Research ArticleResearch on Effects of Blast Casting Vibration and VibrationAbsorption of Presplitting Blasting in Open Cast Mine

Li Ma12 Kemin Li2 Shuangshuang Xiao2 Xiaohua Ding2 and Sydney Chinyanta2

1State Key Laboratory for Geomechanics amp Deep Underground Engineering China University of Mining and TechnologyXuzhou Jiangsu 221116 China2School of Mines China University of Mining and Technology Xuzhou Jiangsu 221116 China

Correspondence should be addressed to Kemin Li likemin513126com

Received 3 January 2016 Revised 16 June 2016 Accepted 29 June 2016

Academic Editor Georges Kouroussis

Copyright copy 2016 Li Ma et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The impact energy produced by blast casting is able to break and cast rocks yet the strong vibration effects caused at the sametime would threaten the safety of mines Based on the theory of Janbursquos Limit Equilibrium Method (LEM) pseudo-static methodhas been incorporated to analyze the influence of dynamic loads of blasting on slope stability The horizontal loads produced byblast vibrations cause an increase in sliding forces and this leads to a lower slope stability coefficient When the tensile stresses ofthe two adjacent blast holes are greater than the tensile strength of rock mass the radical oriented cracks are formed which is theprecondition for the formation of presplit face Thus the formula for calculating the blast hole spacing of presplit blasting can beobtained Based on the analysis of the principles of vibration tester and vibration pick-up in detecting blast vibrations a detectionscheme of blast vibration is worked out by taking the blast area with precrack rear and non-precrack side of the detection objectThe detection and research results of blast vibration show that presplit blasting can reduce the attenuation coefficient of stress waveby half and the vibration absorption ratio could reach 502 the impact of dynamic loads on the end-wall slope stability coefficientis 198 which proves that presplit blasting plays an important role in shock absorption of blast casting

1 Introduction

Blasting operation the initial step in open-pit mining maybreak the ores into fragments so that they can be minedand loaded by excavating equipmentHowever this operationmight create environmental impacts such as air overpres-sure ground vibration fly-rocks and back-break aroundthe blasting zone [1ndash3] Blast casting in open cast mines isusually associated with high bench large hole diameter andlarge explosive charge More than 30 stripping materialsare cast into mined-out area as a result the operation ofsurplus overburdens in mining loading and hauling can berelatively reduced resulting in a reduction in stripping costsand transportation costs Based on the operation featuresof mining and loading equipment the stripping technologycomposed of blast casting with dragline displays evidenteconomic advantages among various mining technologies asblast casting is applied in rock breaking step The shift andtransportation of surplus material can be realized with the

coordinated application of dragline stripping equipmentThetotal number of blast holes in a high bench blast casting can bemore than 500 The explosive charge in one hole is between18t and 27t and the aggregate explosive load reaches 900tto 1500t High bench blast casting may not only cause strongvibration effect and affect large area but also exert severeinfluences on surrounding buildings and pit slope [4 5]Consequently controlling the vibration effects of blast castingand reducing the negative effects are of great importance tomaintaining the regular production and work safety in opencast mines [6 7]

The effective blast energy used for breaking and castingrocks only accounts for 20 to 30 of the gross energyand the rest of the energy is distributed to producing fly-rocks causing vibration effect and dissipating into the airVibration velocity of rock mass particles is an importantindicator for describing the intensity of vibration effectExplosive volume charge position explosive type detonationdirection and charge structure directly affect the vibration

Hindawi Publishing CorporationShock and VibrationVolume 2016 Article ID 4091732 9 pageshttpdxdoiorg10115520164091732

2 Shock and Vibration

Table 1 Basic information of the minable coal seam

Coal measure era Coal seam type

Thickness of coalseam

MinsimmaxAveragem

Coal seam spacingMinsimmaxAveragem

Coal seam structure Stability

Taiyuan formation 66I

010 sim 1265

278

0 sim 958

113

Complex Unstable

6II005 sim 771

326

0 sim 958

113

0 sim 546

025

Complex

6IIIsimVI050 sim 2719

2276

0 sim 546

025

Complex Relativelystable

strength [8] Therefore millisecond blasting together withthe detonation direction is often adopted to control theignition charge over the same period Presplit blasting isoften used to control the blast vibration effect and mitigatedisasters caused by vibrations Changing the charge structureis also a conventional method [9ndash11] with which presplitblasting can exert positive effects on shock absorption andreduce detonation wave propagation since it is able to formpresplit cracks with a definite width and depth before thedetonation of the main blast hole This leads to terminationof the transmission of detonating waves Presplit cracks causereflection and refraction on stress waves causing the stresswave energy transmitted into rock mass within protectionzones to be reduced [12 13] Cai and Ma conducted a seriesof research on vibration reduction mechanism of presplitblasting with the application of joint stiffness model andstress wave theory The research proved that the vibrationabsorption effect can be improved through increasing thelength and depth of presplitting cracks [14] Zou studied thevibration reduction result of presplit blasting with in situinvestigation and figured out that the closer the presplit crackwas the better the vibration reduction results were obtained[15] Salmi and Hosseinzadeh analyzed the mechanism ofpresplit blasting with the help of numerical simulation anddetermined that tensile stress waves induced by the deno-tation of two adjacent blast holes are the primary cause ofpresplit cracks [16] Yang launched tests on trial blast holeswith cross hole method and ultrasonic waves and establishedthat presplit blasting might cause less damage to the rockmass in the slope than loosening blasting [17] Sun et alconducted some research on vibration effect of blast castingand its influences [18 19] Zhang and Song concluded andanalyzed the practical experience of adopting presplittingblast in Heidaigou open cast mine and demonstrated thatpresplitting plays an important role in reducing blast vibra-tion and maintaining the structure of rock mass in the slope[20 21]

Presplit blasting is a major method to reducing thevibration effect of blast casting in higher bench and is of greatsignificance to ensuring safety in blasting and production ofopen cast mines Based on the characteristics of vibrationeffects and the vibration reduction mechanism of presplitblasting the effects of presplit blasting on blast casting areanalyzed on the basis of the study on the detection of resultsof blast vibration

Surface boundaryBottom boundary

Mining district III

Mining district I

Mining district II

Heidaigou surface coal mine

Advancing direction

Figure 1 Mining district division and current exploitation status ofHeidaigou open cast mine

2 Engineering Geology ofthe Experimental Area

Heidaigou open cast mine is located in the southeastern partof Zhungeer Coalfield in Erdos Plateau The average strikelength of themining range is 786 kmand thewidth is 539 kmresulting in a gross area of 4236 km2 Most coals minedwithin this area are long flame coal with the characteristicsof ultra-low-phosphorous low-sulfur and medium- or high-ash-fusion-point The minable coal seam in Heidaigou isthe 6th composite coal seam with thick-layer and massivestructure the average thickness is 288m and dipping lessthan 10∘ Table 1 shows the basic information of the minablecoal seamThe aggregate amount of minable coals within theboundary reaches 14977 million tons The zone is dividedinto three mining districts At present it is in the transitionalperiod from primary mining district to secondary miningdistrict as shown in Figure 1

By adopting loosening blasting the upper soil and rock ofHeidaigou open cast are broken and fragmented into piecesto be excavated and loaded by shovels and then transportedto an internal dump by self-discharging truck With theapplication of blast casting in the rocks above the coal seamroof within the scope of 40sim50m more than 30 of thematerials can be casted into the mined-out section and thesurplus materials are disposed with a dragline The strata of

Shock and Vibration 3

Table 2 Main characteristic parameters of rock stratum in the blasting area

Lithology Rockdensity (120574)

Rock massvelocity (Vrm)

Rock wavevelocity (V

119903)

Integritycoefficient

(119870119894)

Crackcoefficient

(119870119888)

Wave impedance(119877) Blastability

Mudstone 27 gcm3 1273ms 3744ms 012 088 344 times 103 gcm3sdotms MediumSandstone 23 gcm3 796sim1118ms 1586sim3226ms 006sim05 05sim099 22 times 103 gcm3sdotms EasyNote the integrated coefficient of rocks is determined by the square of the ratio of rockmass velocity to rock wave velocity119870119894 = (VrmV119903)

2 the crack coefficientof rocks119870119888 = (119881

2

119903minus 1198812

rm)1198812

119903 the wave impedance of rocks 119877 = 120574 sdot Vrm

Detonation blast hole Blast hole space

Arr

ay p

itch

Blast hole diameter

Presplit blast hole

Bench crest

A

A

200ms150ms

100ms9ms

(a) Schematic diagram of the plane parameters and interconnected design of blastcasting

Minimum burden

Detonator with

intervalBlast hole dip angle

600ms delay

(b) Schematic diagramof the drilling parameters and explosivecharge in blast casting

Figure 2 The schematic diagram of blast casting parameters

the blast casting area are mainly composed of sandstone andmudstone and the main characteristic parameters of rockstrata are shown in Table 2 [22]

The blast hole diameter for blast casting in Heidaigouopen cast is 310mm the blast hole spacing is 9sim12m thearray pitch is 7sim9m the plunge of blast hole ranges from65∘ to 70∘ the unit explosive consumption is 07sim09 kgm3and the minimum burden is 6sim65m In order to controlthe detonation charge over the same period hole-by-holemillisecond initiation control technology is adopted theinterhole delay is 9ms the interarray delay is 100sim200msand the time delay in holes is 600ms [23] Presplit blastingis adopted ahead of the detonation of main blast hole sothat the impacts of blast vibrations on slope stability on highbenches can be reducedThe result is commendable as shownin Figure 2

3 Vibration Effects of Blast Casting andVibration Absorption Mechanism ofPresplit Blasting

31 Vibration Effect of Blast Casting and Its Impact onSlope Stability The displacement velocity and accelerationof particle motion caused by blasts are three factors fordescribing blast vibration strength Moreover since the criti-cal safety values of acceleration and displacement are withina relatively wide limit velocity of blast vibration naturallybecomes the most important parameter for determining thedestruction-bearing capacity of the medium According to

Sadovrsquos empirical formula the velocity of blast vibration canbe determined as [24]

V =

119896

3radic119891 (119899)

(

3radic119876

119877

)

120572

119891 (119899) = 04 + 06119899

3

(1)

where V is the velocity of blasting vibration cms 119876 is themaximum explosive charge ignited over the same period kg119877 is the distance between blasting source center and guardpoint m 120572 is attenuation coefficient of seismic wave relatedto geological conditions 120572 = 1 to 3 119896 is medium parameterrelated to rock properties and blasting methods 119896 = 50sim200119891(119899) is the exponential function of the blasting effect 119899 is theindex of the blasting effect

According to wave theory it can be assumed that blastingseismic wave is composed of several simple harmonic waveswith different amplitudes and different vibration frequencies[25]

119883 = sum

119894

119860

119894sin (120596

119894119905)

119881 = sum

119894

120596

119894119860

119894cos (120596

119894119905 + 120593

1198941)

119886 = sum

119894

120596

2

119894119860

119894sin (120596

119894119905 + 120593

1198941)

(2)

where 119883 is displacement cm 119881 is vibration velocity cms119886 is vibration acceleration cms2 119860

119894is blasting vibration

4 Shock and Vibration

Seismic load

Qi

Ei

Hi

Si

Ni

Wi

120572i

li

Himinus1

Eiminus1

Figure 3 Force diagram on noncircular slip surface with slicesbased on Janbu Method

amplitude cm120596119894is circular frequency120596 = 2120587119891 Hz 119905 is time

s 1205931198941and 120593

1198942denote phase differences

High bench is applied in blast casting with the blastparameters of deep and large blast hole diameter The rockvolume blasted each time and the explosive consumption ishuge Blast vibration effect is a significant factor affectingslope stability of open cast mines When calculating slopestability affected by blasting dynamics with pseudo-staticmethod it is usually assumed that the horizontal loadsof blasting vibration exerted on the slope slip mass areequivalent to static loads [26]

119876

119894= 119870

119904119882

119894

119870

119904=

119870

119863119886

119894

119892

(3)

where 119876

119894is the equivalent static load N 119870

119904is seismic load

coefficient 119886119894is vibration acceleration ms2 119882

119894is the slice

weight of slidingmassN119892 is gravitational accelerationms2119870

119863is reduction coefficient of blasting dynamics whose value

range is 0008sim0152According to the schematic diagram for noncircular slip

surface shown in Figure 3 the following equation based onJanbursquos theory and the equilibrium condition of slice can beobtained [27]

sum119884 = 0

119882

119894+ 119867

119894minus 119867

119894minus1minus 119873

119894cos120572119894minus 119878

119894sin120572119894= 0

sum119883 = 0

119864

119894minus 119864

119894minus1+ 119878

119894cos120572119894minus 119873

119894sin120572119894minus 119876

119894= 0

(4)

According to Mohrrsquos-Coulomb criterion the shear forceon the bottom sliding surface should meet the followingcondition

119878

119894=

119888119897

119894

119865

119904

+ 119873

119894

tan120593119865

119904

(5)

Based on the balance of forces of the whole landslide

sum(119882

119894+ 119867

119894minus 119867

119894minus1) tan120572

119894minussum119878

119894sec120572119894+sum119876

119894= 0 (6)

Combining (4) (5) and (6) the following factor of safetyequation is obtained

119865

119904=

sum (sec2120572119894 (1 + tan120572

119894tan120593119894119865

119904)) [119888

119894119897

119894cos120572119894+ (119882

119894+ 119867

119894minus 119867

119894minus1) tan120593

119894]

sum (119882

119894+ 119867

119894minus 119867

119894minus1) tan120572

119894+ sum119876

119894cos120572119894

(7)

where 119864

119894minus1and 119864

119894are the normal forces of the 119894th slice

119867

119894minus1and 119867

119894are the vertical shear stresses of the 119894th slice

119873

119894and 119878

119894are the vertical reactions and shear forces on the

slipping surface respectively 119897119894is the slicersquos bottom length of

the sliding surface of the 119894th slice 119888119894is cohesive force of the

119894th slice 120593119894is the internal angle of friction of the 119894th slice 119865

119904

is the factor of safetyIt can be seen from Figure 3 and (7) that the horizontal

load produced by blast vibration on the slip mass and thesliding component caused by gravity together constitute thesliding force of the slip mass The factor of safety of the slopethat has been affected by blast vibration is reduced comparedto rock masses that are not affected

32 Vibration Absorption Mechanism of Presplit BlastingBlast casting in high bench of open cast mines causes theproduction of large blasting volume and devastating shock itcan cause relatively severe effects on slope stability of adjacentrock masses which have not been blasted But as a specialmethod for blasting control presplit blasting can be veryeffective in reducing blast vibrations This is achieved by

detonating the explosive charge placed in the presplit hole ofthe main blasting area and then separating the rock massesfrom original ones after cracks are formed along the blastingarea boundary In this way the damages caused by blastvibrations on the original rock masses can be reduced

The necessary condition to ensure the success of presplitblasting is that the pressure of the explosion in the blast holeswill not damage the wall of the hole and the presplit crackwill develop along the predetermined direction Accordingto stress wave interference theory [28ndash30] stress waves ofeach explosion spread radically after the denotation of twoadjacent presplit holes as shown in Figure 4

After the charge is denoted the peak of the stress wavefront weakens as the propagation distance of the stress waveincreases with the attenuation formula [31 32]

119875

119877= 119875

119863(

119903

1

119877

)

120572

119875

119863=

1

119896 + 1

120588119863

2(

119903

1

119903

2

)

minus2119896

119899

(8)

Shock and Vibration 5

Explosive charge Blast hole

Wave front

120590M

pMpM

s2s2

s

E1205760

Figure 4 Wave front of two adjacent blast holes

where 119875

119877is the pressure of stress wave front after the

detonation of explosive charge Pa 1199031is the radius of blast

hole m 119877 is the distance between the center of blast holeand a certain point on the wave front m 120572 is the attenuationcoefficient 120572 = 2 minus 120583(1 minus 120583) 120583 is Poissonrsquos ratio 119875

119863is the

pressure on the wall of the holes Pa 120588 is explosive densitykgm3119863 is explosive speed ms 119903

2is the radius of explosive

m 119896 is adiabatic exponent 119899 is the multiple of pressureincrease of the explosive gas colliding with the blast hole walland 119899 = 8sim11

The stress wave causes radical displacement of the rockmass between two adjacent blast holes while the radicaldisplacement derives the tangential stresses and tangentialstrains The tangential stress 120590

119879can be expressed as [33]

120590

119879=

120583

1 minus 120583

119875

119877 (9)

If the tangential stress on the wall of the hole is greaterthan the rock tensile strength 120590

119905 the initial crack on the wall

of the blast hole will appear Resulting from the stress wave oftwo adjacent blast holes the sum120590

119872of the tangential stress in

the middle of the line connecting the two adjacent blast holes(119877 = 1199042) is

120590

119872=

2120583

(1 minus 120583) (119896 + 1)

120588119863

2(

119903

1

119903

2

)

minus2119896

119899 (

2119903

1

119904

)

120572

(10)

Similarly if the tensile stress produced by blasting 120590

119872is

greater than the tensile strength of rocks that is 120590119872

ge 120590

119905

radial cracks appear along the lines connecting blast holeswhich creates condition for the formation of the presplit faceThe high pressure gas of explosion of the two adjacent blastholes then acts on the walls of the hole thereby forming aquasi-static stress field around the blast holes When the highpressure gas wedges in the initial crack of hole wall thereis a great tensile stress along the line connecting blast holesThe tensile stress concentration is all sides of the walls of thehole A free surface with a certain width is formed whichcan exert positive effects towards the reduction in vibrations

Therefore the important precondition for the formation ofthe presplit face is that tension waves can produce tensioncrack Based on (10) the formula of the blast hole spacing inpresplit blasting should be

119904 le

2119903

1

[120590

119905((1 minus 120583) (119896 + 1) 2120583120588119863

2119899) (119903

1119903

2)

2119896

]

1120572 (11)

Low density ANFO explosive is used as a presplit blastexplosive in Heidaigou open cast with a density of 200 kgm3a speed of 1950ms a presplit blast hole diameter of 310mmcharge diameter of 150mm and a unit explosive consumptionof 085 kgm3 According to (11) the optimum blast holespacing of presplit blasting is estimated as ranging from303m to 416m with 35m selected for application Figure 5shows the presplit blasting effectThe cracks formed from theblast are relatively intact with an even width and the ratio ofthe half hole to the total presplit hole is a little higher

The transmission coefficient of stress wave is

119877

119905=

119860

119905

119860

119894

(12)

where119877119905is the transmission coefficient and119860

119894and119860

119905are the

amplitude of incident wave and the amplitude of transmittedwave respectively

The wave velocity expression is

V = 119860119890

minus120572 sin120596119905 (13)

and the vibration absorption ratio of presplit blasting is

120576 =

1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

V119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max=

1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

119860

119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max= 1 minus 119877

119905 (14)

4 Detection and Analysis of VibrationProduced by Blast Casting

41 The Detection Principles of Blast Vibration Detectionsystem of blast vibration is composed of the blast vibrationtester and the vibration pick-up As the vibration wave istransmitted to the vibration pick-up induced voltage outputsare generated and once the induced voltage signal exceeds thepreset triggering level the tester automatically records andsaves the vibration signals loaded by the sensor After detect-ing the vibration signals the blast vibration waves can beread and analyzed with the connection and communicationbetween special software and vibration tester The principlediagrams of the detection system and the measuring pointlayout are shown in Figures 6 and 7 respectively

Based on the inspection data the regression analysisshould be carried out with Sadovrsquos empirical formula andthe formula of vibration velocity attenuation can thus beobtained

42 Detection Scheme of Blast Vibration In order to recordthe whole vibration process and the attenuation law of blast-ing seismic waves the detection scheme of blast vibration is

6 Shock and Vibration

Figure 5 Presplit blasting effect pictures of surface coal mine

Vibration pick-up

Detection system

Blasting seismic wave

Blasting vibration tester

Parameter set-up Signal input

Data process Signal output

Computer Printer

Figure 6 The principle diagram of the detection system

worked out according to the characteristics of blast castingand the geological and topographic conditions of the blastingzone Detection points are set on the same bench and kept ina straight line on the right side of the blasting zone withoutpresplit blast Another set of detection points are also set onthe same bench in a straight line on the rear blasting zonewithpresplit blast Both of the above-mentioned detection pointsare used to monitor the seismic intensity and variations ofblast vibrations

The blast vibration tester adopted here is a vibrationsignal recorder whose model is UBOX-20016 the maximumsampling rate of which is 200KSpsCH and the signalresolution is 16 bits (165536 of the measuring range) Thevibration pick-up is CD-21magnetoelectric vibration velocitysensor with the sensitivity of 200mvcms and the erroris less than 3 The installation of sensors is based on themeasurement of vibration velocity in different directions andthe censors must be firmly bonded to the ground by gypsumpowder

The primary detection area of blast vibration is the rearpart and the broadside of the blasting zone the former iswith presplit cracks and the latter is without Therefore theeffect of presplit cracks in vibration reduction can be provedby comparison Blast vibration recorder is used for inspectingthe velocity of particles in vertical direction (V-) radialdirection (R-) and transverse direction (T-) Figure 8 showsthe schematic diagram of detection point layout

Vibrationtester

Blasting center

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Figure 7 The schematic diagram of the measuring point layout

43 Analysis on the Detection Results of Blasting Vibration Inall cases blast vibration detection has been carried out three(3) times The gross explosive loads (GEL) for each time are96 times 105 kg 78 times 105 kg and 13 times 106 kg respectively Themaximum explosive charges per delay interval (MECPDE)are 1 times 104 kg 15 times 104 kg and 15 times 104 kg respectivelyand the explosive charge per blast hole is 2 times 103 kg Thedistance between each detection point and the blasting source(DDPBS) as well as the vibration velocity of the largestparticle are shown in Table 3

Standard blast casting is adopted in Heidaigou open castand the blasting acting index 119899 = 1 Based on (1) and thedetection data the attenuation equations for blast vibrationin presplit blasting and non-presplit blasting are obtained byfitting

V

=

9518 (

3radic119876

119877

)

134

119877

2= 0959 (presplit blast)

22161 (

3radic119876

119877

)

140

119877

2= 0795 (non-presplit blast)

(15)

Shock and Vibration 7

Table 3 Location of detection points and blast vibration strength

Detection point 119879- mms 119881- mms 119877- mms Resultant mms DDPBS m GEL kg MECPDE kg RemarksH1-2 141 111 108 174 350 960000 10000 BackH1-3 104 168 78 179 550 960000 10000 BackH1-4 43 99 10 800 960000 10000 BackH1-5 17 23 38 39 1215 960000 10000 BackH1-6 11 19 28 29 1800 960000 10000 BackH2-1 1047 1497 1243 1813 100 780000 15000 BackH2-2 317 565 327 55 200 780000 15000 BackH2-3 118 173 163 204 300 780000 15000 BackH2-4 108 139 187 500 780000 15000 BackH2-5 45 39 37 79 800 780000 15000 BackH2-6 42 25 23 54 1000 780000 15000 BackH2-7 174 30 22 411 380 780000 15000 BackH3-1 667 694 598 874 162 1300000 15000 BackY1-1 286 135 291 303 5749 960000 10000 RightY1-2 196 121 306 311 6046 960000 10000 RightY1-3 126 559 124 145 800 960000 10000 RightY1-4 851 305 851 103 8266 960000 10000 RightY3-1 656 709 708 118 200 1300000 15000 RightY3-2 233 28 255 507 350 1300000 15000 RightY3-4 101 58 mdash 175 550 1300000 15000 RightY3-5 65 24 37 107 650 1300000 15000 Right

Detection pointon the right side

Detection pointon the rear

Presplitting blast Non-presplit blast

H1

H2

H3

H4

H5

Hi

Y1

Y2

Y3

Y4

Figure 8 Location of the blast detection point and blast vibrationsource

According to (15) the attenuation indices under thesetwo conditions are nearly the same that is 134 and 140respectively However the attenuation coefficient might bereduced by half when adopting presplit blasting Becauseof the application of hole-by-hole millisecond detonationthe maximum explosive charge per segment is less than 11times 104 kg and the vibration velocity of the end-wall slopeis 253 cms In addition the equation for calculating theacceleration of blast vibration is [34]

119886 = 0028119876

083119877

minus35119862

119901

2 (16)

where 119886 is acceleration of the blast vibration ms2 119862119901is the

longitudinal wave velocity ms other symbols are consistentwith the former expressions

The transmission velocity of blast vibration in sand-stone rock mass is 1118ms the acceleration is calculated as121ms2 (16) and the seismic load coefficient of blastingis calculated as 0012 (3) According to the mechanicalparameters of rock mass of Heidaigou open cast listed inTable 4 the factors of stability of the end-wall slope arecalculated as 1311 for the condition of static load and 1285for the condition of dynamic load respectivelyTherefore theeffect of dynamic load on factor of safety of the end wall ismerely 198

Meanwhile the resultant vibration velocities of differentdetection points are shown in Table 5 As the distancebetween detection points and blasting centers increasesthe vibration velocities decrease exponentially under thecondition of both presplit blasting and non-presplit blastingA closer distance to the blasting center can better reflectthe vibration reduction effect of presplit blasting Whenthe detection point is 200m away from the blasting centerthe vibration absorption ratio is increased to 502 whichimplies that presplit blasting can effectively absorb vibrations

5 Conclusions

(1) Pseudo-static method has converted the dynamic loadof blast vibration to equivalent static load and Janbu LEMhas been used to analyze the influence of blast vibration onslope stability The horizontal load caused by blast vibrationenhances the sliding force of the slip mass and therefore

8 Shock and Vibration

Table 4 Mechanical parameters of rock mass of Heidaigou open cast

Stratum Density (kNm3) Internal friction angle (∘) Cohesion (kPa)Loess 1950 295 451Sandy mudstone 2450 30 135Fine sandstone 2450 28 150Medium sandstone 2270 315 150Coarse sandstone 2240 320 130Weathered mudstone 247 290 1275Coal 14 35 1851Siltstone 245 313 1768

Table 5 Actual blast vibration detection data and absorption shock rate of presplit blasting

Detection point distance toblasting centerm

Velocity of vibrationcmsdotsminus1

200 400 600 800 1000 1200 1400Presplit blasting 548 221 13 089 066 052 043Non-presplit blasting 1101 397 218 143 103 079 063Vibration reduction ratio 502 443 404 378 359 342 317

reduces the factor of safety Calculated results suggest thatslope stability factors on conditions of static load anddynamic load of blasting are 1311 and 1285 respectively andthe dynamic load of blast casting has slight effect on the endslope stability taking only 198

(2) After the detonation of two adjacent presplit holesstress waves of each explosion spread radially and createtangential stress in the tangential direction Based on thetheory of stress wave interference when the sum of thetangential stress of two adjacent blast holes is greater than therock tensile strength radial cracks come into being along theline connecting blast holes which creates condition for theformation of the presplit face Based on the above conditionthe blast hole spacing in presplit blasting is obtained Accord-ingly the blast hole spacing of presplit blasting of Heidaigouopen cast mine ranges from 303m to 416m with 35m usedin actual production satisfying the presplit blasting effect

(3) The vibration detection principles of vibration testersand pick-ups are analyzed The vibration velocity of blastingparticle is detected in the blasting zonewhose rear part is withpresplit cracks and right side is without Based on Sadovrsquosempirical formula attenuation formulas of blast vibration onconditions with and without presplit blasting are obtained bynumerical fitting respectively The detection results indicatethat presplit blasting can reduce the attenuation coefficientby half and the vibration absorption ratio can reach 502whichmeans presplitting blast is of great significance in shockabsorption of blast casting

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

Acknowledgments

This study was supported by the National Natural Sci-ence Foundation of China (51034005) the Fundamental

Research Funds for the Central Universities (2010QNB232011QNB25) and the Priority Academic Program Develop-ment of Jiangsu Higher Education Institutions

References

[1] K Pathak S Durucan and S Kunimatsu ldquoActivity accountingtechnique for environmental noise assessment in mechanizedsurfaceminingrdquoEnvironmentalMonitoring andAssessment vol56 no 3 pp 241ndash256 1999

[2] A Fisne C Kuzu and T Hudaverdi ldquoPrediction of environ-mental impacts of quarry blasting operation using fuzzy logicrdquoEnvironmental Monitoring and Assessment vol 174 no 1ndash4 pp461ndash470 2011

[3] D J Armaghani E Momeni S V A N K Abad andM Khan-delwal ldquoFeasibility of ANFIS model for prediction of groundvibrations resulting from quarry blastingrdquo Environmental EarthSciences vol 74 no 4 pp 2845ndash2860 2015

[4] T N Singh and V Singh ldquoAn intelligent approach to predictionand control ground vibration in minesrdquo Geotechnical andGeological Engineering vol 23 no 3 pp 249ndash262 2005

[5] U Ozer A Kahriman M Aksoy D Adiguzel and A Karado-gan ldquoThe analysis of ground vibrations induced by benchblasting at Akyol quarry and practical blasting chartsrdquo Environ-mental Geology vol 54 no 4 pp 737ndash743 2008

[6] C Kuzu and E Guclu ldquoThe problem of human response toblast induced vibrations in tunnel construction and mitigationof vibration effects using cautious blasting in half-face blastingroundsrdquo Tunnelling and Underground Space Technology vol 24no 1 pp 53ndash61 2009

[7] D D Li and Z D Deng ldquoEvaluation of the effects of blastingvibration on humans in the excavation of CMICT dockrdquoEngineering Blasting vol 12 no 2 pp 82ndash85 2012

[8] F Zheng W D Duan D W Zhong and B Y Sun ldquoResearchprogress and existing problems of blasting vibrationrdquo Blastingvol 23 no 1 pp 92ndash94 2006

[9] T L Shi and B Z Li ldquoThe effects of millisecond delayinterval charge distribution andmeasuring distance on blastingvibrationrdquo Engineering Blasting vol 9 no 4 pp 10ndash13 2003

Shock and Vibration 9

[10] Y L Gao Q Tan S C Yang L Xue and Y L Yu ldquoExperimentalresearch on relationship between charge layout and blastingvibrationrdquo Engineering Blasting vol 10 no 3 pp 19ndash48 2004

[11] O Uysal and M Cavus ldquoEffect of a pre-split plane on the fre-quencies of blast induced ground vibrationsrdquoActaMontanisticaSlovaca vol 18 no 2 pp 101ndash109 2013

[12] J L Yan and X F Chen ldquoObservation and analysis of vibrationreduction effect of pre-split crack in complicated geologicconditionrdquo Blasting vol 25 no 3 pp 100ndash102 2008

[13] A J Prakash P Palroy and D D Misra ldquoAnalysis of blastvibration characteristics across a trench and a pre-split planerdquoFragblast vol 8 no 1 pp 51ndash60 2004

[14] L J Cai and J J Ma ldquoThe shock absorption mechanism and itseffect analysis of pre-splitting blastingrdquoChinaMiningMagazinevol 14 no 5 pp 56ndash58 2005

[15] Y F Zou ldquoExperimental study on the vibration- isolating effectof pre-split crack and vibration-isolating slotrdquo Blasting vol 22no 2 pp 96ndash99 2005

[16] E F Salmi and S Hosseinzadeh ldquoA further study on themechanism of pre-splitting in mining engineeringrdquo AppliedMechanics and Materials vol 553 pp 476ndash481 2014

[17] N H Yang ldquoExperimental study on rock damage in the slopecaused by presplit blastingrdquo Journal of the China RailwaySociety vol 30 no 3 pp 96ndash99 2008

[18] H R Sun Y J Tong X L Lin and H S Gao ldquoStudy on theVibration Effect of sling blasting in an open coalminerdquo Blastingvol 25 no 1 pp 69ndash73 2008

[19] Q K Chen G C Li and K M Li ldquoMonitor and analysis onexplosive seismic effect of high-bench cast blast of surface coalminerdquo Explosive Materials vol 37 no 6 pp 30ndash33 2008

[20] P K Zhang and F G Song ldquoPre-splitting blasting applied inhigh-bench cast blastingrdquo Opencast Mining Technology no 1pp 35ndash41 2007

[21] P K Zhang ldquoApplication of pre-splitting blasting in high-benchcast blasting of Heidaigou open pitrdquo Inner Mongolia ScienceTechnology amp Economy no 6 pp 257ndash258 2008

[22] W M Hu ldquoBlack dai ditch open-pit coal mine rock wavevelocity testing technologyrdquo Journal of North China Institute ofScience and Technology vol 11 no 9 pp 63ndash67 2014

[23] X H Ding K M Li S S Xiao and W M Hu ldquoAnalysisof key technologies and development of integrated digitalprocessing system for cast blasting designrdquo Journal of CentralSouth University vol 22 no 3 pp 1037ndash1044 2015

[24] C G Jin ldquoVibrating effect of blasting in open-pit sloperdquo MetalMine no 5 pp 18ndash20 1995

[25] Q Liu and S R Lv ldquoResearch on the millisecond delay intervaltime of open-pit bench blastingrdquo Engineering Blasting vol 20no 1 pp 54ndash58 2014

[26] M Chen W Lu D Shu and C Zhou ldquoCalculation method ofequivalent acceleration for limit equilibrium analysis of slopeunder blasting vibrationrdquo Chinese Journal of Rock Mechanicsand Engineering vol 28 no 4 pp 784ndash790 2009

[27] B He and YWang ldquoResidual thrust method and Janbumethodused to calculate landslide stabilityrdquo Safety and EnvironmentalEngineering vol 11 no 4 pp 60ndash62 2004

[28] Y L YuTheory and Technology of Engineering Blasting Metal-lurgical Industry Press Beijing China 2004

[29] W M Ling ldquoA study on the fracture mechanism of smoothblasting and pre-split blastingrdquo Journal of China University ofMining amp Technology vol 19 no 4 pp 79ndash87 1990 (Chinese)

[30] M Sazid and T N Singh ldquoNumerical assessment of spacing-burden ratio to effective utilization of explosive energyrdquo Inter-national Journal of Mining Science and Technology vol 25 no2 pp 291ndash297 2015

[31] B F Li and C B Qi ldquoShaped crack mechanism and parametersdesign of pre-splitting blastingrdquo West-China Exploration Engi-neering no 3 pp 78ndash79 2000 (Chinese)

[32] Q Zong ldquoTheoretical analysis of charge structurersquos influence onpressure on bore wallrdquo Mining and Metallurgical Engineeringvol 26 no 5 pp 9ndash12 2006 (Chinese)

[33] K S Ge Study on Parameter of Pre-Splitting Blasting ChinaUniversity of Geosciences Beijing China 2009

[34] J G Wang L F Luan Z Y Zhang X L Li and C L FanldquoNumerical simulation of blasting vibration effect on stabilityof high-steep sloperdquo Blasting vol 29 no 3 pp 119ndash122 2012

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Shock and Vibration

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2 Shock and Vibration

Table 1 Basic information of the minable coal seam

Coal measure era Coal seam type

Thickness of coalseam

MinsimmaxAveragem

Coal seam spacingMinsimmaxAveragem

Coal seam structure Stability

Taiyuan formation 66I

010 sim 1265

278

0 sim 958

113

Complex Unstable

6II005 sim 771

326

0 sim 958

113

0 sim 546

025

Complex

6IIIsimVI050 sim 2719

2276

0 sim 546

025

Complex Relativelystable

strength [8] Therefore millisecond blasting together withthe detonation direction is often adopted to control theignition charge over the same period Presplit blasting isoften used to control the blast vibration effect and mitigatedisasters caused by vibrations Changing the charge structureis also a conventional method [9ndash11] with which presplitblasting can exert positive effects on shock absorption andreduce detonation wave propagation since it is able to formpresplit cracks with a definite width and depth before thedetonation of the main blast hole This leads to terminationof the transmission of detonating waves Presplit cracks causereflection and refraction on stress waves causing the stresswave energy transmitted into rock mass within protectionzones to be reduced [12 13] Cai and Ma conducted a seriesof research on vibration reduction mechanism of presplitblasting with the application of joint stiffness model andstress wave theory The research proved that the vibrationabsorption effect can be improved through increasing thelength and depth of presplitting cracks [14] Zou studied thevibration reduction result of presplit blasting with in situinvestigation and figured out that the closer the presplit crackwas the better the vibration reduction results were obtained[15] Salmi and Hosseinzadeh analyzed the mechanism ofpresplit blasting with the help of numerical simulation anddetermined that tensile stress waves induced by the deno-tation of two adjacent blast holes are the primary cause ofpresplit cracks [16] Yang launched tests on trial blast holeswith cross hole method and ultrasonic waves and establishedthat presplit blasting might cause less damage to the rockmass in the slope than loosening blasting [17] Sun et alconducted some research on vibration effect of blast castingand its influences [18 19] Zhang and Song concluded andanalyzed the practical experience of adopting presplittingblast in Heidaigou open cast mine and demonstrated thatpresplitting plays an important role in reducing blast vibra-tion and maintaining the structure of rock mass in the slope[20 21]

Presplit blasting is a major method to reducing thevibration effect of blast casting in higher bench and is of greatsignificance to ensuring safety in blasting and production ofopen cast mines Based on the characteristics of vibrationeffects and the vibration reduction mechanism of presplitblasting the effects of presplit blasting on blast casting areanalyzed on the basis of the study on the detection of resultsof blast vibration

Surface boundaryBottom boundary

Mining district III

Mining district I

Mining district II

Heidaigou surface coal mine

Advancing direction

Figure 1 Mining district division and current exploitation status ofHeidaigou open cast mine

2 Engineering Geology ofthe Experimental Area

Heidaigou open cast mine is located in the southeastern partof Zhungeer Coalfield in Erdos Plateau The average strikelength of themining range is 786 kmand thewidth is 539 kmresulting in a gross area of 4236 km2 Most coals minedwithin this area are long flame coal with the characteristicsof ultra-low-phosphorous low-sulfur and medium- or high-ash-fusion-point The minable coal seam in Heidaigou isthe 6th composite coal seam with thick-layer and massivestructure the average thickness is 288m and dipping lessthan 10∘ Table 1 shows the basic information of the minablecoal seamThe aggregate amount of minable coals within theboundary reaches 14977 million tons The zone is dividedinto three mining districts At present it is in the transitionalperiod from primary mining district to secondary miningdistrict as shown in Figure 1

By adopting loosening blasting the upper soil and rock ofHeidaigou open cast are broken and fragmented into piecesto be excavated and loaded by shovels and then transportedto an internal dump by self-discharging truck With theapplication of blast casting in the rocks above the coal seamroof within the scope of 40sim50m more than 30 of thematerials can be casted into the mined-out section and thesurplus materials are disposed with a dragline The strata of

Shock and Vibration 3

Table 2 Main characteristic parameters of rock stratum in the blasting area

Lithology Rockdensity (120574)

Rock massvelocity (Vrm)

Rock wavevelocity (V

119903)

Integritycoefficient

(119870119894)

Crackcoefficient

(119870119888)

Wave impedance(119877) Blastability

Mudstone 27 gcm3 1273ms 3744ms 012 088 344 times 103 gcm3sdotms MediumSandstone 23 gcm3 796sim1118ms 1586sim3226ms 006sim05 05sim099 22 times 103 gcm3sdotms EasyNote the integrated coefficient of rocks is determined by the square of the ratio of rockmass velocity to rock wave velocity119870119894 = (VrmV119903)

2 the crack coefficientof rocks119870119888 = (119881

2

119903minus 1198812

rm)1198812

119903 the wave impedance of rocks 119877 = 120574 sdot Vrm

Detonation blast hole Blast hole space

Arr

ay p

itch

Blast hole diameter

Presplit blast hole

Bench crest

A

A

200ms150ms

100ms9ms

(a) Schematic diagram of the plane parameters and interconnected design of blastcasting

Minimum burden

Detonator with

intervalBlast hole dip angle

600ms delay

(b) Schematic diagramof the drilling parameters and explosivecharge in blast casting

Figure 2 The schematic diagram of blast casting parameters

the blast casting area are mainly composed of sandstone andmudstone and the main characteristic parameters of rockstrata are shown in Table 2 [22]

The blast hole diameter for blast casting in Heidaigouopen cast is 310mm the blast hole spacing is 9sim12m thearray pitch is 7sim9m the plunge of blast hole ranges from65∘ to 70∘ the unit explosive consumption is 07sim09 kgm3and the minimum burden is 6sim65m In order to controlthe detonation charge over the same period hole-by-holemillisecond initiation control technology is adopted theinterhole delay is 9ms the interarray delay is 100sim200msand the time delay in holes is 600ms [23] Presplit blastingis adopted ahead of the detonation of main blast hole sothat the impacts of blast vibrations on slope stability on highbenches can be reducedThe result is commendable as shownin Figure 2

3 Vibration Effects of Blast Casting andVibration Absorption Mechanism ofPresplit Blasting

31 Vibration Effect of Blast Casting and Its Impact onSlope Stability The displacement velocity and accelerationof particle motion caused by blasts are three factors fordescribing blast vibration strength Moreover since the criti-cal safety values of acceleration and displacement are withina relatively wide limit velocity of blast vibration naturallybecomes the most important parameter for determining thedestruction-bearing capacity of the medium According to

Sadovrsquos empirical formula the velocity of blast vibration canbe determined as [24]

V =

119896

3radic119891 (119899)

(

3radic119876

119877

)

120572

119891 (119899) = 04 + 06119899

3

(1)

where V is the velocity of blasting vibration cms 119876 is themaximum explosive charge ignited over the same period kg119877 is the distance between blasting source center and guardpoint m 120572 is attenuation coefficient of seismic wave relatedto geological conditions 120572 = 1 to 3 119896 is medium parameterrelated to rock properties and blasting methods 119896 = 50sim200119891(119899) is the exponential function of the blasting effect 119899 is theindex of the blasting effect

According to wave theory it can be assumed that blastingseismic wave is composed of several simple harmonic waveswith different amplitudes and different vibration frequencies[25]

119883 = sum

119894

119860

119894sin (120596

119894119905)

119881 = sum

119894

120596

119894119860

119894cos (120596

119894119905 + 120593

1198941)

119886 = sum

119894

120596

2

119894119860

119894sin (120596

119894119905 + 120593

1198941)

(2)

where 119883 is displacement cm 119881 is vibration velocity cms119886 is vibration acceleration cms2 119860

119894is blasting vibration

4 Shock and Vibration

Seismic load

Qi

Ei

Hi

Si

Ni

Wi

120572i

li

Himinus1

Eiminus1

Figure 3 Force diagram on noncircular slip surface with slicesbased on Janbu Method

amplitude cm120596119894is circular frequency120596 = 2120587119891 Hz 119905 is time

s 1205931198941and 120593

1198942denote phase differences

High bench is applied in blast casting with the blastparameters of deep and large blast hole diameter The rockvolume blasted each time and the explosive consumption ishuge Blast vibration effect is a significant factor affectingslope stability of open cast mines When calculating slopestability affected by blasting dynamics with pseudo-staticmethod it is usually assumed that the horizontal loadsof blasting vibration exerted on the slope slip mass areequivalent to static loads [26]

119876

119894= 119870

119904119882

119894

119870

119904=

119870

119863119886

119894

119892

(3)

where 119876

119894is the equivalent static load N 119870

119904is seismic load

coefficient 119886119894is vibration acceleration ms2 119882

119894is the slice

weight of slidingmassN119892 is gravitational accelerationms2119870

119863is reduction coefficient of blasting dynamics whose value

range is 0008sim0152According to the schematic diagram for noncircular slip

surface shown in Figure 3 the following equation based onJanbursquos theory and the equilibrium condition of slice can beobtained [27]

sum119884 = 0

119882

119894+ 119867

119894minus 119867

119894minus1minus 119873

119894cos120572119894minus 119878

119894sin120572119894= 0

sum119883 = 0

119864

119894minus 119864

119894minus1+ 119878

119894cos120572119894minus 119873

119894sin120572119894minus 119876

119894= 0

(4)

According to Mohrrsquos-Coulomb criterion the shear forceon the bottom sliding surface should meet the followingcondition

119878

119894=

119888119897

119894

119865

119904

+ 119873

119894

tan120593119865

119904

(5)

Based on the balance of forces of the whole landslide

sum(119882

119894+ 119867

119894minus 119867

119894minus1) tan120572

119894minussum119878

119894sec120572119894+sum119876

119894= 0 (6)

Combining (4) (5) and (6) the following factor of safetyequation is obtained

119865

119904=

sum (sec2120572119894 (1 + tan120572

119894tan120593119894119865

119904)) [119888

119894119897

119894cos120572119894+ (119882

119894+ 119867

119894minus 119867

119894minus1) tan120593

119894]

sum (119882

119894+ 119867

119894minus 119867

119894minus1) tan120572

119894+ sum119876

119894cos120572119894

(7)

where 119864

119894minus1and 119864

119894are the normal forces of the 119894th slice

119867

119894minus1and 119867

119894are the vertical shear stresses of the 119894th slice

119873

119894and 119878

119894are the vertical reactions and shear forces on the

slipping surface respectively 119897119894is the slicersquos bottom length of

the sliding surface of the 119894th slice 119888119894is cohesive force of the

119894th slice 120593119894is the internal angle of friction of the 119894th slice 119865

119904

is the factor of safetyIt can be seen from Figure 3 and (7) that the horizontal

load produced by blast vibration on the slip mass and thesliding component caused by gravity together constitute thesliding force of the slip mass The factor of safety of the slopethat has been affected by blast vibration is reduced comparedto rock masses that are not affected

32 Vibration Absorption Mechanism of Presplit BlastingBlast casting in high bench of open cast mines causes theproduction of large blasting volume and devastating shock itcan cause relatively severe effects on slope stability of adjacentrock masses which have not been blasted But as a specialmethod for blasting control presplit blasting can be veryeffective in reducing blast vibrations This is achieved by

detonating the explosive charge placed in the presplit hole ofthe main blasting area and then separating the rock massesfrom original ones after cracks are formed along the blastingarea boundary In this way the damages caused by blastvibrations on the original rock masses can be reduced

The necessary condition to ensure the success of presplitblasting is that the pressure of the explosion in the blast holeswill not damage the wall of the hole and the presplit crackwill develop along the predetermined direction Accordingto stress wave interference theory [28ndash30] stress waves ofeach explosion spread radically after the denotation of twoadjacent presplit holes as shown in Figure 4

After the charge is denoted the peak of the stress wavefront weakens as the propagation distance of the stress waveincreases with the attenuation formula [31 32]

119875

119877= 119875

119863(

119903

1

119877

)

120572

119875

119863=

1

119896 + 1

120588119863

2(

119903

1

119903

2

)

minus2119896

119899

(8)

Shock and Vibration 5

Explosive charge Blast hole

Wave front

120590M

pMpM

s2s2

s

E1205760

Figure 4 Wave front of two adjacent blast holes

where 119875

119877is the pressure of stress wave front after the

detonation of explosive charge Pa 1199031is the radius of blast

hole m 119877 is the distance between the center of blast holeand a certain point on the wave front m 120572 is the attenuationcoefficient 120572 = 2 minus 120583(1 minus 120583) 120583 is Poissonrsquos ratio 119875

119863is the

pressure on the wall of the holes Pa 120588 is explosive densitykgm3119863 is explosive speed ms 119903

2is the radius of explosive

m 119896 is adiabatic exponent 119899 is the multiple of pressureincrease of the explosive gas colliding with the blast hole walland 119899 = 8sim11

The stress wave causes radical displacement of the rockmass between two adjacent blast holes while the radicaldisplacement derives the tangential stresses and tangentialstrains The tangential stress 120590

119879can be expressed as [33]

120590

119879=

120583

1 minus 120583

119875

119877 (9)

If the tangential stress on the wall of the hole is greaterthan the rock tensile strength 120590

119905 the initial crack on the wall

of the blast hole will appear Resulting from the stress wave oftwo adjacent blast holes the sum120590

119872of the tangential stress in

the middle of the line connecting the two adjacent blast holes(119877 = 1199042) is

120590

119872=

2120583

(1 minus 120583) (119896 + 1)

120588119863

2(

119903

1

119903

2

)

minus2119896

119899 (

2119903

1

119904

)

120572

(10)

Similarly if the tensile stress produced by blasting 120590

119872is

greater than the tensile strength of rocks that is 120590119872

ge 120590

119905

radial cracks appear along the lines connecting blast holeswhich creates condition for the formation of the presplit faceThe high pressure gas of explosion of the two adjacent blastholes then acts on the walls of the hole thereby forming aquasi-static stress field around the blast holes When the highpressure gas wedges in the initial crack of hole wall thereis a great tensile stress along the line connecting blast holesThe tensile stress concentration is all sides of the walls of thehole A free surface with a certain width is formed whichcan exert positive effects towards the reduction in vibrations

Therefore the important precondition for the formation ofthe presplit face is that tension waves can produce tensioncrack Based on (10) the formula of the blast hole spacing inpresplit blasting should be

119904 le

2119903

1

[120590

119905((1 minus 120583) (119896 + 1) 2120583120588119863

2119899) (119903

1119903

2)

2119896

]

1120572 (11)

Low density ANFO explosive is used as a presplit blastexplosive in Heidaigou open cast with a density of 200 kgm3a speed of 1950ms a presplit blast hole diameter of 310mmcharge diameter of 150mm and a unit explosive consumptionof 085 kgm3 According to (11) the optimum blast holespacing of presplit blasting is estimated as ranging from303m to 416m with 35m selected for application Figure 5shows the presplit blasting effectThe cracks formed from theblast are relatively intact with an even width and the ratio ofthe half hole to the total presplit hole is a little higher

The transmission coefficient of stress wave is

119877

119905=

119860

119905

119860

119894

(12)

where119877119905is the transmission coefficient and119860

119894and119860

119905are the

amplitude of incident wave and the amplitude of transmittedwave respectively

The wave velocity expression is

V = 119860119890

minus120572 sin120596119905 (13)

and the vibration absorption ratio of presplit blasting is

120576 =

1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

V119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max=

1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

119860

119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max= 1 minus 119877

119905 (14)

4 Detection and Analysis of VibrationProduced by Blast Casting

41 The Detection Principles of Blast Vibration Detectionsystem of blast vibration is composed of the blast vibrationtester and the vibration pick-up As the vibration wave istransmitted to the vibration pick-up induced voltage outputsare generated and once the induced voltage signal exceeds thepreset triggering level the tester automatically records andsaves the vibration signals loaded by the sensor After detect-ing the vibration signals the blast vibration waves can beread and analyzed with the connection and communicationbetween special software and vibration tester The principlediagrams of the detection system and the measuring pointlayout are shown in Figures 6 and 7 respectively

Based on the inspection data the regression analysisshould be carried out with Sadovrsquos empirical formula andthe formula of vibration velocity attenuation can thus beobtained

42 Detection Scheme of Blast Vibration In order to recordthe whole vibration process and the attenuation law of blast-ing seismic waves the detection scheme of blast vibration is

6 Shock and Vibration

Figure 5 Presplit blasting effect pictures of surface coal mine

Vibration pick-up

Detection system

Blasting seismic wave

Blasting vibration tester

Parameter set-up Signal input

Data process Signal output

Computer Printer

Figure 6 The principle diagram of the detection system

worked out according to the characteristics of blast castingand the geological and topographic conditions of the blastingzone Detection points are set on the same bench and kept ina straight line on the right side of the blasting zone withoutpresplit blast Another set of detection points are also set onthe same bench in a straight line on the rear blasting zonewithpresplit blast Both of the above-mentioned detection pointsare used to monitor the seismic intensity and variations ofblast vibrations

The blast vibration tester adopted here is a vibrationsignal recorder whose model is UBOX-20016 the maximumsampling rate of which is 200KSpsCH and the signalresolution is 16 bits (165536 of the measuring range) Thevibration pick-up is CD-21magnetoelectric vibration velocitysensor with the sensitivity of 200mvcms and the erroris less than 3 The installation of sensors is based on themeasurement of vibration velocity in different directions andthe censors must be firmly bonded to the ground by gypsumpowder

The primary detection area of blast vibration is the rearpart and the broadside of the blasting zone the former iswith presplit cracks and the latter is without Therefore theeffect of presplit cracks in vibration reduction can be provedby comparison Blast vibration recorder is used for inspectingthe velocity of particles in vertical direction (V-) radialdirection (R-) and transverse direction (T-) Figure 8 showsthe schematic diagram of detection point layout

Vibrationtester

Blasting center

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Figure 7 The schematic diagram of the measuring point layout

43 Analysis on the Detection Results of Blasting Vibration Inall cases blast vibration detection has been carried out three(3) times The gross explosive loads (GEL) for each time are96 times 105 kg 78 times 105 kg and 13 times 106 kg respectively Themaximum explosive charges per delay interval (MECPDE)are 1 times 104 kg 15 times 104 kg and 15 times 104 kg respectivelyand the explosive charge per blast hole is 2 times 103 kg Thedistance between each detection point and the blasting source(DDPBS) as well as the vibration velocity of the largestparticle are shown in Table 3

Standard blast casting is adopted in Heidaigou open castand the blasting acting index 119899 = 1 Based on (1) and thedetection data the attenuation equations for blast vibrationin presplit blasting and non-presplit blasting are obtained byfitting

V

=

9518 (

3radic119876

119877

)

134

119877

2= 0959 (presplit blast)

22161 (

3radic119876

119877

)

140

119877

2= 0795 (non-presplit blast)

(15)

Shock and Vibration 7

Table 3 Location of detection points and blast vibration strength

Detection point 119879- mms 119881- mms 119877- mms Resultant mms DDPBS m GEL kg MECPDE kg RemarksH1-2 141 111 108 174 350 960000 10000 BackH1-3 104 168 78 179 550 960000 10000 BackH1-4 43 99 10 800 960000 10000 BackH1-5 17 23 38 39 1215 960000 10000 BackH1-6 11 19 28 29 1800 960000 10000 BackH2-1 1047 1497 1243 1813 100 780000 15000 BackH2-2 317 565 327 55 200 780000 15000 BackH2-3 118 173 163 204 300 780000 15000 BackH2-4 108 139 187 500 780000 15000 BackH2-5 45 39 37 79 800 780000 15000 BackH2-6 42 25 23 54 1000 780000 15000 BackH2-7 174 30 22 411 380 780000 15000 BackH3-1 667 694 598 874 162 1300000 15000 BackY1-1 286 135 291 303 5749 960000 10000 RightY1-2 196 121 306 311 6046 960000 10000 RightY1-3 126 559 124 145 800 960000 10000 RightY1-4 851 305 851 103 8266 960000 10000 RightY3-1 656 709 708 118 200 1300000 15000 RightY3-2 233 28 255 507 350 1300000 15000 RightY3-4 101 58 mdash 175 550 1300000 15000 RightY3-5 65 24 37 107 650 1300000 15000 Right

Detection pointon the right side

Detection pointon the rear

Presplitting blast Non-presplit blast

H1

H2

H3

H4

H5

Hi

Y1

Y2

Y3

Y4

Figure 8 Location of the blast detection point and blast vibrationsource

According to (15) the attenuation indices under thesetwo conditions are nearly the same that is 134 and 140respectively However the attenuation coefficient might bereduced by half when adopting presplit blasting Becauseof the application of hole-by-hole millisecond detonationthe maximum explosive charge per segment is less than 11times 104 kg and the vibration velocity of the end-wall slopeis 253 cms In addition the equation for calculating theacceleration of blast vibration is [34]

119886 = 0028119876

083119877

minus35119862

119901

2 (16)

where 119886 is acceleration of the blast vibration ms2 119862119901is the

longitudinal wave velocity ms other symbols are consistentwith the former expressions

The transmission velocity of blast vibration in sand-stone rock mass is 1118ms the acceleration is calculated as121ms2 (16) and the seismic load coefficient of blastingis calculated as 0012 (3) According to the mechanicalparameters of rock mass of Heidaigou open cast listed inTable 4 the factors of stability of the end-wall slope arecalculated as 1311 for the condition of static load and 1285for the condition of dynamic load respectivelyTherefore theeffect of dynamic load on factor of safety of the end wall ismerely 198

Meanwhile the resultant vibration velocities of differentdetection points are shown in Table 5 As the distancebetween detection points and blasting centers increasesthe vibration velocities decrease exponentially under thecondition of both presplit blasting and non-presplit blastingA closer distance to the blasting center can better reflectthe vibration reduction effect of presplit blasting Whenthe detection point is 200m away from the blasting centerthe vibration absorption ratio is increased to 502 whichimplies that presplit blasting can effectively absorb vibrations

5 Conclusions

(1) Pseudo-static method has converted the dynamic loadof blast vibration to equivalent static load and Janbu LEMhas been used to analyze the influence of blast vibration onslope stability The horizontal load caused by blast vibrationenhances the sliding force of the slip mass and therefore

8 Shock and Vibration

Table 4 Mechanical parameters of rock mass of Heidaigou open cast

Stratum Density (kNm3) Internal friction angle (∘) Cohesion (kPa)Loess 1950 295 451Sandy mudstone 2450 30 135Fine sandstone 2450 28 150Medium sandstone 2270 315 150Coarse sandstone 2240 320 130Weathered mudstone 247 290 1275Coal 14 35 1851Siltstone 245 313 1768

Table 5 Actual blast vibration detection data and absorption shock rate of presplit blasting

Detection point distance toblasting centerm

Velocity of vibrationcmsdotsminus1

200 400 600 800 1000 1200 1400Presplit blasting 548 221 13 089 066 052 043Non-presplit blasting 1101 397 218 143 103 079 063Vibration reduction ratio 502 443 404 378 359 342 317

reduces the factor of safety Calculated results suggest thatslope stability factors on conditions of static load anddynamic load of blasting are 1311 and 1285 respectively andthe dynamic load of blast casting has slight effect on the endslope stability taking only 198

(2) After the detonation of two adjacent presplit holesstress waves of each explosion spread radially and createtangential stress in the tangential direction Based on thetheory of stress wave interference when the sum of thetangential stress of two adjacent blast holes is greater than therock tensile strength radial cracks come into being along theline connecting blast holes which creates condition for theformation of the presplit face Based on the above conditionthe blast hole spacing in presplit blasting is obtained Accord-ingly the blast hole spacing of presplit blasting of Heidaigouopen cast mine ranges from 303m to 416m with 35m usedin actual production satisfying the presplit blasting effect

(3) The vibration detection principles of vibration testersand pick-ups are analyzed The vibration velocity of blastingparticle is detected in the blasting zonewhose rear part is withpresplit cracks and right side is without Based on Sadovrsquosempirical formula attenuation formulas of blast vibration onconditions with and without presplit blasting are obtained bynumerical fitting respectively The detection results indicatethat presplit blasting can reduce the attenuation coefficientby half and the vibration absorption ratio can reach 502whichmeans presplitting blast is of great significance in shockabsorption of blast casting

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

Acknowledgments

This study was supported by the National Natural Sci-ence Foundation of China (51034005) the Fundamental

Research Funds for the Central Universities (2010QNB232011QNB25) and the Priority Academic Program Develop-ment of Jiangsu Higher Education Institutions

References

[1] K Pathak S Durucan and S Kunimatsu ldquoActivity accountingtechnique for environmental noise assessment in mechanizedsurfaceminingrdquoEnvironmentalMonitoring andAssessment vol56 no 3 pp 241ndash256 1999

[2] A Fisne C Kuzu and T Hudaverdi ldquoPrediction of environ-mental impacts of quarry blasting operation using fuzzy logicrdquoEnvironmental Monitoring and Assessment vol 174 no 1ndash4 pp461ndash470 2011

[3] D J Armaghani E Momeni S V A N K Abad andM Khan-delwal ldquoFeasibility of ANFIS model for prediction of groundvibrations resulting from quarry blastingrdquo Environmental EarthSciences vol 74 no 4 pp 2845ndash2860 2015

[4] T N Singh and V Singh ldquoAn intelligent approach to predictionand control ground vibration in minesrdquo Geotechnical andGeological Engineering vol 23 no 3 pp 249ndash262 2005

[5] U Ozer A Kahriman M Aksoy D Adiguzel and A Karado-gan ldquoThe analysis of ground vibrations induced by benchblasting at Akyol quarry and practical blasting chartsrdquo Environ-mental Geology vol 54 no 4 pp 737ndash743 2008

[6] C Kuzu and E Guclu ldquoThe problem of human response toblast induced vibrations in tunnel construction and mitigationof vibration effects using cautious blasting in half-face blastingroundsrdquo Tunnelling and Underground Space Technology vol 24no 1 pp 53ndash61 2009

[7] D D Li and Z D Deng ldquoEvaluation of the effects of blastingvibration on humans in the excavation of CMICT dockrdquoEngineering Blasting vol 12 no 2 pp 82ndash85 2012

[8] F Zheng W D Duan D W Zhong and B Y Sun ldquoResearchprogress and existing problems of blasting vibrationrdquo Blastingvol 23 no 1 pp 92ndash94 2006

[9] T L Shi and B Z Li ldquoThe effects of millisecond delayinterval charge distribution andmeasuring distance on blastingvibrationrdquo Engineering Blasting vol 9 no 4 pp 10ndash13 2003

Shock and Vibration 9

[10] Y L Gao Q Tan S C Yang L Xue and Y L Yu ldquoExperimentalresearch on relationship between charge layout and blastingvibrationrdquo Engineering Blasting vol 10 no 3 pp 19ndash48 2004

[11] O Uysal and M Cavus ldquoEffect of a pre-split plane on the fre-quencies of blast induced ground vibrationsrdquoActaMontanisticaSlovaca vol 18 no 2 pp 101ndash109 2013

[12] J L Yan and X F Chen ldquoObservation and analysis of vibrationreduction effect of pre-split crack in complicated geologicconditionrdquo Blasting vol 25 no 3 pp 100ndash102 2008

[13] A J Prakash P Palroy and D D Misra ldquoAnalysis of blastvibration characteristics across a trench and a pre-split planerdquoFragblast vol 8 no 1 pp 51ndash60 2004

[14] L J Cai and J J Ma ldquoThe shock absorption mechanism and itseffect analysis of pre-splitting blastingrdquoChinaMiningMagazinevol 14 no 5 pp 56ndash58 2005

[15] Y F Zou ldquoExperimental study on the vibration- isolating effectof pre-split crack and vibration-isolating slotrdquo Blasting vol 22no 2 pp 96ndash99 2005

[16] E F Salmi and S Hosseinzadeh ldquoA further study on themechanism of pre-splitting in mining engineeringrdquo AppliedMechanics and Materials vol 553 pp 476ndash481 2014

[17] N H Yang ldquoExperimental study on rock damage in the slopecaused by presplit blastingrdquo Journal of the China RailwaySociety vol 30 no 3 pp 96ndash99 2008

[18] H R Sun Y J Tong X L Lin and H S Gao ldquoStudy on theVibration Effect of sling blasting in an open coalminerdquo Blastingvol 25 no 1 pp 69ndash73 2008

[19] Q K Chen G C Li and K M Li ldquoMonitor and analysis onexplosive seismic effect of high-bench cast blast of surface coalminerdquo Explosive Materials vol 37 no 6 pp 30ndash33 2008

[20] P K Zhang and F G Song ldquoPre-splitting blasting applied inhigh-bench cast blastingrdquo Opencast Mining Technology no 1pp 35ndash41 2007

[21] P K Zhang ldquoApplication of pre-splitting blasting in high-benchcast blasting of Heidaigou open pitrdquo Inner Mongolia ScienceTechnology amp Economy no 6 pp 257ndash258 2008

[22] W M Hu ldquoBlack dai ditch open-pit coal mine rock wavevelocity testing technologyrdquo Journal of North China Institute ofScience and Technology vol 11 no 9 pp 63ndash67 2014

[23] X H Ding K M Li S S Xiao and W M Hu ldquoAnalysisof key technologies and development of integrated digitalprocessing system for cast blasting designrdquo Journal of CentralSouth University vol 22 no 3 pp 1037ndash1044 2015

[24] C G Jin ldquoVibrating effect of blasting in open-pit sloperdquo MetalMine no 5 pp 18ndash20 1995

[25] Q Liu and S R Lv ldquoResearch on the millisecond delay intervaltime of open-pit bench blastingrdquo Engineering Blasting vol 20no 1 pp 54ndash58 2014

[26] M Chen W Lu D Shu and C Zhou ldquoCalculation method ofequivalent acceleration for limit equilibrium analysis of slopeunder blasting vibrationrdquo Chinese Journal of Rock Mechanicsand Engineering vol 28 no 4 pp 784ndash790 2009

[27] B He and YWang ldquoResidual thrust method and Janbumethodused to calculate landslide stabilityrdquo Safety and EnvironmentalEngineering vol 11 no 4 pp 60ndash62 2004

[28] Y L YuTheory and Technology of Engineering Blasting Metal-lurgical Industry Press Beijing China 2004

[29] W M Ling ldquoA study on the fracture mechanism of smoothblasting and pre-split blastingrdquo Journal of China University ofMining amp Technology vol 19 no 4 pp 79ndash87 1990 (Chinese)

[30] M Sazid and T N Singh ldquoNumerical assessment of spacing-burden ratio to effective utilization of explosive energyrdquo Inter-national Journal of Mining Science and Technology vol 25 no2 pp 291ndash297 2015

[31] B F Li and C B Qi ldquoShaped crack mechanism and parametersdesign of pre-splitting blastingrdquo West-China Exploration Engi-neering no 3 pp 78ndash79 2000 (Chinese)

[32] Q Zong ldquoTheoretical analysis of charge structurersquos influence onpressure on bore wallrdquo Mining and Metallurgical Engineeringvol 26 no 5 pp 9ndash12 2006 (Chinese)

[33] K S Ge Study on Parameter of Pre-Splitting Blasting ChinaUniversity of Geosciences Beijing China 2009

[34] J G Wang L F Luan Z Y Zhang X L Li and C L FanldquoNumerical simulation of blasting vibration effect on stabilityof high-steep sloperdquo Blasting vol 29 no 3 pp 119ndash122 2012

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Shock and Vibration

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International Journal of

Shock and Vibration 3

Table 2 Main characteristic parameters of rock stratum in the blasting area

Lithology Rockdensity (120574)

Rock massvelocity (Vrm)

Rock wavevelocity (V

119903)

Integritycoefficient

(119870119894)

Crackcoefficient

(119870119888)

Wave impedance(119877) Blastability

Mudstone 27 gcm3 1273ms 3744ms 012 088 344 times 103 gcm3sdotms MediumSandstone 23 gcm3 796sim1118ms 1586sim3226ms 006sim05 05sim099 22 times 103 gcm3sdotms EasyNote the integrated coefficient of rocks is determined by the square of the ratio of rockmass velocity to rock wave velocity119870119894 = (VrmV119903)

2 the crack coefficientof rocks119870119888 = (119881

2

119903minus 1198812

rm)1198812

119903 the wave impedance of rocks 119877 = 120574 sdot Vrm

Detonation blast hole Blast hole space

Arr

ay p

itch

Blast hole diameter

Presplit blast hole

Bench crest

A

A

200ms150ms

100ms9ms

(a) Schematic diagram of the plane parameters and interconnected design of blastcasting

Minimum burden

Detonator with

intervalBlast hole dip angle

600ms delay

(b) Schematic diagramof the drilling parameters and explosivecharge in blast casting

Figure 2 The schematic diagram of blast casting parameters

the blast casting area are mainly composed of sandstone andmudstone and the main characteristic parameters of rockstrata are shown in Table 2 [22]

The blast hole diameter for blast casting in Heidaigouopen cast is 310mm the blast hole spacing is 9sim12m thearray pitch is 7sim9m the plunge of blast hole ranges from65∘ to 70∘ the unit explosive consumption is 07sim09 kgm3and the minimum burden is 6sim65m In order to controlthe detonation charge over the same period hole-by-holemillisecond initiation control technology is adopted theinterhole delay is 9ms the interarray delay is 100sim200msand the time delay in holes is 600ms [23] Presplit blastingis adopted ahead of the detonation of main blast hole sothat the impacts of blast vibrations on slope stability on highbenches can be reducedThe result is commendable as shownin Figure 2

3 Vibration Effects of Blast Casting andVibration Absorption Mechanism ofPresplit Blasting

31 Vibration Effect of Blast Casting and Its Impact onSlope Stability The displacement velocity and accelerationof particle motion caused by blasts are three factors fordescribing blast vibration strength Moreover since the criti-cal safety values of acceleration and displacement are withina relatively wide limit velocity of blast vibration naturallybecomes the most important parameter for determining thedestruction-bearing capacity of the medium According to

Sadovrsquos empirical formula the velocity of blast vibration canbe determined as [24]

V =

119896

3radic119891 (119899)

(

3radic119876

119877

)

120572

119891 (119899) = 04 + 06119899

3

(1)

where V is the velocity of blasting vibration cms 119876 is themaximum explosive charge ignited over the same period kg119877 is the distance between blasting source center and guardpoint m 120572 is attenuation coefficient of seismic wave relatedto geological conditions 120572 = 1 to 3 119896 is medium parameterrelated to rock properties and blasting methods 119896 = 50sim200119891(119899) is the exponential function of the blasting effect 119899 is theindex of the blasting effect

According to wave theory it can be assumed that blastingseismic wave is composed of several simple harmonic waveswith different amplitudes and different vibration frequencies[25]

119883 = sum

119894

119860

119894sin (120596

119894119905)

119881 = sum

119894

120596

119894119860

119894cos (120596

119894119905 + 120593

1198941)

119886 = sum

119894

120596

2

119894119860

119894sin (120596

119894119905 + 120593

1198941)

(2)

where 119883 is displacement cm 119881 is vibration velocity cms119886 is vibration acceleration cms2 119860

119894is blasting vibration

4 Shock and Vibration

Seismic load

Qi

Ei

Hi

Si

Ni

Wi

120572i

li

Himinus1

Eiminus1

Figure 3 Force diagram on noncircular slip surface with slicesbased on Janbu Method

amplitude cm120596119894is circular frequency120596 = 2120587119891 Hz 119905 is time

s 1205931198941and 120593

1198942denote phase differences

High bench is applied in blast casting with the blastparameters of deep and large blast hole diameter The rockvolume blasted each time and the explosive consumption ishuge Blast vibration effect is a significant factor affectingslope stability of open cast mines When calculating slopestability affected by blasting dynamics with pseudo-staticmethod it is usually assumed that the horizontal loadsof blasting vibration exerted on the slope slip mass areequivalent to static loads [26]

119876

119894= 119870

119904119882

119894

119870

119904=

119870

119863119886

119894

119892

(3)

where 119876

119894is the equivalent static load N 119870

119904is seismic load

coefficient 119886119894is vibration acceleration ms2 119882

119894is the slice

weight of slidingmassN119892 is gravitational accelerationms2119870

119863is reduction coefficient of blasting dynamics whose value

range is 0008sim0152According to the schematic diagram for noncircular slip

surface shown in Figure 3 the following equation based onJanbursquos theory and the equilibrium condition of slice can beobtained [27]

sum119884 = 0

119882

119894+ 119867

119894minus 119867

119894minus1minus 119873

119894cos120572119894minus 119878

119894sin120572119894= 0

sum119883 = 0

119864

119894minus 119864

119894minus1+ 119878

119894cos120572119894minus 119873

119894sin120572119894minus 119876

119894= 0

(4)

According to Mohrrsquos-Coulomb criterion the shear forceon the bottom sliding surface should meet the followingcondition

119878

119894=

119888119897

119894

119865

119904

+ 119873

119894

tan120593119865

119904

(5)

Based on the balance of forces of the whole landslide

sum(119882

119894+ 119867

119894minus 119867

119894minus1) tan120572

119894minussum119878

119894sec120572119894+sum119876

119894= 0 (6)

Combining (4) (5) and (6) the following factor of safetyequation is obtained

119865

119904=

sum (sec2120572119894 (1 + tan120572

119894tan120593119894119865

119904)) [119888

119894119897

119894cos120572119894+ (119882

119894+ 119867

119894minus 119867

119894minus1) tan120593

119894]

sum (119882

119894+ 119867

119894minus 119867

119894minus1) tan120572

119894+ sum119876

119894cos120572119894

(7)

where 119864

119894minus1and 119864

119894are the normal forces of the 119894th slice

119867

119894minus1and 119867

119894are the vertical shear stresses of the 119894th slice

119873

119894and 119878

119894are the vertical reactions and shear forces on the

slipping surface respectively 119897119894is the slicersquos bottom length of

the sliding surface of the 119894th slice 119888119894is cohesive force of the

119894th slice 120593119894is the internal angle of friction of the 119894th slice 119865

119904

is the factor of safetyIt can be seen from Figure 3 and (7) that the horizontal

load produced by blast vibration on the slip mass and thesliding component caused by gravity together constitute thesliding force of the slip mass The factor of safety of the slopethat has been affected by blast vibration is reduced comparedto rock masses that are not affected

32 Vibration Absorption Mechanism of Presplit BlastingBlast casting in high bench of open cast mines causes theproduction of large blasting volume and devastating shock itcan cause relatively severe effects on slope stability of adjacentrock masses which have not been blasted But as a specialmethod for blasting control presplit blasting can be veryeffective in reducing blast vibrations This is achieved by

detonating the explosive charge placed in the presplit hole ofthe main blasting area and then separating the rock massesfrom original ones after cracks are formed along the blastingarea boundary In this way the damages caused by blastvibrations on the original rock masses can be reduced

The necessary condition to ensure the success of presplitblasting is that the pressure of the explosion in the blast holeswill not damage the wall of the hole and the presplit crackwill develop along the predetermined direction Accordingto stress wave interference theory [28ndash30] stress waves ofeach explosion spread radically after the denotation of twoadjacent presplit holes as shown in Figure 4

After the charge is denoted the peak of the stress wavefront weakens as the propagation distance of the stress waveincreases with the attenuation formula [31 32]

119875

119877= 119875

119863(

119903

1

119877

)

120572

119875

119863=

1

119896 + 1

120588119863

2(

119903

1

119903

2

)

minus2119896

119899

(8)

Shock and Vibration 5

Explosive charge Blast hole

Wave front

120590M

pMpM

s2s2

s

E1205760

Figure 4 Wave front of two adjacent blast holes

where 119875

119877is the pressure of stress wave front after the

detonation of explosive charge Pa 1199031is the radius of blast

hole m 119877 is the distance between the center of blast holeand a certain point on the wave front m 120572 is the attenuationcoefficient 120572 = 2 minus 120583(1 minus 120583) 120583 is Poissonrsquos ratio 119875

119863is the

pressure on the wall of the holes Pa 120588 is explosive densitykgm3119863 is explosive speed ms 119903

2is the radius of explosive

m 119896 is adiabatic exponent 119899 is the multiple of pressureincrease of the explosive gas colliding with the blast hole walland 119899 = 8sim11

The stress wave causes radical displacement of the rockmass between two adjacent blast holes while the radicaldisplacement derives the tangential stresses and tangentialstrains The tangential stress 120590

119879can be expressed as [33]

120590

119879=

120583

1 minus 120583

119875

119877 (9)

If the tangential stress on the wall of the hole is greaterthan the rock tensile strength 120590

119905 the initial crack on the wall

of the blast hole will appear Resulting from the stress wave oftwo adjacent blast holes the sum120590

119872of the tangential stress in

the middle of the line connecting the two adjacent blast holes(119877 = 1199042) is

120590

119872=

2120583

(1 minus 120583) (119896 + 1)

120588119863

2(

119903

1

119903

2

)

minus2119896

119899 (

2119903

1

119904

)

120572

(10)

Similarly if the tensile stress produced by blasting 120590

119872is

greater than the tensile strength of rocks that is 120590119872

ge 120590

119905

radial cracks appear along the lines connecting blast holeswhich creates condition for the formation of the presplit faceThe high pressure gas of explosion of the two adjacent blastholes then acts on the walls of the hole thereby forming aquasi-static stress field around the blast holes When the highpressure gas wedges in the initial crack of hole wall thereis a great tensile stress along the line connecting blast holesThe tensile stress concentration is all sides of the walls of thehole A free surface with a certain width is formed whichcan exert positive effects towards the reduction in vibrations

Therefore the important precondition for the formation ofthe presplit face is that tension waves can produce tensioncrack Based on (10) the formula of the blast hole spacing inpresplit blasting should be

119904 le

2119903

1

[120590

119905((1 minus 120583) (119896 + 1) 2120583120588119863

2119899) (119903

1119903

2)

2119896

]

1120572 (11)

Low density ANFO explosive is used as a presplit blastexplosive in Heidaigou open cast with a density of 200 kgm3a speed of 1950ms a presplit blast hole diameter of 310mmcharge diameter of 150mm and a unit explosive consumptionof 085 kgm3 According to (11) the optimum blast holespacing of presplit blasting is estimated as ranging from303m to 416m with 35m selected for application Figure 5shows the presplit blasting effectThe cracks formed from theblast are relatively intact with an even width and the ratio ofthe half hole to the total presplit hole is a little higher

The transmission coefficient of stress wave is

119877

119905=

119860

119905

119860

119894

(12)

where119877119905is the transmission coefficient and119860

119894and119860

119905are the

amplitude of incident wave and the amplitude of transmittedwave respectively

The wave velocity expression is

V = 119860119890

minus120572 sin120596119905 (13)

and the vibration absorption ratio of presplit blasting is

120576 =

1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

V119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max=

1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

119860

119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max= 1 minus 119877

119905 (14)

4 Detection and Analysis of VibrationProduced by Blast Casting

41 The Detection Principles of Blast Vibration Detectionsystem of blast vibration is composed of the blast vibrationtester and the vibration pick-up As the vibration wave istransmitted to the vibration pick-up induced voltage outputsare generated and once the induced voltage signal exceeds thepreset triggering level the tester automatically records andsaves the vibration signals loaded by the sensor After detect-ing the vibration signals the blast vibration waves can beread and analyzed with the connection and communicationbetween special software and vibration tester The principlediagrams of the detection system and the measuring pointlayout are shown in Figures 6 and 7 respectively

Based on the inspection data the regression analysisshould be carried out with Sadovrsquos empirical formula andthe formula of vibration velocity attenuation can thus beobtained

42 Detection Scheme of Blast Vibration In order to recordthe whole vibration process and the attenuation law of blast-ing seismic waves the detection scheme of blast vibration is

6 Shock and Vibration

Figure 5 Presplit blasting effect pictures of surface coal mine

Vibration pick-up

Detection system

Blasting seismic wave

Blasting vibration tester

Parameter set-up Signal input

Data process Signal output

Computer Printer

Figure 6 The principle diagram of the detection system

worked out according to the characteristics of blast castingand the geological and topographic conditions of the blastingzone Detection points are set on the same bench and kept ina straight line on the right side of the blasting zone withoutpresplit blast Another set of detection points are also set onthe same bench in a straight line on the rear blasting zonewithpresplit blast Both of the above-mentioned detection pointsare used to monitor the seismic intensity and variations ofblast vibrations

The blast vibration tester adopted here is a vibrationsignal recorder whose model is UBOX-20016 the maximumsampling rate of which is 200KSpsCH and the signalresolution is 16 bits (165536 of the measuring range) Thevibration pick-up is CD-21magnetoelectric vibration velocitysensor with the sensitivity of 200mvcms and the erroris less than 3 The installation of sensors is based on themeasurement of vibration velocity in different directions andthe censors must be firmly bonded to the ground by gypsumpowder

The primary detection area of blast vibration is the rearpart and the broadside of the blasting zone the former iswith presplit cracks and the latter is without Therefore theeffect of presplit cracks in vibration reduction can be provedby comparison Blast vibration recorder is used for inspectingthe velocity of particles in vertical direction (V-) radialdirection (R-) and transverse direction (T-) Figure 8 showsthe schematic diagram of detection point layout

Vibrationtester

Blasting center

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Figure 7 The schematic diagram of the measuring point layout

43 Analysis on the Detection Results of Blasting Vibration Inall cases blast vibration detection has been carried out three(3) times The gross explosive loads (GEL) for each time are96 times 105 kg 78 times 105 kg and 13 times 106 kg respectively Themaximum explosive charges per delay interval (MECPDE)are 1 times 104 kg 15 times 104 kg and 15 times 104 kg respectivelyand the explosive charge per blast hole is 2 times 103 kg Thedistance between each detection point and the blasting source(DDPBS) as well as the vibration velocity of the largestparticle are shown in Table 3

Standard blast casting is adopted in Heidaigou open castand the blasting acting index 119899 = 1 Based on (1) and thedetection data the attenuation equations for blast vibrationin presplit blasting and non-presplit blasting are obtained byfitting

V

=

9518 (

3radic119876

119877

)

134

119877

2= 0959 (presplit blast)

22161 (

3radic119876

119877

)

140

119877

2= 0795 (non-presplit blast)

(15)

Shock and Vibration 7

Table 3 Location of detection points and blast vibration strength

Detection point 119879- mms 119881- mms 119877- mms Resultant mms DDPBS m GEL kg MECPDE kg RemarksH1-2 141 111 108 174 350 960000 10000 BackH1-3 104 168 78 179 550 960000 10000 BackH1-4 43 99 10 800 960000 10000 BackH1-5 17 23 38 39 1215 960000 10000 BackH1-6 11 19 28 29 1800 960000 10000 BackH2-1 1047 1497 1243 1813 100 780000 15000 BackH2-2 317 565 327 55 200 780000 15000 BackH2-3 118 173 163 204 300 780000 15000 BackH2-4 108 139 187 500 780000 15000 BackH2-5 45 39 37 79 800 780000 15000 BackH2-6 42 25 23 54 1000 780000 15000 BackH2-7 174 30 22 411 380 780000 15000 BackH3-1 667 694 598 874 162 1300000 15000 BackY1-1 286 135 291 303 5749 960000 10000 RightY1-2 196 121 306 311 6046 960000 10000 RightY1-3 126 559 124 145 800 960000 10000 RightY1-4 851 305 851 103 8266 960000 10000 RightY3-1 656 709 708 118 200 1300000 15000 RightY3-2 233 28 255 507 350 1300000 15000 RightY3-4 101 58 mdash 175 550 1300000 15000 RightY3-5 65 24 37 107 650 1300000 15000 Right

Detection pointon the right side

Detection pointon the rear

Presplitting blast Non-presplit blast

H1

H2

H3

H4

H5

Hi

Y1

Y2

Y3

Y4

Figure 8 Location of the blast detection point and blast vibrationsource

According to (15) the attenuation indices under thesetwo conditions are nearly the same that is 134 and 140respectively However the attenuation coefficient might bereduced by half when adopting presplit blasting Becauseof the application of hole-by-hole millisecond detonationthe maximum explosive charge per segment is less than 11times 104 kg and the vibration velocity of the end-wall slopeis 253 cms In addition the equation for calculating theacceleration of blast vibration is [34]

119886 = 0028119876

083119877

minus35119862

119901

2 (16)

where 119886 is acceleration of the blast vibration ms2 119862119901is the

longitudinal wave velocity ms other symbols are consistentwith the former expressions

The transmission velocity of blast vibration in sand-stone rock mass is 1118ms the acceleration is calculated as121ms2 (16) and the seismic load coefficient of blastingis calculated as 0012 (3) According to the mechanicalparameters of rock mass of Heidaigou open cast listed inTable 4 the factors of stability of the end-wall slope arecalculated as 1311 for the condition of static load and 1285for the condition of dynamic load respectivelyTherefore theeffect of dynamic load on factor of safety of the end wall ismerely 198

Meanwhile the resultant vibration velocities of differentdetection points are shown in Table 5 As the distancebetween detection points and blasting centers increasesthe vibration velocities decrease exponentially under thecondition of both presplit blasting and non-presplit blastingA closer distance to the blasting center can better reflectthe vibration reduction effect of presplit blasting Whenthe detection point is 200m away from the blasting centerthe vibration absorption ratio is increased to 502 whichimplies that presplit blasting can effectively absorb vibrations

5 Conclusions

(1) Pseudo-static method has converted the dynamic loadof blast vibration to equivalent static load and Janbu LEMhas been used to analyze the influence of blast vibration onslope stability The horizontal load caused by blast vibrationenhances the sliding force of the slip mass and therefore

8 Shock and Vibration

Table 4 Mechanical parameters of rock mass of Heidaigou open cast

Stratum Density (kNm3) Internal friction angle (∘) Cohesion (kPa)Loess 1950 295 451Sandy mudstone 2450 30 135Fine sandstone 2450 28 150Medium sandstone 2270 315 150Coarse sandstone 2240 320 130Weathered mudstone 247 290 1275Coal 14 35 1851Siltstone 245 313 1768

Table 5 Actual blast vibration detection data and absorption shock rate of presplit blasting

Detection point distance toblasting centerm

Velocity of vibrationcmsdotsminus1

200 400 600 800 1000 1200 1400Presplit blasting 548 221 13 089 066 052 043Non-presplit blasting 1101 397 218 143 103 079 063Vibration reduction ratio 502 443 404 378 359 342 317

reduces the factor of safety Calculated results suggest thatslope stability factors on conditions of static load anddynamic load of blasting are 1311 and 1285 respectively andthe dynamic load of blast casting has slight effect on the endslope stability taking only 198

(2) After the detonation of two adjacent presplit holesstress waves of each explosion spread radially and createtangential stress in the tangential direction Based on thetheory of stress wave interference when the sum of thetangential stress of two adjacent blast holes is greater than therock tensile strength radial cracks come into being along theline connecting blast holes which creates condition for theformation of the presplit face Based on the above conditionthe blast hole spacing in presplit blasting is obtained Accord-ingly the blast hole spacing of presplit blasting of Heidaigouopen cast mine ranges from 303m to 416m with 35m usedin actual production satisfying the presplit blasting effect

(3) The vibration detection principles of vibration testersand pick-ups are analyzed The vibration velocity of blastingparticle is detected in the blasting zonewhose rear part is withpresplit cracks and right side is without Based on Sadovrsquosempirical formula attenuation formulas of blast vibration onconditions with and without presplit blasting are obtained bynumerical fitting respectively The detection results indicatethat presplit blasting can reduce the attenuation coefficientby half and the vibration absorption ratio can reach 502whichmeans presplitting blast is of great significance in shockabsorption of blast casting

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

Acknowledgments

This study was supported by the National Natural Sci-ence Foundation of China (51034005) the Fundamental

Research Funds for the Central Universities (2010QNB232011QNB25) and the Priority Academic Program Develop-ment of Jiangsu Higher Education Institutions

References

[1] K Pathak S Durucan and S Kunimatsu ldquoActivity accountingtechnique for environmental noise assessment in mechanizedsurfaceminingrdquoEnvironmentalMonitoring andAssessment vol56 no 3 pp 241ndash256 1999

[2] A Fisne C Kuzu and T Hudaverdi ldquoPrediction of environ-mental impacts of quarry blasting operation using fuzzy logicrdquoEnvironmental Monitoring and Assessment vol 174 no 1ndash4 pp461ndash470 2011

[3] D J Armaghani E Momeni S V A N K Abad andM Khan-delwal ldquoFeasibility of ANFIS model for prediction of groundvibrations resulting from quarry blastingrdquo Environmental EarthSciences vol 74 no 4 pp 2845ndash2860 2015

[4] T N Singh and V Singh ldquoAn intelligent approach to predictionand control ground vibration in minesrdquo Geotechnical andGeological Engineering vol 23 no 3 pp 249ndash262 2005

[5] U Ozer A Kahriman M Aksoy D Adiguzel and A Karado-gan ldquoThe analysis of ground vibrations induced by benchblasting at Akyol quarry and practical blasting chartsrdquo Environ-mental Geology vol 54 no 4 pp 737ndash743 2008

[6] C Kuzu and E Guclu ldquoThe problem of human response toblast induced vibrations in tunnel construction and mitigationof vibration effects using cautious blasting in half-face blastingroundsrdquo Tunnelling and Underground Space Technology vol 24no 1 pp 53ndash61 2009

[7] D D Li and Z D Deng ldquoEvaluation of the effects of blastingvibration on humans in the excavation of CMICT dockrdquoEngineering Blasting vol 12 no 2 pp 82ndash85 2012

[8] F Zheng W D Duan D W Zhong and B Y Sun ldquoResearchprogress and existing problems of blasting vibrationrdquo Blastingvol 23 no 1 pp 92ndash94 2006

[9] T L Shi and B Z Li ldquoThe effects of millisecond delayinterval charge distribution andmeasuring distance on blastingvibrationrdquo Engineering Blasting vol 9 no 4 pp 10ndash13 2003

Shock and Vibration 9

[10] Y L Gao Q Tan S C Yang L Xue and Y L Yu ldquoExperimentalresearch on relationship between charge layout and blastingvibrationrdquo Engineering Blasting vol 10 no 3 pp 19ndash48 2004

[11] O Uysal and M Cavus ldquoEffect of a pre-split plane on the fre-quencies of blast induced ground vibrationsrdquoActaMontanisticaSlovaca vol 18 no 2 pp 101ndash109 2013

[12] J L Yan and X F Chen ldquoObservation and analysis of vibrationreduction effect of pre-split crack in complicated geologicconditionrdquo Blasting vol 25 no 3 pp 100ndash102 2008

[13] A J Prakash P Palroy and D D Misra ldquoAnalysis of blastvibration characteristics across a trench and a pre-split planerdquoFragblast vol 8 no 1 pp 51ndash60 2004

[14] L J Cai and J J Ma ldquoThe shock absorption mechanism and itseffect analysis of pre-splitting blastingrdquoChinaMiningMagazinevol 14 no 5 pp 56ndash58 2005

[15] Y F Zou ldquoExperimental study on the vibration- isolating effectof pre-split crack and vibration-isolating slotrdquo Blasting vol 22no 2 pp 96ndash99 2005

[16] E F Salmi and S Hosseinzadeh ldquoA further study on themechanism of pre-splitting in mining engineeringrdquo AppliedMechanics and Materials vol 553 pp 476ndash481 2014

[17] N H Yang ldquoExperimental study on rock damage in the slopecaused by presplit blastingrdquo Journal of the China RailwaySociety vol 30 no 3 pp 96ndash99 2008

[18] H R Sun Y J Tong X L Lin and H S Gao ldquoStudy on theVibration Effect of sling blasting in an open coalminerdquo Blastingvol 25 no 1 pp 69ndash73 2008

[19] Q K Chen G C Li and K M Li ldquoMonitor and analysis onexplosive seismic effect of high-bench cast blast of surface coalminerdquo Explosive Materials vol 37 no 6 pp 30ndash33 2008

[20] P K Zhang and F G Song ldquoPre-splitting blasting applied inhigh-bench cast blastingrdquo Opencast Mining Technology no 1pp 35ndash41 2007

[21] P K Zhang ldquoApplication of pre-splitting blasting in high-benchcast blasting of Heidaigou open pitrdquo Inner Mongolia ScienceTechnology amp Economy no 6 pp 257ndash258 2008

[22] W M Hu ldquoBlack dai ditch open-pit coal mine rock wavevelocity testing technologyrdquo Journal of North China Institute ofScience and Technology vol 11 no 9 pp 63ndash67 2014

[23] X H Ding K M Li S S Xiao and W M Hu ldquoAnalysisof key technologies and development of integrated digitalprocessing system for cast blasting designrdquo Journal of CentralSouth University vol 22 no 3 pp 1037ndash1044 2015

[24] C G Jin ldquoVibrating effect of blasting in open-pit sloperdquo MetalMine no 5 pp 18ndash20 1995

[25] Q Liu and S R Lv ldquoResearch on the millisecond delay intervaltime of open-pit bench blastingrdquo Engineering Blasting vol 20no 1 pp 54ndash58 2014

[26] M Chen W Lu D Shu and C Zhou ldquoCalculation method ofequivalent acceleration for limit equilibrium analysis of slopeunder blasting vibrationrdquo Chinese Journal of Rock Mechanicsand Engineering vol 28 no 4 pp 784ndash790 2009

[27] B He and YWang ldquoResidual thrust method and Janbumethodused to calculate landslide stabilityrdquo Safety and EnvironmentalEngineering vol 11 no 4 pp 60ndash62 2004

[28] Y L YuTheory and Technology of Engineering Blasting Metal-lurgical Industry Press Beijing China 2004

[29] W M Ling ldquoA study on the fracture mechanism of smoothblasting and pre-split blastingrdquo Journal of China University ofMining amp Technology vol 19 no 4 pp 79ndash87 1990 (Chinese)

[30] M Sazid and T N Singh ldquoNumerical assessment of spacing-burden ratio to effective utilization of explosive energyrdquo Inter-national Journal of Mining Science and Technology vol 25 no2 pp 291ndash297 2015

[31] B F Li and C B Qi ldquoShaped crack mechanism and parametersdesign of pre-splitting blastingrdquo West-China Exploration Engi-neering no 3 pp 78ndash79 2000 (Chinese)

[32] Q Zong ldquoTheoretical analysis of charge structurersquos influence onpressure on bore wallrdquo Mining and Metallurgical Engineeringvol 26 no 5 pp 9ndash12 2006 (Chinese)

[33] K S Ge Study on Parameter of Pre-Splitting Blasting ChinaUniversity of Geosciences Beijing China 2009

[34] J G Wang L F Luan Z Y Zhang X L Li and C L FanldquoNumerical simulation of blasting vibration effect on stabilityof high-steep sloperdquo Blasting vol 29 no 3 pp 119ndash122 2012

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Shock and Vibration

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DistributedSensor Networks

International Journal of

4 Shock and Vibration

Seismic load

Qi

Ei

Hi

Si

Ni

Wi

120572i

li

Himinus1

Eiminus1

Figure 3 Force diagram on noncircular slip surface with slicesbased on Janbu Method

amplitude cm120596119894is circular frequency120596 = 2120587119891 Hz 119905 is time

s 1205931198941and 120593

1198942denote phase differences

High bench is applied in blast casting with the blastparameters of deep and large blast hole diameter The rockvolume blasted each time and the explosive consumption ishuge Blast vibration effect is a significant factor affectingslope stability of open cast mines When calculating slopestability affected by blasting dynamics with pseudo-staticmethod it is usually assumed that the horizontal loadsof blasting vibration exerted on the slope slip mass areequivalent to static loads [26]

119876

119894= 119870

119904119882

119894

119870

119904=

119870

119863119886

119894

119892

(3)

where 119876

119894is the equivalent static load N 119870

119904is seismic load

coefficient 119886119894is vibration acceleration ms2 119882

119894is the slice

weight of slidingmassN119892 is gravitational accelerationms2119870

119863is reduction coefficient of blasting dynamics whose value

range is 0008sim0152According to the schematic diagram for noncircular slip

surface shown in Figure 3 the following equation based onJanbursquos theory and the equilibrium condition of slice can beobtained [27]

sum119884 = 0

119882

119894+ 119867

119894minus 119867

119894minus1minus 119873

119894cos120572119894minus 119878

119894sin120572119894= 0

sum119883 = 0

119864

119894minus 119864

119894minus1+ 119878

119894cos120572119894minus 119873

119894sin120572119894minus 119876

119894= 0

(4)

According to Mohrrsquos-Coulomb criterion the shear forceon the bottom sliding surface should meet the followingcondition

119878

119894=

119888119897

119894

119865

119904

+ 119873

119894

tan120593119865

119904

(5)

Based on the balance of forces of the whole landslide

sum(119882

119894+ 119867

119894minus 119867

119894minus1) tan120572

119894minussum119878

119894sec120572119894+sum119876

119894= 0 (6)

Combining (4) (5) and (6) the following factor of safetyequation is obtained

119865

119904=

sum (sec2120572119894 (1 + tan120572

119894tan120593119894119865

119904)) [119888

119894119897

119894cos120572119894+ (119882

119894+ 119867

119894minus 119867

119894minus1) tan120593

119894]

sum (119882

119894+ 119867

119894minus 119867

119894minus1) tan120572

119894+ sum119876

119894cos120572119894

(7)

where 119864

119894minus1and 119864

119894are the normal forces of the 119894th slice

119867

119894minus1and 119867

119894are the vertical shear stresses of the 119894th slice

119873

119894and 119878

119894are the vertical reactions and shear forces on the

slipping surface respectively 119897119894is the slicersquos bottom length of

the sliding surface of the 119894th slice 119888119894is cohesive force of the

119894th slice 120593119894is the internal angle of friction of the 119894th slice 119865

119904

is the factor of safetyIt can be seen from Figure 3 and (7) that the horizontal

load produced by blast vibration on the slip mass and thesliding component caused by gravity together constitute thesliding force of the slip mass The factor of safety of the slopethat has been affected by blast vibration is reduced comparedto rock masses that are not affected

32 Vibration Absorption Mechanism of Presplit BlastingBlast casting in high bench of open cast mines causes theproduction of large blasting volume and devastating shock itcan cause relatively severe effects on slope stability of adjacentrock masses which have not been blasted But as a specialmethod for blasting control presplit blasting can be veryeffective in reducing blast vibrations This is achieved by

detonating the explosive charge placed in the presplit hole ofthe main blasting area and then separating the rock massesfrom original ones after cracks are formed along the blastingarea boundary In this way the damages caused by blastvibrations on the original rock masses can be reduced

The necessary condition to ensure the success of presplitblasting is that the pressure of the explosion in the blast holeswill not damage the wall of the hole and the presplit crackwill develop along the predetermined direction Accordingto stress wave interference theory [28ndash30] stress waves ofeach explosion spread radically after the denotation of twoadjacent presplit holes as shown in Figure 4

After the charge is denoted the peak of the stress wavefront weakens as the propagation distance of the stress waveincreases with the attenuation formula [31 32]

119875

119877= 119875

119863(

119903

1

119877

)

120572

119875

119863=

1

119896 + 1

120588119863

2(

119903

1

119903

2

)

minus2119896

119899

(8)

Shock and Vibration 5

Explosive charge Blast hole

Wave front

120590M

pMpM

s2s2

s

E1205760

Figure 4 Wave front of two adjacent blast holes

where 119875

119877is the pressure of stress wave front after the

detonation of explosive charge Pa 1199031is the radius of blast

hole m 119877 is the distance between the center of blast holeand a certain point on the wave front m 120572 is the attenuationcoefficient 120572 = 2 minus 120583(1 minus 120583) 120583 is Poissonrsquos ratio 119875

119863is the

pressure on the wall of the holes Pa 120588 is explosive densitykgm3119863 is explosive speed ms 119903

2is the radius of explosive

m 119896 is adiabatic exponent 119899 is the multiple of pressureincrease of the explosive gas colliding with the blast hole walland 119899 = 8sim11

The stress wave causes radical displacement of the rockmass between two adjacent blast holes while the radicaldisplacement derives the tangential stresses and tangentialstrains The tangential stress 120590

119879can be expressed as [33]

120590

119879=

120583

1 minus 120583

119875

119877 (9)

If the tangential stress on the wall of the hole is greaterthan the rock tensile strength 120590

119905 the initial crack on the wall

of the blast hole will appear Resulting from the stress wave oftwo adjacent blast holes the sum120590

119872of the tangential stress in

the middle of the line connecting the two adjacent blast holes(119877 = 1199042) is

120590

119872=

2120583

(1 minus 120583) (119896 + 1)

120588119863

2(

119903

1

119903

2

)

minus2119896

119899 (

2119903

1

119904

)

120572

(10)

Similarly if the tensile stress produced by blasting 120590

119872is

greater than the tensile strength of rocks that is 120590119872

ge 120590

119905

radial cracks appear along the lines connecting blast holeswhich creates condition for the formation of the presplit faceThe high pressure gas of explosion of the two adjacent blastholes then acts on the walls of the hole thereby forming aquasi-static stress field around the blast holes When the highpressure gas wedges in the initial crack of hole wall thereis a great tensile stress along the line connecting blast holesThe tensile stress concentration is all sides of the walls of thehole A free surface with a certain width is formed whichcan exert positive effects towards the reduction in vibrations

Therefore the important precondition for the formation ofthe presplit face is that tension waves can produce tensioncrack Based on (10) the formula of the blast hole spacing inpresplit blasting should be

119904 le

2119903

1

[120590

119905((1 minus 120583) (119896 + 1) 2120583120588119863

2119899) (119903

1119903

2)

2119896

]

1120572 (11)

Low density ANFO explosive is used as a presplit blastexplosive in Heidaigou open cast with a density of 200 kgm3a speed of 1950ms a presplit blast hole diameter of 310mmcharge diameter of 150mm and a unit explosive consumptionof 085 kgm3 According to (11) the optimum blast holespacing of presplit blasting is estimated as ranging from303m to 416m with 35m selected for application Figure 5shows the presplit blasting effectThe cracks formed from theblast are relatively intact with an even width and the ratio ofthe half hole to the total presplit hole is a little higher

The transmission coefficient of stress wave is

119877

119905=

119860

119905

119860

119894

(12)

where119877119905is the transmission coefficient and119860

119894and119860

119905are the

amplitude of incident wave and the amplitude of transmittedwave respectively

The wave velocity expression is

V = 119860119890

minus120572 sin120596119905 (13)

and the vibration absorption ratio of presplit blasting is

120576 =

1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

V119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max=

1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

119860

119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max= 1 minus 119877

119905 (14)

4 Detection and Analysis of VibrationProduced by Blast Casting

41 The Detection Principles of Blast Vibration Detectionsystem of blast vibration is composed of the blast vibrationtester and the vibration pick-up As the vibration wave istransmitted to the vibration pick-up induced voltage outputsare generated and once the induced voltage signal exceeds thepreset triggering level the tester automatically records andsaves the vibration signals loaded by the sensor After detect-ing the vibration signals the blast vibration waves can beread and analyzed with the connection and communicationbetween special software and vibration tester The principlediagrams of the detection system and the measuring pointlayout are shown in Figures 6 and 7 respectively

Based on the inspection data the regression analysisshould be carried out with Sadovrsquos empirical formula andthe formula of vibration velocity attenuation can thus beobtained

42 Detection Scheme of Blast Vibration In order to recordthe whole vibration process and the attenuation law of blast-ing seismic waves the detection scheme of blast vibration is

6 Shock and Vibration

Figure 5 Presplit blasting effect pictures of surface coal mine

Vibration pick-up

Detection system

Blasting seismic wave

Blasting vibration tester

Parameter set-up Signal input

Data process Signal output

Computer Printer

Figure 6 The principle diagram of the detection system

worked out according to the characteristics of blast castingand the geological and topographic conditions of the blastingzone Detection points are set on the same bench and kept ina straight line on the right side of the blasting zone withoutpresplit blast Another set of detection points are also set onthe same bench in a straight line on the rear blasting zonewithpresplit blast Both of the above-mentioned detection pointsare used to monitor the seismic intensity and variations ofblast vibrations

The blast vibration tester adopted here is a vibrationsignal recorder whose model is UBOX-20016 the maximumsampling rate of which is 200KSpsCH and the signalresolution is 16 bits (165536 of the measuring range) Thevibration pick-up is CD-21magnetoelectric vibration velocitysensor with the sensitivity of 200mvcms and the erroris less than 3 The installation of sensors is based on themeasurement of vibration velocity in different directions andthe censors must be firmly bonded to the ground by gypsumpowder

The primary detection area of blast vibration is the rearpart and the broadside of the blasting zone the former iswith presplit cracks and the latter is without Therefore theeffect of presplit cracks in vibration reduction can be provedby comparison Blast vibration recorder is used for inspectingthe velocity of particles in vertical direction (V-) radialdirection (R-) and transverse direction (T-) Figure 8 showsthe schematic diagram of detection point layout

Vibrationtester

Blasting center

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Figure 7 The schematic diagram of the measuring point layout

43 Analysis on the Detection Results of Blasting Vibration Inall cases blast vibration detection has been carried out three(3) times The gross explosive loads (GEL) for each time are96 times 105 kg 78 times 105 kg and 13 times 106 kg respectively Themaximum explosive charges per delay interval (MECPDE)are 1 times 104 kg 15 times 104 kg and 15 times 104 kg respectivelyand the explosive charge per blast hole is 2 times 103 kg Thedistance between each detection point and the blasting source(DDPBS) as well as the vibration velocity of the largestparticle are shown in Table 3

Standard blast casting is adopted in Heidaigou open castand the blasting acting index 119899 = 1 Based on (1) and thedetection data the attenuation equations for blast vibrationin presplit blasting and non-presplit blasting are obtained byfitting

V

=

9518 (

3radic119876

119877

)

134

119877

2= 0959 (presplit blast)

22161 (

3radic119876

119877

)

140

119877

2= 0795 (non-presplit blast)

(15)

Shock and Vibration 7

Table 3 Location of detection points and blast vibration strength

Detection point 119879- mms 119881- mms 119877- mms Resultant mms DDPBS m GEL kg MECPDE kg RemarksH1-2 141 111 108 174 350 960000 10000 BackH1-3 104 168 78 179 550 960000 10000 BackH1-4 43 99 10 800 960000 10000 BackH1-5 17 23 38 39 1215 960000 10000 BackH1-6 11 19 28 29 1800 960000 10000 BackH2-1 1047 1497 1243 1813 100 780000 15000 BackH2-2 317 565 327 55 200 780000 15000 BackH2-3 118 173 163 204 300 780000 15000 BackH2-4 108 139 187 500 780000 15000 BackH2-5 45 39 37 79 800 780000 15000 BackH2-6 42 25 23 54 1000 780000 15000 BackH2-7 174 30 22 411 380 780000 15000 BackH3-1 667 694 598 874 162 1300000 15000 BackY1-1 286 135 291 303 5749 960000 10000 RightY1-2 196 121 306 311 6046 960000 10000 RightY1-3 126 559 124 145 800 960000 10000 RightY1-4 851 305 851 103 8266 960000 10000 RightY3-1 656 709 708 118 200 1300000 15000 RightY3-2 233 28 255 507 350 1300000 15000 RightY3-4 101 58 mdash 175 550 1300000 15000 RightY3-5 65 24 37 107 650 1300000 15000 Right

Detection pointon the right side

Detection pointon the rear

Presplitting blast Non-presplit blast

H1

H2

H3

H4

H5

Hi

Y1

Y2

Y3

Y4

Figure 8 Location of the blast detection point and blast vibrationsource

According to (15) the attenuation indices under thesetwo conditions are nearly the same that is 134 and 140respectively However the attenuation coefficient might bereduced by half when adopting presplit blasting Becauseof the application of hole-by-hole millisecond detonationthe maximum explosive charge per segment is less than 11times 104 kg and the vibration velocity of the end-wall slopeis 253 cms In addition the equation for calculating theacceleration of blast vibration is [34]

119886 = 0028119876

083119877

minus35119862

119901

2 (16)

where 119886 is acceleration of the blast vibration ms2 119862119901is the

longitudinal wave velocity ms other symbols are consistentwith the former expressions

The transmission velocity of blast vibration in sand-stone rock mass is 1118ms the acceleration is calculated as121ms2 (16) and the seismic load coefficient of blastingis calculated as 0012 (3) According to the mechanicalparameters of rock mass of Heidaigou open cast listed inTable 4 the factors of stability of the end-wall slope arecalculated as 1311 for the condition of static load and 1285for the condition of dynamic load respectivelyTherefore theeffect of dynamic load on factor of safety of the end wall ismerely 198

Meanwhile the resultant vibration velocities of differentdetection points are shown in Table 5 As the distancebetween detection points and blasting centers increasesthe vibration velocities decrease exponentially under thecondition of both presplit blasting and non-presplit blastingA closer distance to the blasting center can better reflectthe vibration reduction effect of presplit blasting Whenthe detection point is 200m away from the blasting centerthe vibration absorption ratio is increased to 502 whichimplies that presplit blasting can effectively absorb vibrations

5 Conclusions

(1) Pseudo-static method has converted the dynamic loadof blast vibration to equivalent static load and Janbu LEMhas been used to analyze the influence of blast vibration onslope stability The horizontal load caused by blast vibrationenhances the sliding force of the slip mass and therefore

8 Shock and Vibration

Table 4 Mechanical parameters of rock mass of Heidaigou open cast

Stratum Density (kNm3) Internal friction angle (∘) Cohesion (kPa)Loess 1950 295 451Sandy mudstone 2450 30 135Fine sandstone 2450 28 150Medium sandstone 2270 315 150Coarse sandstone 2240 320 130Weathered mudstone 247 290 1275Coal 14 35 1851Siltstone 245 313 1768

Table 5 Actual blast vibration detection data and absorption shock rate of presplit blasting

Detection point distance toblasting centerm

Velocity of vibrationcmsdotsminus1

200 400 600 800 1000 1200 1400Presplit blasting 548 221 13 089 066 052 043Non-presplit blasting 1101 397 218 143 103 079 063Vibration reduction ratio 502 443 404 378 359 342 317

reduces the factor of safety Calculated results suggest thatslope stability factors on conditions of static load anddynamic load of blasting are 1311 and 1285 respectively andthe dynamic load of blast casting has slight effect on the endslope stability taking only 198

(2) After the detonation of two adjacent presplit holesstress waves of each explosion spread radially and createtangential stress in the tangential direction Based on thetheory of stress wave interference when the sum of thetangential stress of two adjacent blast holes is greater than therock tensile strength radial cracks come into being along theline connecting blast holes which creates condition for theformation of the presplit face Based on the above conditionthe blast hole spacing in presplit blasting is obtained Accord-ingly the blast hole spacing of presplit blasting of Heidaigouopen cast mine ranges from 303m to 416m with 35m usedin actual production satisfying the presplit blasting effect

(3) The vibration detection principles of vibration testersand pick-ups are analyzed The vibration velocity of blastingparticle is detected in the blasting zonewhose rear part is withpresplit cracks and right side is without Based on Sadovrsquosempirical formula attenuation formulas of blast vibration onconditions with and without presplit blasting are obtained bynumerical fitting respectively The detection results indicatethat presplit blasting can reduce the attenuation coefficientby half and the vibration absorption ratio can reach 502whichmeans presplitting blast is of great significance in shockabsorption of blast casting

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

Acknowledgments

This study was supported by the National Natural Sci-ence Foundation of China (51034005) the Fundamental

Research Funds for the Central Universities (2010QNB232011QNB25) and the Priority Academic Program Develop-ment of Jiangsu Higher Education Institutions

References

[1] K Pathak S Durucan and S Kunimatsu ldquoActivity accountingtechnique for environmental noise assessment in mechanizedsurfaceminingrdquoEnvironmentalMonitoring andAssessment vol56 no 3 pp 241ndash256 1999

[2] A Fisne C Kuzu and T Hudaverdi ldquoPrediction of environ-mental impacts of quarry blasting operation using fuzzy logicrdquoEnvironmental Monitoring and Assessment vol 174 no 1ndash4 pp461ndash470 2011

[3] D J Armaghani E Momeni S V A N K Abad andM Khan-delwal ldquoFeasibility of ANFIS model for prediction of groundvibrations resulting from quarry blastingrdquo Environmental EarthSciences vol 74 no 4 pp 2845ndash2860 2015

[4] T N Singh and V Singh ldquoAn intelligent approach to predictionand control ground vibration in minesrdquo Geotechnical andGeological Engineering vol 23 no 3 pp 249ndash262 2005

[5] U Ozer A Kahriman M Aksoy D Adiguzel and A Karado-gan ldquoThe analysis of ground vibrations induced by benchblasting at Akyol quarry and practical blasting chartsrdquo Environ-mental Geology vol 54 no 4 pp 737ndash743 2008

[6] C Kuzu and E Guclu ldquoThe problem of human response toblast induced vibrations in tunnel construction and mitigationof vibration effects using cautious blasting in half-face blastingroundsrdquo Tunnelling and Underground Space Technology vol 24no 1 pp 53ndash61 2009

[7] D D Li and Z D Deng ldquoEvaluation of the effects of blastingvibration on humans in the excavation of CMICT dockrdquoEngineering Blasting vol 12 no 2 pp 82ndash85 2012

[8] F Zheng W D Duan D W Zhong and B Y Sun ldquoResearchprogress and existing problems of blasting vibrationrdquo Blastingvol 23 no 1 pp 92ndash94 2006

[9] T L Shi and B Z Li ldquoThe effects of millisecond delayinterval charge distribution andmeasuring distance on blastingvibrationrdquo Engineering Blasting vol 9 no 4 pp 10ndash13 2003

Shock and Vibration 9

[10] Y L Gao Q Tan S C Yang L Xue and Y L Yu ldquoExperimentalresearch on relationship between charge layout and blastingvibrationrdquo Engineering Blasting vol 10 no 3 pp 19ndash48 2004

[11] O Uysal and M Cavus ldquoEffect of a pre-split plane on the fre-quencies of blast induced ground vibrationsrdquoActaMontanisticaSlovaca vol 18 no 2 pp 101ndash109 2013

[12] J L Yan and X F Chen ldquoObservation and analysis of vibrationreduction effect of pre-split crack in complicated geologicconditionrdquo Blasting vol 25 no 3 pp 100ndash102 2008

[13] A J Prakash P Palroy and D D Misra ldquoAnalysis of blastvibration characteristics across a trench and a pre-split planerdquoFragblast vol 8 no 1 pp 51ndash60 2004

[14] L J Cai and J J Ma ldquoThe shock absorption mechanism and itseffect analysis of pre-splitting blastingrdquoChinaMiningMagazinevol 14 no 5 pp 56ndash58 2005

[15] Y F Zou ldquoExperimental study on the vibration- isolating effectof pre-split crack and vibration-isolating slotrdquo Blasting vol 22no 2 pp 96ndash99 2005

[16] E F Salmi and S Hosseinzadeh ldquoA further study on themechanism of pre-splitting in mining engineeringrdquo AppliedMechanics and Materials vol 553 pp 476ndash481 2014

[17] N H Yang ldquoExperimental study on rock damage in the slopecaused by presplit blastingrdquo Journal of the China RailwaySociety vol 30 no 3 pp 96ndash99 2008

[18] H R Sun Y J Tong X L Lin and H S Gao ldquoStudy on theVibration Effect of sling blasting in an open coalminerdquo Blastingvol 25 no 1 pp 69ndash73 2008

[19] Q K Chen G C Li and K M Li ldquoMonitor and analysis onexplosive seismic effect of high-bench cast blast of surface coalminerdquo Explosive Materials vol 37 no 6 pp 30ndash33 2008

[20] P K Zhang and F G Song ldquoPre-splitting blasting applied inhigh-bench cast blastingrdquo Opencast Mining Technology no 1pp 35ndash41 2007

[21] P K Zhang ldquoApplication of pre-splitting blasting in high-benchcast blasting of Heidaigou open pitrdquo Inner Mongolia ScienceTechnology amp Economy no 6 pp 257ndash258 2008

[22] W M Hu ldquoBlack dai ditch open-pit coal mine rock wavevelocity testing technologyrdquo Journal of North China Institute ofScience and Technology vol 11 no 9 pp 63ndash67 2014

[23] X H Ding K M Li S S Xiao and W M Hu ldquoAnalysisof key technologies and development of integrated digitalprocessing system for cast blasting designrdquo Journal of CentralSouth University vol 22 no 3 pp 1037ndash1044 2015

[24] C G Jin ldquoVibrating effect of blasting in open-pit sloperdquo MetalMine no 5 pp 18ndash20 1995

[25] Q Liu and S R Lv ldquoResearch on the millisecond delay intervaltime of open-pit bench blastingrdquo Engineering Blasting vol 20no 1 pp 54ndash58 2014

[26] M Chen W Lu D Shu and C Zhou ldquoCalculation method ofequivalent acceleration for limit equilibrium analysis of slopeunder blasting vibrationrdquo Chinese Journal of Rock Mechanicsand Engineering vol 28 no 4 pp 784ndash790 2009

[27] B He and YWang ldquoResidual thrust method and Janbumethodused to calculate landslide stabilityrdquo Safety and EnvironmentalEngineering vol 11 no 4 pp 60ndash62 2004

[28] Y L YuTheory and Technology of Engineering Blasting Metal-lurgical Industry Press Beijing China 2004

[29] W M Ling ldquoA study on the fracture mechanism of smoothblasting and pre-split blastingrdquo Journal of China University ofMining amp Technology vol 19 no 4 pp 79ndash87 1990 (Chinese)

[30] M Sazid and T N Singh ldquoNumerical assessment of spacing-burden ratio to effective utilization of explosive energyrdquo Inter-national Journal of Mining Science and Technology vol 25 no2 pp 291ndash297 2015

[31] B F Li and C B Qi ldquoShaped crack mechanism and parametersdesign of pre-splitting blastingrdquo West-China Exploration Engi-neering no 3 pp 78ndash79 2000 (Chinese)

[32] Q Zong ldquoTheoretical analysis of charge structurersquos influence onpressure on bore wallrdquo Mining and Metallurgical Engineeringvol 26 no 5 pp 9ndash12 2006 (Chinese)

[33] K S Ge Study on Parameter of Pre-Splitting Blasting ChinaUniversity of Geosciences Beijing China 2009

[34] J G Wang L F Luan Z Y Zhang X L Li and C L FanldquoNumerical simulation of blasting vibration effect on stabilityof high-steep sloperdquo Blasting vol 29 no 3 pp 119ndash122 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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DistributedSensor Networks

International Journal of

Shock and Vibration 5

Explosive charge Blast hole

Wave front

120590M

pMpM

s2s2

s

E1205760

Figure 4 Wave front of two adjacent blast holes

where 119875

119877is the pressure of stress wave front after the

detonation of explosive charge Pa 1199031is the radius of blast

hole m 119877 is the distance between the center of blast holeand a certain point on the wave front m 120572 is the attenuationcoefficient 120572 = 2 minus 120583(1 minus 120583) 120583 is Poissonrsquos ratio 119875

119863is the

pressure on the wall of the holes Pa 120588 is explosive densitykgm3119863 is explosive speed ms 119903

2is the radius of explosive

m 119896 is adiabatic exponent 119899 is the multiple of pressureincrease of the explosive gas colliding with the blast hole walland 119899 = 8sim11

The stress wave causes radical displacement of the rockmass between two adjacent blast holes while the radicaldisplacement derives the tangential stresses and tangentialstrains The tangential stress 120590

119879can be expressed as [33]

120590

119879=

120583

1 minus 120583

119875

119877 (9)

If the tangential stress on the wall of the hole is greaterthan the rock tensile strength 120590

119905 the initial crack on the wall

of the blast hole will appear Resulting from the stress wave oftwo adjacent blast holes the sum120590

119872of the tangential stress in

the middle of the line connecting the two adjacent blast holes(119877 = 1199042) is

120590

119872=

2120583

(1 minus 120583) (119896 + 1)

120588119863

2(

119903

1

119903

2

)

minus2119896

119899 (

2119903

1

119904

)

120572

(10)

Similarly if the tensile stress produced by blasting 120590

119872is

greater than the tensile strength of rocks that is 120590119872

ge 120590

119905

radial cracks appear along the lines connecting blast holeswhich creates condition for the formation of the presplit faceThe high pressure gas of explosion of the two adjacent blastholes then acts on the walls of the hole thereby forming aquasi-static stress field around the blast holes When the highpressure gas wedges in the initial crack of hole wall thereis a great tensile stress along the line connecting blast holesThe tensile stress concentration is all sides of the walls of thehole A free surface with a certain width is formed whichcan exert positive effects towards the reduction in vibrations

Therefore the important precondition for the formation ofthe presplit face is that tension waves can produce tensioncrack Based on (10) the formula of the blast hole spacing inpresplit blasting should be

119904 le

2119903

1

[120590

119905((1 minus 120583) (119896 + 1) 2120583120588119863

2119899) (119903

1119903

2)

2119896

]

1120572 (11)

Low density ANFO explosive is used as a presplit blastexplosive in Heidaigou open cast with a density of 200 kgm3a speed of 1950ms a presplit blast hole diameter of 310mmcharge diameter of 150mm and a unit explosive consumptionof 085 kgm3 According to (11) the optimum blast holespacing of presplit blasting is estimated as ranging from303m to 416m with 35m selected for application Figure 5shows the presplit blasting effectThe cracks formed from theblast are relatively intact with an even width and the ratio ofthe half hole to the total presplit hole is a little higher

The transmission coefficient of stress wave is

119877

119905=

119860

119905

119860

119894

(12)

where119877119905is the transmission coefficient and119860

119894and119860

119905are the

amplitude of incident wave and the amplitude of transmittedwave respectively

The wave velocity expression is

V = 119860119890

minus120572 sin120596119905 (13)

and the vibration absorption ratio of presplit blasting is

120576 =

1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

V119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

V119894

1003816

1003816

1003816

1003816max=

1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max minus1003816

1003816

1003816

1003816

119860

119905

1003816

1003816

1003816

1003816max1003816

1003816

1003816

1003816

119860

119894

1003816

1003816

1003816

1003816max= 1 minus 119877

119905 (14)

4 Detection and Analysis of VibrationProduced by Blast Casting

41 The Detection Principles of Blast Vibration Detectionsystem of blast vibration is composed of the blast vibrationtester and the vibration pick-up As the vibration wave istransmitted to the vibration pick-up induced voltage outputsare generated and once the induced voltage signal exceeds thepreset triggering level the tester automatically records andsaves the vibration signals loaded by the sensor After detect-ing the vibration signals the blast vibration waves can beread and analyzed with the connection and communicationbetween special software and vibration tester The principlediagrams of the detection system and the measuring pointlayout are shown in Figures 6 and 7 respectively

Based on the inspection data the regression analysisshould be carried out with Sadovrsquos empirical formula andthe formula of vibration velocity attenuation can thus beobtained

42 Detection Scheme of Blast Vibration In order to recordthe whole vibration process and the attenuation law of blast-ing seismic waves the detection scheme of blast vibration is

6 Shock and Vibration

Figure 5 Presplit blasting effect pictures of surface coal mine

Vibration pick-up

Detection system

Blasting seismic wave

Blasting vibration tester

Parameter set-up Signal input

Data process Signal output

Computer Printer

Figure 6 The principle diagram of the detection system

worked out according to the characteristics of blast castingand the geological and topographic conditions of the blastingzone Detection points are set on the same bench and kept ina straight line on the right side of the blasting zone withoutpresplit blast Another set of detection points are also set onthe same bench in a straight line on the rear blasting zonewithpresplit blast Both of the above-mentioned detection pointsare used to monitor the seismic intensity and variations ofblast vibrations

The blast vibration tester adopted here is a vibrationsignal recorder whose model is UBOX-20016 the maximumsampling rate of which is 200KSpsCH and the signalresolution is 16 bits (165536 of the measuring range) Thevibration pick-up is CD-21magnetoelectric vibration velocitysensor with the sensitivity of 200mvcms and the erroris less than 3 The installation of sensors is based on themeasurement of vibration velocity in different directions andthe censors must be firmly bonded to the ground by gypsumpowder

The primary detection area of blast vibration is the rearpart and the broadside of the blasting zone the former iswith presplit cracks and the latter is without Therefore theeffect of presplit cracks in vibration reduction can be provedby comparison Blast vibration recorder is used for inspectingthe velocity of particles in vertical direction (V-) radialdirection (R-) and transverse direction (T-) Figure 8 showsthe schematic diagram of detection point layout

Vibrationtester

Blasting center

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Figure 7 The schematic diagram of the measuring point layout

43 Analysis on the Detection Results of Blasting Vibration Inall cases blast vibration detection has been carried out three(3) times The gross explosive loads (GEL) for each time are96 times 105 kg 78 times 105 kg and 13 times 106 kg respectively Themaximum explosive charges per delay interval (MECPDE)are 1 times 104 kg 15 times 104 kg and 15 times 104 kg respectivelyand the explosive charge per blast hole is 2 times 103 kg Thedistance between each detection point and the blasting source(DDPBS) as well as the vibration velocity of the largestparticle are shown in Table 3

Standard blast casting is adopted in Heidaigou open castand the blasting acting index 119899 = 1 Based on (1) and thedetection data the attenuation equations for blast vibrationin presplit blasting and non-presplit blasting are obtained byfitting

V

=

9518 (

3radic119876

119877

)

134

119877

2= 0959 (presplit blast)

22161 (

3radic119876

119877

)

140

119877

2= 0795 (non-presplit blast)

(15)

Shock and Vibration 7

Table 3 Location of detection points and blast vibration strength

Detection point 119879- mms 119881- mms 119877- mms Resultant mms DDPBS m GEL kg MECPDE kg RemarksH1-2 141 111 108 174 350 960000 10000 BackH1-3 104 168 78 179 550 960000 10000 BackH1-4 43 99 10 800 960000 10000 BackH1-5 17 23 38 39 1215 960000 10000 BackH1-6 11 19 28 29 1800 960000 10000 BackH2-1 1047 1497 1243 1813 100 780000 15000 BackH2-2 317 565 327 55 200 780000 15000 BackH2-3 118 173 163 204 300 780000 15000 BackH2-4 108 139 187 500 780000 15000 BackH2-5 45 39 37 79 800 780000 15000 BackH2-6 42 25 23 54 1000 780000 15000 BackH2-7 174 30 22 411 380 780000 15000 BackH3-1 667 694 598 874 162 1300000 15000 BackY1-1 286 135 291 303 5749 960000 10000 RightY1-2 196 121 306 311 6046 960000 10000 RightY1-3 126 559 124 145 800 960000 10000 RightY1-4 851 305 851 103 8266 960000 10000 RightY3-1 656 709 708 118 200 1300000 15000 RightY3-2 233 28 255 507 350 1300000 15000 RightY3-4 101 58 mdash 175 550 1300000 15000 RightY3-5 65 24 37 107 650 1300000 15000 Right

Detection pointon the right side

Detection pointon the rear

Presplitting blast Non-presplit blast

H1

H2

H3

H4

H5

Hi

Y1

Y2

Y3

Y4

Figure 8 Location of the blast detection point and blast vibrationsource

According to (15) the attenuation indices under thesetwo conditions are nearly the same that is 134 and 140respectively However the attenuation coefficient might bereduced by half when adopting presplit blasting Becauseof the application of hole-by-hole millisecond detonationthe maximum explosive charge per segment is less than 11times 104 kg and the vibration velocity of the end-wall slopeis 253 cms In addition the equation for calculating theacceleration of blast vibration is [34]

119886 = 0028119876

083119877

minus35119862

119901

2 (16)

where 119886 is acceleration of the blast vibration ms2 119862119901is the

longitudinal wave velocity ms other symbols are consistentwith the former expressions

The transmission velocity of blast vibration in sand-stone rock mass is 1118ms the acceleration is calculated as121ms2 (16) and the seismic load coefficient of blastingis calculated as 0012 (3) According to the mechanicalparameters of rock mass of Heidaigou open cast listed inTable 4 the factors of stability of the end-wall slope arecalculated as 1311 for the condition of static load and 1285for the condition of dynamic load respectivelyTherefore theeffect of dynamic load on factor of safety of the end wall ismerely 198

Meanwhile the resultant vibration velocities of differentdetection points are shown in Table 5 As the distancebetween detection points and blasting centers increasesthe vibration velocities decrease exponentially under thecondition of both presplit blasting and non-presplit blastingA closer distance to the blasting center can better reflectthe vibration reduction effect of presplit blasting Whenthe detection point is 200m away from the blasting centerthe vibration absorption ratio is increased to 502 whichimplies that presplit blasting can effectively absorb vibrations

5 Conclusions

(1) Pseudo-static method has converted the dynamic loadof blast vibration to equivalent static load and Janbu LEMhas been used to analyze the influence of blast vibration onslope stability The horizontal load caused by blast vibrationenhances the sliding force of the slip mass and therefore

8 Shock and Vibration

Table 4 Mechanical parameters of rock mass of Heidaigou open cast

Stratum Density (kNm3) Internal friction angle (∘) Cohesion (kPa)Loess 1950 295 451Sandy mudstone 2450 30 135Fine sandstone 2450 28 150Medium sandstone 2270 315 150Coarse sandstone 2240 320 130Weathered mudstone 247 290 1275Coal 14 35 1851Siltstone 245 313 1768

Table 5 Actual blast vibration detection data and absorption shock rate of presplit blasting

Detection point distance toblasting centerm

Velocity of vibrationcmsdotsminus1

200 400 600 800 1000 1200 1400Presplit blasting 548 221 13 089 066 052 043Non-presplit blasting 1101 397 218 143 103 079 063Vibration reduction ratio 502 443 404 378 359 342 317

reduces the factor of safety Calculated results suggest thatslope stability factors on conditions of static load anddynamic load of blasting are 1311 and 1285 respectively andthe dynamic load of blast casting has slight effect on the endslope stability taking only 198

(2) After the detonation of two adjacent presplit holesstress waves of each explosion spread radially and createtangential stress in the tangential direction Based on thetheory of stress wave interference when the sum of thetangential stress of two adjacent blast holes is greater than therock tensile strength radial cracks come into being along theline connecting blast holes which creates condition for theformation of the presplit face Based on the above conditionthe blast hole spacing in presplit blasting is obtained Accord-ingly the blast hole spacing of presplit blasting of Heidaigouopen cast mine ranges from 303m to 416m with 35m usedin actual production satisfying the presplit blasting effect

(3) The vibration detection principles of vibration testersand pick-ups are analyzed The vibration velocity of blastingparticle is detected in the blasting zonewhose rear part is withpresplit cracks and right side is without Based on Sadovrsquosempirical formula attenuation formulas of blast vibration onconditions with and without presplit blasting are obtained bynumerical fitting respectively The detection results indicatethat presplit blasting can reduce the attenuation coefficientby half and the vibration absorption ratio can reach 502whichmeans presplitting blast is of great significance in shockabsorption of blast casting

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

Acknowledgments

This study was supported by the National Natural Sci-ence Foundation of China (51034005) the Fundamental

Research Funds for the Central Universities (2010QNB232011QNB25) and the Priority Academic Program Develop-ment of Jiangsu Higher Education Institutions

References

[1] K Pathak S Durucan and S Kunimatsu ldquoActivity accountingtechnique for environmental noise assessment in mechanizedsurfaceminingrdquoEnvironmentalMonitoring andAssessment vol56 no 3 pp 241ndash256 1999

[2] A Fisne C Kuzu and T Hudaverdi ldquoPrediction of environ-mental impacts of quarry blasting operation using fuzzy logicrdquoEnvironmental Monitoring and Assessment vol 174 no 1ndash4 pp461ndash470 2011

[3] D J Armaghani E Momeni S V A N K Abad andM Khan-delwal ldquoFeasibility of ANFIS model for prediction of groundvibrations resulting from quarry blastingrdquo Environmental EarthSciences vol 74 no 4 pp 2845ndash2860 2015

[4] T N Singh and V Singh ldquoAn intelligent approach to predictionand control ground vibration in minesrdquo Geotechnical andGeological Engineering vol 23 no 3 pp 249ndash262 2005

[5] U Ozer A Kahriman M Aksoy D Adiguzel and A Karado-gan ldquoThe analysis of ground vibrations induced by benchblasting at Akyol quarry and practical blasting chartsrdquo Environ-mental Geology vol 54 no 4 pp 737ndash743 2008

[6] C Kuzu and E Guclu ldquoThe problem of human response toblast induced vibrations in tunnel construction and mitigationof vibration effects using cautious blasting in half-face blastingroundsrdquo Tunnelling and Underground Space Technology vol 24no 1 pp 53ndash61 2009

[7] D D Li and Z D Deng ldquoEvaluation of the effects of blastingvibration on humans in the excavation of CMICT dockrdquoEngineering Blasting vol 12 no 2 pp 82ndash85 2012

[8] F Zheng W D Duan D W Zhong and B Y Sun ldquoResearchprogress and existing problems of blasting vibrationrdquo Blastingvol 23 no 1 pp 92ndash94 2006

[9] T L Shi and B Z Li ldquoThe effects of millisecond delayinterval charge distribution andmeasuring distance on blastingvibrationrdquo Engineering Blasting vol 9 no 4 pp 10ndash13 2003

Shock and Vibration 9

[10] Y L Gao Q Tan S C Yang L Xue and Y L Yu ldquoExperimentalresearch on relationship between charge layout and blastingvibrationrdquo Engineering Blasting vol 10 no 3 pp 19ndash48 2004

[11] O Uysal and M Cavus ldquoEffect of a pre-split plane on the fre-quencies of blast induced ground vibrationsrdquoActaMontanisticaSlovaca vol 18 no 2 pp 101ndash109 2013

[12] J L Yan and X F Chen ldquoObservation and analysis of vibrationreduction effect of pre-split crack in complicated geologicconditionrdquo Blasting vol 25 no 3 pp 100ndash102 2008

[13] A J Prakash P Palroy and D D Misra ldquoAnalysis of blastvibration characteristics across a trench and a pre-split planerdquoFragblast vol 8 no 1 pp 51ndash60 2004

[14] L J Cai and J J Ma ldquoThe shock absorption mechanism and itseffect analysis of pre-splitting blastingrdquoChinaMiningMagazinevol 14 no 5 pp 56ndash58 2005

[15] Y F Zou ldquoExperimental study on the vibration- isolating effectof pre-split crack and vibration-isolating slotrdquo Blasting vol 22no 2 pp 96ndash99 2005

[16] E F Salmi and S Hosseinzadeh ldquoA further study on themechanism of pre-splitting in mining engineeringrdquo AppliedMechanics and Materials vol 553 pp 476ndash481 2014

[17] N H Yang ldquoExperimental study on rock damage in the slopecaused by presplit blastingrdquo Journal of the China RailwaySociety vol 30 no 3 pp 96ndash99 2008

[18] H R Sun Y J Tong X L Lin and H S Gao ldquoStudy on theVibration Effect of sling blasting in an open coalminerdquo Blastingvol 25 no 1 pp 69ndash73 2008

[19] Q K Chen G C Li and K M Li ldquoMonitor and analysis onexplosive seismic effect of high-bench cast blast of surface coalminerdquo Explosive Materials vol 37 no 6 pp 30ndash33 2008

[20] P K Zhang and F G Song ldquoPre-splitting blasting applied inhigh-bench cast blastingrdquo Opencast Mining Technology no 1pp 35ndash41 2007

[21] P K Zhang ldquoApplication of pre-splitting blasting in high-benchcast blasting of Heidaigou open pitrdquo Inner Mongolia ScienceTechnology amp Economy no 6 pp 257ndash258 2008

[22] W M Hu ldquoBlack dai ditch open-pit coal mine rock wavevelocity testing technologyrdquo Journal of North China Institute ofScience and Technology vol 11 no 9 pp 63ndash67 2014

[23] X H Ding K M Li S S Xiao and W M Hu ldquoAnalysisof key technologies and development of integrated digitalprocessing system for cast blasting designrdquo Journal of CentralSouth University vol 22 no 3 pp 1037ndash1044 2015

[24] C G Jin ldquoVibrating effect of blasting in open-pit sloperdquo MetalMine no 5 pp 18ndash20 1995

[25] Q Liu and S R Lv ldquoResearch on the millisecond delay intervaltime of open-pit bench blastingrdquo Engineering Blasting vol 20no 1 pp 54ndash58 2014

[26] M Chen W Lu D Shu and C Zhou ldquoCalculation method ofequivalent acceleration for limit equilibrium analysis of slopeunder blasting vibrationrdquo Chinese Journal of Rock Mechanicsand Engineering vol 28 no 4 pp 784ndash790 2009

[27] B He and YWang ldquoResidual thrust method and Janbumethodused to calculate landslide stabilityrdquo Safety and EnvironmentalEngineering vol 11 no 4 pp 60ndash62 2004

[28] Y L YuTheory and Technology of Engineering Blasting Metal-lurgical Industry Press Beijing China 2004

[29] W M Ling ldquoA study on the fracture mechanism of smoothblasting and pre-split blastingrdquo Journal of China University ofMining amp Technology vol 19 no 4 pp 79ndash87 1990 (Chinese)

[30] M Sazid and T N Singh ldquoNumerical assessment of spacing-burden ratio to effective utilization of explosive energyrdquo Inter-national Journal of Mining Science and Technology vol 25 no2 pp 291ndash297 2015

[31] B F Li and C B Qi ldquoShaped crack mechanism and parametersdesign of pre-splitting blastingrdquo West-China Exploration Engi-neering no 3 pp 78ndash79 2000 (Chinese)

[32] Q Zong ldquoTheoretical analysis of charge structurersquos influence onpressure on bore wallrdquo Mining and Metallurgical Engineeringvol 26 no 5 pp 9ndash12 2006 (Chinese)

[33] K S Ge Study on Parameter of Pre-Splitting Blasting ChinaUniversity of Geosciences Beijing China 2009

[34] J G Wang L F Luan Z Y Zhang X L Li and C L FanldquoNumerical simulation of blasting vibration effect on stabilityof high-steep sloperdquo Blasting vol 29 no 3 pp 119ndash122 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

6 Shock and Vibration

Figure 5 Presplit blasting effect pictures of surface coal mine

Vibration pick-up

Detection system

Blasting seismic wave

Blasting vibration tester

Parameter set-up Signal input

Data process Signal output

Computer Printer

Figure 6 The principle diagram of the detection system

worked out according to the characteristics of blast castingand the geological and topographic conditions of the blastingzone Detection points are set on the same bench and kept ina straight line on the right side of the blasting zone withoutpresplit blast Another set of detection points are also set onthe same bench in a straight line on the rear blasting zonewithpresplit blast Both of the above-mentioned detection pointsare used to monitor the seismic intensity and variations ofblast vibrations

The blast vibration tester adopted here is a vibrationsignal recorder whose model is UBOX-20016 the maximumsampling rate of which is 200KSpsCH and the signalresolution is 16 bits (165536 of the measuring range) Thevibration pick-up is CD-21magnetoelectric vibration velocitysensor with the sensitivity of 200mvcms and the erroris less than 3 The installation of sensors is based on themeasurement of vibration velocity in different directions andthe censors must be firmly bonded to the ground by gypsumpowder

The primary detection area of blast vibration is the rearpart and the broadside of the blasting zone the former iswith presplit cracks and the latter is without Therefore theeffect of presplit cracks in vibration reduction can be provedby comparison Blast vibration recorder is used for inspectingthe velocity of particles in vertical direction (V-) radialdirection (R-) and transverse direction (T-) Figure 8 showsthe schematic diagram of detection point layout

Vibrationtester

Blasting center

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationtester

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Vibrationpick-up

Figure 7 The schematic diagram of the measuring point layout

43 Analysis on the Detection Results of Blasting Vibration Inall cases blast vibration detection has been carried out three(3) times The gross explosive loads (GEL) for each time are96 times 105 kg 78 times 105 kg and 13 times 106 kg respectively Themaximum explosive charges per delay interval (MECPDE)are 1 times 104 kg 15 times 104 kg and 15 times 104 kg respectivelyand the explosive charge per blast hole is 2 times 103 kg Thedistance between each detection point and the blasting source(DDPBS) as well as the vibration velocity of the largestparticle are shown in Table 3

Standard blast casting is adopted in Heidaigou open castand the blasting acting index 119899 = 1 Based on (1) and thedetection data the attenuation equations for blast vibrationin presplit blasting and non-presplit blasting are obtained byfitting

V

=

9518 (

3radic119876

119877

)

134

119877

2= 0959 (presplit blast)

22161 (

3radic119876

119877

)

140

119877

2= 0795 (non-presplit blast)

(15)

Shock and Vibration 7

Table 3 Location of detection points and blast vibration strength

Detection point 119879- mms 119881- mms 119877- mms Resultant mms DDPBS m GEL kg MECPDE kg RemarksH1-2 141 111 108 174 350 960000 10000 BackH1-3 104 168 78 179 550 960000 10000 BackH1-4 43 99 10 800 960000 10000 BackH1-5 17 23 38 39 1215 960000 10000 BackH1-6 11 19 28 29 1800 960000 10000 BackH2-1 1047 1497 1243 1813 100 780000 15000 BackH2-2 317 565 327 55 200 780000 15000 BackH2-3 118 173 163 204 300 780000 15000 BackH2-4 108 139 187 500 780000 15000 BackH2-5 45 39 37 79 800 780000 15000 BackH2-6 42 25 23 54 1000 780000 15000 BackH2-7 174 30 22 411 380 780000 15000 BackH3-1 667 694 598 874 162 1300000 15000 BackY1-1 286 135 291 303 5749 960000 10000 RightY1-2 196 121 306 311 6046 960000 10000 RightY1-3 126 559 124 145 800 960000 10000 RightY1-4 851 305 851 103 8266 960000 10000 RightY3-1 656 709 708 118 200 1300000 15000 RightY3-2 233 28 255 507 350 1300000 15000 RightY3-4 101 58 mdash 175 550 1300000 15000 RightY3-5 65 24 37 107 650 1300000 15000 Right

Detection pointon the right side

Detection pointon the rear

Presplitting blast Non-presplit blast

H1

H2

H3

H4

H5

Hi

Y1

Y2

Y3

Y4

Figure 8 Location of the blast detection point and blast vibrationsource

According to (15) the attenuation indices under thesetwo conditions are nearly the same that is 134 and 140respectively However the attenuation coefficient might bereduced by half when adopting presplit blasting Becauseof the application of hole-by-hole millisecond detonationthe maximum explosive charge per segment is less than 11times 104 kg and the vibration velocity of the end-wall slopeis 253 cms In addition the equation for calculating theacceleration of blast vibration is [34]

119886 = 0028119876

083119877

minus35119862

119901

2 (16)

where 119886 is acceleration of the blast vibration ms2 119862119901is the

longitudinal wave velocity ms other symbols are consistentwith the former expressions

The transmission velocity of blast vibration in sand-stone rock mass is 1118ms the acceleration is calculated as121ms2 (16) and the seismic load coefficient of blastingis calculated as 0012 (3) According to the mechanicalparameters of rock mass of Heidaigou open cast listed inTable 4 the factors of stability of the end-wall slope arecalculated as 1311 for the condition of static load and 1285for the condition of dynamic load respectivelyTherefore theeffect of dynamic load on factor of safety of the end wall ismerely 198

Meanwhile the resultant vibration velocities of differentdetection points are shown in Table 5 As the distancebetween detection points and blasting centers increasesthe vibration velocities decrease exponentially under thecondition of both presplit blasting and non-presplit blastingA closer distance to the blasting center can better reflectthe vibration reduction effect of presplit blasting Whenthe detection point is 200m away from the blasting centerthe vibration absorption ratio is increased to 502 whichimplies that presplit blasting can effectively absorb vibrations

5 Conclusions

(1) Pseudo-static method has converted the dynamic loadof blast vibration to equivalent static load and Janbu LEMhas been used to analyze the influence of blast vibration onslope stability The horizontal load caused by blast vibrationenhances the sliding force of the slip mass and therefore

8 Shock and Vibration

Table 4 Mechanical parameters of rock mass of Heidaigou open cast

Stratum Density (kNm3) Internal friction angle (∘) Cohesion (kPa)Loess 1950 295 451Sandy mudstone 2450 30 135Fine sandstone 2450 28 150Medium sandstone 2270 315 150Coarse sandstone 2240 320 130Weathered mudstone 247 290 1275Coal 14 35 1851Siltstone 245 313 1768

Table 5 Actual blast vibration detection data and absorption shock rate of presplit blasting

Detection point distance toblasting centerm

Velocity of vibrationcmsdotsminus1

200 400 600 800 1000 1200 1400Presplit blasting 548 221 13 089 066 052 043Non-presplit blasting 1101 397 218 143 103 079 063Vibration reduction ratio 502 443 404 378 359 342 317

reduces the factor of safety Calculated results suggest thatslope stability factors on conditions of static load anddynamic load of blasting are 1311 and 1285 respectively andthe dynamic load of blast casting has slight effect on the endslope stability taking only 198

(2) After the detonation of two adjacent presplit holesstress waves of each explosion spread radially and createtangential stress in the tangential direction Based on thetheory of stress wave interference when the sum of thetangential stress of two adjacent blast holes is greater than therock tensile strength radial cracks come into being along theline connecting blast holes which creates condition for theformation of the presplit face Based on the above conditionthe blast hole spacing in presplit blasting is obtained Accord-ingly the blast hole spacing of presplit blasting of Heidaigouopen cast mine ranges from 303m to 416m with 35m usedin actual production satisfying the presplit blasting effect

(3) The vibration detection principles of vibration testersand pick-ups are analyzed The vibration velocity of blastingparticle is detected in the blasting zonewhose rear part is withpresplit cracks and right side is without Based on Sadovrsquosempirical formula attenuation formulas of blast vibration onconditions with and without presplit blasting are obtained bynumerical fitting respectively The detection results indicatethat presplit blasting can reduce the attenuation coefficientby half and the vibration absorption ratio can reach 502whichmeans presplitting blast is of great significance in shockabsorption of blast casting

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

Acknowledgments

This study was supported by the National Natural Sci-ence Foundation of China (51034005) the Fundamental

Research Funds for the Central Universities (2010QNB232011QNB25) and the Priority Academic Program Develop-ment of Jiangsu Higher Education Institutions

References

[1] K Pathak S Durucan and S Kunimatsu ldquoActivity accountingtechnique for environmental noise assessment in mechanizedsurfaceminingrdquoEnvironmentalMonitoring andAssessment vol56 no 3 pp 241ndash256 1999

[2] A Fisne C Kuzu and T Hudaverdi ldquoPrediction of environ-mental impacts of quarry blasting operation using fuzzy logicrdquoEnvironmental Monitoring and Assessment vol 174 no 1ndash4 pp461ndash470 2011

[3] D J Armaghani E Momeni S V A N K Abad andM Khan-delwal ldquoFeasibility of ANFIS model for prediction of groundvibrations resulting from quarry blastingrdquo Environmental EarthSciences vol 74 no 4 pp 2845ndash2860 2015

[4] T N Singh and V Singh ldquoAn intelligent approach to predictionand control ground vibration in minesrdquo Geotechnical andGeological Engineering vol 23 no 3 pp 249ndash262 2005

[5] U Ozer A Kahriman M Aksoy D Adiguzel and A Karado-gan ldquoThe analysis of ground vibrations induced by benchblasting at Akyol quarry and practical blasting chartsrdquo Environ-mental Geology vol 54 no 4 pp 737ndash743 2008

[6] C Kuzu and E Guclu ldquoThe problem of human response toblast induced vibrations in tunnel construction and mitigationof vibration effects using cautious blasting in half-face blastingroundsrdquo Tunnelling and Underground Space Technology vol 24no 1 pp 53ndash61 2009

[7] D D Li and Z D Deng ldquoEvaluation of the effects of blastingvibration on humans in the excavation of CMICT dockrdquoEngineering Blasting vol 12 no 2 pp 82ndash85 2012

[8] F Zheng W D Duan D W Zhong and B Y Sun ldquoResearchprogress and existing problems of blasting vibrationrdquo Blastingvol 23 no 1 pp 92ndash94 2006

[9] T L Shi and B Z Li ldquoThe effects of millisecond delayinterval charge distribution andmeasuring distance on blastingvibrationrdquo Engineering Blasting vol 9 no 4 pp 10ndash13 2003

Shock and Vibration 9

[10] Y L Gao Q Tan S C Yang L Xue and Y L Yu ldquoExperimentalresearch on relationship between charge layout and blastingvibrationrdquo Engineering Blasting vol 10 no 3 pp 19ndash48 2004

[11] O Uysal and M Cavus ldquoEffect of a pre-split plane on the fre-quencies of blast induced ground vibrationsrdquoActaMontanisticaSlovaca vol 18 no 2 pp 101ndash109 2013

[12] J L Yan and X F Chen ldquoObservation and analysis of vibrationreduction effect of pre-split crack in complicated geologicconditionrdquo Blasting vol 25 no 3 pp 100ndash102 2008

[13] A J Prakash P Palroy and D D Misra ldquoAnalysis of blastvibration characteristics across a trench and a pre-split planerdquoFragblast vol 8 no 1 pp 51ndash60 2004

[14] L J Cai and J J Ma ldquoThe shock absorption mechanism and itseffect analysis of pre-splitting blastingrdquoChinaMiningMagazinevol 14 no 5 pp 56ndash58 2005

[15] Y F Zou ldquoExperimental study on the vibration- isolating effectof pre-split crack and vibration-isolating slotrdquo Blasting vol 22no 2 pp 96ndash99 2005

[16] E F Salmi and S Hosseinzadeh ldquoA further study on themechanism of pre-splitting in mining engineeringrdquo AppliedMechanics and Materials vol 553 pp 476ndash481 2014

[17] N H Yang ldquoExperimental study on rock damage in the slopecaused by presplit blastingrdquo Journal of the China RailwaySociety vol 30 no 3 pp 96ndash99 2008

[18] H R Sun Y J Tong X L Lin and H S Gao ldquoStudy on theVibration Effect of sling blasting in an open coalminerdquo Blastingvol 25 no 1 pp 69ndash73 2008

[19] Q K Chen G C Li and K M Li ldquoMonitor and analysis onexplosive seismic effect of high-bench cast blast of surface coalminerdquo Explosive Materials vol 37 no 6 pp 30ndash33 2008

[20] P K Zhang and F G Song ldquoPre-splitting blasting applied inhigh-bench cast blastingrdquo Opencast Mining Technology no 1pp 35ndash41 2007

[21] P K Zhang ldquoApplication of pre-splitting blasting in high-benchcast blasting of Heidaigou open pitrdquo Inner Mongolia ScienceTechnology amp Economy no 6 pp 257ndash258 2008

[22] W M Hu ldquoBlack dai ditch open-pit coal mine rock wavevelocity testing technologyrdquo Journal of North China Institute ofScience and Technology vol 11 no 9 pp 63ndash67 2014

[23] X H Ding K M Li S S Xiao and W M Hu ldquoAnalysisof key technologies and development of integrated digitalprocessing system for cast blasting designrdquo Journal of CentralSouth University vol 22 no 3 pp 1037ndash1044 2015

[24] C G Jin ldquoVibrating effect of blasting in open-pit sloperdquo MetalMine no 5 pp 18ndash20 1995

[25] Q Liu and S R Lv ldquoResearch on the millisecond delay intervaltime of open-pit bench blastingrdquo Engineering Blasting vol 20no 1 pp 54ndash58 2014

[26] M Chen W Lu D Shu and C Zhou ldquoCalculation method ofequivalent acceleration for limit equilibrium analysis of slopeunder blasting vibrationrdquo Chinese Journal of Rock Mechanicsand Engineering vol 28 no 4 pp 784ndash790 2009

[27] B He and YWang ldquoResidual thrust method and Janbumethodused to calculate landslide stabilityrdquo Safety and EnvironmentalEngineering vol 11 no 4 pp 60ndash62 2004

[28] Y L YuTheory and Technology of Engineering Blasting Metal-lurgical Industry Press Beijing China 2004

[29] W M Ling ldquoA study on the fracture mechanism of smoothblasting and pre-split blastingrdquo Journal of China University ofMining amp Technology vol 19 no 4 pp 79ndash87 1990 (Chinese)

[30] M Sazid and T N Singh ldquoNumerical assessment of spacing-burden ratio to effective utilization of explosive energyrdquo Inter-national Journal of Mining Science and Technology vol 25 no2 pp 291ndash297 2015

[31] B F Li and C B Qi ldquoShaped crack mechanism and parametersdesign of pre-splitting blastingrdquo West-China Exploration Engi-neering no 3 pp 78ndash79 2000 (Chinese)

[32] Q Zong ldquoTheoretical analysis of charge structurersquos influence onpressure on bore wallrdquo Mining and Metallurgical Engineeringvol 26 no 5 pp 9ndash12 2006 (Chinese)

[33] K S Ge Study on Parameter of Pre-Splitting Blasting ChinaUniversity of Geosciences Beijing China 2009

[34] J G Wang L F Luan Z Y Zhang X L Li and C L FanldquoNumerical simulation of blasting vibration effect on stabilityof high-steep sloperdquo Blasting vol 29 no 3 pp 119ndash122 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 7

Table 3 Location of detection points and blast vibration strength

Detection point 119879- mms 119881- mms 119877- mms Resultant mms DDPBS m GEL kg MECPDE kg RemarksH1-2 141 111 108 174 350 960000 10000 BackH1-3 104 168 78 179 550 960000 10000 BackH1-4 43 99 10 800 960000 10000 BackH1-5 17 23 38 39 1215 960000 10000 BackH1-6 11 19 28 29 1800 960000 10000 BackH2-1 1047 1497 1243 1813 100 780000 15000 BackH2-2 317 565 327 55 200 780000 15000 BackH2-3 118 173 163 204 300 780000 15000 BackH2-4 108 139 187 500 780000 15000 BackH2-5 45 39 37 79 800 780000 15000 BackH2-6 42 25 23 54 1000 780000 15000 BackH2-7 174 30 22 411 380 780000 15000 BackH3-1 667 694 598 874 162 1300000 15000 BackY1-1 286 135 291 303 5749 960000 10000 RightY1-2 196 121 306 311 6046 960000 10000 RightY1-3 126 559 124 145 800 960000 10000 RightY1-4 851 305 851 103 8266 960000 10000 RightY3-1 656 709 708 118 200 1300000 15000 RightY3-2 233 28 255 507 350 1300000 15000 RightY3-4 101 58 mdash 175 550 1300000 15000 RightY3-5 65 24 37 107 650 1300000 15000 Right

Detection pointon the right side

Detection pointon the rear

Presplitting blast Non-presplit blast

H1

H2

H3

H4

H5

Hi

Y1

Y2

Y3

Y4

Figure 8 Location of the blast detection point and blast vibrationsource

According to (15) the attenuation indices under thesetwo conditions are nearly the same that is 134 and 140respectively However the attenuation coefficient might bereduced by half when adopting presplit blasting Becauseof the application of hole-by-hole millisecond detonationthe maximum explosive charge per segment is less than 11times 104 kg and the vibration velocity of the end-wall slopeis 253 cms In addition the equation for calculating theacceleration of blast vibration is [34]

119886 = 0028119876

083119877

minus35119862

119901

2 (16)

where 119886 is acceleration of the blast vibration ms2 119862119901is the

longitudinal wave velocity ms other symbols are consistentwith the former expressions

The transmission velocity of blast vibration in sand-stone rock mass is 1118ms the acceleration is calculated as121ms2 (16) and the seismic load coefficient of blastingis calculated as 0012 (3) According to the mechanicalparameters of rock mass of Heidaigou open cast listed inTable 4 the factors of stability of the end-wall slope arecalculated as 1311 for the condition of static load and 1285for the condition of dynamic load respectivelyTherefore theeffect of dynamic load on factor of safety of the end wall ismerely 198

Meanwhile the resultant vibration velocities of differentdetection points are shown in Table 5 As the distancebetween detection points and blasting centers increasesthe vibration velocities decrease exponentially under thecondition of both presplit blasting and non-presplit blastingA closer distance to the blasting center can better reflectthe vibration reduction effect of presplit blasting Whenthe detection point is 200m away from the blasting centerthe vibration absorption ratio is increased to 502 whichimplies that presplit blasting can effectively absorb vibrations

5 Conclusions

(1) Pseudo-static method has converted the dynamic loadof blast vibration to equivalent static load and Janbu LEMhas been used to analyze the influence of blast vibration onslope stability The horizontal load caused by blast vibrationenhances the sliding force of the slip mass and therefore

8 Shock and Vibration

Table 4 Mechanical parameters of rock mass of Heidaigou open cast

Stratum Density (kNm3) Internal friction angle (∘) Cohesion (kPa)Loess 1950 295 451Sandy mudstone 2450 30 135Fine sandstone 2450 28 150Medium sandstone 2270 315 150Coarse sandstone 2240 320 130Weathered mudstone 247 290 1275Coal 14 35 1851Siltstone 245 313 1768

Table 5 Actual blast vibration detection data and absorption shock rate of presplit blasting

Detection point distance toblasting centerm

Velocity of vibrationcmsdotsminus1

200 400 600 800 1000 1200 1400Presplit blasting 548 221 13 089 066 052 043Non-presplit blasting 1101 397 218 143 103 079 063Vibration reduction ratio 502 443 404 378 359 342 317

reduces the factor of safety Calculated results suggest thatslope stability factors on conditions of static load anddynamic load of blasting are 1311 and 1285 respectively andthe dynamic load of blast casting has slight effect on the endslope stability taking only 198

(2) After the detonation of two adjacent presplit holesstress waves of each explosion spread radially and createtangential stress in the tangential direction Based on thetheory of stress wave interference when the sum of thetangential stress of two adjacent blast holes is greater than therock tensile strength radial cracks come into being along theline connecting blast holes which creates condition for theformation of the presplit face Based on the above conditionthe blast hole spacing in presplit blasting is obtained Accord-ingly the blast hole spacing of presplit blasting of Heidaigouopen cast mine ranges from 303m to 416m with 35m usedin actual production satisfying the presplit blasting effect

(3) The vibration detection principles of vibration testersand pick-ups are analyzed The vibration velocity of blastingparticle is detected in the blasting zonewhose rear part is withpresplit cracks and right side is without Based on Sadovrsquosempirical formula attenuation formulas of blast vibration onconditions with and without presplit blasting are obtained bynumerical fitting respectively The detection results indicatethat presplit blasting can reduce the attenuation coefficientby half and the vibration absorption ratio can reach 502whichmeans presplitting blast is of great significance in shockabsorption of blast casting

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

Acknowledgments

This study was supported by the National Natural Sci-ence Foundation of China (51034005) the Fundamental

Research Funds for the Central Universities (2010QNB232011QNB25) and the Priority Academic Program Develop-ment of Jiangsu Higher Education Institutions

References

[1] K Pathak S Durucan and S Kunimatsu ldquoActivity accountingtechnique for environmental noise assessment in mechanizedsurfaceminingrdquoEnvironmentalMonitoring andAssessment vol56 no 3 pp 241ndash256 1999

[2] A Fisne C Kuzu and T Hudaverdi ldquoPrediction of environ-mental impacts of quarry blasting operation using fuzzy logicrdquoEnvironmental Monitoring and Assessment vol 174 no 1ndash4 pp461ndash470 2011

[3] D J Armaghani E Momeni S V A N K Abad andM Khan-delwal ldquoFeasibility of ANFIS model for prediction of groundvibrations resulting from quarry blastingrdquo Environmental EarthSciences vol 74 no 4 pp 2845ndash2860 2015

[4] T N Singh and V Singh ldquoAn intelligent approach to predictionand control ground vibration in minesrdquo Geotechnical andGeological Engineering vol 23 no 3 pp 249ndash262 2005

[5] U Ozer A Kahriman M Aksoy D Adiguzel and A Karado-gan ldquoThe analysis of ground vibrations induced by benchblasting at Akyol quarry and practical blasting chartsrdquo Environ-mental Geology vol 54 no 4 pp 737ndash743 2008

[6] C Kuzu and E Guclu ldquoThe problem of human response toblast induced vibrations in tunnel construction and mitigationof vibration effects using cautious blasting in half-face blastingroundsrdquo Tunnelling and Underground Space Technology vol 24no 1 pp 53ndash61 2009

[7] D D Li and Z D Deng ldquoEvaluation of the effects of blastingvibration on humans in the excavation of CMICT dockrdquoEngineering Blasting vol 12 no 2 pp 82ndash85 2012

[8] F Zheng W D Duan D W Zhong and B Y Sun ldquoResearchprogress and existing problems of blasting vibrationrdquo Blastingvol 23 no 1 pp 92ndash94 2006

[9] T L Shi and B Z Li ldquoThe effects of millisecond delayinterval charge distribution andmeasuring distance on blastingvibrationrdquo Engineering Blasting vol 9 no 4 pp 10ndash13 2003

Shock and Vibration 9

[10] Y L Gao Q Tan S C Yang L Xue and Y L Yu ldquoExperimentalresearch on relationship between charge layout and blastingvibrationrdquo Engineering Blasting vol 10 no 3 pp 19ndash48 2004

[11] O Uysal and M Cavus ldquoEffect of a pre-split plane on the fre-quencies of blast induced ground vibrationsrdquoActaMontanisticaSlovaca vol 18 no 2 pp 101ndash109 2013

[12] J L Yan and X F Chen ldquoObservation and analysis of vibrationreduction effect of pre-split crack in complicated geologicconditionrdquo Blasting vol 25 no 3 pp 100ndash102 2008

[13] A J Prakash P Palroy and D D Misra ldquoAnalysis of blastvibration characteristics across a trench and a pre-split planerdquoFragblast vol 8 no 1 pp 51ndash60 2004

[14] L J Cai and J J Ma ldquoThe shock absorption mechanism and itseffect analysis of pre-splitting blastingrdquoChinaMiningMagazinevol 14 no 5 pp 56ndash58 2005

[15] Y F Zou ldquoExperimental study on the vibration- isolating effectof pre-split crack and vibration-isolating slotrdquo Blasting vol 22no 2 pp 96ndash99 2005

[16] E F Salmi and S Hosseinzadeh ldquoA further study on themechanism of pre-splitting in mining engineeringrdquo AppliedMechanics and Materials vol 553 pp 476ndash481 2014

[17] N H Yang ldquoExperimental study on rock damage in the slopecaused by presplit blastingrdquo Journal of the China RailwaySociety vol 30 no 3 pp 96ndash99 2008

[18] H R Sun Y J Tong X L Lin and H S Gao ldquoStudy on theVibration Effect of sling blasting in an open coalminerdquo Blastingvol 25 no 1 pp 69ndash73 2008

[19] Q K Chen G C Li and K M Li ldquoMonitor and analysis onexplosive seismic effect of high-bench cast blast of surface coalminerdquo Explosive Materials vol 37 no 6 pp 30ndash33 2008

[20] P K Zhang and F G Song ldquoPre-splitting blasting applied inhigh-bench cast blastingrdquo Opencast Mining Technology no 1pp 35ndash41 2007

[21] P K Zhang ldquoApplication of pre-splitting blasting in high-benchcast blasting of Heidaigou open pitrdquo Inner Mongolia ScienceTechnology amp Economy no 6 pp 257ndash258 2008

[22] W M Hu ldquoBlack dai ditch open-pit coal mine rock wavevelocity testing technologyrdquo Journal of North China Institute ofScience and Technology vol 11 no 9 pp 63ndash67 2014

[23] X H Ding K M Li S S Xiao and W M Hu ldquoAnalysisof key technologies and development of integrated digitalprocessing system for cast blasting designrdquo Journal of CentralSouth University vol 22 no 3 pp 1037ndash1044 2015

[24] C G Jin ldquoVibrating effect of blasting in open-pit sloperdquo MetalMine no 5 pp 18ndash20 1995

[25] Q Liu and S R Lv ldquoResearch on the millisecond delay intervaltime of open-pit bench blastingrdquo Engineering Blasting vol 20no 1 pp 54ndash58 2014

[26] M Chen W Lu D Shu and C Zhou ldquoCalculation method ofequivalent acceleration for limit equilibrium analysis of slopeunder blasting vibrationrdquo Chinese Journal of Rock Mechanicsand Engineering vol 28 no 4 pp 784ndash790 2009

[27] B He and YWang ldquoResidual thrust method and Janbumethodused to calculate landslide stabilityrdquo Safety and EnvironmentalEngineering vol 11 no 4 pp 60ndash62 2004

[28] Y L YuTheory and Technology of Engineering Blasting Metal-lurgical Industry Press Beijing China 2004

[29] W M Ling ldquoA study on the fracture mechanism of smoothblasting and pre-split blastingrdquo Journal of China University ofMining amp Technology vol 19 no 4 pp 79ndash87 1990 (Chinese)

[30] M Sazid and T N Singh ldquoNumerical assessment of spacing-burden ratio to effective utilization of explosive energyrdquo Inter-national Journal of Mining Science and Technology vol 25 no2 pp 291ndash297 2015

[31] B F Li and C B Qi ldquoShaped crack mechanism and parametersdesign of pre-splitting blastingrdquo West-China Exploration Engi-neering no 3 pp 78ndash79 2000 (Chinese)

[32] Q Zong ldquoTheoretical analysis of charge structurersquos influence onpressure on bore wallrdquo Mining and Metallurgical Engineeringvol 26 no 5 pp 9ndash12 2006 (Chinese)

[33] K S Ge Study on Parameter of Pre-Splitting Blasting ChinaUniversity of Geosciences Beijing China 2009

[34] J G Wang L F Luan Z Y Zhang X L Li and C L FanldquoNumerical simulation of blasting vibration effect on stabilityof high-steep sloperdquo Blasting vol 29 no 3 pp 119ndash122 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

8 Shock and Vibration

Table 4 Mechanical parameters of rock mass of Heidaigou open cast

Stratum Density (kNm3) Internal friction angle (∘) Cohesion (kPa)Loess 1950 295 451Sandy mudstone 2450 30 135Fine sandstone 2450 28 150Medium sandstone 2270 315 150Coarse sandstone 2240 320 130Weathered mudstone 247 290 1275Coal 14 35 1851Siltstone 245 313 1768

Table 5 Actual blast vibration detection data and absorption shock rate of presplit blasting

Detection point distance toblasting centerm

Velocity of vibrationcmsdotsminus1

200 400 600 800 1000 1200 1400Presplit blasting 548 221 13 089 066 052 043Non-presplit blasting 1101 397 218 143 103 079 063Vibration reduction ratio 502 443 404 378 359 342 317

reduces the factor of safety Calculated results suggest thatslope stability factors on conditions of static load anddynamic load of blasting are 1311 and 1285 respectively andthe dynamic load of blast casting has slight effect on the endslope stability taking only 198

(2) After the detonation of two adjacent presplit holesstress waves of each explosion spread radially and createtangential stress in the tangential direction Based on thetheory of stress wave interference when the sum of thetangential stress of two adjacent blast holes is greater than therock tensile strength radial cracks come into being along theline connecting blast holes which creates condition for theformation of the presplit face Based on the above conditionthe blast hole spacing in presplit blasting is obtained Accord-ingly the blast hole spacing of presplit blasting of Heidaigouopen cast mine ranges from 303m to 416m with 35m usedin actual production satisfying the presplit blasting effect

(3) The vibration detection principles of vibration testersand pick-ups are analyzed The vibration velocity of blastingparticle is detected in the blasting zonewhose rear part is withpresplit cracks and right side is without Based on Sadovrsquosempirical formula attenuation formulas of blast vibration onconditions with and without presplit blasting are obtained bynumerical fitting respectively The detection results indicatethat presplit blasting can reduce the attenuation coefficientby half and the vibration absorption ratio can reach 502whichmeans presplitting blast is of great significance in shockabsorption of blast casting

Competing Interests

The authors declare that there are no competing interestsregarding the publication of this paper

Acknowledgments

This study was supported by the National Natural Sci-ence Foundation of China (51034005) the Fundamental

Research Funds for the Central Universities (2010QNB232011QNB25) and the Priority Academic Program Develop-ment of Jiangsu Higher Education Institutions

References

[1] K Pathak S Durucan and S Kunimatsu ldquoActivity accountingtechnique for environmental noise assessment in mechanizedsurfaceminingrdquoEnvironmentalMonitoring andAssessment vol56 no 3 pp 241ndash256 1999

[2] A Fisne C Kuzu and T Hudaverdi ldquoPrediction of environ-mental impacts of quarry blasting operation using fuzzy logicrdquoEnvironmental Monitoring and Assessment vol 174 no 1ndash4 pp461ndash470 2011

[3] D J Armaghani E Momeni S V A N K Abad andM Khan-delwal ldquoFeasibility of ANFIS model for prediction of groundvibrations resulting from quarry blastingrdquo Environmental EarthSciences vol 74 no 4 pp 2845ndash2860 2015

[4] T N Singh and V Singh ldquoAn intelligent approach to predictionand control ground vibration in minesrdquo Geotechnical andGeological Engineering vol 23 no 3 pp 249ndash262 2005

[5] U Ozer A Kahriman M Aksoy D Adiguzel and A Karado-gan ldquoThe analysis of ground vibrations induced by benchblasting at Akyol quarry and practical blasting chartsrdquo Environ-mental Geology vol 54 no 4 pp 737ndash743 2008

[6] C Kuzu and E Guclu ldquoThe problem of human response toblast induced vibrations in tunnel construction and mitigationof vibration effects using cautious blasting in half-face blastingroundsrdquo Tunnelling and Underground Space Technology vol 24no 1 pp 53ndash61 2009

[7] D D Li and Z D Deng ldquoEvaluation of the effects of blastingvibration on humans in the excavation of CMICT dockrdquoEngineering Blasting vol 12 no 2 pp 82ndash85 2012

[8] F Zheng W D Duan D W Zhong and B Y Sun ldquoResearchprogress and existing problems of blasting vibrationrdquo Blastingvol 23 no 1 pp 92ndash94 2006

[9] T L Shi and B Z Li ldquoThe effects of millisecond delayinterval charge distribution andmeasuring distance on blastingvibrationrdquo Engineering Blasting vol 9 no 4 pp 10ndash13 2003

Shock and Vibration 9

[10] Y L Gao Q Tan S C Yang L Xue and Y L Yu ldquoExperimentalresearch on relationship between charge layout and blastingvibrationrdquo Engineering Blasting vol 10 no 3 pp 19ndash48 2004

[11] O Uysal and M Cavus ldquoEffect of a pre-split plane on the fre-quencies of blast induced ground vibrationsrdquoActaMontanisticaSlovaca vol 18 no 2 pp 101ndash109 2013

[12] J L Yan and X F Chen ldquoObservation and analysis of vibrationreduction effect of pre-split crack in complicated geologicconditionrdquo Blasting vol 25 no 3 pp 100ndash102 2008

[13] A J Prakash P Palroy and D D Misra ldquoAnalysis of blastvibration characteristics across a trench and a pre-split planerdquoFragblast vol 8 no 1 pp 51ndash60 2004

[14] L J Cai and J J Ma ldquoThe shock absorption mechanism and itseffect analysis of pre-splitting blastingrdquoChinaMiningMagazinevol 14 no 5 pp 56ndash58 2005

[15] Y F Zou ldquoExperimental study on the vibration- isolating effectof pre-split crack and vibration-isolating slotrdquo Blasting vol 22no 2 pp 96ndash99 2005

[16] E F Salmi and S Hosseinzadeh ldquoA further study on themechanism of pre-splitting in mining engineeringrdquo AppliedMechanics and Materials vol 553 pp 476ndash481 2014

[17] N H Yang ldquoExperimental study on rock damage in the slopecaused by presplit blastingrdquo Journal of the China RailwaySociety vol 30 no 3 pp 96ndash99 2008

[18] H R Sun Y J Tong X L Lin and H S Gao ldquoStudy on theVibration Effect of sling blasting in an open coalminerdquo Blastingvol 25 no 1 pp 69ndash73 2008

[19] Q K Chen G C Li and K M Li ldquoMonitor and analysis onexplosive seismic effect of high-bench cast blast of surface coalminerdquo Explosive Materials vol 37 no 6 pp 30ndash33 2008

[20] P K Zhang and F G Song ldquoPre-splitting blasting applied inhigh-bench cast blastingrdquo Opencast Mining Technology no 1pp 35ndash41 2007

[21] P K Zhang ldquoApplication of pre-splitting blasting in high-benchcast blasting of Heidaigou open pitrdquo Inner Mongolia ScienceTechnology amp Economy no 6 pp 257ndash258 2008

[22] W M Hu ldquoBlack dai ditch open-pit coal mine rock wavevelocity testing technologyrdquo Journal of North China Institute ofScience and Technology vol 11 no 9 pp 63ndash67 2014

[23] X H Ding K M Li S S Xiao and W M Hu ldquoAnalysisof key technologies and development of integrated digitalprocessing system for cast blasting designrdquo Journal of CentralSouth University vol 22 no 3 pp 1037ndash1044 2015

[24] C G Jin ldquoVibrating effect of blasting in open-pit sloperdquo MetalMine no 5 pp 18ndash20 1995

[25] Q Liu and S R Lv ldquoResearch on the millisecond delay intervaltime of open-pit bench blastingrdquo Engineering Blasting vol 20no 1 pp 54ndash58 2014

[26] M Chen W Lu D Shu and C Zhou ldquoCalculation method ofequivalent acceleration for limit equilibrium analysis of slopeunder blasting vibrationrdquo Chinese Journal of Rock Mechanicsand Engineering vol 28 no 4 pp 784ndash790 2009

[27] B He and YWang ldquoResidual thrust method and Janbumethodused to calculate landslide stabilityrdquo Safety and EnvironmentalEngineering vol 11 no 4 pp 60ndash62 2004

[28] Y L YuTheory and Technology of Engineering Blasting Metal-lurgical Industry Press Beijing China 2004

[29] W M Ling ldquoA study on the fracture mechanism of smoothblasting and pre-split blastingrdquo Journal of China University ofMining amp Technology vol 19 no 4 pp 79ndash87 1990 (Chinese)

[30] M Sazid and T N Singh ldquoNumerical assessment of spacing-burden ratio to effective utilization of explosive energyrdquo Inter-national Journal of Mining Science and Technology vol 25 no2 pp 291ndash297 2015

[31] B F Li and C B Qi ldquoShaped crack mechanism and parametersdesign of pre-splitting blastingrdquo West-China Exploration Engi-neering no 3 pp 78ndash79 2000 (Chinese)

[32] Q Zong ldquoTheoretical analysis of charge structurersquos influence onpressure on bore wallrdquo Mining and Metallurgical Engineeringvol 26 no 5 pp 9ndash12 2006 (Chinese)

[33] K S Ge Study on Parameter of Pre-Splitting Blasting ChinaUniversity of Geosciences Beijing China 2009

[34] J G Wang L F Luan Z Y Zhang X L Li and C L FanldquoNumerical simulation of blasting vibration effect on stabilityof high-steep sloperdquo Blasting vol 29 no 3 pp 119ndash122 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 9

[10] Y L Gao Q Tan S C Yang L Xue and Y L Yu ldquoExperimentalresearch on relationship between charge layout and blastingvibrationrdquo Engineering Blasting vol 10 no 3 pp 19ndash48 2004

[11] O Uysal and M Cavus ldquoEffect of a pre-split plane on the fre-quencies of blast induced ground vibrationsrdquoActaMontanisticaSlovaca vol 18 no 2 pp 101ndash109 2013

[12] J L Yan and X F Chen ldquoObservation and analysis of vibrationreduction effect of pre-split crack in complicated geologicconditionrdquo Blasting vol 25 no 3 pp 100ndash102 2008

[13] A J Prakash P Palroy and D D Misra ldquoAnalysis of blastvibration characteristics across a trench and a pre-split planerdquoFragblast vol 8 no 1 pp 51ndash60 2004

[14] L J Cai and J J Ma ldquoThe shock absorption mechanism and itseffect analysis of pre-splitting blastingrdquoChinaMiningMagazinevol 14 no 5 pp 56ndash58 2005

[15] Y F Zou ldquoExperimental study on the vibration- isolating effectof pre-split crack and vibration-isolating slotrdquo Blasting vol 22no 2 pp 96ndash99 2005

[16] E F Salmi and S Hosseinzadeh ldquoA further study on themechanism of pre-splitting in mining engineeringrdquo AppliedMechanics and Materials vol 553 pp 476ndash481 2014

[17] N H Yang ldquoExperimental study on rock damage in the slopecaused by presplit blastingrdquo Journal of the China RailwaySociety vol 30 no 3 pp 96ndash99 2008

[18] H R Sun Y J Tong X L Lin and H S Gao ldquoStudy on theVibration Effect of sling blasting in an open coalminerdquo Blastingvol 25 no 1 pp 69ndash73 2008

[19] Q K Chen G C Li and K M Li ldquoMonitor and analysis onexplosive seismic effect of high-bench cast blast of surface coalminerdquo Explosive Materials vol 37 no 6 pp 30ndash33 2008

[20] P K Zhang and F G Song ldquoPre-splitting blasting applied inhigh-bench cast blastingrdquo Opencast Mining Technology no 1pp 35ndash41 2007

[21] P K Zhang ldquoApplication of pre-splitting blasting in high-benchcast blasting of Heidaigou open pitrdquo Inner Mongolia ScienceTechnology amp Economy no 6 pp 257ndash258 2008

[22] W M Hu ldquoBlack dai ditch open-pit coal mine rock wavevelocity testing technologyrdquo Journal of North China Institute ofScience and Technology vol 11 no 9 pp 63ndash67 2014

[23] X H Ding K M Li S S Xiao and W M Hu ldquoAnalysisof key technologies and development of integrated digitalprocessing system for cast blasting designrdquo Journal of CentralSouth University vol 22 no 3 pp 1037ndash1044 2015

[24] C G Jin ldquoVibrating effect of blasting in open-pit sloperdquo MetalMine no 5 pp 18ndash20 1995

[25] Q Liu and S R Lv ldquoResearch on the millisecond delay intervaltime of open-pit bench blastingrdquo Engineering Blasting vol 20no 1 pp 54ndash58 2014

[26] M Chen W Lu D Shu and C Zhou ldquoCalculation method ofequivalent acceleration for limit equilibrium analysis of slopeunder blasting vibrationrdquo Chinese Journal of Rock Mechanicsand Engineering vol 28 no 4 pp 784ndash790 2009

[27] B He and YWang ldquoResidual thrust method and Janbumethodused to calculate landslide stabilityrdquo Safety and EnvironmentalEngineering vol 11 no 4 pp 60ndash62 2004

[28] Y L YuTheory and Technology of Engineering Blasting Metal-lurgical Industry Press Beijing China 2004

[29] W M Ling ldquoA study on the fracture mechanism of smoothblasting and pre-split blastingrdquo Journal of China University ofMining amp Technology vol 19 no 4 pp 79ndash87 1990 (Chinese)

[30] M Sazid and T N Singh ldquoNumerical assessment of spacing-burden ratio to effective utilization of explosive energyrdquo Inter-national Journal of Mining Science and Technology vol 25 no2 pp 291ndash297 2015

[31] B F Li and C B Qi ldquoShaped crack mechanism and parametersdesign of pre-splitting blastingrdquo West-China Exploration Engi-neering no 3 pp 78ndash79 2000 (Chinese)

[32] Q Zong ldquoTheoretical analysis of charge structurersquos influence onpressure on bore wallrdquo Mining and Metallurgical Engineeringvol 26 no 5 pp 9ndash12 2006 (Chinese)

[33] K S Ge Study on Parameter of Pre-Splitting Blasting ChinaUniversity of Geosciences Beijing China 2009

[34] J G Wang L F Luan Z Y Zhang X L Li and C L FanldquoNumerical simulation of blasting vibration effect on stabilityof high-steep sloperdquo Blasting vol 29 no 3 pp 119ndash122 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of