borgaon_bhandara
TRANSCRIPT
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Report
On
SOIL TESTINGFOR
CONSTRUCTION OF GSM-GBT TOWERSITE NAME BORGAON BHANDARA
Mr. Sopan H. AkreAt Chicholi Post Dhandla, Tah: Mouda, Disst: Nagpur
FORVIOM NETWORKS
IMPLEMENTING AGENCY
VIOM NETWORKSNagpur
P.T.MASE & ASSOCIATESConsulting Civil Engineers & Structural Engineers
Project Management Consultants
Structural Audit & Assessment Division
Civil Engineering Laboratory & Research Centre
Planning Consultants
240 B 1, BAJAJ NAGAR, NAGPUR-440 010
TEL.NOS: 0712 223 4340, 2237309
FAX NO: 0712 223 4979, 223 3430
MOBILE 098222 20919
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INDEX
SR. NO. PARTICULAR
1. INTRODUCTION
2. TERMINOLOGY
3. SITE INVESTIGATION & EXPLORATION
4. CHARACTERISTICS OF SOIL
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Summary of Test
As per the various test carried out, our recommendations are as
follows.
1.Safe bearing capacity of soil with factor of safety 2.5 is 7.0 T/m2 at3.0 mt depth
2.Remove Excavated soil up to 2.0mt.3.From 2 mt to 3.0 mt use excavated soil for back filling with
addition of 50% external murum or sand.
4.R. C. C. open foundation is recommended for tower, DG and Shelterfoundation.
5.No water table found.6.No chemicals found in soil.7.Raise plot level by 300 mm to avoid lodging in rainy season.
CERTIFICATE
It is hereby certified that the document titled Scope of Work and
Specifications for Soil Investigations and Testing for Telecom towers
for Viom Networks, Version 1.0, dated 4th August, 2010 issued by
Viom Networks has been strictly adhered to.
Certified by: Dr. D. P. Mase
Designation: Structural Engineer
Qualification: B.E. (Civil). M. Tech (Structure), Ph. D. (Civil)
Chartered Engineer No: M-123484/0
MIE, MICI, MACI, MACE.
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INTRODUCTION
The purpose of the soil investigation is to arrive at an optimum design for the
tower foundations. The telecom towers are generally 3 - legged Or 4 legged
braced steel structures varying from 30m to 60m height. The weight ranges
from 5 to 15 tons depending on the type of tower. Under extreme conditions of
wind loading, the load on each leg will be in the range of 25 to 100 ton in
compression, 25 to 100 tons in uplift and 2 to 10 tons in lateral thrust. In most
cases, the uplift capacity of the foundation governs the design.
Scope & Objective of the work:-
The Scope of work includes following points,
1) A trial pit carried out up to depth of 3 meters.2) Collection of disturbed sample3) Conducting laboratory tests4) Preparing soil profile5) Locating ground water level (GWL)6) Preparation and submission of report
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TERMINOLOGY
Following are the terminologies used in the report. (IS: 1904 1966)
1) Safe Bearing Capacity (SBC) The maximum intensity of the loading that the soil will safely carry without risk of shear failure, irrespective of any consolidationsettlement that may results.
2) ClayAn aggregate of microscopic and sub microscopic particles derivedfrom the chemical decomposition and disintegration of rockconstituents.
It is plastic within a moderate to wide range of water content. Theparticles are less than 0.002 mm size.
3) Firm ClayClay, which had its natural moisture content, can be moulded bysubstantial pressure with the fingers and can be excavated with aspade.
4) Soft ClayClay, which had its natural moisture content can be easily moulded
with the fingers and readily excavated.
5) Stiff ClayClay, which had its natural moisture content can not be moulded withthe fingers and requires a pick or pneumatic spade for its removal.
6) FoundationThese parts of the structure, which is in direct with and transmittingload to the ground.
7) Raft Foundation
A foundation continuous into directions, covering an area equal to orgreater than the best area of the building or structure.
8) GravelCohesion less aggregates of rounded, sub rounded, angular, subangular or flat fragments of more or less unaltered rocks or minerals,90% of the particles having a size greater than 2 mm less than 60mm.
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9) Sand
Cohesion less aggregates of rounded, sub rounded, angular, subangular or flat fragments of more or less unaltered rocks or minerals,90% of the particles having a size greater than 0.06 mm less than 2.0
mm in size.
10) Coarse sandSand which contains 90% of particles of size greater than 0.6 mm andless than 2.0 mm.
11) Medium SandSand, which contains 90% of particles of size greater than 0.2 mmand less than 0.6 mm.
12) Fine SandSand, which contains 90% of particles of size greater than 0.06 mmand less than 0.2 mm.
13) SiltA fine granular soil with little or no plasticity. If shaken in the palm ofthe hand, a pat of saturated inorganic silt expels enough water tomake its surface appears glossy. If the pat is stressed or squeezedbetween the fingers, it surface again becomes dull. The size ranges forsilt are as follows:-
a) Coarse Silt : 0.06 to 0.02 mm
b) Medium Silt : 0.02 to 0.006 mmc) Fine Silt : 0.006 to 0.002 mm
14) Soft RockA rocky cemented material, which offers a high resistance to diggingup with pick axes and sharp tools, but which does not normallyrequires blasting or chiselling for excavation.
15) Hard RockA rock which offers a high resistance to digging up with pick axes and
sharp tools and normally which requires blasting or chiselling forexcavation. Also hard rock offers a high resistance to metal tools andgenerates heavy sparks at the time of excavation.
16) Black Cotton SoilInorganic clays of medium to high compressibility, which is generallycohesive in nature and exerts swelling pressure when comes incontact with moisture or water.
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SITE INVESTIGATION & EXPLORATION
The investigation of the site is an essential prerequisite to the construction of
all civil engineering work with a view to assess the general suitability of the sitefor the proposed tower and enable in preparing an adequate and economicaldesign.
In particular, it is necessary to assess the changes that may occur during orafter the construction of the structure due to the choice of material or methodof construction, which may adversely, affects safety of structure or after itsperformance or utility. The investigation of the site is being carried out and inaccordance with the principles set by IS 1892 1979.
Before carrying out soil exploration programme, detail information about the
site is being collected.
Site exploration can be carried out by most common and satisfactory methodseven by IS 1892 1979 are,
a) Method of trial pitsb) Method of boringc) Heading
In our site exploration programme, we have adopted first method, i.e., method
of trial pit. In site exploration programme, particular attention shall be paid tothe ground water level, soil profile is being plotted and variation of soil strata ismarked according to the depth of excavation.
The sites where problem of water logging in rainy season may cause, in suchareas, it is desirable to determine the contour of the water table surface inorder to indicate the direction of the natural drainage and to obtain the basis ofthe design of intercepting drains to prevent the influx of ground water to thesite from higher grounds.
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LABORATORY TESTSCHARACTERISTICS OF SOIL
(AS PER IS: 1498 1970)(Reaffirmed in 1997)
1.Grain Size Analysis
Soil Sample from Borgaon Bhandara site collected from 1 Mt, 2 Mt, 3 Mt, depths was
tested for Engineering classification and opinion on presumptive Bearing Capacity
based on it. The dry Sieve analysis as per IS 2720 (PART IV) was conducted, the
results are as under. Settlement criteria considered for design is 25 mm. Trail Pit Size
2 x 2 x 3.0 mt. with manual Bore.
1 Mt. Depth Sample:-
Gravel : 19%Sand : 27%Silt & Clay : 54%
2 Mt. Depth Sample:-
Gravel : 29%Sand : 29%Silt & Clay : 42%
3 Mt. Depth Sample:-
Gravel : 32%Sand : 26%Silt & Clay : 58%
Engineering Classification : Stiff Clay
Depth of Water Table : 3.0 Mt below G.L.
Angle of internal friction at 3.0 : 26o
Atterberge Limit : Non Plastic at 2.0 Mt Depths
2.Determination of moisture content (As per IS 2720 (Part 2).The method adopted to find moisture content as per section 1-Oven-Drying method
(Standard Method).
The Percent of Water Content W
Moisture content (w)
= 18.12 %
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3. Specific gravity (As per IS 2720 (Part 3)
Section 1-fine Grained Soils
Section 2- Fine, medium and coarse grained soils.
The method adopted to find specific Gravity Gas Jar Method
Specific Gravity G= 2.592
4. Determination of liquid and plastic limit (As per IS 2720 (part 5) method
adopted for the determination of Liquid limit- Mechanical Method
5. Shrinkage Factors as per IS 2720 (Part 6).
Method adopted for Determination of Shrinkage Factor Remoulded Soil)
6. Determination of Dry Density- moisture content Relation By Constant massof Soil method (As per IS 2720 (Part 9). Method adopted Cylindrical metal tube
with base plate.
7. Ph value test as per IS 2720 (Part 26) - Determination of PH value. Appraturuse for PH- Electronic PH meter.
8. Sulphate Content Test & Chloride content Test- as per IS 2720 (Part XXVII) -Determination of total Soluble Sulphates.
SoilSample
BulkDensity
DryDensity
LiquidLimit
Plasticlimit
FreeSwellIndex
PH ChlorideContent
SulphidConten
Unit gm/cc gm/cc % % % ---- % %
1 mt 1.901 1.541 69.1 23.0 48.0 8.1 --- ---
2 mt 1.912 1.530 70.2 23.3 46.1 7.6 -- --
3 mt 1.922 1.561 70.1 22.1 44.1 7.4 -- --
The Soil contains particle from 1 mm to 10 mm size and can be classified as Stiff Clay. As
per IS 1904 Code of particle for structural safety of Building Shallow foundations.
(Second Revision) Table 2 considering factor of safety Two point five. The in situ strength
of this Stratumgenerally varies between 7 to 9 T/m2. lower value of 7 T/m2 is recommendedin present case at the depth of 3.0 Mt. Depth of tower foundation can rest at 3.0 Mt depth.
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Depth of Foundation
i) Depth below FGL for Tower : 3.0 Mt
ii) Depth below FGL for Civil Shelter : 2 Mt
iii) Depth of foundation for D.G. set : 2 Mt
iv) Foundation details : Suitable for Ground Base Tower
v) Back Fill : With external Non cohesive materialor External Murum. Mix with excavatedsoil from 2 mt to 3.0 mt Depth
Note: - At the time of selection for tower foundation, excavation depth recommended is
from the S.B.C. point of view. While selections of foundation type uplift force on tower
leg must be considered. The minimum depth of foundation required to resists uplift
force must be considered. Accordingly over burden on the foundations must be
checked.
Brief Description of Site
1. Site level from Road Site is located at plain ground and requires filling of 300mm above existing ground level to avoid water Lodging in future.
2. Trees at site- No Trees found on site.3. Nearby water bodies- No water bodies found in nearby area.4. Natural Strata found. No filled up Ground5. Water Table- No water table found in trial pit. No well or bore found in nearby
area.
6. Site Location Site is located in field and requires filling of 300 mm aboveexisting ground level to avoid water lodging in future.
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE
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PHOTOGRAPHS OF BORGAON BHANDARA SITE