph = BphZj/ P (10.3)

As follows from these formulae, in order todetermine the photogrammetric coordinatesYph' Xph' Zph of points, one has to know thephotographic base in nature and the focallength of the photographic camera of aphototheodolite and to find on the photo-graphs the values of X" Z" and p. The lengthof a photographic base, the distance from thephoto theodolite to the objects being pho-tographed, and the focal length of a photo-graphic camera are considered the principalparameters of a stereophotogrammetricsurvey.

All objects of a stereophotogrammetricsurvey should always lie within a rangebetween the minimum permissible distanceY ph .and the maximum permissible distance

mln

We have to determine the photogram-metric coordinates of a point K on the land.

Let the image of the point K on theleft-hand photograph be denoted by k, andthat on the right-hand one, kr (see Figs. 10.16and 10.17). The designations adopted in thefigures are as follows: Yph' Xph' and Zph are thephotogrammetric coordinates of the point Kon the land (Yph is also called the distance tothe point K); XI is the abscissa of the point k,on the left-hand photograph; Xr is the ab-scissa of the point kr on the right-handphotograph; ZI is the ordinate of the point k,on the left-hand photograph; Bph is thephotograI'hic base; and fc is the focal lengthof the photographic camera of a phototheo-dolite.

Noting the similarity of triangles KK'Sland k,k~Sl (see Fig. 10.17), we can write:Yphlfc = Bphl(XI -Xr)

Denoting X, -Xr = p (which is called thehorizontal parallax, or x-parallax), we canwrite the formula in the form:

BpJc Bp,jcYph=-=-

xi -Xr p(10.1)


Fig. 10.17 Determining photogrammetric coordinates of point on terrain

Depending on the length of the photo-graphic base, accuracy requirements, andpossibilities of photoreading, the length of thephotographic base can be determined by oneof the following methods:

(I) if a quarry or land portion is surveyedfor mapping, the base can be calculated bythe formula:

2B=Q~ (10.6)

Mfctmin

where y f is the distance to the farther boun-dary of the working portion of a givenstereoscopic pair and Q is a coefficient whichis taken equal to 15 for a single survey of aquarry and to 20 for mapping of the landsurface;

(2) in monthly complementary surveys forcalculating the volumes of excavator cuts, thebase length is found by the formula:

y} .

Y ph from the pho-tographic base. The for-max d "mer IS nee ed lor the appearance of a stereo-

scopic effect and the latter ensures thespecified accuracy of measurements.

The minimum permissible distance de-pends on the technical characteristics ofstereoscopic devices and the specifics of thestereoscopic vision of an observer. It can bedetermined by the formula:

Yph .= (3-4)Bph (10.4)mln

The maximum permissible distance isfound by the formula:

Mfc ~Yph = 1.25-tmin (10.5)

max loo

where fc is the focal length of a phototheo-dolite; M is the denominator of the scale ofthe plan to be compiled; tmin = COS ~ == (x2/fc)sin~ (here ~ is the oblique angle ofa photograph and X2 is t~e largest coordinatex on the right-hand photograph within thelimits of the stereoscopic pair working stage).

Bph = ( 1 0.7)1.8 Mfcdmvtmin


Fig. 10.18 Determining useful area of stereogram

where d is the width of a cut, m; mv is thespecified root-mean square error of the vol-ume measurement, %; and Y I'fc, tmin and Mas in formulae (10.5) and (10.6).

It is also essential to know the overlappingarea in a stereoscopic pair taken from aparticular photographic base. Consider, forexample, the photographic base SlS2(Fig. 10.18). We construct the horizontal vi-sion angles (working angles) a of a photo-theodolite on the land from the ends of thebase. The useful area F us' confined by pointsabcd, is depicted on each photograph of thestereo pair and later processed in a stereo-comparator.

It can be written by reference to Fig. 10.17:Fus = (D/t)(Lmin + Lmax) (10.8)

where D is the depth of a survey; Lmin is thecloser base of a trapezium; and Lmax is thefarther base of a trapezium. The trapeziumbases can be found by the formulae:

a( Bph a)Lmin = 2tan 2 3.5Bph -Tcotan 2 (10.9)

a ( Bph a)Lmax = 2tan- Yph --cotan- (10.10)

2 max 2 2

Noting these expressions, the formula forthe useful survey area will be as follows:

(10.11)

Ground stereophotogrammetric surveyingincludes reconnaissance, geodetic measure-ments, and land photography.

Reconnaissance is done for selecting thelocations of the points of a referenee net,photographic bases, and fiducial (correcting)points. Since the length, number and dire:c!-tion of photographic bases can influencesubstantially the productivity of the surveywork, it is advisable to have a minimumnumber of bases that is sufficient to cover theentire survey area without leaving 'dead'spaces (Fig. 10.19).

In order to obtain the required accuracy inthe determinations of the coordinates ofpoints on the photographs of stereoscopicpairs and the horizontal parallax at eachstation, it is essential to establish a number offiducial (correcting) points whose coordi-nates are determined by the photogram-metric or geodetic method. Thus, it is pos-sible to compare the coordinates obtained bytwo independent methods and to check theste~eophotogrammetric survey. Three cor-recting points are usually established foreach photographed stereoscopic pair at eachstation. One of these points should be locatedin the closer plan and the other two, in thefarther plan of the area being photographed.In order to decrease the number of correctingpoints, some of them are usually made com-mon for adjacent stereoscopic pairs.

Places for establishing the photographicbases are chosen so that the bases can be~llel to the working front and at the samelevel with the objects to be photographed (orsomewhat above them). It is also essentialthat the height difference of the ends of thephotographic bases be as small as possible. Instereoscopic photographs of a quarry takenfrom an inclined base, the like points will bedisplaced relative to each other (vertical f)a-

Base 3 (200 m)Base 3a (BO m) ~

Base 2 (170 m) ./1 \

Base 2a (60 m) ./ .I;:-, ~ i1/ .';Z:A'.-~

::i .\',. I ~, 'x \-I .1 ~' I ~// \ -, .i" <." zee""7-:7'\ -.) -

~ --' ,~ / /-r- .\ ---"t;..~:7

~ / \ ( \

.\Basel(80m) ...\ Base4(100m:

\

\t;') \

I I H8 ~1 Base 5 (100 m)

,.\\ ,\

)

~I"'1

..Fiducial'

points I

~

J100 0 100 200m

Fig. 10.19 Example ,

survey of quarry

of stereophotogrammetric

photographic bases can be located on theflanks of a quarry if the quarry depth is notlarge; in deep quarries, photographic basesare arranged on bench berms;

(2) in working systems with internal wastedumps and in those with conveyer bridges,photographic bases are located directly onthe dumps;

(3) in combined working systems whererocks are transported to external andinternal waste dumps, the upper and lowerbenches are photographed separately. Theupper benches are photographed from thebases located on a non-working flank and thelower ones, from the bases on internal wastedumps.

To take photographs, tripods are set up atthe ends of a base. A theodolite is arrangedon the left-hand end of a base (relative to thedirection onto the objects to be photo-graphed) in order to measure the length ofthe base line. After that, the photographiccamera is oriented relative to the base, andphotographs are taken from the left-handand right-hand end of the base. The opticalaxis of the camera is arranged normally tothe direction of the base line.

Geodetic work in ground stereophoto-grammetry includes the following operations:

I. Determination of the planimetric co-ordinates of the left-hand points of bases andmeasurements of base lengths. The length ofa photographic base can be measured by atape, wire or other instruments, provided thatthe discrepancy between the forward andback measurements is not more than1/5000-1/2000 of the base length. The pla-nimetric coordinates of the left-hand basepoints can be determined by triangulation,method of analytic network, by intersectionsand resections, polygonometric or theodolitetraverses, polar method, and photogram-metry.

2. Determination of a direction angle. Thedirection angle (aB) of a photographic base isfound by measuring in the left-hand base

rallax). This effect can be fully avoided or atleast minimized to a tolerable level in astereocomparator only in cases when theheight difference between the ends of thephotographic base is not more than O.3Bph.Besides, base points should be established inplaces where they can be preserved for a longtime. Adjacent bases should be chosen so asto ensure the specified overlap in adjacentstereoscopic pairs. Places for the location ofphotographic bases should be chosen so thata porti~~ of quarry or land can be photo-graphed With the least possible number ofstereoscopic pairs.

Depending on the size of quarries, workingsystems, and the orientation of the miningfront, the following versions of the arrange-ment of bases in quarries are possible:

(1) in working systems with overburdentransportation to external waste dumps,


point of horizontal angles between the di-rection from that point onto the right-hand point of the base and the directionformed by two certain points of a geodeticreference net. These angles are measured withan accuracy not worse than 5". The error inthe measured direction angle of a base shouldbe not more than:

me (101?)ma = , ,

2yphmax

where p" = 206265" and me is the permissibleroot-mean square error in determining thepositions of contour points.

3. Determination of the elevation marks ofbases and correcting points by technicalgeometric levelling.

The correcting points are fixed by placingmarks on them, which are made as screens ofplywood or another material. The verticaland horizontal sizes (b and a) of screens arecalculated by the formulae:

D

b = O.12yp h /j~,max

a = O.O6yPh /fc

max

(10.13)

Photography proper is a critical procedurein stereophotogrammetric surveys of quar-ries, since the quality of negatives produced isdecisive for the accuracy with which the pointcoordinates and parallax will be detemlined.The best results are obtained on sunny cloud-less days. During exposure, the Sun should bebehind or sideways of a surveyor. On cloudydays, it should be observed that the objectsbeing photographed are not shaded byclouds at the instant of exposure. Photo-graphs are made on high-contrast repro-cduction films or plates. ~\

When making the photographic field work,the phototheodolite is set up on one of thebase points so that two of its foot screws arearranged along the direction of a base line. Alifting apparatus with a sighting mark isestablished on the other base point; the footscrews of this apparatus should also be

oriented along the direction of a base line.Photographs are taken by the techniquesincluding the following procedures:

(I) tripods with lifting devices are set up onboth points of a base line, and the elevationof the left-hand base point is measured;

(2) the phototheodolite is then arranged onthe left-hand point, and the sighting mark, onthe right-hand point;

(3) the phototheodolite is oriented onto theright-hand point of the base, and it is checkedthat the camera lens is closed;

(4) a plate-holder (film-holder) is set inplace, and its shutter is withdrawn;

(5) the plate-holder is pressed against thefocal frame of the camera by means of ascrew on the back cover; the serial number ofthe photograph to be taken and the numberof a station are set up on the numerator, andthe kind of photograph (normal or withright- or left-hand deviation) is recorded;

(6) the positions of spirit levels and theorientation of the phototheodolite arechecked;

(7) the correct exposure time is deter-mined;

(B) the plate is exposed, and the positionsof spirit bubbles and phototheodolite orien-tation are checked again;

(9) the holder shutter is closed, and theplate-holder is taken off from the camera;

(10) new photographs are taken irl thisway, with the camera axis shifted first to theleft and then to the right;

(II) the phototheodolite is taken off, and asighting mark is set up in its place; and

(12) the photo theodolite is set up on theright-hand base point to take new photo-graphs as described.

Stereophotogrammetric office work includesthe processing of exposed plates (films) in alaboratory, preparatory work, and the com-pilation of the plans of mining workings.

The preparatory work includes the fol-lowing procedures:

(a) calculation of the geodetic coordinates

10.2. Reference and Survey Nets and Surveying Work

Zphi

al,

rph

ordinates of points of bench crests. Volumesare calculated by means of digital models ortables of positions of benches with theircharacteristic cross-sectional areas. If verticalsections are used (Fig. 10.20), the areas arecalculated by the following formulae:a -" , a -" ,

;,u-Yph;,u-Yph;.u' ;,I-Yph;,I-Yphi,1a; = 0.5 (a;,u + ai,,)

h ' , , h" " "i = Zi,u -Z;,I' ; = Zi,u -Z;,I

h=0.5 (h~+h'~), S.=a.h., , , , ,

and elevations of base points and referencepoints;

(b) preparation of the processing appara-tus; and

(c) preparation to the correction of amodel.

The results of the planimetric and ele-vation surveying of bases and correctingpoints are processed in the office by commongeodetic methods. The most popular one isthe graphometric method with the use ofstereo autographs and other devices operatingby the principle of photogrammetric inter-sections. These devices can solve mechani-cally the formulae for the normal andequi-deviated cases of photogrammetric sur-vey.

The coordinates of the points of a terrainare determined on stereophotographs bymeans of stereocomparators. The operatingprinciple of a stereocomparator reduces tothe reconstruction of the land portion photo-graphed at a particular instant by construc-ting a geometrical model. Each point of themodel is obtained by making intersectionsfrom the ends of the projection base.

The planimetric coordinates of points, xand y, are found graphically in the stereo-autograph and fixed by counters, in mil-limetres, on the scale of a model. The eleva-tions of points are read off, in metres, fromthe altitude counter of the stereoautograph.By combining the stereo autograph with aplotting table (coordinatograph), it is possibleto construct plans and profiles and deliverthe planimetric and height coordinates ofpoints onto a perforated tape or printer.Plotting a plan is started from drawing theelements of hydrography. After that, hori-zontals are plotted. In the plans of moun-tainous regions, plotting horizontals is star-ted from the highest points.

The results of the stereophotogrammetricsurvey of a quarry can be used for calculatingthe volume of mined rock. This can be doneby using the measured photogrammetric co-

256 Ch. 10. Surveying in 01

Fig. 10.21 Taking aerial photograph of terrain

oblique stereophotogrammetry, the opticalaxis of a camera is held at a specified angle tothe vertical.

The planimetric aerial stereophotogram-metry of quarries is carried out from speciallyequipped aeroplanes and helicopters control-led by an on-board electronic computer. Thisensures automatically that the aircraft willfollow very accurately the given survey routeat the specified altitude. The computer alsocalculates the paths of turns and takes intoaccount descending and ascending air cur-rents and the velocity and direction of wind.The equipment of an air-survey aircraft cancontrol automatically the frequency of expo-sures. The brightness of the land surface ismeasured continuously by exposure meters,and the variations of the terrain relief aretraced by locators.

Since aerial photographs are taken from anappreciable altitude, aerophotogrammetriccameras are of the fixed-focus type, i. e.focussed at the infinity. Photographs aremade mostly on a photographic film. A largenumber of photographs (up to 200-300) canbe taken without recharging the camera. Thesize of photographs can be 18 cm x 18 cm or30 cm x 30 cm.

As may be seen from Fig. 10.21 whichshows the scheme of taking an aerial photo-graph of a terrain, an aerial photograph is thecentral projection of the terrain with theprojection centre in a point S.

The distance fc along the perpendiculardrawn from the projection centre S onto theplane of an aerial photograph is ,called themain focal distance (length) of an ~rial pho-tographic camera. The point of intersectionof that perpendicular with the plane of aphotograph (point 0) is the main point of anaerial photograph. The vertical line SN iscalled the photographic altitude (or clearance)(H), and the point where this line intersectsthe plane of a photograph is called thephotographic nadir. The angle OSN (a) isconventionally called the angle of inclination

of a photograph. If this angle is equal to zero,a photograph is called horizontal.

A horizontal photograph of a flat hori-zontal terrain is virtually the plan of thatterrain. The scale of a horizontal photographis equal to the main scale, i. e. 1 : m = fc : H.Aerial photographs with the angle of incli-nation to the horizontal up to 3° are termedplanimetric. With the inclination angles morethan 3°, oblique, or perspective, aerial photo-graphs are obtained.

Before making an aerial photogrammetricsurvey, it is required to make calculations forselecting the survey parameters.

For quarries with the rate of face advan-cement not more than 30 m, the recom-mended scale of an aerial photogrammetricsurvey is l/Ms = 1/10000; if the rate of faceadvancement exceeds 30 m, it is advisable touse the scale l/Ms = 1/15000.

The selected values of l/Ms are then com-pared with its value calculated by theformula:

(10.14)

D

1.4m~---

Ms-(~).

where m~ = 0.02 mm is the root-mean


Table 10.1 ""''M, Maximum J;.

depth of mmquarry, m

Maximum fc,depth of rnrn

quarry, m

15000 up to 300 100

18000 up to 200 100200-300 140300-500 200

'10000 up to 300 100300-400 140400-500 200

.xv

Fig. 10.22 Making two courses of flight for aerialphotography of quarry of intricate configuration

should have a longitudinal (forward) lap (Fig.10.23) which is denoted by p and expressed aspercentage of the side I of a photograph. Thelongitudinal lap can be calculated by theformula:

hp = 62 + 50 ~ (10.15)

2Hph

If parallel courses are plotted, the photo-graphs of adjacent courses should have alateral (side} lap q which is e~pressed aspercentage of the photograph side length andcalculated by the formula:

square displacement of contour in planexpressed on the scale of a photograph;mv/v = 2.5% is the specified accuracy in de-termining the volume of extracted rock; andD is the width of a face.

If it turns out that the survey scale cal-culated by formula (10.14) is larger than thatadopted initially, the aerial survey should becarried out on a larger scale.

The focal length fc of the aerial photo-graphic camera for quarry surveying is cho-sen depending on the selected scale M. andthe depth of the quarry by reference toTable 10.1

The photographic altitude H ph above themedium plane of the quarry is calculated bythe formula:

Hph = fcM.

The photographed materials are processedin stereophotogrammetric apparatus withprojector cameras similar to those used fortaking photographs. The projector camerasand negatives are arranged mutually in thesame positions they had at the instant ofexposure. In this way there is formed aspatial model of the surveyed terrain on areduced scale, which is analysed by means ofa binocular microscope and spatial marks.

For aerial surveys of quarries, a flightcourse for a photoairC!:alt should be plotted.For most quarries, a single course is usuallysufficient. For those of an intricate confi-guration and large dimensions, a number ofcourses are plotted (Fig. 10.22).

Aerial photographs taken along a course

17-1?70

where 1 is the size of a photograph and m isits scale.

An inclination angle of a photograph caus-es the displacements of points on it. Forplanimetric aerial photographs, it can be

Ch. 10. Surveying in Quarries

~Fig. 10.23 Longitudinal and lateral laps of photographs in courses

displacements on aerial photographs (Fig.10.24). Introducing the designations: AAo = his the height difference of a point A above apoint N; SN = H is the photographic alti-tude; aO = r is the distance on an aerial

photograph from a point a to the main pointof a photograph 0; and aao = L\r is thedisplacement of a point on a photograph due

-q-Qo Q

~s

~

taken approximately that the displacementstake place in the direction of a line con-necting a particular point with the mainpoint of the photograph. Depending on thelocation of a point and the inclination angleof the photograph, this displacement can bedirected towards the main point or awayfrom it. The maximum displacement of apoint in planimetric photographs under theeffect of the inclination angle can be deter-mined by the approximate formula (see Fig.10.21):8" = (r2/fc) (a/p) (10.18)

where r is the distance from the given pointto the main point of a photograph; a is theinclination angle of a photograph; andp = 57.3!1.

For instance, the maximum displacementof a point on a photograph withfc = 200 mm,r = 50 mm, and a = 2° will be:

8" = (502/200) (2/57.3) = 0.4 mm

It then follows that the displacements ofpoints on aerial photographs under the effectof the inclination angle are mostly insignifi-cant and in some cases can be neglected.Since the points of the physical surface of theEarth are located at different heights relativeto a level surface, this oauses their different

"AO N

,Fig. 10.24?Determining displacements of pointson aerial photographs owing to the effect of landrelief


S1S2M l' we have:

H1 = Bphfc/P1 (10.20)

This expression can also be written for anyother point on the terrain, say, M 2:

H2 = Bp/c/P2 (10.21)

Since the elevation difference of two pointscan be regarded as the difference of theirdistances, then:

h=H2-H1

Noting expressions (10.20) and (10.21), weobtain:

h = ~ -~ = Bp/c(P1 -P2)

P2 P1 PtP2

Denoting (Pi -Pi+ J by Lip. we can finallywrite:

MOFig. 10.25 Longitudinal parallax and its relationto distance from point on land to photographicbase

h=~(10.22)

Pi+ ~p

On aerial photographs with an inclinationangle or non-horizontal base, Pi and ~P turnout to be distorted. For that reason, beforecalculating the elevation differences, the valu-es of Pi and ~P are corrected for the effect ofthe inclination angle and inclined base line.This problem can be solved analytically orwith the use of photogrammetric devices.

The observations and measurements onaerial photographs are made by a stereosco-pic method. The simplest stereoscopic deviceis a stereoscope in which a left-hand photo-graph is mounted at the left and viewed bythe left eye and the right-hand one is moun-ted at the right and viewed by the right eye.In this method, a direct stereoscopic effect isproduced, i. e. points which are closer to anobserver in nature will be seen closer in astereomodel.

Before the aerial surveys of a quarry, it isrequired to carry out field preparations. Inparticular, each stereoscopic pair should beprovided with four points of planimetric and

to the terrain relief, it may be written that:

Ar = rh/H (10.19)

Experience shows that the distortions inaerial photographs increase with increasingdistance of points from the main point of aphotograph. Thus, in operation with aerialphotographs, it is advisable to utilize only thecentral portion of photographs, which iscalled the useful (working) area, rather thanthe entire area. Practically, the useful area ofa photograph is limited by the lines drawn inthe mid of the longitudinal and lateral lap.

Photographs obtained by aerial stereopho-togrammetry have a longitudinal lap morethan 50%. Thus, each portion of a terrain isdepicted on two photographs. Let the pointM I of the terrain (Fig. 10.25) be representedby a point mI on the left-hand photographand by a point m~ on the right-hand photo-graph. The distances from the photographiccentres to these points are mI O I = xi on theleft-hand photograph and m~O2 = -x.. onthe right-hand on~)The difference xI -x.. == PI is called the lon-gitudinal parallax. Con-sidering similar triangles m~m~S2 and

17.


the ratio of like line sections s and S takenrespectively on the restored and photo-graphed surfaces, i. e. l/m = s/S.

In order to determine the scale of a model,at least two control points should be avail-able. The horizontalization of the modelreduces to determining the angles of turn ofthe model on the corresponding axes x and yof the geodetic system of coordinates.

Thus, for solving the problem of geodeticorientation of the model, it is required tohave at least three control points, all thecoordinates being known for two of them andthe elevation mark, for the third point. Ingeodetic orientation, the plate is also orien-ted. For this purpose, the measuring mark ofthe device is matched with one of referencepoints, and the centre of a focussing micro-scope is set up above the corresponding pointon the plate. The microscope is then sightedonto another reference point, and the plate isturned until the centre of the microscope willbe on the line connecting these points.

10.3. Mine-Surveying Coverageof Drillingand Blasting Work

Mine-surveying servicing (coverage) ofdrilling and blasting work consists in thefollowing:

(a) preparation of the initial materials formaking a plan of blasting operations;

(b) transfer of the blasting plan intonature;

(c) determination of the actual positions ofblasting holes after drilling; and

(d) determination of the volume of blastedrock and the location of worked-out areaafter rock excavation.

A plan of blasting operations is compiledon a scale of 1/1000 or 1/500. Surveys arecarried out for the purpose, which have todetermine the following characteristics: theposition of the upper bench crest; boundariesof the slope fully cleared up by excavation;

elevation control (control points, or beacons),which are usually arranged in places wherethey can be preserved for a long time andused in subsequent aerial surveys. The plani-metric coordinates of the control pointsshould be determined with an accuracy speci-fied for the coordinates of survey net points.The elevation marks of control points aredetermined with the accuracy of technicallevelling.

Aerial photographs are processed for thepurpose of compilation and complementa-tion of mining work plans. This is done inall-purpose stereophotogrammetric devices.Irrespective of the type of device, processingincludes the preparatory work, mutual orien-tation of aerial photographs in the device,and geodetic orientation.

The preparatory work includes the prepa-ration of plates (application of kilometrenetwork and control points), manufacture oftransparencies, preparation of aerial photo-graphs, checking of the device, calculation ofmodel scale, focal lengths of cameras, etc.

The mutual orientation of aerial photo-graphs is essentially the determination of theposition of one photograph in a stereo pairrelative to the other. This procedure can beperformed by various motions depending onthe design of a particular device. For instan-ce, one of the cameras may be considered tobe fixed and forms a stationary basis relativeto which the position of the other camera ismeasured.

The mutual orientation in a stereophoto-grammetric device is carried out by observingsuccessively a number of points on photo-graphs and eliminating their lateral parallax.Though the problem is solved by the methodof successive approximations, the resultingsolution is quite accurate (to the accuracyoffered by the apparatus for the eliminationof lateral parallax).

The geodetic orientation of a geometricalmodel includes its scaling and horizontali-zation. The scaling consists in determining

10.3. Mine-Surveying Coverage of Work 261

(a\

//

/

~ i~, / .., "/ , ~

/ 4

II"""

QJ0.

~I

I~

(b)

't-:

Fig. 10.26 Surveying of bench profile: (a) bymeans of inclinometer; (b) by means of telescopicrod

boundaries of the muck pile left after earlierblasting work; elevations of the characteristicpoints of the upper and lower berms of abench (in intervals not more than 20 m);positions of contact-line supports and rail-way tracks (in quarries with railway trans-port); boundaries of rocks in the massif withdifferent characteristics of drillability andexplosibility; positions of tectonic disturb-ances and characteristics of cleavage cracks;boundaries of a dangerous zone as deter-mined by the rules of blasting work andpositions of buildings and structures nearthat zone.

According to the plan of blasting opera-tions, the design positions of the mouths ofblasting holes are transferred into nature andfixed by pegs with marks indicating thenumber of a hole, the number of a drilling rig,the design depth of a hole, and the soilresistance. In laying out the hole mouths, themine surveyor, as a rule, transfers instrumen-tally into nature only the boundaries of theblock to be blasted and marks them on theupper crest of a bench. The mouths ofblasting holes in a block are marked by ablaster foreman.

The instrumental layout of the mouths ofblasting holes is carried out only in caseswhen the portions to be blasted are located atthe design boundary of a quarry and per"manent access roads are being built. Themain methods for transferring blasting holesinto nature are the polar method and methodof perpendiculars with the use of points of asurveying net. Angles are laid off with anaccuracy not worse than 5'. Distances up to50 m can be measured by means of rangefinders. In the method of perpendiculars,measured distances are rounded off to adecimetre.

If a quarry has high benches of an irregularshape, these should be surveyed properly.

Since, according to safety regulations, staff-men are prohibited to stand on the slopes ofbenches, such slopes should be surveyed by

instruments which can determine the posi-tions of staff points without the presence ofmen on them, for instance, tacheometers,inclinometers (or theodolites) with an at-tachment for measuring inclined distances, atelescopic rod with a tape, etc.

For making a profile survey by an inclino-meter (Fig. lO.26a), the instrument is set upon the upper crest of a bench to measure theinclination angle onto a characteristic point,after which the distance to the sighting point


is measured by a special tape. In order tomeasure a length, a cord with a weight is tiedto the end of the tape and is let to slide alongthe slope of the bench. One of the workersstands on the upper crest and lowers the tapeend with the weight, whereas another worker,standing on the bench foot in a safe place,stretches the cord and the tape so that thetape beginning is matched with the point tobe measured.

Measurements with a telescopic rod aremade in the following manner (Fig. 10.26b).The telescopic rod with a roller at its end isapplied horizontally to the crest and a mea-suring tape with a weight is passed over theroller to the point of interest on the slope.Two coordinates are measured: the horizon-tal distance from the upper crest to the rodend and (on the tape), the vertical distancefrom the rod end to the surface of the slope.

After drilling the blasting holes, the blockto be blasted should be surveyed. The posi-tions of the holes at the flanks of the blockare fixed from the points of a surveying. Thepositions of intermediate holes are deter-mined by measuring the distances betweenthe holes. Besides, it is required to measurethe distances from the holes to the uppercrest and the soil resistance. If the excavatorwork or clear-up work is carried out on thebench after compiling the plan of blastingoperations, an additional survey of the benchshould be carried out. The height marks ofthe mouths of blasting holes are determinedby geometrical levelling.

Having surveyed a prepared blastingblock, the mine survey6r compiles cross sec-tions through blasting holes on a scale of1/500, 1/1000 or 1/2000, which are needed formaking a corrected plan of blasting work.These sections should show the profile of thebench slope, blasting holes, the design andactual level of the bench foot, contacts ofvarious rocks and mineral, and drillabilityand explosibility characteristics of the rocks.It is also required to draw a plan of the

blasting block which should give the blockboundaries, blasting holes, the positions ofthe upper and lower bench crests, rock con-tacts, and the situation on the bench berms.

Mter blasting, the blasted rock is surveyedin order to determine the boundaries of themuck pile, the break line, and several charac-teristic points along the profile lines on thesurface of the muck pile.

10.4. Survey Work for TransportServicing

This work, which occupies an essentialplace in the daily activity of mine surveyorsin quarries with railway transport, includesthe laying out of routes of face railway tracks,periodic profiling of tracks, etc.

In order to obtain initial data for layingout railway tracks, a levelling survey of thebench surface is done after the removal of thefirst strip of the rock from the muck pile. Thissurvey determines the recessed places whichshould be filled with soil and the protrudingones which should be cut off for evening theberm. After that, the railway track axis istransferred onto the working berm of thebench. Two circumstances should be consi-dered in this case: the axis should be laid outso that two bands of an excavator cut can becharged into cars without relaying the rail-way track, and the tracks should not occupythe zone of the muck pile of a next blast.

As the design axis of the railway track istransferred into nature, picket points areestablished along it, and geometric or trigo-nometric levelling is carried out. By theresults of levelling, it is decided to correct thetrack profile in accordance with the permis-sible ruling gradient.

The surveys of permanent railway tracks ina quarry and beyond its boundaries are madeby the method of perpendiculars or polarmethod from the sides of a theodolite tra-verse run along the track axis. These surveyshave to determine: the axis of a track; centres

26310.5. Survey Work in Trenching

30 -3~=--3'{,1-

!':-

O 40 64 4'O

of switches; the top gauge width; the width offilling and grooves at the top and bottom;places for kilometre poles; etc. Track curvesare surveyed by the method of perpendi-culars: chords are drawn between the ends ofa curve and distances to the axis of the curveare measured along perpendiculars to thesechords.

The layout work for the construction ofautomobile roads is carried out by minesurveyors according to the design materialswhich give the gradients, curvature radii,width of roadbed, etc. At the end of roadconstruction, instrumental survey should becarried out in order to check that the actualcharacteristics of the road correspondproperly to the design values.

~~cT 1- .

~o 93 ~/'lc

1?0 ~2

J~

~~

~

..A.-A

I, ~2

"10.5. Survey Work in Trenching

This work is carried out on the basis ofdesign materials which should include: theplan of a trench with the coordinates ofjunction points, direction angles of junctions,angles of turn, distances between the vertexesof turning angles and radii of connectingcurves; longitudinal and transverse sectionsof a trench which should show the profiles ofthe Earth's surface and the design profile ofthe trench bottom, the sequence, cross sec-tions and axes of cuts, and railway and drain-age ditches; the plan of blasting holes withthe coordinates of their mouths, directionangles of hole axes, and hole cross sections.

For laying out a trench on the ground, atheodolite traverse is run. The positions ofupper crests (for trenches to be cut in looserocks) or the positions of blasting holes (forthose to be made in hard rocks) are transfer-red into nature from the sides of that tra-verse.

In making trenches by power shovels with-out blasting work, the following cases ofmine-surveying servicing are possible:

1. A trench is dug in a slope and theextracted rock is dumped downhill

" "

88

Fig. 10.27 Trench digging in slope

(Fig. 10.27). The main task of the mine sur-veyor in this case is to observe that the trenchaxis has a specified gradient.

Initially, the junction point 1 of the trenchaxis is transferred onto the ground accordingto the design coordinates. A theodolite tra-verse is then run according to the preliminarydirection of the trench axis. This direction isfixed by temporary picket points in intervalsof 50-100 m. With the known points of thetrench bottom, points 10' 20, 30, 40 aredetermined in nature; these points form theline along which the plane of the trenchbottom intersects the slope. After that, thecorrected trench axis is laid out (points 1, 2, 3,4) by using the intersection line and thedesign width of the trench. Finally, the linesof the upper crest (points 1", 2",3", 4") and ofthe lower crest (points 2' and 3') are marked


c-c

'/\I'fi~~r#\ I III I /\JrLI-~1

1°°° 1 0°°' i 0 0 0 0 0 072

1000 0001C I c

-.1-0 -0-0- ~-0-o-0-'-- I'

I... ...1

1...t..~1

1...t...1: ... ! ...I IB B

-+ ~.~-81-

>---r

~y

A

A-A

iJ7

Fig. 10.29 Trenching by excavating explosions

Fig. 10.28 Trench cutting with continuous faceand rock loading into railway cars 3. A trench is made by excavating explo-

sions (Fig. 10.29). In this case, the designpositions 2 of the blasting holes are transfer-red into nature by means of theodolite tra-verses or geodetic intersections. After drilling'the blasting holes 1, they are surveyed for thecorrection of the plan of explosions.

Mter blasting, another survey is done todetermine the volume of blasted rock: thenthe axis and side crests of the trench aretransferred into nature, and bench marks areestablished to control the trench footgradient.

on the ground by measuring from the trenchaxls.

2. A trench is cut in a continuous face andthe extracted rock is loaded into transportvehicles on the trench flank (Fig. 10.28) or therock is extracted by drag line and dischargedonto the trench sides.

A theodolite traverse is run as described inthe previous example. The trench axis AB istransferred and fixed in straight portions atdistances up to 50 m and in curved portionsat intervals up to 10 m. At the same time, theaxis of the railway track is laid out on thetrench flank (or the axis of the waste rockdump if the trench is dug by a drag line).During the cutting of the trench, benchmarks are established in intervals of 20-30 m(R1,R2, R3, etc.) which give the elevations ofthe trench foot. The bench marks should bedisplaced from the trench axis so as to be onthe line of one of excavator tracks.

10.6. Survey Workin Open-Cast Miningwith Conveyer Bridges

The specifics of survey work in this caseare associated with the fact that conveyerbridges have a rather intricate design and avery larg~ mass (sometimes more than 7000 t)(Fig. 10.30), that is why high dynamic loadsthat may cause overstressing the bridge el-

10.6. Survey Work in Open-Cast Mining 265

Fig. 10.30 Conveyer bridge: I-facing console truss; 2-facing support; 3-middle truss; 4-dumpingsupport; 5- dumping console truss

ements are inadmissible. This necessitatesadditional survey observations on the trussesand other e,lements of conveyer bridges inorder to preserve their strength. The mine-survey servicing of conveyer bridges consistsin checking the plan position and gradients ofthe railway tracks of bridges and controllingthe horizontal, vertical and angular mobilityof a bridge.

The plan position of tracks is controlled bytheodolite surveying with measuring the spa-cings between the rail lines by a steel tape; thetrack gradient is controlled by geometriclevelling.

The control of horizontal mobility is carriedout in view of the fact that the distancebetween the facing and dumping supports ofa conveyer bridge can be increased or decrea-sed depending on the varying geometry offaces. An increase or decrease of this spacingbeyond the specified limits is however inad-missible. The mine surveyor has to controlperiodically the spacings between the axes ofthe facing and dumping supports. For thispurpose, theodolite traverses are run along ornear the track axes on the working berms ofbenches on which the bridge supports aremoving. The theodolite traverses should al-ways be connected to the points of a re-ference net. A series of profile lines roughlyperpendicular to the mining front are also laidout in a quarry. In each profile, the distancesfrom the sides of the theodolite traverse to

the nearest rail are measured by the methodof perpendiculars and recalculated into thedistances to the support axes. By the resultsof field measurements, the positions of sup-port axes are marked on the mine-surveyingplan which serves as the basis for correctingthe positions of tracks and supports of aconveyer bridge.

The control of vertical mobility of conveyerbridges is done to check that the heightdifference between the supports of a bridgedoes not exceed the specified safety licnit.

The detailed surveys of coQveyer bridgesare carried out for determining their de-formations in order to prevent the appear-ance of dangerous deformation. This workrequires the stoppage of a bridge for a longtime.

In these surveys, points are marked at theintersections of beam axes in each unit of themetal structure of a bridge. The axial line bb'(Fig. 10.31) is fixed at the upper and lowerhorizontal belts of the bridge. A theodolite isthen set up at the edge of the upper beltabove a point 19-b', and the directions onto apoint lI-b (longitudinal axis of the belt) andpoints 19-a' and 19-c' are determined. Inorder to determine the lateral deformationsof the bridge truss, the ordinates from theaxial lines to the centres of units of metalstructures are measured by a millimetre-graduated rule or ordinatometer arrangedperpendicular to the collimation axis of the

266 Ch. 10. Surveying in Ouarries

Top cho

~***~~1918171615141312 A 1110 9 876 54 3210111a a'

-b

b' --c

c'

Axis

Bottom chord

a,19181716151413 12All 10 9876543210111111.

~ ~~~=a~. ---b.c

c

Fig. 10.31 Fixation of axial lines of conveyer bridge for detailed surveys

theodolite. The distances between the pointsalong the collimation axis of the theodoliteare measured by a controlled-tension steeltape. Similarly, the distances in cross sectionsto the extreme points of the belt are de-termined. The results thus obtained are usedfor plotting the actual state of the bridge onthe design plan and listing the deformationsof all units of the upper belt of the main truss.

The horizontal surveying of the lower beltof the main truss is carried out by the methodof ordinates from the sides of a theodolitetraverse run on side ladders along the truss.Measurements are made by controlled-ten-sion steel tapes with an accuracy to a milli-metre. A plan of the lower belt is plotted bythe results of a survey, and the actual posi-tions of structures are marked on it.

10.7. Calculations of Volumesof Extracted OverburdenRock and Mineralin Quarries

ed-out area has a more or less regular shape,and the required accuracy in calculations ofthe volumes of excavator cuts can be ensuredby any method of surveying, includingtacheometry.

2. On some kinds of loose deposits, theworked-out area has an irregular shape, sothat tacheometry cannot ensure the specifiedaccuracy. In such cases it is recommended toemploy the ground stereophotogrammetricsurveymg.

3. In the extraction of igneous and hardro9ks with preliminary loosening to thewidth of one excavator cut, the calculationsof volumes should be carried out by theresults of ground stereophotogrammetric sur-veys or by weighing the mined rock andconsidering its density.

4. If rocks are loosened by multirow blas-ting and the loosened rock is later loaded byseveral excavators, the calculations of vol-umes can only be done by the results ofweighing of the mined rock (of the knowndensity), since other methods are insuffi-ciently accurate.

The determination of volumes by the re-sults of weighing of the mined rock (operativeaccounting) has a number of essential ad-vantages:

(a) the method offers the highest accuracyand can be used with all technologicalschemes of mining;

In mine surveying, the volumes of extrac-ted mineral and overburden rock are calcu-lated by the main plans of mining worklevels. The choice of the best calculationmethod depends on the mining technologyand the surveying method employed.

I. In open-cast mining of loose rocks byconveyer bridges, excavators, etc. the work-

10.7. Calculations of Volumes of Rock and Mineral 267

are established by an instruction so that theerror ay is not greater than IO%.

The ~thod of arithmetic mean is recom-mended for cases when the mining technol-ogy permits the determination of the volumesof the mined rock (recalculated to theundisturbed rock) directly by the results ofbench surveying. The volume of a block iscalculated in that case by the formula:

v= Shm

where S is the area of the base of a figure orsection, m2, and hm is the mean depth of acut, m, or by the formula:

V=~S!h2 m

where Su and SI are the cross-sectional areasat the upper and lower bench crests, m2, andhm is the mean depth of a cut, m.

The mean depth of a cut can be found bythe formula:hm = 1: 2u/nu -1: 2l/nl

where 1: 2u and 1: 21 are the sums of elevationsrespectively at the upper and lower benchcrests and nu and nl are the numbers of staffpoints on these crests.

The method of horizontal sections is ad-visable in cases when bench crests and in-termediate sections are indicated on the planof mining workings. This is usually done bystereophotogrammetric surveying. In thismethod, the total volume is calculated as thesum of volumes of individual horizontallayers.

The areas of horizontal sections are mea-sured by a planimeter or measuring grid ordetermined analytically. Planimetry is carriedout twice, following the contours of sectionsclockwise and counterclockwise. The discre-pancy between the two measurements shouldnot exceed 3% for areas up to 15 cm2 or 2%for larger ones. The final result is taken as thearithmetic mean of the two measurements.Large areas and sections of a regular shape

(b) it provides timely information on thevolumes of mining and stripping work evenfor individual mining teams and for any timeinterval; and

(c) it is possible to control efficiently howfully the transport vehicles are loaded.

The volumes of extracted and blasted over-burden rock and mineral can be calculatedby the method of arithmetic mean, horizontaland vertical sections, volumetric measuringgrid, etc., provided that the 'errors in theirdetermination do not exceed the followingpermissible values.

1. If the volume of the extracted over-burden (mineral) is found directly by sur-veying of benches, the permissible error cry,%, can be calculated by the formula: p

cry = 1500/JV (10.23)p

where V is the volume of the extracted rock(recalculated to the undisturbed rock), m3.

Formula (10.23) is applicable for volumesfrom 20000 m3 to 2000000 m3. For largervolumes, it may be taken that cry = 1 %; for

smaller volumes, the method of surveyingand calculatiO;n of volumes is established byan instruction so that the error cry is not

pgreater than 10%.2. If the volumes of the extracted (blasted)

overburden rock and mineral are determinedin the loosened state and recalculated to thevolume of the undisturbed rock (using theloosening factor), the permissible error cry,

p%, can be found by the formula:

cry = 2200/JV (10.24)p

where V is the volume of the extracted(blasted) rock recalculated to that of theundisturbed rock, m3.

Formula (10.24) is applicable for volumesranging from 45000 m3 to 2200000 m3. Forgreater volumes, it is taken that cry = 1.5%

pand for volumes smaller than 45000 m3, themethod of surveying and volume calculationand the determination of the loosening factor


2

..!:.Q.

~: ~\

-/\\\1:,\

volumes of blasted rock if this is shown on aplan in projections with numerical marks orin cases when a cut has intricate contoursand surface.

The volume of the rock in this method isfound by the formula:

s .n

'\. \ n

sLh,1

vFig. 10.32 Determining mineral reserves byvertical sections where S is the area of the grid base, m 2; n is

the number of bases within the boundaries ofthe contour being measured; and h is thethickness of the layer of extracted (blasted)rock in the centre of each grid base.

The choice of a method for volume cal-culation depends on the shape of the work-ed-out area and muck pile, as well as on themethod of surveying.

In surveying of undisturbed rock, variousmethods can be used for the calculations ofvolumes. With a tacheometric survey whichdetermines the positions of bench crests, themethod of horizontal sections is preferable.With tacheometric surveys carried out once amonth, area measurements should be done

-..on plans plotted on a scale not smaller than~ln-l tlU.L:» .1/1000. If calculations are done once a quar-

ter of a year, plans on a scale 1/2000 can beused.

If surveying is done by ground stereopho-togrammetry, rock volumes can be calculatedby the method of horizontal or that ofvertical sections. In the former case, areas aremeasured by a planimeter. In the method ofvertical sections, areas can be determined by

) analytical or graphoanalytical methods.In the surveys of mined rock in a muck pile\ .I. 2 by a tacheometric method, the volumes can

where I is the spacing between the sections, be calculated by the method of verticalm; S are the areas of intermediate sections, sections; if the muck pile is surveyed bym2; and n is the number of sections. stereophotogrammetry, the method of verti-

The spacings between the sections should cal and that of horizontal sections are ap-be not greater than the distances between the plicable. Recalculation from the volume ofstaff points. loosened rock to that of undisturbed rock is

The method of volumetric measuring grid is done by dividing the measured volume by arecommended for the calculations of the loosening factor.

can be divided into simple geometrical figureswhose elements are measured by a rnilli-metre-graduated rule. Analytical determina-tion of areas is also possible.

The method of vertical sections (Fig. 10.32)is usually employed for calculating the vol-umes of blasted rock surveyed by tacheo-metric methods. The following formulae areused in calculations:

(I) in cases when spacings between thesection planes are different:

SI + S2l S2 + S3lv- +-2 I 2 2

S.-1 +Sn.+

where s 1 and S. are the cross-sectional areasat the boundaries of an extracted cut (block),m2; S2' S3' ..., S.-1 are the areas of inter-mediate sections, m2; and 11,12, 13' ...,1.-1are the spacings between the sections, m;

(2) "in case of equal spacings between the

10.8. Reclamation of Land 269

The calculations of the volume of a muckpile produced by multirow blasting can in-volve certain difficulties, since the looseningfactor of rock may vary within rather widelimits (its average variation may attain 8% oreven more). In such cases, the calculations ofblasted rock and the determination of aloosening factor should be carried out se-parately for each block before and afterblasting.

for blocks exploded onto a cleared-upslope, the mean loosening factor can be foundby the formula:k, = ~/V.n

loosening factor for the first cut, whichshould be determined experimentally.

In the calculation of the volume of the firstcut of a block, a correction (with a plus sign)for the generalization of the slope shape isintroduced:

AV= (O.O3h3 + O.7h) L

where h is the mean height of a slope and L isthe length of a block.

The volumes of subsequent cuts are cal-culated without this correction. The loosen-ing factors for the subsequent cuts aredetermined by considering the factor for thefirst cut, the mean loosening factor of theblock, and the areas of corresponding verticalsections of the first cut and the remainingportion of the block:V" = V"

/ k"

un , 1

k'1 -kl (P' + pI') + k;P', -11

p

where k7 is the loosening factor of the secondand subsequent cuts in a block; k, is the meanloosening factor of the rock; k; is the loos-ening factor of the rock in the fJ.fst cut, and p'and p" are the weights of the looseningfactors, which are taken equal numerically tothe mean areas of vertical sections in the firstand subsequent cuts.

where ~ is the volume of a block in theloosened state and ~n is the volume ofundisturbed rock in a block.

If blasting is done onto an uncleared slope,the volume of undisturbed rock in the blastedblock should be summed with the volume ofthe blasted rock left on the slope from theprevious blasting; the loosening factor of thisrock is taken such as adopted for the cal-culations of the volumes of the last extractedcuts.

Thus, the mean loosening factor is cal-culated by the formula:k. = ~/V'

where J-; is the volume of the loosened rock;V~. = v.. + V~, (here v.. is the volume of theundisturbed rock in the block and V~l is thevolume of the blasted rock remained from theprevious blasting, recalculated to the volumeof the undisturbed rock).

By the resl,llts of surveying before and afterthe extraction of the first excavator cut, it ispossible to calculate the volume of that cutand the mass of rock in it and in theremaining portion of the blasted rock.

The volume of the undisturbed rock in thefirst cut can be found by the formula:V~. = V;/k;

where V; is the volume of rock of the first cutin the loosened state and k; is the mean

10.8. Reclamation of Land

The problem of the restoration of landareas spoiled by opell-cast mining of mineraldeposits is of crucial importance.

A complex of measures aimed at the resto-ration of land on the territories abandonedon opell-cast mining is called land reclama-lion.

Land reclamation can be carried out byengineering, biological and construction tech-mques.

A mining enterprise should carry ellgin"eering reclamation which consists in thepreparation of land territories. freed after


open-cast mining, for biological or constructioncultivation. Engineering reclamation includesthe following operations: preservation of theupper (vegetable) soil layer, levelling ofdumps, construction of drainage networks,chemical melioration of the soil composition,for instance, chalking of acid soils (whenrequired), and covering the levelled surfacewith a layer of fertile soil. The mine-surveying service of a mining enterprise par-ticipates in the engineering reclamation ofland. Mine surveyors have to observe thatthe upper soil layer is removed properly fromthe territory of future quarries and dumps, tocontrol the levelling of worked-out areas anddumps and the covering of prepared areaswith fertile soil.

10.9. Survey Work in Open-CastMining of Placer Deposits

Placer deposits with the bedding depth upto 15 m are worked out, as a rule, byopen-cast mining. Open-cast workings for-med by mechanization means (bulldozer-scraper complexes or excavators) are calledpolygons if their depth is substantially smallerthan the width; deep and narrow workingsare called pits. Valley placers are often minedby dredges.

In open-cast mining of placer deposits,reference nets are usually developed at theperiod of detailed prospecting so as to pro-vide basis for surveys on a scale 1/2000. Inregions not covered by a national referencenet, individual reference nets can be estab-lished by triangulation or trigonometry. Sur-veying nets are developed according to therequirements for land surveys. The points ofa surveying net should be established beyondthe contours of a placer deposit. At leastthree or four permanent points should beprovided per kilometre of the length of adeposit, and these points should lie at distan:-ces not more than 150-200 m from exploringand mining workings.

The design position of workings on theterrain is usually determined by the polarmethod from control points or by tape meas-urements from the nearest exploring wor-kings whose mouths are shown on the plansof mining workings. The elements of layoutwork are determined graphically on plansplotted on a scale 1/1000 or 1/2000.

The positions of workings relative to thesurveying net points should be determined onthe plan with an accuracy not worse than1.6 m. Elevation marks should be determinedwith an accuracy to 0.3 m in valleys with aweakly expressed thalweg (valley floor) or to0.5 of the vertical contour interval in thosewith a pronounced thalweg.

The main objects of mine-survey servicingin open-cast mining of placer deposits are asfollows: the determination of the volumes ofthe mining work performed, control of themining work and of the completeness of sandextraction. For these purposes, mine survey-ors fix on the ground the design contours ofpolygons, hydraulic sections, waste dumps,berms, access roads, and working platformsfor excavating machines; make the surveys ofpqlygons or pits and determine the volumesof stripped turfs and washed sands and minedrock; control the thickness of stripped andundisturbed turfs and the depth of mining;complement mine-surveying plans and sec-tions; determine the reserves, losses and dilu-tion of sands; and compile the documents onthe volumes of stripped and transferred sandsand of mined and washed sands.

The following methods of surveying aremainly employed in open-cast mining ofplacer deposits: surface levelling by a rectan-gular network, ground stereophotogramme-try, tacheometry, and surveys by profile lines.

Surface levelling by a rectangular networkis used for surveying of polygons on per-mafrost placers which are worked out layer-wise with an average thickness of layers 0.5-1.5 m. The surface of polygons is levelledbefore the beginning of the mining work and

27110.9. Survey Work in Open-Cast Mining of Placer Deposits

at the end of each planned period. Thecontours of polygons and sections at theupper and lower crest are usually surveyed bythe polar method from the points of surveycontrol.

Ground stereophotogrammetry is employ-ed for surveying of large polygons when anarea of at least 25 000 m2 can be photo-graphed from a single photographic base.

Tacheometry and method of profile lineshave found use for surveying of pits and alsoof polygons which are deepened by morethan 1.5 m monthly, i. e. when a placer de-posit is being mined by excavators or hyd-raulic machines actually to the entire depthof bedding of loose deposits. The techniquesof tacheometric surveying on placer depositsare the same as elsewhere. Range lines whichare parallel to one another are laid out acrossthe strike of a pit.

In the method of profile lines, the upperand lower crests of the side slopes of a pit arefirst surveyed and plotted on the plan of themining work, after which transverse verticalsections are marked with intervals of20-25 m, the depths in the equidistant pointsof each section are measured, and a sketch ofmeasurements .is drawn.

The survey work in dredging consists es-sentially in surveying of dredge faces and pits,determination of the volume of mined rockand losses, and the dilution of the mineral.The periodicity of face surveying is determi-ned by the accuracy of measurement of thegeometric parameters of dredge pits (poly-gons). For instance, for dredges of moderatecapacity, each third or fifth face should besurveyed, i. e. roughly after every 10 m ofdredge advancement.

Surveying of dredge pits can be performedby one of the following methods.

With the linear method, surveying is done

by the points of the upper unflooded crests ofslopes in a polygon with a smooth surfacerelief where there is the required number ofsurveying net points and control points. Thedistances between the surveyed points andpickets or control points are measured bytapes.

Tacheometric surveying has found appli-cation in all main regions of dredging work.In this method, the line of a lower crest isfixed upon determining the combination ofpoints of the largest depths at the foot of afacing slope. With depths more than 2 m, thepositions of the crests of the facing slope is, asa rule, determined by the position of thecentre of the lower bucket drum as it movesover the facing platform.

On some placer deposits, tacheometricsurveying is used only for determining theposition of the upper crest of a facing slope.The position of the lower crest is drawn onthe plans of the mining work relative to thatof the upper crest considering the specifiedslope angle, which is determined experimen-tally for different depths and lithologic cha-racteristics of loose placer deposits. Thismethod is applicable only in rare cases whenthe flanks of a dredge pit are composed ofrocks quite resistant to caving, so that theface retains its initial configuration during theentire period between measurements.

The mean depth of a dredge face is foundby averaging the measured face depths (depthof digging plus the height of freeboard) or byaveraging the differences of elevation marksof the polygon surface in the upper crestcontour and the bottom of the dredge pit.The depth of digging can be measured by alead-and-line, mechanical depth gauge, echosounder or asdic (sonar). The error in depthmeasurements should not exceed 0.1 m.

Chapter Eleven

Rock Disturbance and Protection

of Surface Structures

force T is counterbalanced by the reaction ofthe rock under the worked-out space, themotion of the same portion (layer) C 1 abovethe worked-out space (i. e. displacement ofthe roof) will take place only under the effectof the normal component. The same rea-soning is true of the overlying layers C2' C3'etc. It then follows that the fracture of theroof rock layers above the worked-out spaceshould occur at the upper and lower boun-dary of the stoping working and propagatealong the normals to the bedding plane.Thus, the displacement angles in this case are13 = 90° -a and y = 90° + a, where a is the

angle of dip of a seam.In 1867, J. von Sparre developed further

the hypothesis of normals, but he supposedthat displacement took place due to thefracture in dangerous sections where the

11.1. Introductory Notes

Underground voids and cavities left onmineral extraction can impair the stability ofenclosing rock and result in the disturbance(displacements) of the rock massif and thesubsidence of the Earth's surface. Examplesof destruction of underground and surfacestructures under the effect of rock distur-bance are quite numerous.

Rock displacements attracted miners' at-tention from the earliest times. In Liege(Belgium), already in the lSth century, col-liery owners were obliged by the local law tomine coal at depths not less than 100 m inorder to minimize the harmful effect of rockdisturbance on municipal buildings. Thescientific studies of the process of rock dis-turbance under the effect of undergroundworkings were started in the first half of the19th century when hypotheses were proposedto explain the laws of rock displacement. In1838, Toilliez expressed an idea that rocklayers above a stopiIig space destroyed alongthe planes perpendicular to the beddingplane. This idea was utilized by Gonot ofBelgium for explaining the destruction ofbuildings in Liege. Later, these ideas weregeneralized into a hypothesis which wascalled the 'rule of normals' and reduced to the

following.The mass of a portion C 1 of the roof above

the worked-out space (Fig. 11.1), denoted byQ, has two pressure components: N which isnormal to the bedding plane and T which isdirected along that plane. Assuming that the nonnalFig. 11.1 Scheme explaining the 'rule

11.1. Introductory Notes 273

confining the subsidence zone relative to thehorizontal becomes equal to the angle ofrepose of 1he rock.

In 1885, H. Fayol published a work whichconfirmed Rziha's hypothesis. According toFayol, rock displacement occurs by the cav-ing mode and involves a zone having theshape of a cupola (dome). By Fayol's assump-tion, the dome retains its stability even whenits end supports have collapsed; this is due tofilling of the dome space by caved-in rock. ByFayol's reckoning, the loosening factor of thecaved-in rock is equal to 1/200. Thus, withthe depth of the mining work equal to 200 m(where m is the thickness of a seam) theextraction of a seam should have no effect onthe surface.

In 1864, J. Goodwin, a British scientist,carried out instrumental observations of SUf-face subsidence on coal fields and determinedthe displacement angles ~ depending on theangle of dip a:

Angle of dipa, 0 10 15 20 24 27 31 40

Displacementangle 13, ° ..73 71 70.5 70 68 67 64

In his experiments, the displacement angle'Y was always equal to 83-85°.

In 1895-97, R. Hausse proposed anotherhypothesis of rock displacement according towhich the mechanical properties of rocks andtheir alternation played an essential part inthe process. He also emphasized the effect of

bending moment was at the maximum. Con-sidering rock layers as beams built in into therock massif at both ends, Sparre derived theformula for the length of a span along whichthe displacement (fracture) of a rock layershould occur:1 = J2kd/D cos a

where 1 is the length of a span; k is thebending strength of rock; d is the thickness ofthe rock layer; D is the mass of the rock layer;and a is the angle of dip of a seam. Sparresupposed also that rock displacement shouldoccur not along the normals to a seam, butalong the lines somewhere between the nor-mals and verticals. Thus, the dangerous sec-tion in the lower portion of the roof shouldprotrude, as it were, from the rock and that inthe upper section should pass through theroof rock (Fig. 11.2).

In 1882, F. Rziha suggested the hypothesisof rock displacement according to which thecaving surface of a roof could be likened to aparaboloid (Fig. 11.3). As caving proceeds,the volume of the rock involved into displa-cement increases. Caving (displacement)comes to an end when the angle a of the lines

18-1270

Fig. 11.3 Scheme to Rziha's hypothesis

274 Ch Rock Disturbance and Protection of Structures

a b

Fig. 11.4 Scheme depicting Hausse's hypothesis Fig. 11.5 Scheme of bisector rule

sidence have been carried out extensively andon a wider scope and have included theproblems of the pressure of rocks and fillingmaterials, specific effects of rock pressure inmines with powered supports, laws of rockpressure in ore deposits. Recent investiga-tions of the mechanism of such dangerouseffects as rock, coal and gas bursts carriedout in a number of countries have providedthe basis for developing effective measures toprevent the dynamic effects of rock pressure.

working systems on the pattern of rockdisplacement.

According to Hausse, the process of rockdisplacement can be represented as follows(Fig. 11.4). A zone abdc forms immediatelyabove the worked-out space, in which rock isdisplaced by caving and bending. Above thatzone, there is another zone, dcef, where onlythe bending of rock layers is observed. Thethickness of the cave-in zone was found to beequal to (30-60) m, where m is the thickness ofthe mined seam.

A large contribution to the advancement ofthe theory of rock displacement was made byA. Goldreich in 1913 when he published amonograph based on his instrumental ob-servations of rock subsidence. He came to aconclusion that the fault fissures in rocks ofthe coal age should have directions governedby the bisector rule (Fig. 11.5), i. e. thedisplacement boundary is a line coincidentwith the bisector of an angle between thenormal to a seam and the vertical. Fortertiary rocks, it was proposed to determinethe angles of displacement by considering theangle of reposee = 45° + p/2

where p is the angle of repose. Further,Goldreich was one of the first to refer to thehorizontal displacements of rocks.

In recent time, the studies of rock sub-

11.2. General Dataon Rock Disturbance

The stressed state that appears after theformation of a cavity in the rock massif (say,upon driving a working) is determined byinitial stress fields. The magnitude and distri-bution of stresses depend substantially on theshape of workings.

At the initial period when a stope workingstill has not been advanced far from the rockmassif, the roof of a deposit is in a relativelystable state, and its bending is insignificant.As however the worked-out space is widened,the amount and rate of roof bending increase,the continuity of rock layers is disturbed,they are stratified, fissures form in the rock,and finally, roof layers cave in into theworked-out space.

With an increase of the dimensions of the

27511.3. Rock Displacement Parameters

(a)

(b) Fall.through

--~~-~1-~=~7 , ., \, ,,

~(',

Fig. 11.6 Pattern of rock displacement aroundstope working: (a) with gently dipping bedding;(b) with steep dipping of seam

According to natural observations, thethickness of the cave-in zone along the nor-mal to a seam in most coal basins does notexceed three- or four-fold thickness of theseam.

The bend zone II which can be observedboth in the overlying roof and underlyingbedrock. Rock deformations in this zoneoccur by the separation of the bent layer intostrata, though the bonds between the in-dividual blocks remain undisturbed. Twoportions are distinguished in the bend zone: afissured portion just above the zone of com-plete caving and the portion above it wherebending takes place without fissuring of therock.

The zone of bearing pressure III which canform in the rock massif near the boundariesof a stope working. Bearing pressure appearsin places near a driven working where theoverlying rock massif becomes unsupported,hangs up, and its weight is redistributed ontothe enclosing rock of the working. The sizeand pattern of the bearing pressure zone inthe overburden rock depend on the extent ofrock hanging at the boundaries of workings,the depth of the mining work, and rockproperties.

The zone of total displacement IV which canform both at the surface and in the rockmass. It is assumed conventionally that thestressed state in this zone is close to thegravitational state.

In working of thick steeply dipping coalseams, the rock at the )ying wall often slidesdown and forms fall-throughs on the surfaceabove seam outcrops.

worked-out space, the zone of rock defor-mations, or displacement zone, becomes lar-ger. At a certain ratio of the dimensions ofthe worked-out space and the depth of themining work, the displacement zone reachesthe Earth's surface.

In the general case, the following zones ofrock deformation around a stope workingcan be distinguished (Fig. 11.6):

The cave-in zone I which is formed im-mediately at the worked-out space. Here,rock layers separate from the massif, disin-tegrate into blocks, and fall into the worked-out space. The thickness of the cave-in zonedepends mainly on the ratio of thicknesses ofrock layers in the roof and seam of extractedmineral, the strength of the roof rock, theworking system employed, and the angle ofdip of the seam.

IS.

11.3. Rock DisplacementParameters

An area of the ground surface affected bythe displacement from the mining work iscalled a displacement trough, or basin. Itusually appears as a plate- or trough-like(seldom cup-shaped) depression of the

Ch. 11. Rock Disturbance and Protection of Structures

(a)

Fig. 11.7 Displacement angles in section acrossstrike: (a) with gently dipping bedding; (b) withsteeply dipping seam

Earth's surface. Of particular interest are thevertical sections through a displacementtrough in which the trough ends are at thefarthest distance from the boundaries of aworking. These sections usually pass throughthe centre of a trough on and across thestrike and are called the main sections of adisplacement trough.

The displacements and deformations of theEarth's surface within a trough are distri-buted non-uniformly. A portion of the displa;,cement trough where the deformations of theground are such that can cause damage tosurface structures is called the hazardousdisplacement zone. Hazardous displacementzones are defined on the Earth's surface byusing displacement angles which are meant asthe exterior angles relative to the worked-outspace, formed in the main vertical sections ofthe displacement trough on and across thestrike by horizontal lines and by lines con-necting the boundaries of the worked-outspace with the boundaries of critical surfacedeformations.

Displacement angles are determined fromthe conditions of complete underworking. Thisis understood as the state of the troughbottom in which further expansion of thearea being worked out does not increase thedisplacement in this portion of the trough.Not all deformations appearing on surfacesubsidence are dangerous for the objectsbeing underworked. The highest deforma-tions of the Earth's surface which still causeno damage to surface structures are called thecritical, or ultimate safe, deformations of sur-face. Though the critical deformations forvarious structures are different, experienceshows however that for the majority ofstructures the following levels of critical de-formations can be taken: 4 x 10-3 for incli-nation, 0.2 x 10-3 for curvature, and2 x 10-3 for expansion. It is distinguishedbetween the displacement angles in bedrocksand sedimentary rocks. For bedrocks, insections across the strike, the displacement

angles in the hanging wall at the lowerboundary of the worked-out space are de-noted by ~ and at the upper boundary, by y(Fig. 11.7a). For steeply dipping bedding, thedangerous zone is determined from the lowerboundary of the worked-out space by thedisplacement angle ~ in the hanging wall andby the angle ~1 in the lying wall (Fig. 11.7b).In sections on the strike, the displacementangles are taken to be the same at both sidesof the worked-out space and denoted by O(Fig. 11.8). For sedimentary rocks, the displa-cement angles are the same in all three~irections and denoted by <p.

Displacement angles depend on the struc-ture of deposits and the physico-mechanicalproperties of rocks and are different forvarious deposits. Their values for coal basinsand principal ore deposits are determined byinstrumental observations.

Boundary angles (~O' Yo' 00, and ~01) arethe angles which are exterior with respect tothe worked-out space and formed on com-plete underworking in the main verticalsections of a displacement trough by ahorizontal line and by lines connecting theboundaries of the worked-out space with the

Fig. 11.8 Displacement angles in section onstrike

11.3. Rock Displacement Parameters 277

(a) ibt

Fig. 11.9 Boundary angles for seams: (a) gently dipping ((J-angle of maximum subsidence); (b) steep

Earth's surface may subside to the samedepth (maximum for the given conditions)over a large area. Further expansion of theworking will not increase the subsidence area,and the latter is then considered to be underthe conditions of complete underworking.Otherwise, underworking is incomplete.

The area of complete underworking isdetermined by means of angles of total displa-cement, i. e. the interior angles relative to theworked-out space, which are formed in thevertical main sections of a displacementtrough by the seam lines and the linesconnecting the boundaries of the worked-outspace with the boundaries of the flat bottomof the trough.

It is distinguished between the angles ofcomplete underworking in sections across thestrike: "' 1 at the dipping end and", 2 at therising end of the worked-out space(Fig. 11.10) and those in sections on thestrike; "' 3 at both sides of the worked-outspace.

\1.1. 0/1

~I~I

boundary points, i. e. the points on theEarth's surface in which subsidence does notexceed the mean error of levelling. In practice,the boundaries of a displacement trough aredefined by points with a subsidence of 15 mmor relative horizontal tensile deformations0.5 x 10-3.

It is distinguished between the boundaryangles in sections across the strike ([30' [301'and y ° in Fig. 11.9) and those in sections onthe strike (00).

Boundary angles depend substantially onthe depth of the mining work, dipping angleof seams, and, rock density.

Boundary angles are used in preliminarycalculations of displacements and deform-ations of the Earth's surface.

With the horizontal bedding of a seam, thecentre of a displacement trough lies above themiddle of the worked-out space. With dip-ping seams, it is shifted from the middle by anangle e (Fig. 11.9a) which is called the angleof maximum subsidence. This angle is mea-sured at the dipping end of a seam in thevertical main section of the displacementtrough across the strike and is formed by ahorizontal line and the line connecting themiddle of the working with the point on thesurface having the maximum subsidence orwith the middle of a plate-shaped displace-ment trough.

If the dimensions of the worked-out spaceare large relative to the bedding depth, the Fig. 11.10 Complete underworking angles

278 Ch. 11. Rock Disturbance and Protection of Structures

(a)

1

Ib)

jc)

The process of rock displacement is oftencharacterized by the coefficient of underwor-king which is understood as the ratio of thelength of a stope working to the minimallength required for complete underworkingof the Earth's surface in the given direction.The coefficients of underworking can bedetermined along the dipping line and on thestrike of a seam.

Denoting, respectively, the actual dimen-sions of a working on the dip and on thestrike by Dl and D2 and the minimal di-mensions for complete underworking by DOland Do2, the coefficient of underworking onthe dip will be nl = Dl/Dol and that on thestrike, n2 = D2/Do2.

An important characteristic of underwor-king is the ratio of the length of a longwall Dto the depth of a mine H at which completeunderworking occurs. It is taken that com-plete underworking takes place at nl :;:?; 1 andn2:;:?; I.

In many cases, rock displacement causesfissures in the trough. The portion of thedisplacement trough in which fissures areobserved is delineated by rupture angles (cav-ing angles), i. e. the exterior angles relative tothe worked-out space, that are formed in thevertical main sections of the displacementtrough by a horizontal line and the linesconnecting the boundaries of the worked-outspace with the nearest surface fissures at thetrough edges (Fig.ll.ll). It is distinguishedbetween the rupture angles in sections across

A 8\=::7 ' \ 82 \

AI ~ --~C

A 81 8

"\\ \ "c ~~

81

A

Fig. 11.12 Deformations: (a) vertical; (b) and(c) r~spectively compressive and tensile horizontaldeformations

the strike (13" and y") and those in sections onthe strike (0").

Surface subsidence (11), i. e. the verticalcomponent of the displacement vector, hasbeen studied much more thoroughly thanother parameters. It is distinguished betweenthe maximum subsidence in complete under-working, 110' and that in incomplete under-working, 11m.

Vertical deformations may arise due tonon-uniform subsidence and are characteriz-ed by inclination, curvature, and radius ofcurvature.

Referring to Fig. 11.12a, points I, 2, 3 arebench marks on the surface before under-Fig. 11.11 Rupture angles

11.3. Rock Displacement Parameters 279

AA 1 be drawn through the point B. It is alsoclear that AlBl is the length of the sectionAB after surface deformation. The relativehorizontal deformation will be:

AB- AlBl CB2E ---

AB-AB -AB

Thus, horizontal deformation (tensile orcompressive) is the elongation or contractionof the initial length of a section related to thislength.

The duration of the displacement processmay be of interest mainly when deciding onthe possibilities of the construction of buil-dings on an underworked area. It is agreed todistinguish three stages of surface subsidence:the initial, active, and attenuating. The initialstage, i. e. that during which deformationinitiates, usually continues to the momentwhen a mine is advanced under a particularobservation point and can be characterizedby the subsidence rate from tenths of amillimetre to 1-1.5 mm per day. The activestage is the period in which the rate ofsubsidence exceeds 50 mm/month on gentlydipping seams or 30 mm/month on steepones. The displacement process is consideredto be finished at that day of observationsafter which the total subsidence during sixmonths does not exceed 30 mm.

The duration of the subsidence processmainly depends on the depth of the miningwork, thickness of seams, and the physico-mechanical properties of rocks.

The path of the motion of surface pointsand the distribution of displacements anddeformations within a displacement troughobey definite regularities. As a mine faceapproaches, the paths of points deviate fromthe vertical towards the face. After the facehas passed beneath the points, their pathsdeviate towards the advancing face. Finally,as the face has been moved sufficiently far,the paths of points become perfectly vertical.

When solving problems associated with theprotection of surface structures, it is essential

working and J', 2', 3' are the same pointsafter underworking; 111' 112' 113 are the sub-sidences of respective bench marks; 11-2' 12-3are the distances between the points beforeunderworking; and ~1' ~2' ~3 are the ho-rizontal displacements of respective benchmarks.

The inclination of an interval on the sur-face is determined relative to the initialposition of that interval. For instance, theinclination of a section 2-3 after underwor-king is expressed by an angle i2-3. In prac-tice, inclination is measured as the differenceof subsidences of extreme points of a sectionrelated to the initial length of the section:

113 -112'2-3 =4-3

The inclinations of adjacent sections in adisplacement trough are in most cases dif-ferent. This non-uniform subsidence gives riseto another kind of vertical deformation, cur-vature. Non-uniform subsidence of the sur-face can be characterized by the difference ofinclination angles of two adjacent sections:

i2-3 -il-2k2 =11-2/2 + 12-3/2

i. e. curvature is the ratio of the difference ofinclinations of two adjacent sections to thehalf-sum of the lengths of these sections.

The radius of curvature is the inverse ofcurvature:R = l/k

Horizontal deformation is one of the mostimportant characteristics of surface subsid-ence. Let us analyse the combined motion oftwo surface points, A and B (Fig. ll.12b). Asa result of displacement, the point A will beshifted to A1 and the point B, to B1. In thecase of the compression of a section AB,vectors AA 1 and BB 1 will be directed as inFig. 11.12b and in the case of tension, as inFig. 11.12c.

Let a line parallel and equal to the vector


~

The last point is the point of the maximumsubsidence, minimum horizontal displace-ment, and maximum contraction. The pointsE and El are the inflection points of asubsidence curve. They are the points towhich the maximum inclination, maximumdisplacement, and zero horizontal deforma-tion are confined. The maximum tension isobserved roughly amid between the inflectionpoints and trough boundary.

With an inclined bedding of seams(Fig. ll.13b), the patterns of these curves aredifferent. With an increase in the angle of dipof seams, a curve 1 becomes more asymmetri-cal on the rise: the point of zero horizontaldisplacement does not coincide with themaximum subsidence point, whereas thepoints E and El become asymmetrical rela-tive to O and O 1. The asymmetry of curvesincreases further with an increasing angle ofdip of seams.

Fig. 11.13 Distribution of surface displacementsand deformations: 1-vertical displacements; 2-horizontal displacements; 3- horizontal deforma-tions

to know the distribution of displacementsand deformations within a displacementtrough. It is usually sufficient to analyse thedistribution of the following elements in atrough: the maximum values of the hori-zontal and vertical components of motion;maximum deformations in the main sectionsof the trough on and across the strike;maximum inclination; maximum curvature;and maxifuum elongation and contraction.

The curves of the distribution of surfacedeformations on a gently dipping seam in asection across the strike are illustrated inFig. 11.13a.

With horizontal and gently dipping seams,the curves of inclinations usually follow thepattern of the curves of horizontal displa-cements. The curves of curvature are similarto the curves of horizontal deformations.

With horizontal (flat) seams, the points ofessential importance, in addition to boundarypoints A and B, are also points E, £1, and 0.

11.4. Factors Responsiblefor Rock Displacement

Physico-mechanical properties of rocks andbedding conditions. The state of rocks islargely responsible for the pattern of displa-cement. For instance, with loose-grainedrocks having a low cohesion, subsidenceproceeds rapidly, appears sharply on thesurface, and often leads to the formation ofledge-shaped fissures. A typical example isthe Moscow district coal basin where, withthe mining work carried out at a depth of40-50 m, the roof subsidence becomes no-ticeable on the surface already in 2 or 3hours. Plastic rocks, such as clay shales,promote plastic deformations, so that rockdisplacement occurs uniformly and smoothlyfollowing the advancement of a mine face; thesurface subsides slowly and does not causelarge damage to surface structures.

The structure of a deposit can influencesubstantially the pattern of displacement.With alternating hard and soft rock strata in

28111.4. Factors Responsible for Rock Displacement

a bed, secondary subsidence can appear inthe mine roof, especially when quickly cavingsoft rocks lie immediately on the roof,whereas the layers (bands) of hard rock areoverlying and hang up periodically over alarge area. Poorly predictable cavings ofthese bands can develop an elevated rockpressure in stope workings and adjacentpreparatory workings and sometimes are thecause of emergencies and rock bursts inmmes.

Quicksands can complicate substantiallythe process of rock displacement. Cases havebeen recorded when quicksands occurring inthe rock massif being underworked causedsharp flattening of displacement angles. Un-derworking of quicksands can involve largewater losses, which can result in surfacesubsidence far ahead of the working face.

The angle of dip of a deposit is among thecritical factors governing the rock displa-cement process qualitatively and quantita-tively. The pattern of displacement of theoverlying rock is closely associated with theangle of dip. With steep angles of dip, sub-stantial shear deformations in displaced rockare quite typical. With horizontal or gentlydipping seams, the main kind of deformationis bending of rock strata. With steep bedding,the horizontal component of a displacementvector is predominant, whereas the verticalcomponent prevails in the rock displacementon flat seams. It is found by observationsthat, under similar conditions, structuresabove workings in seams with steeper anglesof dip suffer from greater deformations. Forinstance, in the Donetsk coal basin, mining ingently dipping seams at a depth of 200-250 mcauses no fissuring on the surface, whereasthe mining work in steep seams, even at adepth of 600 m, can lead to the appearance oflarge rupture cracks on the surface.

An increase in the angle of dip of a depositinvolves a change in the position of a displa-cement trough relative to the worked-outspace, i. e. the trough is shifted towards the

strike. The distribution of hazardous zones ina trough is also associated with the angle ofdip.

A steeply dipping structure of a deposit,sharp changes in the angle of dip, foldedbedding, and the presence of moderate andlarge tectonic disturbances can lead to theappearance of concentrated deformations, fis-sures and ledges in the surface. Depending onthe thickness of seams and bedding depth,these deformations may vary from a fewmillimetres to tens of centimetres and arequite dangerous for surface structures, sincestructures located on ledges then suffer fromsubstantial deformations or even break downif these deformations exceed 20-30 cm.

The sites for the construction of newobjects should, as a rule, be located onnon-underworked territories or on those withfavourable geological conditions. If a needarises to erect new objects in underworkedzones which can cause the appearance oflarge deformations and ledges, protectivemeasures should be taken to increase thestrength and spatial rigidity of buildings andstructures (reinforced-concrete, belts in theunderground portions of buildings, cast-in-situ concrete foundations, reinforced joints,continuous horizontal reinforced-concretebelts at the level of floor ceilings and parti-tions, division of buildings into sections,provision of horizontal sliding joints, etc.).

The construction of new objects on areasabove old stope workings at depths of20-80 m can only be started after preliminarygeological examination to reveal empty ca-vities in the worked-out space. The construc-tion of residential buildings above the zonesof preparatory mining workings at depthsless than 10 m (where m is the height of aworking) is possible only after geologicalexamination for determining the non-cavedportions of workings (voids). In all cases,detected voids should be filled in.

The depth of the mining work can influencesubstantially the magnitude of rock displa-

Ch. 11. Rock Disturbance and Protection of Structures282

cement and the time and rate of its ma-nifestation. With an increase in the miningdepth, the amount of displacement decreasesand the process becomes smoother and lessdangerous for surface structures, though thisis true only to a certain depth. An increase inthe depth of the mining work always in-creases the time of the displacement process.

The thickness of an extracted seam. Com-pared with the depth of the mining work, thethickness of a seam has an inverse effect onthe rock displacement: with a larger thick-ness, the process of displacement is morepronounced and involves higher horizontaland vertical deformations. With an appre-ciable thickness of a seam, the zone ofsmooth sagging can disappear fully, and therock then subsides by caving and with theformation of terraces.

On seams of a small thickness, the rockdisplacement occurs mostly by bending ofstrata. The cave-in zone develops only weak-ly and only in the direct vicinity of theworked-out space.

The presence and thickness of sedimentaryrocks and the surface relief In bed rocks, the.rock displacement occurs so that points ,move almost along the normals to the beddingplane. In sedimentary rocks of an appreciablecapacity, the rock displacement occurs indirections from the edges to the centre of adisplacement trough. In the contacts on therise of a seam, sedimentary rocks and bedrocKs are displaced in opposite directions,which often causes the separation of sedi-mentary layers from the bed rock and thedestruction of underground objects.

The effect of the surface relief on rockdisplacement is appreciable only in moun-tainous regions where underworking of steepslopes often triggers landslides. Rock stabilitydepends substantially on the angle of internalfriction and the cohesion at slip planes. Therock displacement then results in loosening ofthe rock massif and associated reduction ofthe strength properties of rock (mainly of

cohesion), which in turn leads to a loss ofstability of slopes and landslide phenomena.

The disturbance of the rock massif by oldstope workings. Numerous field observationshave demonstrated that the mining work in adisturbed rock massif can activate rock dis-placement by increasing deformations, rates,and non-uniformity of surface subsidence.The activization of rock displacement may bedue to the following factors:

(I) voids formed due to hanging up ofoverlying rock layers during primary un-derworking. Repeated underworking can lar-gely eliminate hang-ups and produce bettercompaction of the disturbed rock massif;

(2) primary underworking decreases thestrength of a rock massif by opening old andforming new fissures. For that reason, rockdisplacement on repeated underworking pro-ceeds at a high rate, since it takes place in therock massif with impaired strength proper-ties.

Working systems. The principal parametersof working systems which can influence rockdisplacement are the height of levels, lengthof a mining field, method of roof control, rateof face advance, and the completeness ofmineral extraction.

The height of a mining level and the lengthof a mining field are equally important, sincethey determine the shape of a displacementtrough. With small dimensions of the work-ed-out space, a cup-shaped trough usuallyforms. With an increase in the space di.mensions, a cup-shaped trough changes to aplate-like form.

The best method of roof control to preventthe surface subsidence is backfilling of theworked-out space. The filling decreases thesize of voids, supports the overlying rock, anddecelerates and decreases to a certain extentthe process of rock displacement.

The effect of filling depends on the fillingmaterial used. Continuous dry filling decreas-es the volume of voids only insufficiently(sometimes only by 40 per cent). Hydraulic

11.5. Monitoring Rock Displacement. Observation Stations 283

filling and hardening filling produce the mostfavourable effect on surface subsidence. Withcarefully packed hardening filling, the surfacesubsidence may be as low as only 3 per centof the seam thickness. In this case, surfacedisplacements are uniform and smooth, sothat even large structures settle down slowlyand without large damage.

With continuous working systems, espe-cially with a large-Iength longwall and com-plete roof caving, surface displacement occurssmoothly and uniformly. With pillar androom-pillar working systems having roofcaving where safety pillars are left at shortintervals in the worked-out space, the overlyingrock massif may be broken by the pillars intoindividual blocks, with fissures propagatingup to the surface and causing largely unevensubsidence.

11.5. MonitoringRock Displacement.Observation Stations

An observation station on the surface is asystem of fixed points (bench marks) placedin the ground or surface structures(Fig. 11.14). Bench marks are usually set upalong the profile lines on and across thestrike of a deposit. In mountainous, woodedand densely built-up areas, broken profilelines are permissible.

When examining the underworking condi-tions for railroads, pipelines and otherstretched objects, the profile lines may bearranged diagonally to the strike. In somecases, say, for monitoring underground gaspipelines, stations may be established as anetwork.

An observation station is set up accordingto the design plan which includes an ex-planatory note and graphical appendices.

The graphical material of the design planshould contain: (a) a joint plan of the landsurface and underground workings with pro-file lines of an observation station (on a scale

1/500, 1/1000 or 1/2000); it should give theboundaries of the mining field, the currentstate of the mining work and its furtherdevelopment, the supposed position of thedisplacement zone, tectonic disturbances, andthe scheme of junction of control points; (b)geological cross sections along the profilelines with indication of the workings; and (c)the designs of control and working benchmarks.

The place for establishing the observationstation is chosen by considering the positionsof mining workings and according to theparticular object of observations. An area ona flat country with few structures and awayfrom haulage tracks and roads is a conve-nient place for an observation station. Usu-ally, two profile lines across the strike andone on the strike are laid out. When workingdeposits with varying geological and miningconditions, the profile lines are laid outseparately on the sections which differ fromone another in the bedding elements, thick-ness of a seam, working system, etc.

The profile line across the strike which isthe closest to undisturbed (intact) rock islocated at a distance not less than 0.85 Hmfrom a breakthrough or the point where theface is stopped (Hm is the mean depth of aworking). If the longwall face has alreadymoved from the breakthrough, the distancefrom the latter to the profile line is found bythe formula:d = Hm cotalloo :;::?; 0.85Hm

The next profile line is laid out at adistance of 50 m from the previous one.

The length of profile lines drawn across thestrike (Fig. ll.l5a) is determined on verticalsections by the boundary displacementangles. Two control bench marks are es-tablished on the continuations of the profilelines beyond the expected displacement zone.The distance from the first control benchmark to the end of the working portion of theprofile line should be not less than 50 m, and


the spacing between the control bench marks,50-100 m depending on local conditions.

The profile line on the strike passesthrough the point of the maximum sub-sidence of a displacement trough. To find thispoint on the vertical section across the strike,a line is drawn at an angle 9 from the middleof the worked-out space up to its intersectionwith the surface.

The length of the profile line on the strikeis found in the following way (Fig. ll.15b).The point where the face will be supposedlystopped is projected onto the surface (pointk). A distance B = Hmcotan 00 is the~ laid off

towards the undisturbed rock massif, and adistance 1.75 Hm, towards the worked-outspace.

Control bench marks are established bythe same rules as for the profile lines acrossthe strike.

Working bench marks are set up along theprofile lines at intervals decided by the depthof the mining work.

Bench marks should be designed so as toensure their stability and preservation for along period; in addition, they should beinexpensive and convenient for establishingand observations. Bench marks for long-term

11.5. Monitoring Rock Displacement. Observation Stations 285

(b)

Fig. 11.15 Determination of length of profile lines: (a) in section across the strike; (b) in section on thestrike

and ordinary stations are made from metaltube sections, studs or rail pieces which areset up below the freezing line and concreted.For temporary stations, they can be madefrom wooden stakes or pegs driven into thesoil. For better preservation, bench marks areoften buried in the ground to a depth of30-40 cm.

Observations. Observations at stations onthe surface include tying (connecting) controlbench marks to an existing reference net,primary observations on the bench marks inhorizontal and vertical planes, and secondaryobservations. The horizontal connection ofcontrol bench marks is carried out by trian-gulation or by closed theodolite traverses. Itis permissible to run a hanging theodolitetraverse, provided that the angles and sidesare measured in the forward and back direc-tion. The permissible relative discrepancy of atheodolite traverse should not exceed 1/2000.The vertical connection of control benchmarks is done from the points and benchmarks of a levelling net by means of geomet-ric levelling with a discrepancy not more than

15 JL, mm (where L is the length of a levelline, m).

Upon connecting a station, it is possible tostart primary and secondary observations. Acomplete set of instrumental observationscontains: the levelling of all bench marks; themeasurements of bench spacings along pro-file lines; determination of the deviations ofworking bench marks from a profile line;surveys of surface fissures with records of thetime of their appearance; and the measure-ments of the deformations of structures.

The first observation at a station is recom-mended to be carried out in 7-10 days aftersetting up of bench marks (if these have beenconcreted) or in 2-3 days for bench marksdriven into the ground. Primary observationsare carried out twice, and the final result isobtained as the arithmetic mean of the twoobservations.

The time intervals between the observa-tions depend on their task. If it is essential toobtain detailed information on rock displa-cement, at least four intermediate observa-tions between the initial and final observa-


...

..:E.~

tion should be made, in time intervals deter-mined by the formula:

t = H/6c

where H is the depth of the mining work atthe lower boundary of a working and c is therate of the face advance, m/day.

During the initial and active stage of rockdisplacement, observations are carried out atleast three times a month and during theattenuation stage, at least once a month.

After checking field measurements, the dis-placements and deformations are calculated,and curves are plotted. Calculations aremade by the formulae:

subsidence:11 = Hn -Hn-l (11.1)

inclination:i = (11n -11n- J/I (11.2)

curvature:k = (in -in- J/lm (11.3)

horizontal displacement:~ = D2 -Dl (11.4)

and horizontal deformation:

E=(ln-In-J/I (11.5)

where 11 is the subsidence of a bench mark;Hn- 1 is the absolute elevation of the benchmark in the previous observation; Hn is theabsolute elevation of the bench mark in thecurrent"observation; i is the inclination of asubsidence curve; k is the curvature of thatcurve; in and in -1 are the inclinations of thecurrent and previous interval; ~ is the hori-zontal displacement; Dl, D2 are the distancesfrom a control bench mark to the givenbench mark in the previous and currentobservation; E is the horizontal deformation;In' In- 1 are the length of intervals in thecurrent and previous observation; and Im isthe half-sum of the lengths of intervals in theprevious and current observation.

The calculated deformations and displace-

11.6. Calculations of Rock Displacement 287

ments of the Earth's surface are tabulated asgiven in Tables 11.1 and 11.2.

11.6. Calculationsof Rock Displacement

An increase in the depth of the miningwork leads to an increase of the zones ofharmful effects on the surface, and therefore,more objects on the surface will be subjectedto these effects and require protection. On theother hand, with an increase in the miningdepth, surface deformations decrease, so thatit becomes possible to underwork even criti-cal structures which could not be underwor-ked when mining was done at higher mininglevels. In densely inhabited areas with multi-storey residential and public buildings andextended networks of gas and water supplyand sewerage systems, underworking requirescomplicated engineering calculations for de-termining the expected deformations anddegree of damage to structures. It is alsoneeded to carry out observations on thesurface subsidence and the state of structuresand control the protective measures and therepairs of damilged buildings.

The existing methods of calculation of rocksubsidence can be divided into the followinggroups: (a) empirical methods; (b) methodsbased on distribution function; and (c) meth-ods based on theoretical models. Empiricalmethods are the most preferable since theyuse the results of direct observations onsubsidence.

Among the empirical methods, the methoddeveloped in this country is quite accurate. Itis used in cases when the roof control iseffected by complete caving of the back-fillingof the worked-out space and is applicablewhen the underworking ratio is Him > 20 forthe angles of dip between 0° and 55° orHim > 15 for the angles larger than 55°.

The underworking ratio is here the ratio ofthe mean mining depth H to the extracted oreffective thickness of a seam, m.

Depending on the completeness of initialdata, it is possible to detennine the expectedor probable displacements and defonnationsof the Earth's surface. The expected displa-cements and defonnations can be calculatedwhen the calendar plans of the mining workdevelopment are available and the probableones, when there are no such plans. In thecalculations of the expected displacementsand defonnations of the Earth's surface, thefollowing characteristics are detennined: sub-sidence 11, horizontal displacements ~, incli-nations i, curvature k and curvature radius R,horizontal defonnations E, and displacementsand defonnations caused by rock motionalong the bedding.

If the angle of dip a is smaller than thelimiting value a" the expected displacementsand defonnations are detennined by thecalculation method for the conditions whenthere is no rock motion at the lying wall. Ifthe angle of dip is equal to or greater than thelimiting value, the calculation method consi-ders rock motion at the lying wall. Thelimiting angle of dip of a seam, a" is the angleat which dangerous displacements of rock atthe lying wall can appear. ,

The calculation of displacements and de-fonnations is started from constructing thegeological sections on and across the strike,in which sedimentary and bed rocks shouldbe indicated. These sections should also showthe driven and projected workings (with thedates of driving), the depth of the miningwork, and the dimensions of workings andpillars. The extracted thickness m of a seam isdetennined as the total sum of the thicknes-ses of layers of coal and enclosing rockextracted from the stope workings. Withback-filling of the worked-out space, thecalculation of displacements and defonna-tions is carried out by considering the effec-tive thickness of the seam:

mer=(hc+hin)(I-BJ+Blm (11.6)

where hc is the convergence of the roof and

Ch. 11. Rock Disturbance and Protection of Structures288

Table 11.2

Bench mark Interval length, m

No.

Subsidence Inclination Inclination Curvature Radius of Subsidence Inclinationdifference of i difference k, l/m curvature difference of iinterval ends, R. m interval ends,

mm mm

0O

+3+4+8+8+4

+23+45+73

+136

156.2629.893

10.03110.00210.13410.0629.9519.9439.972

10.051

0++

+++++++

+0.1-0.1+0.1

0.0+0.1

0.00.0

+0.3-0.4

0.03-0.01+0.01

0.00+0.01

0.000.00

+0.03-0.04

+33.3

-100

+100

++++++++

+1

+1O

+1+1+2+2+2+5+1

23456789

10

+100

+33.3-25.0

floor before back-filling (if there are noobservation data and the face is advanced by8-20 m ahead of the filling, hc is taken equalto 0.15 m); hin is the incompleteness of filling(mean distance from the top of a filling massifto the roof of a seam), which is determinedexperimentally; m is the extracted thickness ofa seam; and B 1 is the shrinkage factor offilling whose values are given below:

Hydraulic filling: B1sand. 0.05-0.15crushed rock. .0.15-0.30

Pneumatic filling 0.25-0.40Gravity-f1ow fil-ling:

crushed rock. .0.25-0.45ordinary rock. .0.35-0.50

In the calculations of displacements anddeformations, it is essential to consider theinfluence of all projected stope workings andof those driven earlier, which can activate thedisplacement process in the given section.

The maximum subsidence of the Earth'ssurface is found by the formula:

llm = qomcosaNllN2 (11.7)

~ F( 1zx,

L3

for a half-trough on the dip:

°

0.1

0.1

°

0.1

0.1

0.2

0.2

0.2

0.5

0.1

0.30.40.80.80.42.34.50.733.5

where qo is the relative maximum subsidence;m is the extracted thickness of a seam; a is theangle of dip of a seam; and N 1 and N 2 are thefactors depending on the ratio of the designlength of a longwall Dd to the mean miningdepth H,

T he subsidence of the Earth's surface in thepdints of the main sections of a displacementtrough is determined by the formula:Tl(x, y) = TlmS(z) (11,8)

where S(Z) is the function of a typical subsi-dence curve, which depends on coefficient N 1and N 2'

The inclinations in the main sections of adisplacement trough are determined by thefollowing formulae:

for a half-trough on the strike:

11.6. Calculations of Rock Displacement 289

lst-4th observations

Inclination Curvature k. Radius of cur- Subsidencedifference I/m vature R. difference of

m interval ends,mm

Inclination i Inclination Curvature k,difference I/m

Radius of

curvature R,m

0

+6+9

+10+9

+13+27+57+79

+163

0+0.3+0.1+0.4

0.0-0.4+1.9+2.1+2.8+5.2

+0.01+0.01+0.04

0.0-0.04+0.19+0.21+0.28+0.52

+ 100.0

+ 100.0

+25.0

-25.0

+52.5

+47.5

+35.7

+19.2

+0.6+0.3+0.1-0.1+0.4+1.5+2.6+2.5+3.5

+0.02+0.03+0.01-0.01+0.04+0.15+0.28+9.25+0.85

+I-I+++++

+0.6+0.9+1.0+0.9+1.3+2.8+5.4+7.9

+16.4

T he horizontal displacements of the pointsin the main sections of a displacement troughare found as follows:


fox = O.5ao1lmF'(zx) (11.15)


f,yl = O.5ao Tlm F'(zyJ (11.16)

and for a half-trough on the rise:

~y2 = O.5ao Tlm F'(Zy2) (11.17)

where the factor ao is the relative maximumhorizontal displacement and functions F'(zx),F'(zyJ, and F'(zyJ are the same as in formu-lae (11.12)-(11.14).

The horizontal deformations (tensile andcompressive) in the main sections of a displa-cement trough are determined by the for-mulae:


1lmF'(zx) (11.18)" = O.5ao -Lx 3

19-1270

50.033.300.000.025.067.538.540.011.8

290 Ch.1 Rock Disturbance and Protection of Structures


~ F'(zyJEyl = O.5aoLl

and for a half-trough on the rise

of surface structures will be discussed below.I. Mining measures may consist in (a) the

(11.19) protection of structures by back-filling of theworked-out space and (b) the application ofspecial methods of mineral extraction, whichensure proper safety of surface structures.

E = 0.5a ~ F'(z ) (11.20) Among these methods, it is worth to mentiony2 O L2 y2 the following: (a) extraction sections are plan-

ned so that the surface structures turn out tobe on the portions of a displacement troughwhere earth subsidence is the most uniform;(b) a stope face is advanced continuously and

.quickly so as to minimize the time of influen-11.7. sMe;sure;t for tProtectIng ce of the stope working on surface structures;ur ace ruc ures and (c) mineral is extracted at both sides of a

The problems of the protection of buil- breakthrough which is located under thedings and structures against harmful effects centre of a surface structure, etc.of underground mining have become crucial One of the most efficient methods ofin recent time, especially in large coal fields structure protection is the provision of stripwhere underworking of buildings leads either pillars having a large strength margin andto a substantial increase of the cost of mining spaced at intervals which ensure proper sta-(owing to expensive additional measures for bility of the roof. The essence of the methodthe protection of buildings) or to large losses consists in the following: ~s the intermediateof coal in safety pillars. chamber pillars, which are left between the

The conditions of safe mining are determi- barrier pillars, are destroyed, the caving pro-ned by using the concepts of permissible cess is localized in the space confined betweendeformations and ultimate deformations. the. barrier pillars. In that case, the overlying

Permissible deformations are taken as the rock will cave in only within the equilibriumdeformations of the Earth's surface which dome, whereas the rock massif above itcause only repairable damage to surface remains undisturbed.structure. Ultimate deformations of the Earth's 2. Construction measures decrease the stres-surface are understood as the ultimate limit ses and deformations in structures and buil-for deformations; any deformations above dings and increase the load-carrying capacity,this limit"Will be dangerous for the stability of but do not exclude the appearance of finebuildings and structures and the life of people. fissures in walls, foundations, and floors. The

For determining the conditions of safe principal construction measures for minimi-underworking of objects above a single seam zing the deformations of structure are asor the first seam of a suite, it has been follows:proposed to use the concept of safe mining (a) settlement joints by which long buil-depth which is understood as the depth dings are divided into sections of a suitablebelow which mining operations cannot cause size and closed contour. Settlement joints arein structures the deformations exceeding the arranged near internal partition walls. Theirpermissible ones. At mining levels below the thickness should be such that the buildingsafe depth, the mining work can be carried sections can settle down independently underout without taking protective measures. the effect of underworking. It is recommen-

The principal measures for the protection ded to divide a building by settlement joints

where functions F'(zx), F'(Zyl)' and F'(Zy2) arethe same as in formulae (11.12)-(11.17).

11.8. Construction of Safety Pillars 291

to its entire height (except for the founda-tion);

(b) yieldable foundations which absorb thehorizontal stresses in buildings. This is achie-ved by providing a horizontal joint to sepa-rate the underground portion of a buildingfrom the foundation; the joint is filled with amaterial having a low coefficient of friction;

(c) foundation plates. The idea consists inthat a reinforced-concrete plate is laid ontothe levelled and compacted soil surface. Theplate is cut through by diagonal joints filledwith an elastic material. A layer of wet sandup to 5 cm thick is laid on the plate andabove it another plate (without joints) isplaced on which the building will be erected.

Effective protection of buildings againstthe effect of underworking is provided bycompensating ditches dug in the groundalong a building; they diminish horizontaldeformations by 33-50 per cent. The bottomof a ditch is made somewhat lower (around50 cm) than the foundation foot. Compensa-tion ditches are filled with corrugated steel,fine coke or a mixture of soil and sawdust.

3. Safety (protective) pillars are left in theworked-out area of mines. This method isresorted to when other protective measuresare inefficient or too expensive.

11 .8. Constructionof Safety Pillars

Safety pillars can be constructed by themethod of vertical sections or method of

perpendiculars.

11.8.1. Method of Vertical Sections

Let us consider two examples of the appli-cation of this method: construction of safetypillars for a building and for an extendedobject.

Example 1. It is required to construct asafety pillar for a four-storey brickwork

19.

building of a rectangular form 28 x 45 m inplan (Fig. 11.16) and arranged diagonally (at45°) to the strike of a seam. Another seam, 11,of a thickness m = 0.9 m and an angle of dipa = 30°, lies under the seam mentioned. Thethickness of sedimentary rock is 25 m. Thedisplacement angles are: <p in sedimentaryrock and 13, y, and O in bed rock. The width ofa safety berm, which depends on the type ofbuilding to be protected, is taken equal to15 m in the case considered.

The construction of the pillar is started bydrawing lines parallel and perpendicular tothe seam strike through the corner points 1,2, 3, 4 of the building. A berm 15 m wide isplotted around the rectangle thus obtained.This gives another rectangle, ABCD. A verti-cal section across the strike is plotted, andthe corner points of the building and bermare projected onto it. Lines are drawn throughpoints A (B) and D (C) in the sedimentaryrock at the displacement angle <p up to thecontact with the bed rock. Lines are drawnin the bed rock through points K 1 and K 2thus obtained, at the angle yon the dip andthe angle 13, on the rise.

The boundaries of the pillar on the dip sideare points a and b which are the points of theintersection of the seam with the line drawnat the angle y; on the rise side, the boundarypoints are c and d obtained by the intersec-tion of the "line drawn at the angle 13 to theseam line.

A vertical section on the strike is thenconstructed, and the corner points of theberm, B (C) and A (D) are projected onto it.Lines are drawn in the sedimentary rockthrough these points at the angle <p up to theintersection with the bed rock, which givespoints K3 and K4, after which lines at theinclination angle O are drawn through thesepoints. The intersections of these lines withthe lines of the upper and lower boundary ofthe pillar determine the pillar dimensions inthe section on the strike.

Upon the construction of the vertical sec-

2004080mI I I I I I I

a

Fig. 11.16 Construction of safety pillar for building by method of vertical sections

the bed rock on the dip. The two latter anglescan be found from the formulae:

cotanf3' = Jcotan2f3 cos2e + cotan2o sin2e

cotany' = Jcotan2y cos2e + cotan2o sin2e

where 13, y, and O are the displacement anglesin the main sections of a displacement troughfor the given seam and e is the acute anglebetween the strike line of the seam and thecontour of the object to be protected.

The boundaries of the safety pillar aredetermined by plotting a number of verticalsections perpendicular to the railway line inthe characteristic points of the protected area(1-2, 3-4,5-6, 7-8, and 9-10). In these sections,the traces of protected planes are drawn fromthe berms in the sedimentary rock at thedisplacement angle <p and then in the bed

tions of the pillar, the plan contours of thepillar are determined (abcd).

The reserve of coal in the pillar is calcula-ted by multiplying the seam thickness by thetotal area of the pillar.

Example 2. It is required to construct asafety pillar for a railway bed in a brown coalfield (Fig. 11.17). The railway bed is arrangeddiagonally to the seam strike. The seamthickness is 1.3 m and the angle of dip, 25°.The overlying bed rock is represented by clayshales, argillites, and aleurolites. The thick-ness of sediments is 20 m. The displacementangles are: ~ = 47°, y = 65°, O = 65°, and<p = 45°.

For objects extended diagonally to thestrike, safety pillars are constructed by thedisplacement angles: <p in the sedimentaryrock, ~' in the bed rock on the rise, and y' in

11.8. Construction of Safety Pillars 293

9-10

10 ~o 9 ~

47~ ~5°

5-6 3-4~ 45O 4 ° 5 4 45° -45° 3

-I 0° 50 ~6O -,- 65°-, I I I II I, I

I

1-2

7-8

//

? ~o-- --8 --

---

--~~~.6

-45"2 45°

W

400 --

375 -~

350 --

325 -

300.r-I

~

/

~~-225

3-4

!1 Section No.1 6113'11'11-2 '~1561651

Fig. 11.17 Construction of safety pillar for extended object by method of vertical sections

rock at displacement angles J3i and yi. Thebedding deptb of the seam under the railwaybed is determined as the difference of eleva-tions between the Earth's surface and theseam foot. This depth is laid off in thesections, and the line of the seam is drawn atan angle ai through the points thus obtained.

The angle of dip of the seam ,in the sectionplane is determined graphically. The pointsobtained by the intersection of seam traceswith protection planes are transferred ontothe plan where straight lines or smoothcurves are drawn to determine the contoursof the pillar.

Seam outcrop to overburden

1~<)6

250~

2

" .',/ ",---

278~200 -

"~--~-'2'

280~150- --

""

100

Fig. 11.18 Construction of safety pillar by method of perpendiculars


11.8.2. Method of Perpendiculars

In this method, the boundaries of a pillarare obtained directly on a plan, i. e. withoutplotting vertical sections. The lengths ofperpendiculars are determined by the for-mulae:

the seam foot; a is the angle of dip "of theseam; M is the thickness of the sedimentaryrock; and 13' and y' are the displacementangles.

Consider, as an example, the constructionof a safety pillar for a railway bed passingdiagonally to the strike (Fig. 11.18). Pointsare chosen in the characteristic places of theprotected area and perpendiculars are drawnin these points to the contour of a safetyberm. The corresponding lengths q and 1 arelaid off along the perpendiculars. Points 1, 2,3, J', 2', and 3' are connected by lines whichdefine the boundaries of the safety pillar. Thecoal reserve in the pillar is then calculated.

(H -M) cotan [3'q=

1 + cotan [3' tan 11 cos e

(H -M) cotan y'I=

1 -cotan y' tan 11 cos e

where q is the length of perpendiculars to therise; I is the length of perpendiculars to thedip; H is the depth from the Earth's surface to

Chapter Twelve

Stability of Quarry Flanks

12.1 Principal Causes and Kindsof Rock Deformation

Rock displacements in open-cast mining ofminerals determine to a large extent themining economics and labour safety.

The loss of stability (displacement) offlanks and benches in quarries is mainlyassociated with changes in the stressed stateof the undisturbed rock massif, which can becaused by open-cast mining.

In this process, the destruction of rockmainly occurs under the action of tangentialstresses which under particular conditionscan induce irreversible shear deformations inthe rock massif along the surfaces called slipplanes.

The studies of the patterns of stressed statein quarry flanks demonstrate that in thegeneral case the distribution of shear stressesin a rock massif weakened by a side cut (suchas a flank) may be represented by stressdiagrams like those shown in Fig. 12.1 (lines1-1, 11-11, and 111-111). The points of themaximum shear stresses, which are located atdifferent heights of the flank, form the direc-tion of the weakest plane abcde. In the case ofultimate stresses, this plane becomes a slipplane. A slip plane of this kind mainlycorresponds to a homogeneous (isotropic)rock massif. If the massif has anisotropicplanes (bedding planes, jointing systems,tectonic disturbances, etc.), the position of aslip plane changes and in some cases may becoincident with the planes of anisotropy.

The whole diversity of rock deformations

in quarry flanks can be divided into fiveprincipal kinds: taluses, downfalls, landslides,subsidences, and mud-streams {mud-flows).

A talus takes place when small volumes ofloose rock roll gradually from the top of aslope to its bottom. This can occur when theangle of a slope is steeper than the angle ofinternal friction of loose rock, and the latterhas practically no internal cohesion.

A downfall is essentially quick movementof rock masses along slip surfaces, such assurfaces weakened by geological disturbancesor fissures. These surfaces may be plane orcurved, in the latter case, mostly circular-cy-lindrical.

In order to prevent downfalls, .quarryflanks and benches are designed by conside-ring the specific characteristics of the rockmassif or by providing artificial measures forincreasing the rock stability.

Landslides are characterized by that themotion of rocks occurs slowly, the processmay continue for a long time and entrainslarge masses of rock. The moving rock massifin a landslide is subjected to plastic deforma-tions. Both bed rocks and rocks of wastedumps may be involved into the process.

A subsidence is essentially a vertical sinkingof loose rock masses at the edges of flanks,which occurs without forming a continuousslip surface. Landslides can occur on compac-tion of loose rocks in waste dumps, which arestrengthened on wetting; on saturation ofhigh-porous sediments with water; or in caseswhen there are soft plastic layers in the baseof waste dumps.

296 Ch. 12. Stability of Ouarry Flanks

Mud-streams (mud-flows) can occur insome rocks whose state changes from solid tofluid on water saturation. Mud-streams areobserved most often upon saturation of looseand high-porous sedimentary rocks (loesses,loess-like loams, etc.) or when sands arecarried off from sediments by filtering waterflows. Mud-streams can be prevented bydrainage.

straight section mn to the an axis is called theangle of internal friction and the tangent ofthat angle is the coefficient of internal friction.A section OA describes the ultimate tensilestrength of the rock, at' and a section OD isnumerically equal to the ultimate compres-sive strength ac.

In the general form the equation of thecurve of ultimate equilibrium is 't = f(an) andcan be described by a parabola, cycloid or astraight line depending on the kind of rock. Alinear equation of equilibrium (Fig. 12.2b) hasthe form:'t = an tanp + k (12.1)

where 't is the tangential stress in a shearplane, MPa; an is the normal stress in thatplane, MPa; p is the angle of internal frictionof the rock, degrees; and k is the coefficient ofcohesion of the rock, MPa. The curves ofultimate equilibrium are plotted by the re-sults of shear tests of rock specimens.

A real rock is essentially a complex me-dium possessing a certain non-uniformity(anisotropy) of properties. The main factorresponsible for anisotropy is the structure ofa rock massif, in particular, various planes ofweakness (bedding and stratification planes,fissures, etc.). Because of anisotropy, the laws

12.2. Factors AffectingFlank Stability

The stability of quarry flanks depends onthe correlation between the forces that tendto retain a slope and those which displace it.These forGes can be influenced by manyfactors.

The determination of the stable angles ofinclination of quarry flanks (slopes) is essen-tially a problem of the theory of ultimateequilibrium according to which the strengthof a rock can be characterized by a certaincurve plotted in coordinates t, O"n (shear andnormal stress), see Fig. l2.2a. A curve ARC inthe figure determines the ultimate state of therock in a specimen. A section OB' cut off bythe curve on the t axis determines thecohesion. The angle of inclination of a

12.2. Factors Affecting Flank Stability 297

Fig. 12.2 Strength certificate: (a) with curvilinear envelope of Mohr's circles; (b) with straight envelope

tests of rock specimens. The angles of inter-nal friction for selected rocks are given inTable 12.1.

The angles of internal friction at contactsof layers are taken equal to the angle offriction obtained by the results of laboratorytests for friction on these surfaces. The anglesof friction obtained in tests at contacts oflayers and fissures are given in Table 12.2.

The mechanical properties of rocks in amassif (especially cohesion) not only differfrom those in specimens, but are variable anddepend substantially on the size ratio of theobject being deformed, dimensions of struc-tural blocks, and the strength of rock inspecImens.

During their formation and especially afterthe formation, rock massifs were subjected to

T

of geometrical similarity which are true forisotropic solids (metals, plastics, etc.) areinapplicable to rock massifs. For that reason,the mechanical properties of a rock massifmay differ from those obtained by testingrock specimens.

The properties of rocks in a massif aredetermined by special tests of rock prismsdelineated in their natural bedding and orien-ted in a definite way relative to the planes ofanisotropy. Forces p applied to a prism aredeveloped by ,powerful jacks (Fig. 12.3).

A prism usually breaks along a certainsurface ab. The knowledge of the position ofthis plane makes it possible to determine thestrength characteristics of a rock massif.Experiments have shown that among the twoparameters characterizing the shear strength(cohesion and angle of internal friction), co-hesion is subject to larger variations. There-fore, taking a particular value of friction bythe results of laboratory tests of rock speci-mens, it is possible to determine the cohesionin the rock massif by considering that theresultant force of external pressure p can beresolved into a normal component N and atangential component 1:

If slip surfaces do not coincide with theplanes of contact between rock layers in amassif, the angle of internal friction can betaken equal to the angle determined in shear Fig. 12.3 Diagram of natural shear tests of priSJ

298 Ch. 12. Stability of Quarry Flanks

Table 12.1

Rock Angle of inter- Angle of re-nal friction in pose, degreeslumps, degrees

3633

27-303429

34-3634-3634-3633-3533-35

33-3536

SandstonesAleurolitesArgillitesLimestonesMetamorphic schistsQuartz-porphyries and

granodiorite porphy-ries

Syenites and porphy-ries

35 35

proceed from considering individual struc-tural blocks.

Plastic deformations of rocks are charac-terized by the appearance of two conjugatesystems of fissures which, in the case of anisotropic medium, make an angle <p = 45° --p/2 to the main active force. In the case offissured rocks, however, slip surfaces canpartially propagate along the existing planesof weakness, i. e. the massif breaks through atthe existing surfaces. In deformations invol-ving large masses of rock (such as landslides)a slip zone is formed, rather than a slipsurface, and involves a number of structuralblocks. The displacements of these blocks inthe zone can occur both by slip and byrotation.

In the destruction of a rock massif, itsstructural blocks are also destroyed to someor other extent depending on the size ofblocks (smaller blocks are less subject todestruction) and their strength (weakerblocks are more probable to be destroyed).Various coefficients of structural weakeninghave been proposed to account for the effectof structural blocks on the strength proper-ties of rock massifs. The cohesion of a rockmassif in a direction not coincident with theplanes of weakness can be determined by the

various changes and transformationswhich were associated with the appearance ofrupture cracks, cleavages, stratification pla-nes, etc. These surfaces divide rock massifsinto individual polyhedrons or structuralblocks which are essentially the elementarystructural particles from which a rock massifis composed. In deformations of large rockmassifs, structural blocks can be likened tomineral grains in small specimens subjectedto deformations.

Thus, for the estimation of the strengthproperties of rock massifs, it is essential to

Table 12.2

28-31 24-28 22-27 20-26

25-28 20-23 17-20

24-27

23-26

23-25

23-25

21-23

20-22

20-22

18-20

13-15

16-19

15-18

9-12

Porphyries, hornfelses, jaspilites, strong sand-stones

Secondary quartzites, granodiorites, quartz-por-phyries, granodiorite porphyries, skarnated rocks,syenites, diorites, aleurolites

Limestones, metamorphic schists, magnetites

Clay shales, argillites

Phyllites, talcochlorite and sericitic schists

12.2. Factors Affecting Flank Stability 299

Table 12.3 (after G. Fisenko)

Rock group Cohesion in lumps, CoefficientMPa a

Rocks and type of jointing

III 0.4-0.9 0.5

3.0-8.0

10,0-15.015.0-17.017.0-20.0

20.0-30.030.020.0

3345

67

10

Weakly compacted and weakly fissured sand-clay sediments;strongly weathered, fully kaolinized igneous rocks; compactedsand-clay sediments with normal jointing

Strongly kaolinized igneous sand-clay rocks; compacted sand-clay rocks with developed diagonal jointing; moderate-strength laminated rocks mostly with normaljointing

Hard rocks mostly with normal jointing

Hard igneous rocks with developed diagonal jointing

following fornlula suggested by G. Fisenko:

kk = sp (12.2)m 1 + a In(H//)

where km and ksp are the coefficients ofcohesion of the rock in a massif and aspecimen, MPa; a is coefficient which can befound in Table 12.3; and H/l is the ratio ofthe flank height to the mean size of structuralblocks delinea~ed by fissures.

Thus, for estimating the mechanical pro-perties of rocks in massifs, it is essential toknow the specific features of their jointing, inparticular, the primary and secondary systemof joints Uoint sets), contribution of eachsystem to the total quantity of fissures,spatial angles between the systems of joints,intensity of jointing, patterns of distributionof fissures in the quarry field, and the signifi-cance of each jointing system in the structureof a deposit and the stability of slopes.

The field observations of jointing are car-ried out on natural and artificial rock out-crops and in exploring and drainage wor-kings. The density of sections for the meas-urements of jointing and their mutual ar-rangement are deternlined by the geologicalstructure of a deposit or quarry field. Mea-suring sections should be located so that the

entire complex of rocks and all structuralelements of a deposit is involved into exami-nation. In rock massifs divided into blocks bygeological disturbances, each blockshould have one or two measuring sections.With a simple structure of a deposit orquarry field, measuring sections can be spa-ced at distances of 150-200 m from oneanother. In each measuring section, there aredetermined the bedding elements of all join-ting systems, elements of stratification andfoliation, linear dimensions of individual fis-sures, distances between the fissures in eachjointing system, pattern of fissure surface, andthe shape and size of structural blocks.

The bedding elements of fissures are mea-sured by an inclinatorium. The total numberof measurements of bedding elements on anarea depends on the number of jointingsystems and the pattern of surface of fissures.As a general rule, 15-20 measurements ofbedding elements should be made for eachjointing system. With a large discrepancybetween the measured results, the number ofmeasurements should be increased up to 30.

Office work consists in determining thetypical orientations of fissures and the inten-sity {density) of jointing. The elements offissure orientation in space can be measuredmost conveniently by means of stereographic


ation the climatic factors: atmospheric preci-pitation, local temperature conditions, micro-relief, and wind velocity. Without properdrainage, atmospheric precipitation cancause the inundation of sand-clay rocks to astate when capillary water changes to gravi-tational water, thus reducing sharply theshear strength, and therefore, the stability ofslopes. Temperature changes and winds of-ten accelerate weathering and thus diminishrock stability. Some kinds of microrelief canbe the cause of swamping.

Rock stability can depend substantially onengineering factors, especially on the methodof blasting work. After blasting, the strengthof rock in some portions of the massif candrop to 20-25 per cent of the initial (natural)strength. In order to prevent landslides anddownfalls, it is then required to changeproperly the elements of working systems(width of berms and platforms, heights andangles of slopes and benches, etc.), thoughsometimes at the expense of the miningproductivity.

It is also essential to consider other engi-neering factors which can influence the stabilityof, flanks, such as the width of stoping andtransport berms, profile of working, plat-forms, underworking of flanks, etc.

grids. Statistical processing of stereographicgrids makes it possible to divide the entiretotality of fissures in the rock massif intoparticular systems.

The number of fissures, i. e. the density ofjointing, can be determined by two methods:

I. ~sually. i .e. by recording all detectedfissures in each system; the results are thencorrected by the data of statistical processingof a small number of selective measurementsin systems.

2. By statistical processing of a fairly largenumber of measurements of bedding el-ements of fissures.

The density of jointing can be character-ized by several coefficients:

(I) a linear coefficient which gives the ratioof a unit length to the mean spacing betweenthe fissures. In some cases, the unit lengthmay be taken as the length of the object beingstudied, for instance, the height of a quarryflank, etc.;

(2) an area coefficient. or the ratio of a unitarea to the area confined between two pairsof fissures forming a structural block; and

(3) a volume coefficient, i. e. the ratio of aunit volume to the volume of an averagedblock.

An important factor affecting rock stabilityis weathering, i. e. degradation of rocks on theEarth's surface caused by natural agents(temperature, water, oxygen, carbon dioxide,living organisms, etc.). Weathering effect isespecially noticeable in the flanks of oldquarries.

Rock stability can be influenced substan-tially by hydrogeological factors: inflow ofground waters, hydrostatic and hydrody-namic pressure, suffosion, leaching, suddenwater outbursts, and mud-flows. Acting sep-arately or in combination, these factors candecrease substantially the strength charac-teristics of rock, in particular the shearstrength.

When estimating the stability of quarryflanks, it is also essential to take into consider-

12.3. Mine-SurveyingObservations on RockMining Deformationsin Open-Cast Mining

Observations on rock disturbance inopen-cast mining and processing of the re-sults of observations are an important objectof mine-surveying service in quarries. Obser-vations on landslides include two stages: (a)exploration and detection of seats of land-slides and (b) observations on landslide seatsand development of particular measures toprevent landslide phenomena.

In view of the continuous technologicalmobility of slopes in quarries, the organi-

30112.3. Mine-Surveying Observations

zation of observations has certain specificfeatures. Observation points established inslopes cannot be preserved for a long time(especially those on the benches of workingflanks). In that connection, it is essential toorganize observations so as to complete themin relatively short terms. There are twoprincipal kinds of observations: (1) obser-vations on visible deformations of flanks andbenches in order to predict the shape of alandslide and the pattern of its developmentin space and time and (2) observations onsections where deformations are invisible butcan appear and cause serious damage to themining plant.

The results of observations should estab-lish the displacements of particular points ofa rock massif in space and time; dimensionsof a sliding massif, slip surfaces, stages of thedisplacement process (initial, active, and at-tenuating), and the degree of hazard of rockdisplacements for mining operations and forsurface structures.

For observations on rock displacements,observation stations are established on theflank of a quarry, and instrumental obser-vations are made at them in specified timeintervals. An observation station is essentiallya system of bench marks set up along thelines perpendicular to the length of a quarryflank. In order to take into consideration theeffects of various factors on flank stability,the profile lines of an observation station areusually located in sections of rocks havingdifferent geological conditions.

The length of profile lines should be suchthat one or both ends of the line is beyondthe zone of expected displacements. In quar-ries of a small depth, profile lines can bedrawn through the entire quarry. Spacingsbetween the bench marks of a profile linedepend on the quarry depth and dimensionsof benches. At least two bench marks shouldbe established on each bench: one near thebench crest and the other at the foot of theoverlying bench. Bench marks should be

located on benches so as to ensure safety foran observer. Control bench marks are provi-ded at the ends of profile lines. During theconstruction of an observation station, atleast three initial bench marks are establishedso as to guarantee their preservation. Controlbench marks of all lines are connected to theinitial bench marks.

Mine-surveying observations at stationsinclude the following procedures: levelling ofall bench marks, including control benchmarks; measurements of spacings betweenthe bench marks by controlled tension steeltapes (with recording the temperature duringmeasurements); instrumental surveying ofparticular benches, muck piles, bedding el-ements, jointing, existing displacements, etc.

All measurements should be made withchecking. The accuracy of measurementsshould satisfy the following conditions:

(I) in geometric levelling, the difference oftwo measured elevations should be not morethan 3 mm;

(2) in measuring the spacings between thebench marks, the discrepancy of two mea-surements should be not more t:han 2 mm;

(3) in trigonometric levelling, the differencebetween two measurements of the same el-evation should be not more than 5 mm forlengths up to 10 m or 8 mm for lengths above10 m.

The results of measurements are presentedin the following graphical documents: theplan of an observation station (Fig. 12.4) on ascale 1/500, 1/1000 or 1/2000 which shouldshow profile lines, mining workings, the situ-ation and relief of the land surface; verticalsections for each profile with the positions ofa flank at the moment of laying out a profileline and during a given series of observations;vector diagrams of bench mark displace-ments in the vertical plane on a scale 1/1,1/5, I/lO or 1/20; and the diagrams of therates of bench mark movement in the direc-tions of these vectors.

In observations on landslides, it is also


required to determine the position of a slipsurface in the body of a slope and establishthe cause of its appearance. When the resultsof observations are analysed on profile lines,it is assumed that all displacement vectors ofindividual points on the slip surface coincidewith the movements of the points of the slopesurface which are located on normals to theslip surface. Then, having determined thedisplacement vectors from the results ofmine-surveying observations, it is possible todetermine the position of a slip line. Theposition of a slip surface is found in thefollowing manner (Fig. 12.5):

(I) the profile of a slope is constructed bythe results of observations on the movementof a landslide, and all bench marks andfissures that appeared during the landslideare marked on it; fissures in the top portionand at the foot of the slope should bedocumented especially carefully;

(2) the displacement vectors of benchmarks are plotted on a profile, and a perpen-dicular from the mid of each vector is drawntowards the rock massif;

(3) line sections parallel to the displace-ment vectors of bench marks are laid off oncorresponding perpendiculars from the upperFig. 12.4 Plan of observation station

Fig. 12.5 Determining position of slip line by results of observations on displacements of bench marks

12.4. Stability of Benches and Flanks of Quarries

1TT1n-

-J.-J.-+-+--~~I I I I... t...'I , I "

~

l".,j", I,,

/i

,'. )

Fig. 12.6 Determination of angle of internal fric-tion and cohesion by results of surveying oflandslide

and lower boundary of a landslide (from thebreak fissure at the top and from the supportline at the bottom). The broken line thusconstructed is essentially the slip line of thelandslide.

The results of observations on landslidescan be used for determining the angle ofinternal friction p and the coefficient ofcohesion k of the rock by the method ofinverse calculation.

A rock massif at the moment when it losesbalance is assumed to be under the action ofthe system of thrust forces ~ and retainingforces: the force of friction tan p1;N i and theforce of cohesion kL (Fig. 12.6):

1;~ = tan p1;Ni + kL (12.3)

where L is the length of the landslide surfacein the section considered.

After a certain displacement, the movingmass of rock stops in a new state of equili-brium in which the thrust forces are counter-balanced by the forces of friction.

Solving the above equation for this state ofequilibrium under the action of friction for-ces, we find the angle of internal fric~ion ofthe rock massif. Substituting the value of pinto Eq. (12.3), it is then possible to determinethe coefficient of cohesion k of rock in themassif.

\/

\II'

~v,

~

~1~.JJ

y

where k is the coefficient of cohesion; p is theangle of internal friction; and y is the meandensity of the rock.

In the calculations of the stable position ofd quarry flank on a circular-cylindrical slipsurface, it is rather difficult to find the centreof the most dangerous arc of slip. Theanalysis of equilibrium of a landslide wedgegives us only one equation, so that theproblem cannot be solved uniquely. Because

12.4. Stability of WorkingBenches and Flanks ofQuarries

In the design, construction and operationof quarries, it is essential to choose a suitablemethod for calculating the inclination anglesof quarry flanks so as to ensure properstability of flanks and benches, provide placefor berms and roads, and achieve a higheconomic efficiency of mining.

There are a number of methods for calcu-lating the flank stability which is estimated interms qf a stability coefficient. This is under-stood as the ratio of the sum of all retainingforces to the sum of thrust forces acting on alandslide wedge:

n = ~F fr + ~F c + A (12.4)

~Fthr + B

where ~F fr = j"i:.N i is the sum of frictionforces; ~F c = kL is the sum of cohesionforces; ~F thr = ~ ~ is the sum of thrust forces;f is the coefficient of internal friction of therock; k is the coefficient of cohesion deter-mined by the force acting on a unit surfacearea; and A and B are some additionalretaining and thrust forces.

Tensile forces acting in the top portion of aslope produce vertical rupture cracks, be-cause of which the length of the slip surfacedecreases. The length of such a crack is foundby the formula:

2k cotan (45° -p/2)If-= I"'C\

Ch. 12. Stability of Quarry Flanks

from a point a up to the intersection with theline ED (a point E);

(7) two perpendiculars are raised to thelines aE and MK respectively in points Nand M (Rl and R2 in Fig. 12.7); the inter-section of these perpendiculars determinesthe centre of the circle passing through thepoints M and E.

After these geometrical constructions, acheck of the slope stability is made. For thispurpose, the landslide wedge is plotted on alarger scale and divided by vertical lines intoa number of prisms (Fig. 12.8). The area ofeach block Si is measured, and the mass of therock in each prism per metre of the quarryfront is calculated by the formula Qi = sir.The vertical lines, which are the boundariesof prisms, are continued downwards to adistance corresponding to the mass of aprism on the given scale. Perpendiculars areraised from the points of the intersection ofthese lines with the slip surface. After that, N iand 1; are found by the formulae: N i = Qicos 9; and 1; = Qi sin 9; (values of N i and 1;are given in Table 12.4), and the angle 9;between Qi and N i is measured.

Fig. 12.8 Scheme of landslide wedge for calculat

ing slope stability

of this, the centre of this arc is found by thetrial-and-error method which involves la-borious calculations.

It is however possible to use a methodwhich immediately determines the position ofthe slip surface when the landslide wedge hasthe least reserve of stability. The method isessentially as follows (Fig. 12.7):

(I) a horizontal line BD at a distance H9ofrom the slope surface and a vertical line ABare drawn on the vertical section of a slope;

(2) an arbitrary point D is taken on a lineBD and a line at an angle 45° + p/2 to theline BD is drawn from that point (a line DC);a line BC is drawn from a point B at the sameangle;

(3) a line M K is constructed from thelowermost point of a slope (a point M) at anangle 45~ -p/2;

(4) equal sections MP, PP', and P'P" arelaid off on the line MK from the point M andequal sections CC', C'C", and C"Co, on aline DC from a point C;

(5) lines parallel to the slope line MA aredrawn from points P, P', and P" and linesparallel to BC, from points C', C", and Co;the intersections of these lines are points E ,E l' E 2' and E 3; a straight line EO is drawnthrough these points up to the intersectionwith the line MK;

(6) a straight line parallel to DC is drawn

12.5. Measures for Controlling Landslides 305

Table 12.4

Block No. Qi.MN e" deg. N;.MN 1;, MN

III

IIIIVV

2.332.912.721.970.75

453927207

1.652.262.431.850.748.93

1.651.831.240.670.095.48

The length L of the slip surface is thenfound, after which the stability coefficient iscalculated by the formula:

tan pI:N i + kL (12.6)n=

1:1;;

popular: flattening out the inclination anglesof benches and flanks; leaving safety pillars ofoverburden rock or mineral it.l zones wherelandslide centres are probable to appear;decreasing the load on a slope in order todiminish the forces developed by the activepressure prism; removing the rock from pro-bable centres of landslides; and strengtheningartificially the rocks in the massif.

In undertaking measures for the preven-tion of landslides, it should be distinguishedbetween the cases when the slip surface isdistinctly pronounced in nature (along clea-vage planes, layer contacts, etc.) and when itis a merely imaginary line. In the former case,the slip surface can be represented by weakcontacts in a rock bed dipping towards aworking. Slip surfaces can also pass along theinterlayers of clays and loams in a homoge-neous bed of rock in a slope or along thecontacts of inundated rocks.

In the latter case, the position of the slipsurface cannot be detected visually and isdetermined only by survey observations onslope deformations or analytically. Such asurface cannot be determined precisely, buteven an approximate determination of itsposition makes it possible to predict the kindof expected landslide and take suitable pro-tective measures. With a known position ofthe slip surface, landslides can be preventedby one of the methods described below.

Flattening out the slope angle. This methodconsists essentially in diminishing the angleof inclination of a slope or bench to a certainsafe value at which the landslide is impos-sible. The calculation is carried out succes-sively for a number of different values of aninclination angle (Fig. 12.9). The results ofstability calculations for these angles arerepresented graphically as a curve 11 = .f(a) onwhich the angle a corresponding to thespecified stability coefficient is found. In theexample shown in Fig. 12.9, with 11 = 1.5, theinclination angle of the flank should be 41°.Mter that, the mine surveyor calculates the

where p is the angle of internal friction,degrees; k is the coefficient of cohesion of therock; and L is the length of the slip surface.The forces A and B (see Eq. 12.4) are notconsidered here.

If the calculated stability coefficient isgreater than or equal to the specified value,the flank is considered to be stable, if other-wise, it is unstable, and it is then required toflatten out the slope or employ artificialmeasures for increasing the rock stability.

12.5. Measures for ControllingLandslides

Landslides in quarries cause enormousdamage to mining plants, disturb the normalcourse of mining operations, often lead tolarge losses of stripped and prepared reservesof minerals, and necessitate multiple transferor even haulage of sliding rock masses.

If the working flanks and benches of aquarry are designed correctly, their totalstability will be guaranteed. It is not exclu-ded, however, that local landslide centres willappear in certain sections. It is economicallyefficient to prevent these local events bytaking appropriate anti-landslide measuresamong which the following ones are more

20-1270

Ch. 12. Stability of Quarry Flanks306

less than 18-20°. Underworking of the stratainevitably leads to rock sliding along beddingplanes. To preclude a landslide, it is goodplan to remove part of the rock mass inadvance and thus to increase stability.

I1/

y 12.6. Artificial Strengtheningof Rock Massif

/

>T2

'ix

~~\~'.4

\:\~k,..,,~~ ' Q.

35 40 45 a. degrees

Fig. 12.9 Flattening out of slope angle

position of the point corresponding to 11 == 410 on the top platform of the flank. Thispoint is marked on the ground by a peg anddetermines the line to which the slope mustbe flattened.

Unloading the active pressure prism. Whenthe mining work is being carried out in zoneswhere deep landslides occur or are probableto occur, the stability of slopes can becontrolled efficiently by unloading the activepressure prism or, on the contrary, by increa-sing the mass of the support prism at the footof the waste dump. The efficiency of thismethod can be explained by the circumstancethat landslides on flank slopes with lowinclination angles develop only slowly, sothat there is enough time to transfer a largemass of rock from the active prism into thezone of a passive prism (support prism).

Removing the centre (locus) of a landslide.This method gives good results in cases whenthe bed strata are dipping towards the wor-ked-out space and the inclination angle is not

Artificial strengthening of slopes in quar-ries is principally effective in cases when thespecified inclination angle

AI:h.a = arctan ' (12.7)

I:a. + I:h.cotano., , I

turns out to be flatter than the angle foundfrom the conditions of slope stability. (In theformula above: hi is the height of a bench; aiis the. width of a berm; and Oi is the incli-nation angle of a bench slope).

The existing methods of slope strengthen-ing can be divided into the following groups:(1) those based on mechanical principles;(2) those which increase the mechanicalcharacteristics of rock by the injection ofstren,gthening materials; and (3) those em-ploying durable coatings of slope sections(mainly for rocks liable to quick degrada-tion).

The first group includes methods in whichslopes are strengthened by bolting, cables,retaining walls, etc.

In the second group, the most popularmethod is the injection of cement slurry.The injections of liquid polymer resins areefficient in some cases.

In the third group, gunned-concrete, bi-tumen and epoxy-resin coatings are usedmore often. An artificial coating is oftenapplied onto a metal net or bolting.

Each of these methods may be preferableover others under particular conditions. Forinstance, slopes with distinct cleavage planes:tectonic fissures, laminations, disturbancezones, etc. can be strengthened reliably by

12.6. Artificial Strengthening of Rock Massif 307

~

(b)

k,V,&/~/~//i

ii,/J.(

,y--" , j (

¥"

~

Fig. l2.11 Slope strengthening: (a) by bolting;(b) by flexible cables

as a variety of bolting. Cases are known whenflexible cables were arranged in boreholes upto 30 m long. Flexible cables are especiallyefficient under the conditions when streng-thening elements are subjected to bending aswell as to tensile stresses.

For slopes composed of sand andsand-clay rocks, strengthening methods ba-sed on the use of direct-current electric fieldsare promising. As a d. c. electric field isapplied to a rock massif, it causes certainphenomena of electric transfer (movement ofelectrically charged particles between the fieldpoles). The associated electrokinetic and elec-trochernical processes give rise to coagulationand crystallization phenomena which decreasethe moisture content of the rock and increaseits density, and therefore, strength.

It is advantageous to form electric fields inwhich the lines of force are thickened towardsthe cathode. This is achieved by arrangingthe anodes around the cathode. In that case,the strengthened zone in a rock massif ac-quires the shape of a cylinder with the radiusequal to the distance between the unlikepoles.

In practice, the method of rock strengthen-ing by d. c. electric field is realized as follows.The clusters of holes are drilled in the slopeto be strengthened, with the anode holesbeing arranged around a single cathode hole.The depth of holes should be 10-15 per cent


Fig. 12.12 Slope strengthening in quarry flank by do c. electric field

instance, 40 per cent of Portland cementgrade 300 or 350, 10 per cerit of quicklimewith an activity 85-92 per cent, and 50-55 percent of Neogene clay).

The composition binder interacts with therock, so that clays in a certain volumearound the hole are dried due to the hydra-tion of the binder, and the associated chemi-tal and adsorption processes lead to theformation of water-resistant and strong cal-cium hydrosilicates which bind disperse clayparticles. With the hole diameter 23 cm, thestre~gthened zone has a diameter upto 50 cm.

greater than the thickness of the zone ofunstable rock. Spacings between the holeclusters are chosen so as to ensure thestability of the entire slope. The scheme ofslope strengthening by this method is il-lustrated in Fig. 12.12.

In clays with disturbed or undisturbedstructure and a high concentration of fine-dispersed particles and rather low coefficientof filtration, strengthening rock piles canbe formed efficiently by using compositionbinders. A hole is drilled in the rockmassif and filled with a composition binderconsisting of cement, quicklime, and clay (for

Chapter Thirteen

Mine-Surveying Control of Mining Safety

13.1. Role of Mine-SurveyingService in Mining Safety

Modem mining can be characterized byever increasing depths of mines and accor-dingly, more complicated geological and hyd-rogeological conditions. With an increase inthe mining depth, rock pressure increasesintensively. Moreover, the cases of suddenrock, coal, gas and water outbursts, self-igni-tion of coal, etc. are more probable to occurin deeply bedded seams. Under such con-ditions, special methods and means are requi-red for carrying out the stoping and prepara-tory mining operations, which should bestrictly observed and controlled properly toensure the safety and efficiency of mining.

Under the conditions of elevated hazard ofmining, mine-surveying service plays an espe-cially important part and has certain speci-tics. In many aspects of mining safety, mine-surveying service takes the prime role and isresponsible for making decisions which areobligatory for all other mining specialists andworkers. To effect safety control, mine sur-veyors determine the boundaries of hazard-ous zones and represent them on the plans ofthe mining work; inform mine managers andforemen beforehand when mining workingsare approaching hazardous zones, participatein the development of safety measures, andobserve that these measures are fulfilled

properly.There are three principal groups of hazard-

ous zones which may be associated with (I)flooded mining workings; (2) formation ofzones of elevated rock pressure between adjac-

ent seams, and (3) foffi1ation of unprotectedzones and zones of elevated rock pressure inseams liable to outbursts.

Hazardous zones associated with floodedworkings can in turn be divided into thefollowing types: (a) zones near flooded orgassy workings in a single seam; (b) thosenear flooded or gassy workings in adjacentseams; (c) zones near flooded workings drivenin the overburden; (d) those near unpluggedor poorly plugged boreholes; and (e) zonesnear tectonic disturbances (dislocations).

In mine-surveying practice, dangerous con-ditions are encountered most often in wor-kings approaching flooded or gassy old wor-kings. Methods for the construction of safeboundaries and special safety measures of themining work have been developed for eachtype of hazardous zone.

13.2. Control of Mining Worknear Old Workings

When the mining work is carried out nearflooded or gassy abandoned old workings,special engineering measures should be takento prevent sudden outbursts of water or gasinto the existing workings. In that case,mine-surveying service has to determine howreliable are the contours of old workings onsurvey plans, to calculate the width of barrierpillars (boundaries of safe mining), and plotthe pillars on a survey plan.

The contour of an old working is con-sidered reliable if there are the results of minesurveying obtained upon complete stopping

310 Ch. 13. Mine-Surveying Control of Mining Safety

vertical shafts, pits, and large-diameter bore-holes is taken not less than 20 m in alldirections and can be determined by theformula:

d = 0.05 H + 0.002 L+ 5 (13.3)

where H is the depth of a shaft to the mininglevel on which the barrier pillar will be left,m; and Lis the same as in formula (13.1).

The boundaries of safe mining workshould be determined by considering thematerials of the geological structure of theflooded portion of a mine field, stored in themine-surveying department of a miningplant, geological parties, archives, etc., thecalculations and graphical documentationof the period when the working was inoperation, and other information. Dependingon the available materials, it is possibleto determine approximately the error ofthe contours of flooded workings and toestablish the boundary of the zone safe miningwork. As a rule, the dimensions of that zonemay vary from the width of two barrier pillarsup to 200 m or sometimes 300 m.

Measures for ensuring safe mining work inhazardous zones should solve the principalproblems of organization and give engi-neering solutions and terms for effecting ofthese measures and their control. A typicalexample of such measures is an optimalscheme of the arrangement of unwateringand advancing boreholes. The number,length and direction of advancing boreholesshould be such as to preclude the break-through of a new working into an old one.The calculation of the expected water inflowfor an unwatering borehole can be done bythe formula:

(13.4)

where Q is the expected water inflow to thehole, m3/h; b is the hole diameter, m; His theheight of a water column above the hole

of mining in the working. As a rule, a contouris considered reliable if the old plan of themining work and field books with the coor-dinates of theodolite surveys and measure-ments of workings carried out after theworking has been abandoned are on hand. Incases when the contour of an old working isnot confirmed by mine-surveying documents,it is regardcd as unreliable.

Mine-sur\cying service is responsible forthe reliability of the contours of floodedworkings. With a reliable contour, the boun-dary of a barrier pillar is established. If thecontour is unreliable, the mine surveyor de-termines the boundary of safe mining work.In coal fields; the width of a barrier pillar, dfor seams up to 3.5 m thick and angles of dipup to 30° can be found by the formula:

d = 5 m + 0.05 H + 0.002 L (13.1)

where m is the extracted thickness of a seam,m; H is the mining depth, m; and L is thelength of underground theodolite traversesrun from the initial survey points to thecontour of flooded workings and the boun-dary of a barrier pillar, m. The width of abarrier pillar should however be not less than20 m. In seams more than 3.5 m thick andwith angles of dip more than 30°, barrierpillars are not usually left. Instead, as aworking approaches an old working, waterfrom the latter is pumped off in due time.

For flooded workings driven in the over-burden ro�k, the width of a barrier pillar isdetermined by the formula:

d = 0.05 H + 0.002 L+ Lln (13.2)

where H and L are as in formula (13.1); Lln isequal to zero for barrier pillars extended onthe strike with the angles of dip of the rockbetween 0 and 30°; with the angles of dipbetween 45° and 90°, Lln = 10 m; and withthe angles of dip between 30° and 45°, Lln isfound by interpolation. For barrier pillarsextended to the dip, Lln = 0.

The width of barrier pillars near flooded

13.3. Calculation and Construction of Dangerous Zones 311

mouth, m; 9 = 9.8 m/s2 is the accelerationdue to gravity; and 1 is the length of a hole, m.

The mouths of unwatering and advancingboreholes should be packed hermetically. Bythe most popular method of packing, a guidetube is inserted into a hole drilled to a depthof 10-15 m and fixed in place by a cementslurry. A gate valve is mounted on the tube,and the whole system is tested for strengthand tightness by pumping in water into thehole at a pressure exce~ding 1.5 times that inflooded workings.

=28.6m

13.3. Examples of Calculationand Constructionof Dangerous Zones

Calculation and construction of a barrierpillar in a seam with flooded workings. Sup-pose that a worked-out field in a seam 161.5 m thick and an angle of dip of 20° isflooded at a depth of 350-450 m from theEarth's surface (Fig. 13.1). The contour of themining work (1-2-3-4) is reliable. The lengthof mine survey lines for determining the

Vertical section across the strike

Level 350 m

I. tI\.,\.~11'£,e"311' 6

\v=20'

Level 450 m

Plan

6

~li E 4 -

~"'1""'"

~dl=2B.6 mId2=36.4m

3.li,,-'to 3"

I Jd2=36.4m5 23'

Fig. 13.1 Graphical construction of barrier pillarat flooded workings

contour of flooded workings is 1800 ill on theairway level 350 ill and 3200 ill on thehaulage level 450 ill.

In accordance with formula (13.1), thewidth of a barrier pillar on the airway level is:

dl = 5 x 1.5 + 0.05 x 350 + 0.002x 1800 = 28.6 ill

and that on the haulage level is:

dl = 5 x 1.5 + 0.05 x 450 + 0.002x 3200 = 36.4 ill

On the horizontal projection (Fig. 13.1),the sections of length dl = 28.6 ill are laid offfrom points 1 and 2; the points l' and 2' thusobtained define the boundaries of a barrierpillar on the strike on the airway level. At thelevel 450 ill, the sections of length dl == 36.4 ill are laid off from points 3 and 4; theresulting points 3' and 4' give the boundaryof a barrier pillar on the strike on the haulagelevel.

To find the pillar boundaries on the dip ofa seam, the horizontal projection of dl, i. e. dlcos v = 36.4 cos 20° = 34.2 ill is laid off fromthe points 3 and 4. The resulting points 311and 4" determine the boundaiy of a barrierpillar on the dip. The contour of the barrierpillar at flooded workings in the inclinedseam field 16 passes through points 1'-2'-5-6.It is depicted on the plan of the mining work.

Calculation and construction of a safetypillar under flooded workings. Let a seam 142 ill thick be bedded along a normal at adistance of 25 ill under a seam 16 (Fig. 13.2).The seam 14 is expected to be worked out inone or two years. Since it is bedded along thenormal under the seam 16 in which theworkings are flooded, in order to preventwater inrush from the seam 16 into 14, a safetypillar is constructed at a distance not lessthan 40 times the seam thickness. The pro-tected area is represented by a contour 1'-2'-5-6 which confines the flooded workings ofthe inclined field together with a barrierpillar. The construction of the safety pillar is

Ch. 13. Mine-Surveying Control of Mining Safety312

Fig. 13.2 Graphical construction of safety pillarunder flooded workings of overlying seam

boundary in that section. The points 71, 81,91 and 101 are projected from the sectionsacross and on the strike onto the plan. Thisgives the general contour of the safety pillar(hazardous zone) in the seam 14' which isconfined in the plan by the contour withcorner points 7-8-9-10.

Calculation and construction of a barrierpillar near an unplugged prospecting borehole.A prospecting borehole is drilled through aseam [6 at a depth of 320 m and stopped in7 m after passing out from the seam (Fig.13.3). The position of the borehole in theseam [6 is determined by the measurements ofthe hole curvature. A seam [4 is bedded at40 mbelow the normal, The seam thicknessis: [6 = 1 m and [4 = 0.9 m. The total exten-sion of mine-surveying theodolite traverses is4 km in the seam [6 and 5.5 km in theseam 14.

carried out by using rupture angles. For theconditions considered, the rupture angles are:~' = 64°, y' = 70°, and 0' = 70°.

The points I' (2') and 5 (6) are projectedfrom the plan onto the vertical section acrossthe strike, which gives points 11 (21) and 51(6J and onto that on the strike, which givespoints 1',2.: on the level 350 ill and points 51,61 on the level 450 ill.

In the section across the strike, lines aredrawn from the points 11 (21) and 51 (6J atangles ~' = 64° and y' = 70° respectively upto the intersection with the seam 14. Points 71(8J and 91 (IOJ found in this way determinethe boundaries 9f a safety pillar on the riseand on the dip. Mter that angles 0' = 70° arelaid off from the points 1',2', 61, and 51 onthe levels 350 ill and 450 ill on the verticalsection on the strike. The resulting points 11,81,91, and 101 in the seam 14 define the pillar

13.3. Calculation and Construction of Dangerous Zones 313

Vertical section across the strike

Hole No.100

//$/ ~/""')Y /~/AW/~ / ~ /~

~d16=29m

'1'*'--- 7m

:..:

sea((\\&6

5

seali\ 14

iI-J'wI I 1

~' "5' O ,

~4 B

Fig. 13.3 Construction of barrier pillar nearunplugged curved borehole

By fofl1lula (13.1), the width of a barflerpillar will be:for the seam 16:

dl = 5 x 1.0 + 0.05 x 320 + 0.0026 x 4000 = 29 ill

and for the seam 14:

dl = 5 x 0.9 + 0.05 x 360 + 0.0024 x 5500 = 31.5 ill

In the vertical section across the strike, llnesections equal to half the pillar width, i. e14.5 ill are laid off from a point 01 in theseam 16 on the rise and on the dip. Theresulting points 1 and 2 fix the barrier pillarboundary. These points are then projectedonto the plan (points I' and 2'). The sectionsof the half-width of a barrier pillar are againlaid off from the point 01 along the strike linepassing through the intersection of a bore-hole with the seam 16, which gives points 3and 4. These points define the pillar boun-dary on the strike. After that, points I', 3, 2',and 4 are connected by a smooth curve which

deteffilines in plan the contour of the barrierpillar in the seam 16.

Since the borehole has been stopped in theunderlying rock at a depth of 7 m below theseam foot, the actual distance from the seam14 is 33 m. Since, however, the safe distancebetween the seams is 40 times the thickness ofthe seam 14, i. e. 40 x 0.9 = 36 m, and the

B .. II actual distance between the borehole bottom~ arrlerplar d h 1 . II ...

d~ in seamJ6 an t e seam 4 lS sma er, it lS reqwre to¥ I dt4=31.5m leave a barrier pillar in the seam 14. For

I I Barrier pillar constructing this pillar, a noffilal is drawn, I I In seam [4 ...

-from the hole bottom to the mtersectlon with-the seam, which gives a point O2. The

'1 B' ~ sections of a length dl /2 = 15.75 m are then+ ~ laid off from that point on the rise and on the

I dip, which gives points 5 and 6. Similarly, thepoints 5 and 6 are projected onto the plan toobtain points 5' and 6'. Mter that, the sec-tions of length dl/2 = 15.75 m are laid offfrom the point o24in the direction perpendi-cular to a line 5'-6', which gives points 7 and8. Finally, the points 5', 7, 6', and 8 areconnected by a smooth curve which definesthe contour of the barrier pillar in theseam 14.

Arrangement of advancing boreholes whenapproaching flooded old workings. When aworking is approaching flooded old wor-kings, the mine surveyor develops the schemeof the arrangement of advancing (unwatering)boreholes and determines the number ofholes from the following considerations: theprobability of the breakthrough of a newworking into the old working should becompletely precluded; the distance from ad-vancing boreholes to the flooded old workingin the section considered should not exceedthe width of the crushed edge zone of abarrier pillar in stope workings, i. e. 5 m; thepitch of the advancement of the workingshould be chosen so as to ensure a constant(not reducing) advance of the prospectedportion of the boundary of safe mining work,but not less than the width of the barrierpillar.


11=2m~rr'-

2.,r I... d= 20m

iui! ~

~1

2=5m-~ij~~~r~~~d -;d"gej' , - ~TI///I "~O:J.

I,.. ~O\e le ~0.'3 -

\",.0------

--Hole ~!

u~

1=50md= 20 m87.1

,{'Reserve ventilating B .

F:==:=- =3entry in seam m4 I'

1"'"-

Jl

Eo"'II

...

"Seam m4

m=l.omTIO°-.,---

i- d=20~L ~ -1~

4

Fig. 13.4 Arrangement of advancing boreholes across barrier pillar

When driving a single working in thehazardous zone in a seam with floodedworkings, a fan of diverging advancing bore-holes is drilled.

Consider a case of the arrangement ofadvancing boreholes when driving a singleworking in the hazardous zone with thewidth d of a barrier pillar 20 ill (Fig. 13.4).The planned ventilation adit in a seam m4'boundary of the hazardous zone (I-II), andthe boundary of a pillar (1-2-3-4), wherewater inrush is probable and which should beproved by advancing holes, are plotted onthe plan of the mining work. Lines 1-2 and3-4 are drawn at a distance d = 20 ill frOmthe axis 9f the projected working. The firstborehole (No. 1) is directed along the axis ofthe projected working (ventilation adit in aseam m4)' and its optimal length is 50 ill. Thesecond borehole (No.2) is directed into apoint which ensures the control of a band ofwidth 12 = 5 ill. For this, the shortest possibledistance to the flooded working (11 = 2 ill) islaid ofT from a point 1, which gives a point A.The zone of the crushed edge portion of abarrier pillar 5 ill wide is constructed fromthe point A. An arc of radius 5 ill is drawn bycompasses from the point A, and the bore-

hole is directed along ;1 tangent to this arc.Considering the distance between the bot-toms of boreholes No.1 and No.2, thenumber of additional advancing holes isdetermined, noting that a distance of 5 m atboth sides is controlled by each borehole andthat the entire zone controlled by a boreholeshould be not wider than 12 m. In theexample considered, it is required to drill anadditional borehole (No.3). In a similar way,the directions and number of boreholes forcontrolling the hazardous zone on the dip aredetermined. Thus, five holes are drilled fromthe point of the first setting of a drilling rig (apoint Bl).

The place for drilling another group ofboreholes is determined from the conditionthat the working face should be stopped in apoint B2 which is spaced from the point Bl ata distance d = 20 m. The number of advan-cing boreholes in the second and subsequentgroups diminishes by one both on the riseand on the dip of a seam.

Arrangement of advancing boreholes atdistortions intersecting flooded workings.When mining workings are approaching thedistortions which intersect flooded oldworkings, exploratory drilling should be

1 3.4. Construction of Zones of Elevated Rock Pressure 315

Fig. 13.5 Arrangement of advancing boreholesfor a working approaching geological distortion

advancing boreholes 2 are usually drilled.One of them is arranged normally to theplane of a dislodger and the other is drilledhorizontally along the axis of a working.Places for the arrangement of advancingboreholes are determined by the boundary ofa hazardous zone.

Barrier pillars in mines in an upper seambeing worked or in underlying seams locatedat a distance along a normal not less than40 m from overlying seams (where m is theextracted thickness of an underlying seam)can be calculated by formula (13.1). In suchcases, L is found by considering the totalextension of theodolite traverses from theadjacent shafts to the barrier pillar. If thedistance along a normal between the adjacentworking seams is less than 40 m, the barrierpillar in the underlying seam is constructedas a safety pillar under flooded workings. Theprotected area is taken as the boundary ofthe barrier pillar in the overlying seam.

made. This is done for determining the degreeof inundation of a dislodger zone and forpreventing the probable water inrush, sincethe disturbed rocks in the distortion zone areconsidered to be flooded and, when establish-ing the boundaries of a hazardous zone, areequated to flooded old workings. The widthof the hazardous zone at a discontinuousgeological disturbance (distortion) is deter-mined in each particular case depending onthe accuracy with which the disturbance isrepresented on the plans of rocks, gypso-metric plans, and geological sections. In allcases, however, the boundary of the hazard-ous zone should be at a distance not lessthan 30 m along a normal to a dislodger. Ifthe dislodger of a discontinuous geologicaldisturbance has been opened and intersectedby preparatory workings and it has beenestablished that the inundation of the rock inthe disturbed zone is insignificant, the widthof the hazardous zone can b~ calculated byformula (13.1), but it should be not less than20 m. If the intersection of distortion andflooded workings gets into the zone of rockdisplacement by the future stope working, thewidth of the hazardous zone is increased sothat the distance along a normal from theseam to the dislodger is not less than 40 m,where m is the seam thickness. The width ofthe hazardous zone in this case can bedetermined by the formula:

40 m cos v (cotan v cotan O + cos ro) sin Ad=

cotan v cos (I) -cotan O

where d is the distance in a plan alonga normal from the line of the intersection ofa seam and dislodger to the boundary ofa hazardous zone; v is the angle of dip ofa seam; O is the angle of dip of a dislodger; (I)is the plan angle between the lines of dip of adislodger and seam; and A is the plan anglebetween the line of dip of a seam and theintersection line. With a working approach-ing a discontinuous distortion which inter-sects a flooded working 1 (Fig. 13.5), two

13.4. Construction of Zonesof Elevated Rock Pressure

Operations in stope workings can causethe deformations and displacements of rocks.The displacement process can influence thestate of the rock massif and coal seams. Theseam being extracted is bedded in a suite inwhich one or more seams have already beenworked out earlier and coal pillars have been


la)

-4

~ .. ~

1 'I~... ~

~I

3

'1 I

~

1..fJ

(b) O

NILr

5

0.4 08 1.2 1,6 all

3

0 04 08 12 t6 all

Fig. 13.6 Nomograms to determine distance ofinfluence of zones of elevated rock pressure infaces: (a) under pillars or edge portions; (b) abovepillars or edge portions; 1 -zone of elevatedhazard; 2- dangerous zone; 3- prediction zone(solid lines for perpendicular pillars and dottedlines for parallel ones)

left, so that the projections of these pillars getinto the displacement zone on the seam beingworked out. This gives rise to an additionaleffect which is called the bearing pressure andforms a zone of elevated rock pressure.

It is distinguished between three types ofzones of dangerous effect of pillars and edgeportions of adjacent seams.

The zone of elevated hazard is characterizedby a sharp loss of stability of rocks in theroof, in the first place, immediately above aworking. Dynamic effects of rock pressurecan be observed, such as instantaneousdestruction of the rock massif around astoping face. These effects can raise catastro-phically the load on the supports and oftenlead to rock bursts in stoping faces. Strongswelling of ground and squeezing of coal canoften occur in the zones of elevated hazard.

The dangerous zone can be characterized bya reduced stability of the lower layers of aroof in the worked-out seam owing toincreased fissuring and stratification. Thisusually leads to roof rock inrush and some-times to rock bursts in stoping faces.

The prediction zone has no noticeabe effecton the lining of stoping faces, but the localchanges of the stability of the lower roof layerand phenomena of secondary subsidence ofthe main roof are possible.

The dimensions of influence zones undervarious conditions of seam underworking (oroverworking) are determined by the distanceof influen~ of pillars and edge portions andby the influence angles. The boundaries ofzones of elevated rock pressure are con-structed graphically on vertical geologicalsections perpendicular to the boundaries ofpillars or edge portions of a seam. Pillars andedge portions of seams may be in a differentposition relative to the line of a stoping face.

In this case, pillars are understood asnon-extracted portions in adjacent coalseams, which have a width up to 2 1, whereasthe portions of a width more than 2 1 areregarded as the edge portions of a seam (here

I is the width of the zone of bearing pressure).For the pillars of a width less than 2 I. theboundaries of dangerous zones are notconstructed. The dimensions of zones ofelevated rock pressure in stoping faces drivenunder pillars (edge portions) can be deter-mined in the nomogram 2 in Fig. l3.6a andof those driven above pillars, in the nomo-gram 3 (Fig. l3.6b).

For constructing the boundaries of thezone of elevated rock pressure, the followingcharacteristics should be known: the beddingdepth H of the seam in which a pil)ar or edgeportion is left; the extracted thickness m ofthat seam; the thickness h of the interlayerbetween the worked-out seam and the seamin which a pillar or edge portion is left; thewidth a of a pillar; the width I of the zone ofbearing pressure in the seam with the left

13.4. Construction of Zones of Elevated Rock Pressure 317

N Ii is found in the nomogram (here N is thedistance of influence, m). In the nomogramsof Fig. 13.6, curves 1 correspond to theboundary of influence of zones of elevatedhazard, curves 2 to the distance of influenceof dangerous zones, and curves 3 to pre-diction zones. To change from the dimen-sionless ratio N Ii to dimensional N, thisratio should be multiplied by I, the width ofthe bearing pressure zone. Mter that, avertical section through the given pillar isplotted (Fig. 13.8) on which the seam ofinfluence and the worked-out seam, the pillar(or the edge portion of a seam), and theposition or a stoping face in the worked-outseam are shown. The calculated distances ofinfluence of the zones of elevated hazard,dangerous zones and prediction zones arelaid off in the roof and foot of the seam of thepillar perpendicular to the bedding plane.Then, lines parallel to the influence seam aredrawn through the points obtained (3-4, 5-6,7-8, 3'-4', 5'-6', and 7'-8').

7 8

50

40

3020

10

40 80 120 160 200 240 Hm

Fig. 13.7 Norn.ograms to determine width 1 ofbearing pressure zone: (a) for depths 200-1200 m;(b) for depths 20-280 m DZ

~ !" E HZ I

Seam '8 \ ,1 ~

~

pillar or edge portion. The last characteristiccan be found in the nomograms of Fig. 13.7.

The zones of elevated rock pressure areconstructed in the following way. For theknown mining depth H and seam thicknessm, the width I of the zone of bearing pressureis found in the nomogram of Fig. 13.7. Forinstance, with H = 750 m and m = 2 m, thewidth of the bearing pressure zone isI = 65 m. On the nomogram of Fig. 13.6, thedistance of influence of the zones of elevatedrock pressure is then determined. For thispurpose, the width of a pillar, a, is divided bythe width of the bearing pressure zone, I,which gives the dimensionless ratio allaccording to which the dimensionless ratio

BA \ poll ISeam I I ar 10 !

10'1

'-Seam I ~

~

Fig. 13.8 Construction of zones of elevated rockpressure from pillar


As an example, let us determine the zonesof influence of elevated rock pressure in theroof and foot if the width of the zone ofbearing pressure is 1 = 65 m and the width ofthe pillar is a = 50 m. The ratio of the pillarwidth to the width of the bearing pressurezone is a/[= 0.77. Using this ratio, we findN /I for faces passipg under pillars (N 1// = 2,N fl = 3.4, and N 3/[ = 5) and for thosepassing above pillars (N'1/1 = 3.5, N~/l = 4.9and N~/l = 5.9). The distance of influence of apillar for underlying faces will be as follows:for the zone of elevated hazard: N =

1= 65 x 2 = 130 m; for the dangerous zone:N 2 = 65 x 3.4 = 221 m, and for the predic-tion zone: N 3 = 65 x 5 = 325 m. For over-lying faces we have: for the zone of elevatedhazard: N'l = 65 x 3.5 = 227.5 m, for thedangerous zone: N~ = 65 x 4.9 = 318.5 m,and for the prediction zone: N~ == 65 x 5.9 = 383.5 m.

For the construction of zones of elevatedrock pressure from a pillar (see Fig. 13.8),lines are drawn from points 1 and 2 at anangle of 60 o to the bedding plane up to the

intersection with the line of distance ofinfluence of elevated hazard zone in points 3and 4 (3' and 4'). Perpendiculars to thebedding plane are then drawn from thesepoints up to the intersection with the lines ofdistance of influence of dangerous zone andprediction zone in points 5 and 6 (5' and 6')and 7 and 8 (7' and 8'). To determine the sideboundaries of the elevated hazard zone, sec-tions 1-9 (1'-9') and 2-10 (2'-10'), each 20 mlong, are laid off in the bedding plane frompoints 1 and 2 (I' and 2'). Points 9 (9') and 10(10') are connected with points 3 and 4 (3'and 4') by lines which define the side bounda-ries of the elevated hazard zone. For a seam[8' the width of the elevated hazard zone isequal to (AB) and for a seam [4' to (CD). Theconstruction of the boundaries of the zones ofelevated rock pressure from the edge portionsat the side of the worked-out space is done inthe same way as for the pillar, but at the side

of the rock massif. The boundary of the zoneof elevated rock pressure is a straight linedrawn perpendicular to the bedding plane ata distance corresponding to the width of thezone of bearing pressure.

If a number of coal seams are being minedunder (above) pillars, the boundaries of thezones of elevated rock pressure are construc-ted for each seam. If pillars have been left in anumber of seams under (above) the seam,being mined, the boundaries of the zones ofelevated rock pressure are constructed foreach pillar. If the zones of elevated rockpressure from a number of adjacent seamsoverlap on the seam being mined, they areconsidered in the first place by the degree ofhazard.

13.5. Construction of DangerousZones for Mining Workin Seams Liable to Coal,Gas and Rock Bursts

The mining work in deeply bedded coalseams increases the risk of harmful anddangerous effects of rock and gas pressurewhich, may be associated with dynamicphenomena: sudden bursts of coal, gas androck. Soviet scientists have studied the natureof the principal engineering and geologicalfactors causing gas-dynamic phenomena androck bursts, established the relationshipsbetween the effects of gas and rock pressure,determined the parameters for the construc-tion of dangerous zones, and developed themeasures for preventing outbursts. One ofthe main methods for preventing suddenoutbursts is working out of protective seams.

A protective seam is a seam (or interlayer,or rock layer) which, when being worked out,ensures complete safety from outbursts inanother seam of a suite that is to be protec-ted, or relieves partially the rock pressure.

In mining of a suite of seams which aredangerous in outbursts, a non-dangerousprotective seam is extracted in the first place.

13.5. Dangerous Zones in Seams Liable to Bursts 319

Upon the extraction of this seam, the rockpressure in the massif decreases due to thedisplacement of underworked rock volumes.Protective seams should be worked out with-out leaving coal pillars.

The duty of mine-surveying service in thiscase is to construct the protected zones andzones of elevated rock pressure, depict themon the plans of the mining work, and informminers and foremen when workings ap-proach to dangerous zones by 20 m.

For seams liable to coal and gas outbursts,the protected zones and zones of elevatedrock pressure are constructed on the basis ofthe following initial data: mining depth H inthe protective seam; extracted thickness m ofthe protected seam; angle of dip v of theReam; concentration 11, per cent, of sand

(cl

I'

I

[iFig. 13.9 Construction of protected zone inworking of protective seam on dip: (a) section onstrike with b < 2~; (b) section on strike withb > 2~; (c) section across strike; l-protectiveseam; 2 and 3- seams to be protected; 4- protectedzone; 5- zone of dangerous loads

r2

'Q1

I~~

Table 13.1

Values of S~, mValues of S:' mDepth of work H,m

Smallest dimension, a or b, of working in plan, Smallest dimension, a or b, of working in plan,m (refer to Figs. 13.9 and 13.10) m (refer to Figs. 13.9 and 13.10)

125

~

100 125 150 200 250

87 90 9271 74 7662 66 6855 59 6145 49 5041 44 4537 40 41

150 175 200 250 50 7550 75 100

100 125 148 172 190 205 220 5685 112 134 170 155 182 194 4075 100 120 154 142 164 174 2967 90 109 138 126 146 155 2454 80 90 117 103 127 135 2141 57 71 100 88 114 122 1837 50 63 92 80 104 113 16

67503934292523

76584943363230

83665650413632

70585045332724

300400500600800

10001200

this is done by using protection angles O andpressure angles <p (Figs 13.9 and 13.10). Thevalues of these angles are given in Table 13.2.

In cases when h ~ 25 m, v ~ 30°, m ~ 1.3 m,and the roof control is effected by com-plete caving, the angles O are taken equal to90°. The zone of the restoration of dangerousloads can only form when a ~ ~ + ~ and

b ~ 24 simultaneously.The values of ~. ~, and 4 can be

calculated by the formula:

on the strike. It is required to take intoconsideration only pillars whose dimensionsexceed the following values: 4 m for the seamthickness up to 1 m; 3 m for the seamthickness from 1 m to 2.7 m, and 8 m for theseam thickness above 2.7 m.

The dimensions of the protected zone inthe roof, SI' and in the foot, S2 (Fig. 13.9) canbe determined by the formulae:SI = ~1~2S'1 and S2 = ~1~2S~ (13.6)

where ~I is a coefficient depending on themethod of roof control: (13.7)Li = [31L;

mef

ma

~1 =where L; is to be found on a nomogram(Fig. 13.11b).

The permissible maximum and minimumvalues of advancement of the stoping face inthe protective seam relative to the miningwork in the seam being protected (Figs 13.9and 13.10) are given in Table 13.3.

Construction of protected zone. The protec-tive seam is worked out at a depth of 1000 m,the extracted thickness is m = 0.7 m, and theangle of dip v = 50°. The inclined height of alevel is 150 m and the size of the worked-outspace on the strike is 650 m. A pillar 15 mwide is left on the airway level. The roof iscontrolled by complete pneumatic back-fil-

but should not be less than unity; mo is thecritical thickness of a protective seam whichcan be found in the nomogram ofFig. 13.11a; ~2 is a coefficient considering theconcentration 11, per cent, of sandstones inthe interlayer:~2 = 1 -0.4(11/100)

and S'I and S~ are taken from Table 13.1.If hI < SI in underworking or h2 < S2 in

overworking, it is required to separate sec-tions where dangerous loads can appear again;

13.5. Dangerous Zones in Seams Liable to Bursts 321

(a)

b,"'" .,

.1--if

(b)L3 4 ?

H

, 1 /i ;.:,

"{45~: ~\

"' 2 t

~ b2~!~Fig. 13.10 Construction of protected zone in working of protective seam on strike: (a) section acrossstrike with a < 4 + ~; (b) section across strike with a >4 + ~; (c) section on strike; I-protective seam;2 and 3- seams to be protected; 4- protected zone; 5- zone of restoration of dangerous loads

ling. A seam dangerous in rock bursts isbedded in the ground at a distance h2 == 10 m. The interlayer contains 50 per centof sandstones.

Since the size of the pillar between thelevels is greater than 4 m, then a is taken asthe inclined height of a level, i. e. a = 150 m.

The size of the protected zone towards thefoot of a protective seam is:S2 = f31f32S~

21-1270

According to the nomogram (Fig. 13.11a),with a = 150 m and H = 1000 m, the criticalthickness is mo = 0.68 m. For the roof controlby pneumatic back-filling, k = 0.3, andtherefore:

me! = km = 0.3 x 0.7 = 0.21 m

~1 = me!lmo = 0.21/0.62 = 0.31

~2 = 1 -0.4(11/lOO) = 1 -0.4(50/lOO) = 0.80

From Table 13.1, we find: S~ = 45 m,

Table 13.2

Angle of Protection angles 0, deg Pressure angles <p,dip v, deg deg

whence the size of the protected zone along anormal to the bedding plane is:

S 2 = 0.31 x 0.80 x 45 = 11 m

From the nomogram of Fig. 13.11b, wefind ~ and 1; for jhe inclination anglev = 50°; they are equal respectively to 180 mand 230 m. Thus, we have:

Ll = L'l13l = 180 x 0.31 = 56 m

0401 B, 03 !P2 <1>3<PI

75757570707070727580

64

62

60

59

58

56

54

54

54

54

64636059565452484643

64

63

61

59

57

55

53

52

50

48

80777369657472747075

80838790909090909080

75757577808080807875

0102030405060708090

£2 = £~J32 = 230 x 0.8 = 184 m

Since a < 4 + ~, the zone of the restora-tion of dangerous loads cannot form and,according to Table 13.3, the permissibleadvancement b2 is not limited, and the mini-mal advancement b~ can be taken equal to20 m. We find from Table 13.2 that 01 = 70°and 03 = 80°. The construction of zones ofelevated rock pressure is illustrated inFig. 13.12. For the zone of elevated rock

N ole: If the direction of stoping work coincides withneither the line of strike nor the line of dip, angle v is takenas the angle of inclination of the seam in a section

perpendicular to the face direction.

Table 13.3

Permissible advancementprevent outbursts, m

Mining conditions Pernlissible advancement toprevent rock bursts, m

Minimal advancement:b; in underworkingb; in oveI;;Working

Maximal advancement**b1 in underworkingb2 in overworking:

if a < Ll + L2if a > Ll + L2

h1, but not less than 20 m*h2, but not less than 20 m

khlh2

Not limitedNot limited

Not limitedb1 < L3 + h1 cotan ~3

b2 < L3 -0.3 h2

* Coefficient k depends on the rate of advance of a stoping face in the protected seam:

v, m/day up to 2 2 to 5 over 5k I 1.2 1.4

** Permissible advancements are given for the stoping work on the strike. If the stoping work is carried out on thedip, LJ and <PJ are replaced by L, and <PI; if on the rise, they are replaced by 4 and <P2. Permissible advancement isdetermined on the departure of a stoping face from breakthrough by a distance more than 2LJ (or LJ + L2 if the stoping

work is carried out on the dip or on the rise).

32313.5. Dangerous Zones in Seams Liable to Bursts

(a)

ron

/.I\200

0.81150 III

IIII100 \ \

0.4

\=50m

\0 400 800 H,m

t(J&,II

I~~(b)

300,

La

L~ ~

250

200\- .,,\

y0 30 60 IXo y

Fig. 13.12 Zones of influence , of seam edgeportion: I -protected zone; 11- unprotected zone;111- zone of elevated rock pressure

21.

Chapter Fourteen

M ine-Surveying Controlof Geological Exploration

14.1. Brief Data on GeologicalExploration

Geological exploration is essentially acycle of investigations which are carried outin a definite sequence and can be character-ized by the following stages:

1. The stage of regional geological recon-naissance which is aimed at determining theprincipal bedding characteristics of variousminerals in a particular region so as to makeprognostic valuations of the perspectives oftheir extraction and outline areas for moredetailed geological prospecting. This stagecan be divided into two substages: (a) re-gional geological and geophysical reconnais-sance and (b) regional geophysical and geo-logical surveys and hydrogeological andengineering-geological work.

Geological and geophysical reconnaissance(the Ist substage) is effected for the formationof a new or renovation of the existing geo-logical and geophysical basis which is neededfor establishing the principal characteristicsof the geological structure of large regionsand the regularities of the location ofminerals within their boundaries.

The results of geological and geophysicalreconnaissance are used for plotting geo-logical, prognostic and other general andsheet maps, geological and geophysical keysections, and schemes of the geological struc-ture of deep levels.

The main purpose of prospecting opera-tions at the second substage is (I) to analyse

the geological structure of the region in viewof the collected geophysical and geochemicaldata and (2) to use the established regularitiesof mineral location in order to find out themost perspective geological structures, evalu-ate their prognostic resources, and determinefurther directions of geophysical and geo-logical survey and search.

2. The stage of geological survey and gen-eral search is the main stage when large-scaleinvestigations of geological structures arecarried out in order to distinguish local areasand structures which are promising for thedetection of mineral deposits. Geological sur-veys at this stage should be made primarilywithin the limits of mining areas. The resultsof surveys and prospecting at this stage arerepresented in the form of geological maps,register maps of minerals, and prognosticmaps of mineral location.

3. The stage of geological search is carriedout in order to detect mineral deposits withinthe limits of known and potential ore fieldsand basins of sedimentary minerals where theprevious exploration work has revealed theprobability of the detection of deposits. Thesearch work at this. stage takes place inboreholes and pits with the use of geo-physical and geochemical methods, rocksampling, panning, etc.

Investigated areas are represented on geo-logical maps which show the regularities ofthe localization of mineral bodies.

4. The search-valuation stage is an inter-mediate stage between the reconnaissance

14.2. Mine-Surveying Control of Geological Work 325

pographic and mine-surveying operationswhich are done to attain the followingobjectives:

I. The formation of the geodetic basis forthe layout, connection and geological surveywork required for geological prospecting;provision of a control network for topo-graphic surveys when these are needed; andthe solution of various engineering problemswhen driving mining and exploring workingsor making the geophysical and drillingwork.

2. The formation of the topographic basisfor geological prospecting; this is meant as atopographic plan or map with the points offield observations, which is plotted in asimpler form, i. e. without showing someelements of the topographic situation andrelief that are inessential for the constructionof geological boundaries.

The topographic and geodetic materialscollected at the stage of geological prospec-ting are latt;r used in the design and exploita-tion of mining plants.

14.2. Mine-Surveying Controlof Geological Work

The mine-surveying control of geologicalwork includes the following procedures: thetransfer of the design positions of objects ofgeological observation (boreholes, miningworkings, etc.) into nature; determination ofthe planimetric and height coordinates ofthese objects; and the formation of thetopographic basis for geological and otherspecial maps.

The geodetic control for the mine-sur-veying work can be provided by:

(a) geodetic nets;(b) elements of survey control, such as

planimetric, elevation and combined plani-metric-elevation surveying nets and indivi-dual points, and geodetic reference nets;

(c) distinct contour points of depositswhose coordinates can be found on topo-

and the exploration of mineral deposits. Themain object of this stage is to evaluate thecommercial significance of detected deposits,reject. those which are of no interest for themining industry, and select objects for pre-liminary prospecting. The results of thesearch-valuation work are represented in theform of preliminary geological maps andgeological sections of a detected deposit.

5. The stage of preliminary prospecting isdone in order to obtain trustworthy informa-tion for reliable geological, technological andeconomic evaluation of commercial signifi-cance of deposits. Most deposits are exploredby prospecting boreholes.

The results of preliminary prospecting arerepresented in the form of approved tempo-rary specifications and technico-economicalreport on the expediency of the detailedexploration of a deposit.

6. The stage of detailed prospecting (explo-ration) is carried out only for deposits whichare evaluated positively by preliminary pros-pecting and recommended for commercialexploitation.

7. The stage of complementary prospec-ting can be fulfilled both on explored depositswhich are not still mined commercially andon those which are being mined.

8. The stage of exploitation prospecting iscontinued during the whole period of miningof a deposit and is carried out for collectingsystematic reliable information required forcurrent (annual) and operative (quarterly,monthly, and daily) planning of mineralextraction and the control of the comp-leteness and quality of extraction.

The main objects of exploitation prospec-ting consist in determining more accuratelythe contours of mineral bodies and theirinternal structure and bedding conditions,quantity and quality of mineral resources,geometrization of technological types andgrades of a mineral, etc.

All stages of geological reconnaissance andprospecting are associated with geodetic, to-

Ch. 14. Mine-Surveying Control of Geological Exploration326

Table 14.1

Root-mean square errors of positions of geological obser-vation objects relative to initial points, m

Stages of geological prospecting

in plan in elevation

90(100)40(50)20 (25)

10(20)5 (10)2(3)

(2)

I. Regional geological investigations, geological sur-vey work, and geperal search with compilation ofmaps on a scale:

1/100000 and smaller1/500001/25000

2. Search work, search-valuation work and prelimi-nary prospecting with compilation of maps on ascale 1/10000

3. Search-valuation work, preliminary and detailedprospecting with compilation of maps on a scale1/5000 and larger

0.5

N ole: Numbers in brackets are rms errors for determining the positions of geological observation objects

desertous, woody, and mountainous regions.

the accuracy recommended in Table 14.1.The elevations of these objects should bedetermined with errors not exceeding thefollowing data:

(a) in hydrogeological surveys, 0.5 of theadopted interval of hydroisohypses on hyd-rogeological maps, but not more than twicethe error given in Table 14.1;

(b) for individual hydro geological surveysfor determining the gradients of undergroundflows, inundations of sections and miningworkings (mines, shafts, etc.), within t!!eaccuracy for technical levelling, i. e. 50 J L,mm, where L is the length of a geometriclevel line, km.

The coordinates of the mouths of station-ary hydraulic boreholes should be determi-ned from the closest bench marks and pointsof a national levelling net with an rmsaccuracy not worse than I 10 cm.

In geological work, deep geological map-ping and general search with the compilationof maps on a scale 1125000 and smaller, theobjects of geological observations are trans-ferred into nature and connected, as a rule,

graphic maps (plans) or aerophotogrammetricplans with the required accuracy; and

(d) objects of geological observationswhose coordinates are determined with the

required accuracy.The mine-surveying control for transfer-

ring the design positions of objects of geolo-gical observations into nature includes the

following steps:(a) the preparation of initial data and the

compilation of schemes and the plan of work;(b) measurements for determining the posi-

tions of observation objects on the ground;and

(c) the fixation of the positions of trans-ferred objects.

The accuracy of the determination ofplanimetric and height coordinates of geolo-gical observation objects can be taken byreference to Table 14.1 for deposits of solidminerals and to Table 14.2, for oil and gas

deposits.For the objects of hydrogeological obser-

vations, the survey work for determining theplanimetric coordinates should be done with

14.3. Topographic Basis of Geological Exploration 327

Table 14.2

Kind (category) of borehole Ultimate errors, m

transfer into

naturepreliminary deter-mination of eleva-tions of borehole

mouths

150 150 100 5.0Single reference and parametricboreholes

Structural and search boreholesExploratory boreholesBoreholes on exploited areasBoreholes in water areas

50251020

10

5

5

30

12

4

10

1.0

0.5

0.3

0.5

Notes: I. Errors are given relative to the points of a national geodetic net and geodetic densification nets.2. As initial points of connection, it is possible to use any points including those by which the structural maps

are plotted, provided that this ensures the accuracy indicated in the table.

mining the boundaries of mineral deposits,revealing geophysical anomalies, etc; and forcompiling special maps, sections, prospectingprofiles, and other graphical documentation.

according to the topographic maps andmaterials of aerophotogrammetric surveys,Instrumental field measurements at thesestages of geological work are only possible inexceptional cases when topographic maps areunavailable or cannot ensure the specifiedaccuracy of the connecting work.

The points of a geodetic net or surveyingnets fixed on the ground by permanent benchmarks can be used for the layout, connectionand geological survey work, planimetric andelevation control of topographic surveys, andfor solving certain engineering-geologicalproblems.

The points of geodetic survey control fixedby temporary bench marks, points of geode-tic reference nets, and distinct contour pointson the terrain whose coordinates are takenfrom a topographic map can be used only forthe layout, connection and geological surveywork.

The coordinates of geological observationobjects can be used: for marking the positionsof these points on maps and sections with anaccuracy that can ensure reliable representa-tion of the results of observations and accu-rate calculation of mineral resources; for deter-

14.3. Topographic Basisof Geological Exploration

The topographic basis for the geologicalexploration work can be provided by:

(a) topographic maps (plans);(b) large-scale plans; or(c) special topographic plans. .

In the geological, search and explorationwork, the scale of the topographic basisshould correspond to that of the map to beplotted.

The recommended scales of the topogra-phic basis for preliminary and detailed geolo-gical prospecting are given in Table 14.3.

In the maps and plans of the topographi(;basis on a scale 1/10000 and smaller, theerrors in the positions of contours, orienta-tion marks and horizontals should be notmore than 2.5 times the errors permissible innational topographic maps.

In special topographic plans used as the

determination ofplanimetric posi-tion of borehole

mouths

detenninationof elevations ofborehole mouths

328 Ch. 14. Mine-Surveying Control of Geological Exploration

Table 14.3

Stage of geological prospec- Scale for topographic sur.ting veying

Preliminary prospecting 1/10000 to 1/5000Exploration of:

(a) metal ores 1/10000 to 1/1000(b) carbonate rocks,

phosphorites, sands,and gravels 1/25000 to 1/5000

(c) salts 1/25000 to 1/10000(d) coals and oil shales 1/1000 to 1/2000(e) underground water 1/1000 to 1/5000(I) other non-metallic

minerals 1/10000 to 1/5000

1.0 m for a scale 1/2000, and 1.0 m for a scale1/1000. For mountainous regions and foot-hills, the recommended contour intervals arerespectively 5.0 m, 5.0-2.0 m, and 1.0 m.Hydrographic objects are indicated on thetopographic basis only as the coastal lines ofseas, lakes, rivers, etc. without detailed char-acteristics. Vegetation is not shown. Woodsare marked by contours. Swamps and mar-shes are shown by conventional symbolswithout detailed characteristics. Other typicalfeatures of the terrain and ground are notindicated on the topographic basis.

The topographic basis of geophysicalmaps should give only the situation associa-ted with the text of the report; land relief isshown only in rare cases.

14.4. Transfer of Planof Exploratory Workingsinto Nature

Exploratory workings are transferred intonature according to the plan of the mine-surveying work. Depending on local condi-tions and the specifics of geological pros-pectiDg, this plan may involve various kindsand volumes of the topographic and mine-surveying work. For instance, Fig. 14.1shows the plan of the topographic andmine-surveying work for detailed prospectingof a deposit by drilling exploratory boreholesalong profile lines. The plan envisages trian-gulation surveys (points I, II, III and IV);running of base lines (main theodolite tra-verses) for the layout of profile lines; theconnection of base lines (by closed theodolitetraverses) to triangulation points III and IV;plane;.table surveying of the territory of adeposit on 10 plates; and the transfer andconnection of points for borehole drilling.

Exploratory workings and objects of geo-logical observations are transferred into na-ture and connected relative to the points ofreference nets which can include main theo-dolite traverses (base lines), profile lines. and

topographic basis, the errors in the positionsof land contours and objects relative to thenearest points of a surveying net should. notexceed the pef111issible errors of correspondingtopographic maps by more than 1.5 times fora scale 1/5000 or 2 times for larger scales.

The errors of relief surveys relative to thenearest points of elevation control on thetopographic basis should not exceed 0.5 mfor contour intervals of 1 m or 1/3 of thecontour interval in other cases.

For better clarity, the amount of topo-graphic details on geological maps on a scale1/10000 and larger is diminished. Coordinategrids are shown as ticks of kilometre lines inintervals of 10 cm. The points on geodeticnets and on the schemes of geological obser-vations are.taken selectively, i.e. only thosepoints which are essential for the compilationof geological and geophysical maps are used.The points of a national geodetic basis areshown only in cases when this is specified bythe design. Land relief is indicated byhorizontals and numerical marks of indivi-dual heights. For the topographic basis on ascale 1/10000, land relief is shown in thesame vertical contour intervals as on nationaltopographic maps. For larger scales, thefollowing contour intervals may be recom-mended: 2.0 m for a scale 1/5000; 2.0 m or

14.4. Transfer of Exploratory Workings Plan into Nature 329

ric shape and consist of a system of parallelbase lines intersected by a system of parallelprofiles (Fig. l4.2a). In many cases, somebase lines can be matched conveniently withextended objects on the terrain (roads, riverbanks, open watersheds, etc.). In such cases,base lines may have a curvilinear shape(Fig. l4.2b).

As a rule, the plans of exploration nets aretransferred into nature by instrumentalmethods.

the points of a surveying net and nationalgeodetic net.

The layout work is carried out with anaccuracy which can ensure the requiredaccuracy of connection. If an object istransferred into nature with an accuracyinsufficient for connection, additional con-nection to the closest control points shouldbe carried out.

Networks for detailed geological prospec-ting usually have a relatively regular geomet-

Ch. 14. Mine-Surveying Control of Geological Exploration330

(b)(a)

.-~::. Main traverse

...Profile with observation points

Fig. 14.2 Construction of base lines and prospecting profiles

angle between the direction of the base lineand the direction onto another point of thereference net (for instance, angle 13, Fig. l4.3a)is measured on a topographic map. Thisangle is then laid off on the ground by anangle-measuring instrument set up in theinitial point;

(b) base lines pass far from the points of ageodetic reference net. Then a point of thereference net near the base lines is selected,from which two or three adjacent referencepoints are visible, and a theodolite traverse isrun between the selected reference point andthe base line (Fig. l4.3b). By means of thistraverse, the base lines can be connected tothe existing local system of coordinates;

(c) the region of geological prospecting islocated in an inhabited area, so that thepoints of a geodetic reference net are invisiblefrom it. In that case, the directions of baselines can be assigned by means of a magneticazimuth. If the prospected region is located in

In laying out geological exploration nets,the mine-surveying and geodetic work ispractically organized on the following prin-ciples:

(a) the initial points and directions aretransferred into nature, and the survey area isdelineated by laying out base lines, whichprovides a 'framework' for subsequent layout

operations;(b) the. base lines delineating the survey

area are connected to the points of a geodeticnet, i. e. the 'framework' is connected to theexisting system of coordinates; and

(c) profiles are laid out and picked pointsare established.

For transferring the initial points intonature and assigning direction to the initialportions of base lines, the following methodscan be employed:

(a) one of the base lines passes through apoint of the geodetic reference net existing inthe region being explored. In that case, the


(a)

.,A/

-

~(32

--c.

(b)

==

-~B. """6

Fig. 14.3 Scheme of base lines

a closed area with poor visibility (woods, etc.)and where there is a magnetic anomaly, baselines can be' connected by a geographicazimuth.

The intervals between the pickets (obser-vation points) on profile lines are measuredin one direction by means of range finders ortapes. Inclination angles wider than 5° aremeasured by theodolites or inclinometers; insuch cases a length laid off between thepickets is corrected for the inclination angle.The coordinates of the final pickets of profilesare determined by running theodolite tra-verses between the ends of profiles.

For observation points and exploratoryworkings not coincident with the points of areference net, connection can be done bytacheometric or plane-table surveys, lengthmeasurements or intersections.

14.4.1. Connection and Transferof Geological ObservationObjects from TopographicMap into Nature

In the geological survey and search workmade on a scale 1/25000 or smaller, geolo-gical observation objects are transferred intonature and connected by reading off theirpositions on topographic maps or aeropho-tographic maps and plans.

For regions with a small quantity of con-tours and for which renovated maps are notavailable, the plane coordinates and eleva-tions of geological observation objects aretransferred into nature and connected accor-ding to the materials of the aerophotogram-metric surveys of the latest years.

Objects can be transferred from aeropho-tographs onto a topographic map by visual,graphical or instrumental methods.

Ch. 14. Mine-Surveying Control of Geological Exploration

I ~ ' 430 431 432

2'

Fig. 14.4 Transfer of points from aerial photo.graphs onto topographic map by intersections

map; the directions connecting the centralpoints on the transparent paper sheets arematched with the corresponding line of thetopographic map. The intersections of likedirections determine the positions of thepoint being transferred on the map.

The accuracy of the position of pointstransferred by the method of intersectionscan be estimated by reference to Table 14.4.

The method of resections consists in that atleast four reference points are chosen on anaerial photograph and a topographic map(for instance, points a, b, c, and d on an aerialphotograph and points A, B, C, and D on amap). A sheet of transparent paper is laid onthe aerial photograph, and directions aredrawn from the point to be transferred (say,x) onto the selected reference points a, b, c,and d. The transparent paper sheet is thenlaid on the map so that the drawn directionsx-a, x-b, x-c, and x-d pass through the pointsA, B, C, and D on the map. After that, thepoint x is punched from the transparentpaper onto the map.

The instrumental method of point transferis the most accurate and least labour-consu-ming.

Geological observation objects can beconnected or transferred into nature from atopographic map (aerial photograph) by oneof the following methods.

In the visual method, a point is transferredby linear intersections from two or threereference points on a map. In that case, thelengths of corresponding sections on theaerophotographs and map are comparedvisually.

The visual method is employed in caseswhen the terrain has distinct contours andonly slightly dissected relief. Experience hasshown that, for transferring of points with theroot-mean square error of I mill, the distancefrom reference points to the given object onmaps should be not more than 5 mill for flatland, 3 mm for foothills, and I mm for moun-tainous regions.

The graphical methods of transfer mostoften employ direct intersections from thecentral points of aerophotographs and resec-tions.

In the method of direct intersections, thecentral points of aerophotographs are firsttransferred onto the map by the method ofphoto triangulation. The points to be trans-ferred onto the topographic basis are read offand punched on two adjacent aerial photo~graphs. The central points (431 and 432 inFig. 14.4) and points to be transferred (say,points I, 2, 1', and 2' in Fig. 14.4) arepunched from each aerial photograph ontotransparent paper. Then, the directions ontothe central points and points to be transfer-red are drawn on the sheets. Mter that, thesheets of transparent paper are laid onto thetopographic basis and oriented so that thecentral point of each sheet is coincident withthe corresponding point on the topographic

Table 14.4

Accuracy of positions of points, mm, formean difference of elevations between

points, m

Map scale

50 150 200

5.42.71.80.50.30.3

500

15000110000125 00015000011000001200 000

2.01.00.40.30.30.3

1.4

0.6

0.3

0.3

0.3

0.3

2.71.40.50.30.30.3

6.72J1.40.70.3


1. By reading off a point if this pointcoincides with a contour point on the map.

2. If the given point is located between twocontour points on the map, by measurementson the range line of these points from one ofthe points to the point to be connected (ortransferred).

3. If the point to be determined is visiblefrom contour points, its position can befound by direct intersections.

4. If three typical points are visible fromthe point to be determined and these pointsare indicated on the map, the position of thatpoint can be found by resection.

The determination of the planimetric coor-dinates and elevations of geological observa-tion objects on topographic maps (aerialphotographs) includes the following steps:

(a) contours and orientation marks depic-

Table 14.5

Pattern of terrain and relief Root-mean square errors (m) of elevations determined by interpolation betweenmarked points (numerators) and between horizontals (denominators)

map scale

0.4-0.8

0.5-0.8

0.4-0.8

0.6-1.0

0.8-1.6

0.8-1.6

0.9-1.6

1.2-2.0

1.2

1.5

1.5

2.5

2.5

3.0

3.5

5.0

5.0

6.0

7.0

10.0

11.0

12.0

14.0

20.0

Flat terrain (inclinationangles up to 2°)

Flat woody terrain (inclina-tion angles up to 2-4°)

Flat densely inhabited ter-rain (inclination angles upto 2°)

Hilly rugged (open) terrainwith prevailing inclinationangles up to 6°

Hilly rugged (closed) terrainwith prevailing inclinationangles up to 6°

Foothill and mountainousterrain with prevailing in-clination angles up to 15°

High-mountainous terrain

1.0 1.8-2.2 4.0 8.5 17.0Error not more than 1.5 of contour interval

33.0

40.010.0 20.0Error not more than 2.0-2.5 of contour interval

ted on a topographic map are found on theterrain; measurements are carried out, whenneeded, on the terrain between the objectsbeing determined and the orientation marks;and the objects are indicated on the map;

(b) observation objects are transferredfrom aerial photographs onto a map; and

(c) the planimetric coordinates and eleva-tions of observation objects are read off on amap.

Measurements on maps and terrain shouldbe carried out by methods which can deter-mine the plan positions of objects relative toa known contour with a root-mean squareerror not exceeding 0.2 mm on the map beingused.

The measurements of planimetric coordi-nates and elevations on maps are made twice.The errors in elevations of observation


objects on topographic maps should corres-pond to the data given in Table 14.5.

The determination of the planimetric coor-dinates and elevations of geological objectson topographic maps should be made with acheck of at least 20 per cent of the pointsbeing measured.

of the oriented directions from the rotorcentre in order to establish deviations and

(b) the layout and fixation on the groundof the design direction of boreholes and thedetermination of the plan position of faces.

14.5. Layout of ExploratoryDitches

The layout of open exploratory workings(ditches, trenches, etc.) consists in transferringthe design position of an axis and side crestsof a working into nature. The layout pro-cedure is started by transferring the ends ofthe axis onto the ground, which can be doneby various methods or their combinationsdepending on the conditions of measurementsand the provision of a geodetic basis. Thesemethods have been discussed earlier. On aclosed (woody or hilly) terrain it is howevermore preferable to use the method of a designtheodolite traverse.

In the plan shown in Fig. 14.5, points Kand N are the ends of the design axis of aditch and A and B are the points of ageodetic basis. In order to transfer the pointsK and N onto the ground by the method of adesign theodolite traverse, it is essential toknow angles /3B and /3K and horizontaldistances BK = S BK and KN = S KN whichcan be obtained by solving inverse geodeticproblems by the formulae:

YK -YBtanaBK = ,

XK -xB

YK-YB XK-XB----

sin IlBK COS IlBK

YN -YK

SBK

tanaKNXN XK

YN-YK XN-XKSKN= .=

smaKN cosaKN

13B = aBA -aBK' 13K = aKB -aKN

where x K' Y K' X N' and Y N are the coordinates

of the points K and N determined graphically

14.4.2. Transfer of GeologicalObservation Objectsfrom Reference Netinto Nature

In the geological search and explorationwork made on a scale 1/10000 or larger,exploratory workings and geological obser-vation objects are transferred into nature andconnected by instrumental methods to thepoints of a national geodetic net, densifica-tion nets, surveying nets, or reference nets. Ifworkings are located at distances not morethan 300 m from a reference net, their posi-tions can be determined by a polar method(by a theodolite 01 a plane table), the distan-ces being measured by a range finder. Thepositions of points near profile lines can bedetermined by the method of perpendicularswith the distances measured by measuringtapes or range finders.

The positions of fixed boreholes andmining workings can be determined by ana-lytical methods relative to the points of anational geodetic net, densification nets, sur-veying nets or base lines.

The work for the connection of geologicalobservation objects includes:

(a) the compilation of a connection scheme;(b) measurements for determining the pla-

nimetric coordinates and elevations of geolo-gical observation objects; and

(c) the compilation of the list of plani-metric coordinates and elevations of geolo-gical observation objects.

With directional drilling of boreholes, thefollowing additional operations are made:

(a) the layout and fixation on the ground

14.5. Layout of Exploratory Ditches 335

(a)

v~

~o~o

60( .

..inewood 7 PK :0

0 v

VIvv

Fig. 14.5 Layout of exploratory ditch

on the plan; x B' y B are the coordinates of thepoint E taken from the list of calculatedcoordinates of the points of a geodetic net;and aBA is the initial direction angle takenfrom the list of the calculated coordinates ofthe points of a geodetic net.

A theodolite is set up in the point E andthe junction angle 13B is constructed from adirection EA at two different positions of acircle, after which the length of a line S BK is

laid off in that direction, and the point K thusobtained is fixed.

The angle ~K is constructed in the point Krelative to a direction KN, the design lengthS KN of a ditch is laid off, and the point N isfixed.

The upper crests of a ditch are laid out byusing a number of profiles which are plottedon millimetre-squared paper on a large scale(say, 11200). The width 1 of the ditch bottom

(Fig. 14.5, where it is shown by a dotted line),the depth h, and the inclination angle of ditchsides are taken from the design and theelevations of the points of the Earth's surface,from the plan. In the case considered, threeprofiles are plotted: a longitudinal profilealong the axis KN (Fig. 14.5b) and twotransverse profiles through the points K andN (Fig. 14.5c).

The construction of profiles gives thepoints of intersection of ditch crests with theEarth's surface (1, 2, 3, 4, 5, and 6). Inclineddistances K-l, K-2, N-3, and N-4 are thenfound on transverse profiles and K-6 andN-5, on a longitudinal profile. These distan-ces are laid off on the ground from the pointsK and N; the former four perpendicularly tothe ditch axis and the latter two, along theaxis. The points 1, 2, 3, 4, 5, and 6 are fixed onthe ground.

The angles of the upper crests of the ditch(points 7, 8, 9 and 10 in Fig. 14.5) areobtained at the intersections to the continuedlines 1-4 and 2-3 and perpendiculars raised tothe ditch axis in the points 5 and 6.

If the terrain is flat, cross-sectional profilesare not constructed, and the distance fromthe ditch axis to its crest is determined by theformula:

N-4 = N-3 = 112 + d

where d is calculated by the formula:

d = hltan..<p

fields, either existing in nature or formedartificially. Any kind of these fields can becharacterized by its specific parameters. Forinstance, a gravitational field can be repre-sented by the acceleration due to gravity orsecond derivatives of the gravity force poten-tial; a magnetic field is characterized by thetotal intensity vector and its components(vertical, horizontal, etc); an electromagneticfield is characterized by the vectors of magnet-ic and electric components; an elastic field isdescribed by the time of the propagation ofvarious elastic waves; etc.

The principal possibility of geophysicalmethods of prospecting with the use ofvarious physical fields is based on the factthat the distribution of field parameters onthe Earth's surface, underground, in air, outerspace, and in the Ocean is determined by thegeneral structure of the Earth and the nearspace, variations in the physical properties ofrocks, and the dimensions and beddingdepths of geological objects.

Geophysics has to solve two types ofproblems: a direct problem and an inverseone. Since the parameters of physical fieldsdepend uniquely on the properties anddimensions of the geological objects beingprospected, the parameters of a field can beuniquely determined when one knows theproperties and dimensions of geologicalobjects. This is the direct problem to besolved in geophysics. The inverse problemconsists in determining the dimensions, bed-ding depth and other characteristics of geolo-gical objects by the measured parameters of aphysical field, which, as a rule, cannot bedetermined uniquely.

The inverse problem can be solveduniquely by studying a complex of fields.

Geophysical prospecting methods can beemployed in outer space, on the Earth'ssurface, in seas, and underground. Accordingto the problems and objects of investigation,geophysical prospecting can be divided intoregional, structural, prospecting for ores,

14.6. Geodetic Controlof Geophysical ProspectingMethods

14.6.1 .General Data on GeophysicalProspecting Methods

Geophysical prospecting includes themethods of the investigation of the Earth'scrust, search and prospecting for minerals,and engineering geological studies which arebased on the analysis of various physical

14.6. Geodetic Control of Geophysical Prospecting 337

petroleum and gas, and engineering geo-physics.

Among the various methods used forgeophysical prospecting, the gravitational,magnetometric, electric, seismic, nuclear andgeothermal methods are more popular.

14.6.2. Principles of GravitationalProspecting

Gravitational prospecting is based onmeasuring the acceleration due to gravityand its variations (gradients) in differentdirections. The parameters of the field ofgravity force depend, on the one hand; onsome factors associated with the shape androtation of the Earth (normal field) and, onthe other, on the density variations of rocksin the lithosphere (anomalous field).

The gravitational (normal) field of theEarth is the field of the gravity force which isthe resultant of two forces: the force ofattraction of the Earth and the centrifugalforce caused by the rotation of the Earth onits axis. The force of gravity can be measuredin terms of the acceleration 9 acquired by afreely falling body. In gravitational prospec-ting, the unit of acceleration is 1 cm s- 2

which is called the gal.Gravitational prospecting is based on

measuring the anomalies of the gravity force,i. e. its deviations from normal values. Thenormal field of the gravity force can beanalysed by the formula:

Yo =Ye(l- ~sinB- ~lsin22B)

where

~ = (Yp -Ye)/Y, ~1 = (1/8)a2 + (1/4)a~

a is the contraction of the Earth's ellipsoid; Bis the geodetic latitude; Y p is the normalgravity field at a pole; and Ye is the normalgravity field at the equator.

Thus, the anomaly of the gravity force isessentially the difference between the gravityforce observed and its theoretical value whichcan be calculated by one of the formulae for

22-1270

the normal gravity force with the introduc-tion of corrections (reductions). In gravita-tional prospecting, the most popular formulafor describing the inhomogeneous density ofthe Earth's crust is based on Bouguer'sanomaly (Bouguer's effect):AgB = gm -'Yo + Agl + Ag2 + Ag3

where gm is the measured gravity force; Aglis the correction for altitude which reducesthe measured value to the sea level (Faye'scorrection), A 9 1 = 0.308 H (H is the altitudeabove sea level, m; Ag2 is the correction forthe attraction of an intermediate layer, whichis equal to the attraction of the masseslocated between the sea level and a realsurface, Ag2 = 0.0419 o-H (0- is the meandensity of rocks in that layer and H is thealtitude of an observation point); and A g3 isthe correction for relief. The relief correctiontakes into account the deviations of thephysical surface of the Earth from the hori-zontal plane passing through the given point.For calculating the relief correction, the por-tion of the Earth's surface around the pointof observation is divided in a particularmanner into a number of areas so as toapproximate the relief by simple geometricbodies whose gravitational effects can bedetermined analytically.

The correction for the surrounding relief iscalculated for particular annular zones ar-ranged concentrically around a gravimetricpoint. Since the shape of the relief in eachzone may be variable, these zones are dividedfurther into curvilinear prisms. The actual(physical) surface of the Earth within eachprism is replaced by a horizontal plane whosealtitude is equal to the mean altitude of theprism relative to the observation point.

The effect of the terrain on the topographiccorrection decreases proportionally with anincrease in the distance from the observationpoint, because of which the entire region forwhich the correction is taken into account isdivided into three zones: the closer (up to


200 m), the mid (from 200 m to 2000 m), andthe farther (from 2000 to 13000 m).

The highest effect is produced by the reliefelements in the closer zone. In some cases, acentral zone of a radius of 10-50 m is separa-ted in the closer zone. In high-precisiongravimetric surveys, the relief corrections inthe mid and closer zone are determined byinstrumental methods.

14.6.3. Electric Prospecting

The electric methods of geological prospec-ting are based on studying natural andartificial electromagnetic fields in the Earth'scrust. Natural fields may be either permanentor variable in time. The former are conven-tionally called electric fields and the latter,electromagnetic.

In electric prospecting, both normal andanomalous fields are studied. Normal fieldsare those which exist above a semispacehaving homogeneous electromagnetic pro-perties. An anomalous field may appear dueto an inhomogeneous structure of the geo-electric section of an area being prospected,i. e. of the combination of geological bodiesand seams, each of which has particulardimensions and specific electromagneticparameters.

In electric prospecting, the measured fieldparameters are the amplitudes and phaseshifts of the intensities of electric and mag-netic fiel~. The principal electric properties(parameters) of rocks are the specific electricresistance, dielectric constant, magnetic per-meability, electrochemical activity, and po-larizability.

Depending on the problems to be solved,all methods of electric prospecting can bedivided into three groups: (I) profiling, whichis used for the examination of inhomoge-neous geoelectric sections represented byclosely folded strata and electromagneticallyinhomogeneous inclusions; (2) probing,which is employed for the investigation of

sections composed of horizontally bedded orgently dipping structures; and (3) under-ground electric prospecting used for the detec-tion of geoelectric inhomogeneities betweenthe boreholes or underground workings andthe Earth's surface.

Electric prospecting deals with the fol-lowing kinds of field:

I. Local natural electric fields, includingthose of electrochemical and electrokineticorigin. Electrochemical fields can be causedby oxidation-reduction reactions at bounda-ries between the electronic conductors (ore ormineral bodies) and ionic ones (undergroundwater surrounding an ore body). Electro-kinetic fields exist due to the filtration ofunderground waters through porous rocksand the associated processes of diffusion andadsorption of ions on solid particles.

2. Regional natural electromagnetic fields(called magneto-telluric fields) which appearin the Earth's crust in the regions of anappreciable area. Their origin is attributed tothe influence of flows of charged particlesemitted by the Sun on the ionosphere of theEarth, and therefore, they depend on thesolar activity.

3: Artificial permanent electric fields pro-duced in the Earth by means of earthedcables connected to a d. c. voltage source.

4. Artificial variable harmonic electromag-netic fields formed by various electric gen-erators producing a voltage that varies har-monically in time.

With the use of an alternating current, afield can be excited by an inductive (contact-less) method. For this, a loop of a number ofwire coils, usually of a square shape with thesize from 10 m to 1000 m, is laid on theEarth's surface and connected to an a. c.generator.

5. Transient electric and electromagneticfields excited by quick switching of rectan-gular d. c. pulses into the feed line.

In any method of electric prospecting, theset of instruments contains electric generators

14.6. Geodetic Control of Geophysical Prospecting 339

and other supply sources, measuring andrecording instruments, earthing electrodes ornon-earthed contours for the galvanic orinductive field excitation, earthing electrodesand antenna rods for measuring the electricfield components or frames and loops formeasuring the magnetic components, andauxiliary equipment.

14.6.4. Seismic Prospecting

Seismic prospecting for minerals is ageophysical method based on studying thepropagation of elastic waves excited byexplosions or other sources.

Since rocks have different density and arecharacterized by different velocities of thepropagation of elastic waves in them, reflec-ted and refracted waves can appear at theboundaries between the rock strata and,besides, elastic waves of a different kind canform in inhomogeneous media. The recordsof these waves provide information on thestructure of the region being studied.

Seismic prospecting is based on theanalysis of the kinematics and dynamics ofwaves.

The seismic .methods of prospecting consistessentially in the excitation of elastic wavesand detection of the induced soil oscillationswhich are transformed into electric pulses;these pulses are amplified and recorded onseismograms and magnetograms. These areprocessed in order to separate various kindsof seismic waves and determine the time oftheir propagation to a point with the knowncoordinates. Quantitative interpretation ofthe results of seismic prospecting gives thevelocities of wave propagation, variations oftheir propagation along the depth and overan area, bedding depths of seismogeologicalboundaries, their dipping, extension, etc.Using additional geological characteristics, itis often possible to establish the geologicalnature of detected boundaries of geologicalbodies, i. e. to construct a seismogeologicalsection.

22.

The principal methods of seismic prospec-ting are as follows: reflected wave method;refracted wave method, sometimes called ref-racted wave correlation method; transmittedwave method; method of common reflectionpoint; method of vertical seismic profiling;etc.

In practice, the reflected wave method isused most often, in particular for the dissec-tion of sedimentary beds. It is the leadingmethod for structural investigations andprospecting for petroleum, gas, and otherminerals.

The refracted wave method can provideinformation on the elastic wave velocities andthe depth of beds composed of rocks withhigh elastic moduli and on the beddingdepths of these rocks. The transmitted wavemethod is employed for detecting variousinhomogeneities in rock beds.

14.6.5. Magnetic Prospecting

Magnetic prospecting is a geophysicalmethod based on studying the spatial distri-bution of variations of the geomagnetic fieldwhich can appear due to different magneti-zation of rocks.

The principal methods of magnetic pros-pecting are the aeromagnetic, hydromagneticand ground magnetic surveys, undergroundand borehole observations, and the measure-ments of the magnetic properties of rockspecimens.

In any point on the Earth's surface, thereexists a magnetic field which can be describedby the total magnetic intensity vector T or itsvertical (2) and horizontal (H) components.

As a first approximation, the magnetic fieldof the Earth can be likened to the field of auniformly magnetized sphere or dipole (To).In addition to this unifQrm field of themagnetized sphere, however, the magneticfield of the Earth also has the components ofanomalous geomagnetic fields which areassociated with continental (TJ, regional (T2),and local (T3) anomalies. In the practice of


latter case, however, the starts and ends ofprofiles and the centres of anomalies areconnected instrumentally.

14.7. Mine-Surveying Workin Geophysical Prospecting

The principal object of the mine-surveyingwork in geophysical prospecting is to layoutthe set-up points for instruments and todetermine their planimetric and height coor-dinates. A particular method of geodeticcontrol in geophysical surveys is chosenmainly depending on the scale of geophysicalwork, provision of the geodetic basis, andphysico-geographic conditions in the pros-pected region.

The elevations and plan coordinates ofpoints for geophysical measurements can bedetermined easily and efficiently by referenceto topographic maps. If reliable maps areunavailable, the plan positions of points inregional geophysical surveys can be determi-ned on aerial photographs. The elevations ofthese points are usually determined bybarometric levelling.

In geophysical field surveys on scales1/50000 to 1/10000, point coordinates aremost often determined by running maintraverses (base lines) and laying out profilesbetween them. Theodolite traverses and levellines are then run along base lines andsometimes along profile lines.

The topographic and geodetic control ofgeophysical prospecting includes the fol-lowing steps:

(a) the design positions of prospectingprofiles or individual observation points aretransferred into nature and fixed on theground; in gravimetric and magnetometricprospecting, all observation points should betransferred into nature, and in seismic andelectric prospecting, this involves all centresof excitation and reception of signals; thepositions of profiles and individual pointsshould be transferred onto the ground with

magnetic prospecting, the normal magneticfield is usually taken as the field of a uniform-ly magnetized sphere (To) plus the continentalanomaly (TJ. The normal geomagnetic fieldcan be characterized by a normal gradient,i. e. a change in field intensity per kilometre.The deviations of the observed values ofmagnetic vectors from the normal field areregional or local anomalies depending on thearea of their appearance.

In magnetic prospecting, the measure-ments of the magnetic field may be eitherabsolute or relative. In ground magneticprospecting, however, relative vertical com-ponents of the geomagnetic field, A Z, aremeasured most often and, less frequently,relative values of the total vector, A 1;' i. e.increments of these characteristics relative toan initial (reference) point.

Ground magnetic surveys can be done onscales from 1/50000 to 1/2000 and larger.With scales 1/50000, 1/25000 and 1/10000,geological magnetic surveys are carried outfor mapping the territory being studied, aswell as directly for searching iron-containingores.

Magnetic surveys on scales 1/10000,1/5000 and 1/2000 are fulfilled for moredetailed analysis of magnetic anomalies,detection of ore bodies and tectonic distor-tions, and for the estimation of the dimen-sions, shape and location of ore bodies.

Ground magnetic surveys are carried out,as a rule,. on areas which are recognizedprospective by the results of aeromagneticsurveys. Observation profiles are assignedacross the strike of anomalies on aeromag-netic maps. Spacings between the profilesdepend on the scale of surveys and can rangefrom 500 m (1/50000) to 50 m (1/5000).Distances between the observation points onprofiles should be 50-60 per cent smaller thanthe profile spacings.

The connection of observation points canbe done by instrumental (in prospectingwork) or semi-instrumental methods. In the

14.7. Mine-Surveying Work in Geophysical Prospecting 341

the accuracy of planimetric connection;(b) observation points located on profiles

and beyond them are connected, i. e. theirplan coordinates and elevations are deter-mined; this should be done for all points ofgeodetic observations;

(c) the topographic basis for geophysicalmaps is formed; and

(d) height differences around the gravi-metric points are determined in order to takeinto account the effect of a terrain relief onthe measured values of a gravity force.

In aerogeophysical prospecting, the planconnection of aerogeophysical routes isusually done by aerial photogrammetry.

14.7.1. Mine-Surveying Workin Gravitational Prospecting

The mine-surveying work in gravitationalprospecting consists of the following opera-tions:

(a) the transfer of the design position ofreference and ordinary gravimetric pointsinto nature (laying-out of base lines, profiles,etc.);

(b) fixation of the points by suitable marks;

(c) determination of the plan and elevationcoordinates of observation points;

(d) determination of relative height dif-ferences around observation points in order totake into account the effect of a terrain relief;

(e) provision of the geodetic basis forgravimetric maps; and

(f) the technical control and estimation ofthe accuracy of the work performed.

The planimetric connection of gravimetricprospecting points can be carried out byusing topographic maps on scales corres-ponding to or larger than the scale of agravimetric survey, aerophotogrammetricmaterials, instrumental geodetic methods,autometric topoconnectors, etc.

For determining the elevations of gravi-metric points, it is possible to use topo-graphic maps on scales which ensure the re-quired accuracy; geometric and trigonometriclevelling; barometric levelling; materials ofstereophotogrammetric surveys; and hydro-static levelling.

The permissible errors for determining thepositions of the points of gravimetric obser-vations are given in Table 14.6.

In cases when the surface of observations

Table 14.6

Scale of gravimetric

mapInterval, milligal Root-mean square erros (m) of point position relal

initial points

in elevationin plan

flat terrain flat terrainmountainousterrain

mountainousterrain

flat terrain mountainousterrain

'1000000'200000'100000150000

::t200::t100::t80::t40::t40::t20::t20::t4::t4::t2

:!: 5.0

:!: 2.5

:!: 1.2

:!: 0.70

:!: 0.35

:!: 0.35

:!: 0.25

:!: 0.20

:!: 0.10

:!: 0.05

:t 100

:t 100

:t 50

:t 50

:t 25

:t 25

:t5

:t5

:t2

:I: 3.0:I: 1.8:I: 1.6:I: 0.9:I: 0.9

:I: 0.45:I: 0.25

0.5

0.25

0.25

0.20

0.20

0.10

0.05

1.00.500.500.250.500.200.10

1/25000

:to.1


cartographic materials of an appropriateaccuracy, which are not always available,especially for what is called the closer zone,i. e. the portion of the Earth's surface in thedirect vicinity of a gravimetric point. In suchcases, levelling of the surrounding terrain iscarried out along radial rays (eight or six-teen). The radial distances from a gravimetricpoint to staffing points are usually takenequal to 1.2 m, 2 m, 6 m, 15 m, 35 m, 75 mor 150 m.

~

~

"Z--(

~

14.7.2. Mine-Surveying Workin Electric Prospecting

The mine-surveying work in all kinds ofelectric prospecting is carried out mainly forthe preparation and connection of obser-vation points and detected anomalies on theterrain and for laying-out and surveying ofbase lines and profiles.

The principal requirements to the accu-racy of the mine-surveying work in electricprospecting are given in Table 14.7.

The mine-surveying work in various kindsof electric prospecting has certain specifics.

Fig. 14.6 Terrain relief represented as combina-tion of elementary separations

differs substantially from a planar one deter-mining the relief corrections which are intro-duced into the observed values of the gravityforce has certain specifics. With either posi-tive or negative relief, the gravity forcedecreases, because of which the relief cor-rection is always introduced with a positivesign.

Corrections for the surrounding relief arecalculated for individual annular concentriczones around a gravimetric point. Since theterrain relief in an annular zone may bevariable, these zones are further subdividedinto curvilinear prisms which are calledelementary separations (Fig. 14.6). The realsurface of each elementary separation isreplaced by a horizontal plane whose eleva-tion is equal to the mean elevation of theelementary separation relative to an obser-vation point.

The correction for the surrounding reliefcan be determined directly on a topographicmap or by instrumental measurements.

For determining the relief corrections withthe required accuracy, it is essential to have

B

Fig. 14.7 Electric prospecting by probing

14.7. Mine-Surveying Work in Geophysical Prospecting 343

Table 14.7

Method of electric prospecting Map scale Root-mean square errors of point position relativeto initial points

in plan in elevation

flat terrain mountainousterrain

1/5000

1/10000

1/25000

1/50000

1/50000

1/200000

Natural field, induced polarization, transient,electroprofiling, isolines, etc.

4

8

20

40

40

160

5

10

25

50

50

200

5

5

10

10

1/50 of reference

level depth, but not

more than 15 m

Specified

Telluric currents, magnetotelluric profiling,and magnetotelluric probing

Vertical electroprobing; dipole probing,partial electromagnetic probingFormation of electromagnetic field

Ditto Ditto Ditto

Ditto Ditto Ditto 1/50 of referencelevel depth

receiving loop q, an active distance 001 andan angle 6 (Fig. 14.7). The length of thefeeding dipole can be calculated by the coor-dinates of the feeding dipole AB centre 0 andthe centre of a receiving circuit 01. Theconnection of points A, B, 0, and 01 isusually done by means of topographic mapsor aerophotogrammetric materials.

14.7.3. Mine-Surveying Workin Seismic Prospecting

In seismic prospecting by the reflectedwave method, seismic profiles are laid out onthe ground and connected in plan and ver-tically by instrumental methods. In the ref-racted wave correlation method, seismic pro-files are connected instrumentally, and theexplosion points located beyond the profilesare connected in plan. In seismic logging, it isrequired to determine the distances betweenthe logged and explosion boreholes, heightdifferences between them, and the directionangle from the logged boreholes onto explo-sion points. In spatial mass probing, the planand elevation positions of probes and explo-

For instance, in the method of isolines, linearelectrodes are laid on the ground at distancesof 500-1500 m from one another and connec-ted by insulated wires to the poles of acurrent source. The points of the same poten-tial are found on the terrain by means ofwhat is called a search circuit. The mine-surveyor's task in this case is to determine thepositions of these points. In regional pros-pecting, the coordinates of these points aremainly determined by the materials of aero-photogrammetry and in detailed work, byinstrumental methods.

In induction, natural direct current and thelike methods, the points for setting up instru-ments in regional prospecting are determinedby reference to aerophotogrammetric mate-rials and topographic maps and in detailedwork, by measurements on a preliminarilylaid-out square or rectangular network.

In electric prospecting by probing meth-ods, the object of mine-surveying is todetermine the plan and elevation coordinatesof a record point Q, which is required for theconstruction of a geoelectric section, thelength of a feeding dipole AB, the area of a


Table 14.8 Table 14.9

Scale of magnetic Root-mean square Relative error ofsurveying error of connection measured distance

of initial point of between profileprofile or base line pointsrelative to initial

pointsin plan in elevation

1/500001/250001/100001/50001/20001/1000

15

15

8

1/100 of intervalbetween pointson profile

8

sion points are determined, and the figure forthe arrangement of seismographs is con-structed.

The accuracy requirements for the mine-surveying work in seismic prospecting aregiven in Table 14.8.

In seismic prospecting in seas at a smalldistance from the coast, observation pointscan be connected by means of a reflectingcircle (index) by the method of resectionsonto the initial points on the coast. In suchcases, profiles are ranged out by poles orbuoys set up at intervals not more than2-3 km in detailed surveys or 5-6 km inregional surveys. In cases when the seismicwork is being carried out far from the coastalline, observation points are connected mainlyby radiogeodetic methods.

(a) profile methods with a preliminarilylaid-out observation network;

(b) profile methods with the simultaneoussemi-instrumental layout of an observationnetwork; and

(c) route methods with the observationpoints being read off from a topographic mapor aerophotogram.

In magnetic prospecting with a prelimi-narily laid-out observation network, theaccuracy of the mine-surveying work shouldbe as given in Table 14.9.

Profile methods with the simultaneoussemi-instrumental layout of an observationnetwork are usually employed in the searchwork on a scale of 1/50000, 1/25000 or1/10000 in woody territories; in that case,survey profiles can be ranged out by amagnetic azimuth, and distances along aprofile can be measured by striding.

Magnetic surveys are carried out, as a rule,along roads, forest cuttings, footpaths, rivers,etc., and the surveying net is connectedvisually to the orientation marks which arepresent both on the ground and on the map.The errors of the planimetric positions ofpoints on a survey line should not exceed 1/4of the spacing between the points, but notmore than 250 m in any case.

14.7.4. Mine-Surveying Workin Magnetic Prospecting

In ground magnetic surveys, the mine-surveying work includes the transfer of thecontours of a survey area, layout, connectionand fixation of observation points, and theconnection and fixation of detected anom-alous zones, structures, etc.

In ground magnetic prospecting, the meth-ods of the preparation of observation pointscan be divided into three main types:

14.8. Barometric Levelling of Observation Objects 345

Table 14.11

Root-mean squareerror of measured

heights, m

Time intervals between meas-urements of pressure and tem-perature of atmospheric air at

barometric stations, min

in flatland re-gions

in mountain-

ous regions

0.35

0.5

1.0

2.5

5.0

10

10

15

20

30

1010101520

accuracy. In all methods, however, the mea-surements of air temperature at particularpoints and initial barometric stations aredone at the same time with measuring theatmospheric pressure. Barometric stationsshould be located on open places with smoothshapes of the relief. It is not advisable tolocate stations on sharp summits, in deep andnarrow valleys, on the crests of cliffs, and (insummer time) near large water basins.

Instruments for atmospheric pressuremeasurements should be placed at baromet-

14.8. Barometric Levellingof GeologicalObservation Objects

Barometric levelling has found rather wideuse for the elevation control of geologicalsurveys. It is mainly resorted to in cases whenother levelling methods are insufficientlyaccurate or less efficient economically. Themethod is especially popular in gravitationalprospecting. An essential advantage of baro-metric levelling is that it is applicable evenwhen the points to be levelled are mutuallyinvisible.

The accuracy of barometric levelling de-pends on the instruments employed, kind of aterrain relief, and the techniques of levelling.

Barometric levelling is based on a certaincorrelation between the elevation of a terrainand atmospheric pressure. As has been de-monstrated by the practice of levelling, withproperly organized work it is possible tomeasure elevations with an error less than0.5 m. Depending on the accuracy of mea-surement of the elevations of geological ob-servation points, the recommended accuracyin the measurements of atmospheric pressureis given in Table 14.10.

Barometric levelling in geophysical surveyscan be carried out by various methods, thechoice of a particular method being depen-dent on the scope of work, available instru-ments, number of observations, and required

Table 14.12

Root-mean Mean distance Mean height differencesquare error of observed of observed points re-of height dif- points from lative to TBS *, m

ference, m TBS *, kInTable 14.10

without cor- with cor-rection for sys- rectiontematic errorof air tempe-rature meas-

urement

Root-mean square Root-mean square error of meas-error of measured ured atmospheric pressure, mb

heights, m

at observation-~:-,.

at barometric

0.4:>0.700.902.0

L.-()

2-9

2-13

10-25

)U-IU80-20

110-10210-30

14U-4j

245-55

320-45

680-180

:I: 0.35:I: 0.5:I: 1.0:I: 2.5:I: 5.0

::!: 0.015

::!: 0.020

::!:0.05

::!: 0.15

::!: 0.30

:t 0.010

:t 0.015

:t 0.03

:t 0.05

:t 0.10 .TBS -temporary barometric station.


Table 14.13

Root-mean square errorof height difference, m

Time of traverse Mean length of tra.run, h verse, km

Mean height difference of observed pointsrelative to TBS, m

without correctionfor systematic errorof air temperature

measurement

with correction

0.25 1.02.04.01.02.04.01.02.04.01.02.04.06.08.02.04.06.08.0

2.7

2.6

2-4

5-15

5-14

5-9

5-40

5-25

5-155-50

5-40

5-20

5-13

5-12

10-50

10-30

10-15

10-15

20-5

20-5

20-5

50-10

40-10

40-5

85-35

85-35

75-10110-50

110-10

100-25

100-10

95-5

240-200

240-200

230-210

220-200

70-25

70-10

60-5

140-25

130-20

120-10

240-70

240-90

235-65

320-130

320-40

310-40

290-50

280-5

700-550

700-540

700-590

700-570

0.45

0.70

0.90

2.0

Table 14.14 Table 14.15

Root-mean Mean dist- Mean height difference ofsquare error ance between points relative to RBS * inof height dif- RBS *, km calculation, m

ference, m

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Permissible fInS error ofcomparison of mercurybarometers at referencestations, mb

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measurement

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150

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34714.8. Barometric Levelling of Observation Objects

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Time intervals between the measurementsat barometric stations and points depend onthe error in elevation measurements at thepoints and can be determined according toTable 14.11.

Barometric levelling can be carried out byone of the following methods.

Barometric levelling by the methods oflevel lines can be performed with reference toone initial point.(closed level lines) or to twopoints (open lines). A temporary barometricstation is arranged at the initial point of aclosed level line. With an open level line, onetemporary station is placed at the initialpoint and another, in any point of the line.

In the method of closed level lines, it ispossible to work with one or two barometers.

Barometric levelling by the method ofclosed level lines should"be done according tothe requirements given in Table 14.12.

Barometric levelling by the method ofopen level lines is carried out with the use oftwo sets of barometers. In this method, thedeviations of observed points from the range

~

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~


where H~, H~, and H~ are the preliminaryelevations of the point observed and k1, k2,and k3 are the weight coefficients whichdepend on the position of the point and canbe found by the formulae:k1 = 11/ Ll, k2 = 12/ L2, k3 = 13/ L3

where 11 = Oa, 12 = Ob, 13 = Oc, L1 = Aa,L2 = Bb, and L3 = Cc.

The elevation of the observed point iscalculated by a scheme given in Table 14.16.The elevations, H, of reference stations arerecorded in column 4. The distances, I, fromthe observed point to the side connecting twoother barometric stations are written as nu-merators in column 5 and the distances, L,from a barometric station to the same sidethrough the point being observed, as deno-minators in the same column. Columns 7, 8,9, and 10 contain data from the field books.The difference in atmospheric pressure, l\P ,between the barometric station and the pointobserved is calculated in column 11. Column12 contains the values of barometric stages.The values given in columns 11 and 12 arethen multiplied to give the height differencebetween the barometric station and the pointobserved (column 13). The preliminary valuesof elevations found by algebraic summationof the elevations of barometric stations andelevation differences are written in column14. Finally, column 15 gives the elevation ofthe 'point observed, which is obtained bysumming the products of preliminary eleva-tions and the c9rresponding coefficients.

line of initial points should be not more than0.2 of the distance between these points. Theprincipal requirements to the field work bythis method are given in Table 14.13.

In barometric levelling by the method withseveral barometric reference stations, thesestations are located so that all points ofobservation can be inside the figure formedby the stations (in most cases a triangle). In aparticular case, barometric reference stationscan be located on the range line. The permis-sible distances between the barometric re-ference stations should be as recommended inTable 14.14.

In this method, it is possible to use meteo-rological stations or special temporary ref-erence stations. All barometers used at thestations are standardized by determiningtheir corrections relative to one of themwhich is taken as the standard instrument.The standardization of barometers should becarried out with an accuracy as specified inTable 14.15.

The elevations of observed points are de-termined by the results of the measurementsof air temperature and pressure at thesepoints, which are done at the same time withair temperature and pressure measurementsat the stations. The point elevations arecalculated as weighted mean values, by con-sidering the following circumstances.

Let an observed point O be inside areference .triangle ARC (Fig. 14.8). The ele-vation of the point O can be calculated by theformula:H = H~k1 + H~k2 + H~k3

Chapter Fifteen

Mine-Surveying Work for Mineral Extractionin Water Areas of Seas and Oceans

15.1. General

One of the novel trends in mining industryis the exploitation of mineral resources of theOcean bottom. Our knowledge of the Oceanis still insufficient for large-scale mining of itsminerals, but it can be already stated quitedefinitely that the mineral reserves in theshelf and deep-sea zones of the Ocean areenormous and can be estimated approxi-mately by the following figures: 4 x 1015 t ofaluminium, 100 x 109 t of cobalt, 300 x 109 tof nickel, 350 x 109 t of copper, 42 x 109 t ofmanganese, 120 x 106t of zirconium, 80 x 106tof molybdenum, etc. In addition, almost allelements of the Periodic Table are present inthe Ocean in the dissolved state.

The sea medium has certain specific fea-tures which can influence the organizationand accuracy of the mine-surveying work.The principal among them is the dynamics ofwater masses. The level surface of the Oceanis subject to periodic, non-periodic and secu-lar variations. Periodic variations mainlyinclude tidal oscillations. Non-periodic va-riations may be of geodyllamic or geothermalorigin, i. e. they may be caused by earth-quakes, underwater volcanic eruptions, tec-tonic disturbances in the Earth's crust, watersurges, occasional sharp changes of atmos-pheric precipitation, changes of atmosphericpressure, etc. For estimating the dynamicconditions of the level surface of the Ocean,of prime importance are the tidal phenomenawhich may depend substantially on the geo-graphic latitude, depth of sea, and the shapeof a coastal line. The highest water level at

tides is called high water, the lowest level atebbs is low water, and the medium level iswhat is called mean water. In open sea, thetidal variations of the water level are equal toroughly 1 m; near coasts, especially at thehead of narrow bays, the difference betweenhigh and low water may attain a few tens ofmetres.

The surface of seas and oceans to a depthup to 60 m can be disturbed substantially bywinds which often create waves up to 12-13 mhigh. The effect of wind disturbance is espe-cially detrimental for the accuracy of mine-surveying observations, since prospectingand mining work in seas are carried out nowand will be done in the nearest future only inthe shelf zone where the effect of wind wavesis quite strong.

Water waves can be characterized by thelength, height, velocity, period, front, andsteepness. The length A of waves is thehorizontal distance between the crests (ortroughs) of adjacent waves; height h is thevertical distance from the trough to the crestof a wave; velocity v is the distance coveredby a wave crest in unit time; wave period Tisthe time interval during which two wavecrests pass successively through a given point;wave front is a line perpendicular to thedirection of wave motion; and steepness is theheight-to-length ratio of a wave.

As a wave approaches the coastal line, itsprofile changes substantially. The top portionof the wave slope facing the coast becomessteeper, i. e. the wave profile becomes asym-metrical. The asymmetry of waves is notice-

350 Ch. 15. Mine-Surveying Work in Water Areas of Oceans

portion of the bottom at the external edge ofthe shelf. Its width is rather small and usuallymeasures from 15 km to 30 km. Inclinationangles are equal to 3-6° on the average,ranging from lO to around 45°. The surface ofthe continental slope is often furrowed byU-shaped valleys called submarine canyons.Submarine canyons may have a length froma few tens to a few hundreds of kilometresand penetrate to depths of 3-4 km.

The continental slope changes to what iscalled the continental base, a slightly inclinedundulating plain at depths of 2-4 km.

2. The transition zone II is an intermediatezone between the submerged margin I of thecontinent and the ocean bottom (floor) III.This zone has the basin of marginal sea at theside of the continental base and island arcslIb and deep-sea troughs IIc, at the side ofthe ocean. The deep-sea troughs form theboundary between the continent and ocean,so that one of their slopes is represented bythe continental crust and the other by theoceanic crust.

3. The ocean floor III is represented by theoceanic type of the Earth's crust and lies atdepths of 2500-6000 m. It mostly has a hillyrelief of the accumulative type with largeoceanic troughs and uplifts.

able at depths roughly twice the wave height.At the coast, wave crests tip over and formfeathers, or breakers.

As the wind velocity decreases, water wa-ves attenuate slowly, the rate of attenuationbeing proportional to the wave length. Thewaviness of the sea surface that remains afterwinds have ceased to blow is called swell, oraftertossing.

15.2. Brief Data on Geomorphologyof Ocean Bottom Relief

By modern concepts, the ocean bottom hasfour structural zones (Fig. 15.1 ).

I. The first is the submerged margin I,which includes the shelf la, continental slopeIb, and continental base Ic. The submergedmargin is regarded geologically as the flood-ed portion of the continental plateau which ischaracterized by relatively calm tectonicconditions and markedly prevailing slowvertical deformations of the surface. The shelfis essentially a shallow-water portion of thesubmerged margin, which extends from thecoastal line to a sharp bend of the bottomsurface, usually at a depth of 130-140 m. Thepart of a shelf to a depth of 30-50 m is calledshoal.

The continental slope is a relatively steep

Fig. 15.1 Profile of ocean bottom: l-submerged margin; la-shelf; lb-continental slope; lc-contin~ntalbase; ll-transition zone; lla-pits of marginal seas; llb-island arcs; IIc-deep-sea troughs; III -oceanbottolD; lV -mid-ocean ridges

15.4. Geological Prospecting and Mining 351

4. Mid-ocean ridges are essentially moun-tainous formations of a width of 500-2000 kID.A depression, or rift valley, usually runsalong the axial line of a ridge. At both sidesof the rift valley, there are rift crests withindividual summits 7000-8000 m high abovethe foot of a mid-ocean ridge. Earthquakecentres (foci) are confined to rift crests.

15.3. Characteristicsof Some Solid Minerals

At present, over loo countries are carryingout geological prospecting in the water areaof seas and oceans, and enormous reserves ofminerals have already been discovered(Fig. 15.2).

Submarine deposits of minerals are con-ventionally classified by the following groups:metal-bearing concretions and red clays;primary deposits; and submarine sedimenta-ry deposits, mainly shelf placers andmetal-bearing silts.

At present, shelf deposits attract the maininterest, in particular, placer deposits formeddue to the dynamic activity of seas and thechemical processes occurring in sea water.

By the time of origin, submarine placerscan be classed into buried (concealed), con-tinental, and young (present-day). Buriedplacers formed on overlapping of ancientplacer deposits by younger sediments atchanges of the sea level and displacement ofthe coastal line. Continental buried depositsare formed due to sinking of the coastalsurface of land below the sea level. All buriedsubmarine placers, as a rule, are not subjectto hydrodynamic actions and lithodynamicchanges. Present-day placers are more easilyaccessible for exploitation than other types,since they are not covered by sediments.Present-day placers mostly have the shape ofbands extended along the coastal line.

Delta placers have an irregular shape inplan and variable characteristics. Shelf pla-cers can be characterized by a very thin bed

of sands and a high concentration of usefulcomponents in them (up to 90% of non-na-tive ones). As a rule, band-shaped shelf pla-cers have discontinuities at capes and in riverestuaries.

Placers in the continental slope are usuallylocated at distances from 500 m to 15 kmfrom the coastal line and have a length of afew tens of kilometres and width, .a fewhundreds of metres.

The mechanism of transfer of heavierminerals forming a submarine placer is deter-mined by the same processes as the transferof the mass of sediments forming the bottomtopography.

15.4. Mine-Surveying Serviceof Geological Prospectingand Mining in Water Areas

In prospecting for submarine deposits, themine-surveying service has the followingobjects:

(a) the collection and examination of geo-detic, hydrographic and meteorologicaldocuments available for a given water area;

(b) the provision of the planimetric andelevation survey control for the coastal partof land and alloted water area;

(c) the complementary surveys of the bot-tom relief and prospecting workings;

(d) the control of the positions of pros-pecting and mining workings in the waterarea upon their transfer into nature;

(e) the compilation of the graphicaldocumentation of the alloted water area,which should reflect the bottom relief of abasin, the shape, dimensions and geologicalcharacteristics of a deposit, and the charac-teristics of enclosing rocks;

(f) surveying of underwater workings;(g) the calculation of the mineral reserves;

and(h) the analysis of the lithodynamic chan-

ges of the bottom relief.In the construction of underwater wor-

352C

h. 15.

Mine-S

urveying W

ork in

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35315.5. Marine Mine-Surveying Reference Nets

15.5. Marine Mine-SurveyingReference Nets

Marine mine-surveying reference nets aredeveloped for making various surveys asso-ciated with prospecting and mining of thebottom of seas and oceans (Fig. 15.3). De-pending on the distance from the coast, theycan be divided into off-shore nets which areformed in the zone of geometric visibilityfrom the coastal line and open-sea nets, i. e.those beyond the geometric visibility.

Off-shore surveying nets are developedfrom geodetic nets on the shore land and

kings and the exploitation of deposits, thetasks of the mine-surveying service are asfollows:

(a) survey work for the construction ofengineering structures in the water area(wharfs, pulp pipelines, hydro-engineeringobjects, etc.);

(b) the development of measures for theprotection of structures and environmentagainst harmful effects of underwater wor-

kings;(c) the transfer of the geometrical elements

of designed structures and objects into na-ture.,

(d) the control of assembling of plants,hydro-engineering objects, etc.;

(e) the assignment of directions to strip-ping and preparatory mining workings;

(1) servicing and control of the dynamics ofstripping and mining work;

(g) the complementation of mine-sur-veying plans, sections and graphical docu-mentation with the results of the surveys ofmining workings and waste dumps;

(h) the compilation of mining-geometricafgraphs for more accurate determination ofthe shape of a deposit, quality of a mineral,properties of enclosing rocks, and the distri-bution of useful components;

(i) the control of the variations in litho-dynamic processes during the exploitation ofdeposits and the prediction of changes in thedepth and contours of underwater workings;and

0) the calculation of the dynamics ofmineral reserves, output, losses and dilutionof minerals.

Mine-surveying measurements in the waterarea should provide data on the dimensions,shape and structure of submarine deposits,which are then represented in graphicaldocuments. The mine-surveying work inwater areas consists mainly in profiling of thesea bottom and underwate:r workings.

23-1270


1a) Ibl (c)

12

(d) (e)

Fig. 15.4 Bench marks for marine mine-surveying nets: (a) pole-type; (b) pile-type; (c) wooden frame;(d) metallic frame; (e) buoyant; 1- bottom of sea or basin; 2 ~ water line; 3 ~ earth embankment; 4- tube orrod; 5- bench mark centre; 6- end fastening (plug); 7 ~ concrete filling; 8- instrumental platform enclosure;9-navigation signal; 10-bench mark platform or pontoon; 11-boundary of compacted layer;12-concrete filling; 13-concrete base; 14-counterweights; 15-buoy rope; 16-anchors; 17-bottomcentrethose in the open sea, from the points of a polygonometric method is mostly employedmarine mine-surveying net, in particular for deposits extended along the coastal line.from a local net connected to the geodetic The root-mean square error of determi-reference net on the land. nation of the direction angles of sides in

Marine mine-surveying nets can be const- marine mine-surveying nets should not ex-ructed by the methods of triangulation, trila- ceed I'. For the plan positions of the points ofteration and polygonometry. Reference nets a net, the rms error should be not more thanfor deposits located near the shore can be 0.2 mm on the scale of a plan.constructed by the methods of intersections, The elevation control for the surveyingcombined intersections or resections. The work in the near-shore water area is provided

15.6. Special Mine-Surveying Work in Water Areas 355

nometric traverse; L is the length of theclosing line of a traverse; mp is the rms errorof angle measurement; n is the number ofsides in a traverse; and D is the distance fromthe centre of gravity of a traverse to eachturning point.

The best time for observations and mea-surements is when the temperature of watersurface is close to that of air, since thisminimizes the effect of refraction on meas-ured results.

by levelling points. The absolute elevationmarks of survey points on the shore aredetermined by geometric or trigonometriclevelling and of those in the water area,mostly by trigonometric levelling. The rmserror in the determination of heights of thepoints of marine (off-shore) nets relative toinitial (control) bench marks should not ex-ceed 0.02 m and the rms error of heightdifference between two adjacent points,should be not more than 0.05 m. When thewater area is covered by firm ice, it is morepreferable to use geometric levelling.

The points of marine reference nets arefixed by means of special bench marks (bea-cons) which may be of the pole-type (Fig.l5.4a), pile-type (Fig. l5.4b), with a woodenor metallic frame (Fig. l5.4c and d), orbuoyant (Fig. 15.4e) with automatic correc-tion or recording of their deviations from thecentre.

Marine bench marks should be set upbefore the beginning of stormy seasons, andeach should be provided with a navigationsignal. If a marine mine-surveying net isdeveloped on ice, its points can be marked bymetal rods qr wooden poles frozen into theice.

Polygonometric traverses should be run sothat the mean arithmetic error of the finalpoint of a traverse line of any shape is nothigher than the value calculated by theformula:

15.6. Special Mine-SurveyingWork in Water Areas

In the general case, all kinds of the mine-surveying work carried out on submarinedeposits can be divided into special androutine.

In special mine-surveying work, mine sur-Veyors together with geologists determine thegeological and hydrogeological characteris-tics of deposits, geomorphological and li-thodynamic specifics, hydraulic conditions inthe water area, etc. The main object of specialwork is, however, to analyse the lithodyna-mic processes responsible for the variabilityof a given relief and to determine the prin-cipal parameters of the deposit and under-water workings. Surveys for mapping of adeposit should be carried out both in theperiod of detailed prospecting and duringexploitation. It is principally important todecide on the frequency of repeated obser-vations which should be such that the varia-tions of relief that may occur between thesurveys can be commensurable with theaccuracy of surveying. The frequency of ob-servations is usually determined experimen-tally.

Special mine-surveying work also includesthe formation and development of planimet-ric and elevation control (for off-shore andopen-sea mine-surveying nets), establishmentof level-gauging stations, navigation marks,etc.


dinates and depth measurements are plannedso as to attain the required accuracy andminimize the number of traverses which mayhave different directions depending on thepattern of the bottom relief and the purposeof surveying (Fig. 15.6). The survey methodwith parallel traverses is used most often(Fig. 15.6a). Traverses should be directed inthe sense of the highest ruggedness of thebottom relief; for workings, they should beoriented perpendicular to their axis. Depthmeasurements can be made by zig-zag(Fig. 15.6b and c) or radial traverses (Fig.15.6d). Zig-zag traverses are used when it isessential to reveal sharp bends of the relief,such as in hollows, valleys, ranges, etc. Radialtraverses are run in cases when they canrepresent a relief without noticeable distor-tions (which is possible since radial traversesdiverge from the coast or control points, i. e.distances between them increase with movingfarther into the sea). Radial traverses areused, for instance, for surveying of capes,off-shore bars, islands, and extended andweakly dissected surfaces of the bottom relief.

The root-mean square error of locating thebottom relief points in mine surveys shouldbe not more than 1.5 mm on the scale of a

15.7. Routine Mine-SurveyingWork in Water Areas

The main objects of the routine mine-sur-veying work are to provide the basis andcontrol for geological prospecting and thebasis for the mining work.

The basis for geological prospecting inwater areas is done by preliminary investi-gations which consist in observations on thehydrologic conditions of the sea and thelithodynamic processes in loose sediments onthe bottom. These observations include lar-ge-scale surveys of the bottom relief and thedetermination of the planimetric and heightcoordinates of prospecting boreholes, con-tours of ditches and trenches, points of geo-logical sampling, and the corner (final) pointsof traverses in mine-surveying and geophy-sical profiling.

In the period of underwater mining work,mine-surveying service makes the surveys ofunderwater workings and represents them onthe plans of the mining work and compilesprofiles and sections. The results of surveysmake it possible to calculate the volumes ofextracted rock and determine the places ofmineral losses and sources of mineral dilu-tion.

The set of mining graphical documentationincludes the plans of the submarine miningwork on scales 1/1000 or 1/2000, lithologicalsections along prospecting lines, and theprofiles of ~arlier exploring and mining wor-kings in the most typical directions.

The contours of a deposit and designboundaries of underwater workings aretransferred into nature and marked by meansof stakes, beacons or buoys (Fig. 15.5) set upin the sea at intervals of 100-200 m.

During prospecting and mining of a de-posit, surveys are carried out in order toobtain the plan coordinates and depths of thepoints of the bottom relief and underwaterworkings. In practice, these measurementsare usually made simultaneously. In the ge-neral case, the surveys of planimetric coor-

15.7. Routine Mine-Surveying Work in Water Areas

(a:

(c)Id)

,~~-I

~

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~

Fig. 15.6 Typical schemes of traversing in bottom relief surveying: (a) with parallel traverses; (b) withzig-zag extension traverses; (c) zig-zag traversing with control extension traverses; (d) radial traversingwith additional transverse extension traverses

base line and the line of sight on a vessel); Dland D2 are the distances from the base pointsto a vessel; and mp is the instrumental rmserror of angle measurement.

The plan position of a moving target isdetermined by the method of linear intersec-tion with the use of optical or radio rangefinders and with reference to two or threeinitial points. Optical range finders are emp-loyed in cases when linear intersections aremade to relatively shortJ distances (up to2 km and less frequently, up to 4-5 km).When the objects of marine surveys areremoved from the coast to distances morethan 3 km, use is made of high-precisionradiogeodetic and radionavigation systemswhich can determine the positions of pointsin the sea with the rms error around 1 m.

15.9. Depth Measurements

The measurements of the depths of bottompoints relative to the sea level can be made bysounding poles, sounding leads, echo sounders,photometric and stereophotogrammetricmethods. At present, echo sweeps and bot-tom-scanning sonars (asdics) are being emp-loyed widely.

A sounding pole is a metal or woodenround pole up to 5 cm in diameter and up to8 m long, which has 5-cm or 10-cm gradua-tions. Depths can be measured by soundingpoles with an accuracy to 2-3 cm. A handsounding lead consists of a hemp or metalrope with a lead or cast-iron weight around5 kg in mass tied to its end. The rope isgraduated in metres and decimetres by themarks of different colour. Hand leads canmeasure depths up to 50 m with a relativeaccuracy of I/lOO to 1/200. A mechanicallead (sounding machine) has a winch with acounting mechanism, rope, and weight up toloo kg in mass. The accuracy of depth mea-surements by sounding machines depends onthe degree of rope sagging which is deter-mined by the size and shape of the weight,

where v is the vessel velocity, m/s; D is thedistance from an observer to the measuredpoint, m; <p is the angle between the sightingline and the traverse line; p" = 206265"; andmIl is the rms error of angle measurement ofan instrument.

Noting the accuracy of angular measure-ments with a moving target, the rms error ofthe plan position of a moving target deter-mined by the method of intersections can beexpressed by the formula:

2 b2 [ ( .2 A .2 A )mmt = 2 .4 mIl Sill 1'1 + Sill 1'2p Sill '1

D~

where b is the length of a base; 'Y is the angleat the measured point; 1:11 and 1:12 are theangles at the base points (angles between the

+~)J

35915.9. Depth Measurements

Fig. 15.7 Operation oflaser-acoustic system in bottmark; R,,-elevation of point (bench mark) in adoptelho -reading of nth stage of photodetector; hi -readil

water flow velocity, variations of water ve-locity along the depth, and the length of arope. At present, depth measurements aremost often made by using echo sounderswhose operating principle is based on thepropagation of ultrasonic pulses emitted byan ultrasonic source and reception of pulsesreflected from the sea bottom.

The oscillations of floating vessels in roughsea reduce substantially the accuracy ofdepth measurements by echo sounders. Thiseffect is largely eliminated in laser-acousticsystems which have come into use in recenttime.

A laser-acoustic system (Fig. 15.7) is acombination of a laser and echo sounder andconsists of a laser sight 1 with a scanningattachment 2, vertical staff 3 with a photo-detector, acoustic system 4, electric pulsegenerator, amplifier, and a recorder.

The laser sight sends a beam 0-01 whichdefines a reference plane and enters thephoto-detector on the staff. The received

om profiling: Ah3 -height of laser sight above benchd system; h -depth of measured point on echogram;Ig of laser beam on vertical staff

pulse is transmitted to a pulse delay gene-rator which fonns a delayed pulse and thensends a starting pulse to the generator. Thelatter produces an electric pulse to excite theacoustic system which transfonns electricpulses into acoustic signals. Upon reflectionfrom the sea bottom, acoustic signals aretransfonned back into electric pulses. Theseare sent to the recorder which makes a recordof the sea bottom depths and the elevationmarks of the sea level.

The measured values of depths are reducedto a particular level of sea surface which iscalled the hydrographic datum, or datumlevel. For seas with small amplitudes of leveloscillations (height of tide up to 0.5 m), themean water level of many-years observationsis taken as the datum level. For seas withsubstantial level oscillations, the lowest levelsurface of the sea is taken as the datum level.

In surveys in water areas, depths aremeasured relative to a conventional (phan-tom) horizon which is called the datum and is


ing methods: (I) by the results of surveying;(2) by measuring the volumes of extractedrock shipped in ore carriers or contained inon-shore stores; (3) by the readings of flowmeters and consistometers mounted on pulppipelines.

Volume calculation by results of surveys.This method can be recommended for caseswhen the contours of mining workings arenot changed substantially during the periodof measurements.

The calculation of the volume of the ext-racted mineral on the basis of the results ofsurveys can be made most easily by themethod of horizontal sections. The volume ofa working is determined by the formula:

somewhat lower than the horizon of thelowest level. This is done in order thatcalculated levels may be always positive.

A level-gauge station, or simply gauge, ismade in the form of a level-measuring polewhich is fastened to a pile, wharf or anotherstationary structure. Level-gauge poles aremostly made of cast iron and have insertedporcelain pieces forming 2-cm graduations.Enamel-painted metal poles are also in use.

Depth measurements are also carried outfor studying the lithodynamic processes, inparticular, the intensity and amount ofwash-out (erosion) or, on the contrary, theaccumulation of drifted sediments on thebottom and in underwater workings.

The thickness of an active layer of sedi-ments is established by measuring the max-imum depth in fixed points in the periods ofrough sea, which can be done by the methodof a 'movable disc' or by successive mea-surements between the periods of rough sea.

The former method is employed at depthsup to 3 m and consists essentially in that thedisc is let to slide down a metal rod fixed inthe bottom, after which the depth of discsinking is determined on the staff that isconnected with the disc and protrudes fromwater. If the bottom ground is washed out,the disc sinks deeper and this is detected bythe changed position of the staff. Staff rea-dings can be done instrumentally from theon-shore or off-shore points of a referencenet. .

The method of successive measurements isnot as accurate as the former, but is lesslaborious. Measurements are carried outstrictly on the same profiles, and the thick-ness of an active layer is determined bydifferences between successive measurements.

15.10. Calculation of Volumesof Extracted Rock

The volumes of rock extracted in subma.rine mining can be calculated by the follow.

v = hm8m

where hm is the mean depth of a working, mand 8m is the mean area of a working, m2.

The mean area is found as the half-sum ofthe upper and lower areas:8m = (8u + 8,)/2

and the mean depth:h = ~h./nm I

where ~hi is the sum of measured depthswithin the boundaries of a working floor, mand n is the number of measurements.

In practice, the mean extractive capacity ofa mineral is usually determined as the dif-ference of the mean elevation marks of thesurface of a submarine deposit (within theboundaries of the upper crests of slopes) andof the bottom or as the difference of the meandepths of a working floor and the meandepths of the initial surface of the sea bottom.

Calculation of volumes in vessels and on-shore stores. In this method, the mine sur-veyor has to make the following operations:

(a) measuring the geometrical parametersof a vessel or store;

(b) determining the coefficient of filling ofa capacity with loose rock mass;

(c) calculating the volumes of loose rock in

15.10. Calculation of Volumes of Extracted Rock 361

Table 15.2

Rock Looseningfactor

Rock Looseningfactor

--1.15-1.301.30-1.451.40-1.601.45-1.65

1;--

a waste dump or vessel by the formula for thevolumes of regular geometrical bodies (acone, pyramid, cylinder, cube, etc.);

(d) determining the loosening factor of theextracted rock by considering the physicalstate and quality (moisture content, granu-lometric composition, etc.), time of storage,and the amount of settling;

(e) recalculating the volume of loose rockto that of rock in the rock massif, using theloosening factor;

Sand 1.01-1.02 LoamRiver gravel 1.03-1.04 ClaysGravel 1.07-1.18 ShingleCoarse- and Hard rocks

medium-grain sand I.

Pebbles,crushedstone I.

Sandv ]nam 1.1

14-1.28 Frozen flood

plain de-

posits in

23-1.30 river val-

07-1.18 leys and

estuaries 20-1.17

(I) making an additional survey of sub-marine workings in order to determine themineral reserves left in the ground and theamount of losses and dilution.

The most difficult step is the determinationof a loosening factor, but this can be takenfrom Table 15.2.

Determination of volumes of rock masstransported through pulp pipelines. In thiscase, the volumes of rock mass are determi-ned in terms of the flow rates of pulptransported through pipelines and measuredby means of flow-meters and consistometers.

Hydraulic-type flow-meters are used tomeasure the flow rate of hydraulic mixture(pulp) sucked in by a dredge. The density of apulp is determined by the pressure gradientappearing in the pulp in a vertical pipelineowing to the settlement of heavier fractions.Automatic recorders have been developedwhich record instantaneous and summarizeddata on the throughput capacity of a pum-ping station and dredge, pulp density, andactual time of operation. The error of volumemeasurements by flow-meters is not morethan 3 per cent.

mine surveying

Documents

survey work

survey underground nets

surveys chapter

vertical surveys

surveying of workings

surveying work

underground theodolite

geodetic survey nets