2 Report Shivam Modasa (1)

Report No: MaRS/MAT/227

INDEXINDEX

Sr. Sr. No.No.

ContentsContents PagePage

1. Introduction 1

2. General Geology 1

3. Field Investigation 2

4. Laboratory Investigation 5

5. Sub Soil Strat i f icat ions 9

6. Computation of Safe Bearing Capacity 9

7. Summary of Safe Bearing Capacity 13

8. Conclusion & Recommendation 14

9. Result Sheet 18

10. Drawings P-1&2

0 MaRS Enviro Research & Engineering Services Private Limited, Ahmedabad


1.0 INTRODUCTION

M/S Dr. Yogesh Upadhyay, Modasa proposed to conduct soil investigation of construction of

“Residential/ Commercial Building (G+4) at near Shivam Society at Modasa, State: Gujarat.

Accordingly, land soil investigations were envisaged to evolve various soil/rock parameters in

order to carry out engineering analysis and foundation design. In this connection, the soil

investigation work was awarded to “M/S MaRS Enviro Research & Engineering Services

Private Limited, Ahmedabad” vide reference letter Date: 23/1/14 to carry out land soil

investigation at the proposed site.

Broad objectives of the investigation are as follows,

a) To evaluate the parameters of soil/rock at the proposed site.

b) To assess the engineering parameters and to estimate the safe bearing capacity of soil.

2.0 GENERAL GEOLOGY

Modasa is a city in Aravalli district in the Indian state of Gujarat. Modasa became headquarters

of new Aravalli district, carved out from tribal-dominated areas of Sabarkantha. Pre-Aravalli

migmatites and gneisses exposed in the northeastern part form the oldest rocks in the area

Metasedimentary bands of quartzite, phyllite, mica schist and calc silicate rocks occur as

restites within the migmatites complex. A number of amphibolite bands also occur within this

complex. The migmatites complex has a faulted contact with the Lunavada Group comprising

phyllite, mica schist, metagreywacke and quartzite. The sediments have suffered at least two

phases of deformation resulting in complex zig- zag pattern of quartzite outcrops and show

metamorphism up to green schist facies. The Champaner Group occurring to the southwest

comprises a folded sequence of metasub-greywacke, sandy phyllite, mica schist, quartzite etc.



3.0 FIELD INVESTIGATION

3.1 Boring

The exploratory borehole of 100mm diameter was drilled by Rotary drilling method without

casing. The depth of the test bore at the proposed location is as under:

Bore Hole No. Location Depth of Borehole below EGL(m)

BH-1 At Near Shivam

Society, Modasa

6.00

3.2 Sampling

3.2.1 Disturbed Samples

Disturbed samples were collected during the boring and also from the split spoon sampler. The

samples recovered were logged, labeled and placed in polythene bags and sent to laboratory

for testing on Date: 24/1/14.

3.2.2 Undisturbed Samples

Undisturbed soil samples were collected in thin walled Shelby tubes and using piston type

sampler as per IS-2132. The samples were sealed with wax, labeled and transported to our

laboratory at Changodar, Ahmedabad for testing on Date: 24/14/14.

3.2.3 Standard Penetration Test

The Standard Penetration Tests (SPT) (IS-2131, 1981) was carried out in the bore hole at

predetermined depths. It gives indirect evaluation of strength–deformation characteristics of the

sub soil. The test includes driving a split spoon sampler using a 63.5 kg hammer with a free fall

of 750mm. The first 15cm is considered as seating drive. The No. of blows required to

penetrate next 30 cm is reported as N-value. Empirical relations are established to correlate N-

Value with the shear parameters or bearing capacity of soil. A disturbed soil sample is collected

inside the split spoon sampler which can be used to find soil classification and In-situ water

content.



If the no. of blows exceeds 50 before desired penetration is achieved, it is reported as N- value

>50 with the actual penetration achieved. Corrections to SPT N-value are applied for Cohesion

less soil as given below:

1. Due to Overburden – The N value for cohesion less soil shall be corrected for overburden as

,where po =existing overburden in t/m2

2. Due to Dilatancy – The value obtained above shall be corrected for dilatancy, if the stratum

consists of fine sand and silt below water table for values of ‘N’ greater than 15, as (N ”) :

*SPT ‘N’ values are co-related with relative density of non-cohesive stratum and with

consistency of cohesive stratum are tabulated as below.

Co-Relation for Saturated Sand / Non-Plastic Silt

Relative Density Penetration Value (Blows/30cm)

Very loose 0 to 4

Loose 4 to 10

Medium 10 to 30

Dense 30 to 50

Very Dense >50

Co-Relation for Saturated Clay/Plastic Silt

Consistency Penetration Value (Blows/30cm)

Very Soft 0 to 2

Soft 2 to 4

Medium Stiff 4 to 8

Stiff 8 to 15

Very Stiff 15 to 30

Hard 30 to 50



3.2.4 Ground Water Table

Ground Water table was not encountered in the borehole up to 6.00m termination depth below

EGL at investigation carried out in the month of (January - 2014)



4.0 LABORATORY INVESTIGATION

The laboratory tests on soil samples were started immediately after the receipt (Date:25/1/14)

of the same in the laboratory. Following laboratory tests are carried out to determine the

physical and engineering properties of undisturbed and disturbed soil samples.

1. Dry Density and Natural Moisture Content (IS - 2720, Part – II)

2. Particle Size Analysis (IS - 2720, Part – IV, 1985)

3. Atterberg's Limit (IS -2720, Part – V, 1985)

4. Specific Gravity (IS -2720, Part – III, 1980)

5. Shear Test (IS -2720, Part -XI 1986)

4.1 Field Dry Density & Natural Moisture Content

The weight of undisturbed soil sample with sampler (Shelby tube) is determined after removing

peraffin wax and loose soil. The total length of soil sample recovery is determined after

deducting empty length from the total length of sampler. The volume of soil mass retained in

sampler is thus determined from the known inside diameter of sampler and total length of soil

mass. The soil mass is then removed and the average moisture content is determined by

keeping the soil sample along with crucible in oven at 100-105 degree centigrade for 24 hours.

The empty weight of the sampler is then found out. From the total weight of sampler with soil

mass, the weight of empty sampler is deducted. The field density is then found out as

Field density (bulk)

Field dry density

Where w is water content.

4.2 Particle Size Analysis

The sieve analysis is carried out in accordance with IS-2720, Part-IV, 1985. The results are

presented in the form of Grain size distribution curve. Representative soil sample is obtained

from the bulk soil sample collected or received from site by method of coning and quartering.

Quantity of soil taken will be dependent on the maximum size of particle size present in the

soil. Sieve analysis is conducted in two parts:



1) Soil fraction retained on 4.75mm ISS

Soil portion retained on 4.75 ISS is weighed. The sample is then separated into various

fractions by sieving through the following sieves:

100, 75, 19 and 4.75 mm ISS

While sieving through each sieve, sieve is agitated so that sample rolls in irregular motion over

the sieve, at no time the particles are pushed through; Care is also taken to see that no

individual soil particles are broken, though particles adhering one another are rubbed by

rubber pestle when required. Care is also taken not to over load the sieve beyond the

permitted maximum load for respective sieve.

The mass of the material retained on each sieve is recorded The percentage of soil retained on

each sieve is then calculated on the basis of the total mass of soil taken and from these

results, the percentage passing through each sieve is calculated.

2) Soil fraction passing 4.75 ISS

The portion of the soil passing 4.75 mm ISS is oven dried at 105oC to 110oC. The portion is

coned & quartered to obtain required representative quantity of the material. The material is

weighed and placed in tray/bucket filled with water for soaking and loosening the adhered

cohesive materials. The soaked soil specimen is then washed on 75 micron IS Sieve until the

water passing the sieve is almost clear. The material retained on 75 micron IS Sieve is then

transferred in a tray, dried in oven.

Sieve analysis is then conducted on a nest of sieves (viz. 2 mm, 425 and 75 micron ISS) either

by hand or by using mechanical sieve shaker. The fraction retained on each of the sieves is

weighed separately and masses recorded. Cumulative mass of soil fraction retained on each

sieve is then calculated. The weights are then converted into cumulative percentage retained

and passing on the basis of the mass of the sample passing 4.75 ISS taken. The combined

gradation on the basis of the total sample taken for analysis is finally calculated.

4.3 Atterberg’s Limit

Liquid and Plastic Limits are determined by using procedure given in IS: 2720, Part-V, 1985.

The results are given in result sheet. The weight of cone plus rod and plate is 148 gm. A soil



sample weighing about 150gm from the thoroughly mixed portion of soil passing 425 micron

was used for testing. The thoroughly wet soil paste is transferred to the cylindrical trough

150mm diameter and 50mm high of the cone penetrometer apparatus and levelled up to the

top of trough. The penetrometer is adjusted such that the cone point just touches the surface

of the soil paste in trough. The scale of the penetrometer is adjusted to zero and the vertical

rod is released so that the cone is allowed to penetrate into the soil paste under its own

weight. The penetration is noted after 30 sec. from the release of the cone. The reading is

considered if the penetration reading is between 20mm and 30 mm. The moisture content of

the soil paste corresponding to this is determined. The liquid limit of the soil which corresponds

to the moisture content of a paste which would give 25 mm penetration of the cone is

determined using formula:

WLL = Wx + 0.01 (25 - W) (Wx + 15)

For determination of plastic limit, a soil sample weighing at least 20 gm from the soil sample

passing 425micron IS sieve is thoroughly mixed with water such that it can be easily

moulded with fingers. A ball is formed with about 8 to 10 gm of this soil & is rolled between the

fingers and the glass plate with just sufficient pressure to roll the mass into a thread of uniform

diameter of 3mm throughout its length. The soil is then kneaded together to a uniform mass

and rolled again. The process is continued until the thread crumbles. The pieces of crumbled

soil thread are collected and moisture content is determined and reported as plastic limit.

4.4 Specific Gravity

The specific gravity of soil solids is determined by a 50ml density bottle. The weight (W1) of the

empty dry bottle is taken first. A sample of oven-dried soil about 10-20 g cooled in a

desiccator, is put in the bottle, and weight (W2) of the bottle and the soil is taken. The bottle

is then filled with distilled water gradually removing the entrapped air either by applying vacuum

or by shaking the bottle. The weight (W3) of the bottle, soil and water (full up to the top) is then

taken. Finally the bottle is emptied completely and thoroughly washed and clean water is filled

to the top and the weight (W4) is taken.

Specific Gravity (G) =



4.5 Shear Test

Direct shear test is carried out using shear box with the specimens (60mmx60mmx25mm).

Specimen with plain grid plate at the bottom of the specimen and plain grid plate at the top

of the specimen is fitted into position in the shear box housing and assembly placed

on the load frame. The serrations of the grid plates are kept at right angle to the direction of

shear. The loading pad is kept on the top grid plate. The required normal stress is applied and

the rate of longitudinal displacement/shear stress application so adjusted that no drainage can

occur in the sample during the test (1.25mm/min). The upper part of the shear box is raised

such that a gap of about 1mm is left between the two parts of the box. The test is conducted by

applying horizontal shear load to failure or to 20 percent longitudinal displacement whichever

occurs first. The test is repeated on identical specimens.



5.0 SUB SOIL STRATIFICATION

Field and laboratory test data reveal the general stratification as under:

Soil Stratification of Borehole

BoreholeNo

Depth (m)

StratificationObserved SPT value

Ground Water Table

(m)

BH-1

0.00 -2.30 Observed to consist of brownish to colour medium dense non plastic silty sand (SM).

10

Not met with2.30-6.00

Observed to consist of completely weathered very poor rock obtained in crushed and boulder form.

Refusal

6.0 COMPUTATION OF SAFE BEARING CAPACITY

The following formula is used for calculating ultimate net bearing capacity in the case of

footings: (Ref: IS: 6403 - 1981)

a) In case of general shear failure:

qd = C Nc + q (Nq-1) 0.5 Br Nr

b) In case of local shear failure:

qd’ = 2/3 C N'c + q (N'q-1) + 0.5 Br Nr'

The ultimate net bearing capacity obtained for footing is modified to take into account, the

shape of the footing, inclination of loading, depth of embedment and effect of water table. The

modified bearing capacity formula is given as under:

a) In case of general shear failure:

qd = C Nc Sc dc ic + q (Nq-1) Sq dq iq + 0.5 Br Nr Sr dr ir W'

b) In case of local shear failure:

qd' = 2/3 C N'c Sc dc ic + q (N'q-1) Sq dq iq + 0.5 Br N'r Sr dr ir W'

c) In case of stiff cohesive soil:

qd = C Nc Sc dc ic



Shape Factor Sc Sq Sr

Continuous strip 1.00 1.00 1.00

Rectangular 1+0.2 (B/L) 1+0.2 (B/L) 1-0.4 (B/L)

Square 1.3 1.2 0.8

Circle 1.3 1.2 0.6

Depth Factor

dc

dq = dr 1 for φ < 10 degree

dq = dr

Assuming that overburden soil is not compacted properly, dc = dq = dr = 1.0

Considering applied load as vertical, ic = iq = ir = 1.0

Settlement Calculation for foundation resting on sand

In case of subsoil strata is cohesion less in pressure bulb as per IS: 8009 (Fig 9) settlement v/s

N - value charts for calculation of settlement. For that graph for corrected N-value and

according to width of foundation for 10 t/m2 value of settlement (mm) find.



Table- 1 Safe bearing capacity based on shear criterion

FAILURE TYPE = GeneralC (Kg/cm2) = 0.15Ф (degree) = 31.00

FOOTING TYPE = SquareB (m) = 1.50 1.50 2.00 2.00 3.00 3.00L (m) = 1.50 1.50 2.00 2.00 3.00 3.00

Df (m) = 2.00 3.00 2.00 3.00 2.00 3.00 GWT CONDITION Not Met With

DD (kg/cm3) = 0.00194 0.00194 0.00194 0.00194 0.00194 0.00194FOS = 3.00 3.00 3.00 3.00 3.00 3.00

BE

AR

ING

CA

PA

CIT

Y

FA

CT

OR

S

Nc = 32.67 32.67 32.67 32.67 32.67 32.67Nq = 20.63 20.63 20.63 20.63 20.63 20.63Nv = 25.99 25.99 25.99 25.99 25.99 25.99Sc = 1.30 1.30 1.30 1.30 1.30 1.30Sq = 1.20 1.20 1.20 1.20 1.20 1.20Sv = 0.80 0.80 0.80 0.80 0.80 0.80dc = 1.00 1.00 1.00 1.00 1.00 1.00dq = 1.00 1.00 1.00 1.00 1.00 1.00dv = 1.00 1.00 1.00 1.00 1.00 1.00

Ic = Iq = 1.00 1.00 1.00 1.00 1.00 1.00Iv = 1.00 1.00 1.00 1.00 1.00 1.00

W ' = 1.00 1.00 1.00 1.00 1.00 1.00q,d (kg/cm2) = 18.54 23.11 19.54 24.11 21.56 26.13

q,na (kg/cm2) = 6.18 7.70 6.51 8.04 7.19 8.71q,na (t/m2) = 61.79 77.02 65.15 80.38 71.87 87.10



Table- 2 Bearing pressure based on settlement criterion

Width of footing, B (m) = 1.50 2.00 3.00

Placement depth, Df (m) = 2.00-3.00 2.00-3.00 2.00-3.00

Average N-Value = 50.00 50.00 50.00

GWT Condition = Not Met With

Permissible settlement (mm) = 50.00 50.00 50.00

GWT Correction, W' = 1.00 1.00 1.00

Settlement for 10t/m2 = 4.20 4.80 5.10

Permissible load (t/m2) = 119.05 104.17 98.04



7.0 SUMMARY OF SAFE BEARING CAPACITY

Table - 3 Summary of Safe Bearing Capacity and Safe Bearing Pressure

Size(m)

Depth below

EGL (m)

Safe Bearing Capacity

(SBC)(t/m2)

Safe Bearing Pressure (SBP)

(t/m2)(50mm)

Recommended Value of SBC (t/m2)

(50mm)

1.50 x 1.50 2.00 61.79 119.05 25.00

1.50 x 1.50 3.00 77.02 119.05 25.00

2.00 x 2.00 2.00 65.15 104.17 25.00

2.00 x 2.00 3.00 80.38 104.17 25.00

3.00 x3.00 2.00 71.87 98.04 25.00

3.00 x 3.00 3.00 87.10 98.04 25.00



8.0 CONCLUSION & RECOMMENDATION

1. Sub soil investigation is in general found to consist of medium dense non plastic silty

sand followed by completely weathered very poor rock obtained in crushed and boulder

form up to 6.00m termination depth below EGL.

The ground water table was not encountered in the borehole up to 6.00m depth below

existing ground level at the time of investigation. (January – 2014).

2. The safe bearing capacity considering laboratory and field shear and settlement

parameters is recommended as given vide Para-7 (Table - 3) of report, with permissible

settlement 50mm in natural condition of soil. The recommended value of SBC shall be

for static vertical loading only.

3. The soil having no swelling characteristics hence it is suitable to use for backfilling or

plinth purposes.

FOR, MARS ENVIRO RESEACH & ENGINEERING SERVICES PVT. LTD.

AUTHORISED SIGNATORY



Table No.4 Observed & Corrected N-Values

BoreHoleNo.

Depthin

(m)

Nos. of blow to drivesampler for penetration of

N-valuefor last

300(mm)

Overburden Pressure

Correction

Corrected N Value

0–150(mm)

150-300(mm)

300-450(mm)

BH-1 1.00 2 4 6 10 1.55 15

3.00 10 50(12cm) - Refusal Refusal Refusal





NOTATIONS

C Cohesion

DS Disturbed Sample

UDS Undisturbed Sample

SPT Standard Penetration Test

GWT Ground Water Table

EGL Existing Ground Level

BH Borehole

FOS Factor of Safety

Γ Density of Soil

LL Liquid Limit

PL Plastic Limit

PI Plasticity Index

NP Non Plastic

Nc,Nq,Nγ Bearing Capacity Factors

Sc Sq, Sγ Shape Factors

Dc Dq, Dγ Depth Factors

B Width of Foundation

D Depth of Foundation

DST Direct Shear Unconsolidated Undrain Test

SM Silty Sand

CWR Completely Weathered Rock



REFRENCES

Indian Standard IS 2720 Pt II, III, IV ,V ,XIII ,XXXI ,XXVII,XXVI,IS 1498,IS

6403,IS 1904,IS 8009,IS 1892

Murthy V.N.S. Soil Mechanics and Foundation Engineering

Lambe T.W. Soil Testing Engineers

Peck,R.S. Hanson Foundation Engineering

Nayak N.V. Foundation Engineering Manual

Kaniraj S.R. Design Aids in Soil Mechanics and Foundation engineering

Alam Singh Modern Geotechnical Engineering

Hunt Foundation Engineering Analysis

Shamsher Prakash Analysis and Design of Foundation and Retaining Structures

Winterkorn H.F. & Fang H.Y. Foundation engineering Handbook

R.P. Rethaliya Soil Engineering Book



Geotechnical Investigation Work (Site Photos)


2 Report Shivam Modasa (1)

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