Complete Project ISRAR

SOIL INVESTIGATION AND DESIGN OF FOUNDATION OF MULTI STOREYED

BUILDING

PROJECT REPORTSUBMITTED IN PARTIAL FULFILLMENT OF THE

REQUIREMENT FOR THE AWARD OF THE DEGREE OF

BACHELOR OF TECHNOLOGY

In

Civil engineeringUNDER THE SUPERVISION OF

DR. MEHBOOB ANWER KHAN DR. MASROOR ALAM

SUBMITTED BY MD RASHID KHAN (GROUP LEADER) ISRAR AHMAD ASHWINE KUMAR HAIDER ALI YOUSEF AYMAN YOUSEF THAHER ABDUL QAVI ABDUL BASIT KHAN TANVIR ALAM MOHD OBAID KURAISHY FAKRE ALAM

DEPARTMENT OF CIVIL ENGINEERINGZ. H. COLLEGE OF ENGINEERING & TECHNOLOGY

ALIGARH MUSLIM UNIVERSITYALIGARH (U.P.) INDIA

2012

DEDICATED TO ALMIGHTY ALLAH

AND OUR PARENTS

DEPARTMENT OF CIVIL ENGINEERINGZAKIR HUSSAIN COLLEGE OF ENGG. & TECHNOLOGY

ALIGARH MUSLIM UNIVERSITYALIGARH

CERTIFICATE

The project report entitled “SOIL INVESTIGATION AND DESIGN OF

FOUNDATION OF MULTI STOREYED BUILDING” in partial fulfillment

of the requirement for the award of Bachelor of Technology, Department of Civil

Engineering , Zakir Hussain College of Engineering & Technology, Aligarh

Muslim University, Aligarh.

This project is undertaken in our supervision and guidance:

Dr. Mehboob Anwer Khan Dr. Masroor alam Associate Professor Associate Professor Dept. of Civil Engg. Dept. of Civil Engg AMU, ALIGARH. AMU, ALIGARH.

PREFACE

The paucity of suitable land has lead to unprecedented surge in the vertical

expansion of construction. It has become essential to conduct detailed studies and

investigation of sub surface soil. This will ensure proper designing of foundation to

ensure safety and serviceability of multistory buildings.

Inspired by this zeal, I have undertaken this study on “Foundation

Engineering and Soil Mechanics”.

It is my deep pleasure coupled with immense satisfaction that after rigorous

studies and toilsome investigations, we have been successful in completing the

present project entitled “Soil Investigation and Design of Foundation of Multi

Storeyed Building”. The results drawn out of this study has significantly

contributed in enriching my knowledge and insight about the various aspects

related to soil engineering issues. The findings of this research project will

contribute in understanding of complex behavior of soil and will also promote the

vision, to coordinate various aspects of civil engineering.

The fields of knowledge are vast and varied and no knowledge can be

absolute and final. The present project might have certain limitations but it will

prove a milestone in the field of knowledge and shall expand new horizons in the

field of soil engineering.

ACKNOWLEDGEMENT

To start with, let’s first acknowledge the blessings of the Almighty who gave

strength for completing this work. The project is the result of the cumulative efforts

and knowledge of my co-partners and well wishers who are duly acknowledged.

The words are not sufficient to communicate my deep sense of gratitude for the

able guidance of Dr. Mehboob Anwer Khan for his meticulous guidance and

clear vision, which helped me to overcome all the hurdles related with the project.

I pay my gratitude to Prof. S. S. Shah for his overall supervision during the

project work. My thanks are also due to Dr. M. Masroor Alam who guided me in

this project.

We are also highly thankful to Prof. M. M. Ashhar, Chairman Department of Civil

Engineering, for providing us laboratory and field facilities to make the project a

great success.

We are also thankful to our friends, colleagues and family members for providing

us assistance and encouragement at different stages of this project.

MD RASHID KHAN (GROUP LEADER) ISRAR AHMAD ASHWINE KUMAR HAIDER ALI YOUSEF AYMAN YOUSEF THAHER ABDUL QAVI ABDUL BASIT KHAN TANVIR ALAM MOHD OBAID KURAISHY FAKRE ALAM

NOTATIONS

A X- Sectional Area of MemberAst Area of Tension SteelB Breadth of SectionD Effective Depth of sectionD Effective Depth of SectionDf Depth of Foundation Below Ground Level

M Bending MomentSf Settlement of FoundationSp Settlement of PlateBf Width of FoundationBp Width of PlateN SPT Values

N’’ Corrected “N” ValuesE Eccentricity of loadI Moment of InertiaL Span of BeamP Axial LoadVu Shear ForceJd Lever Arm

Nc, Nq, Nγ Bearing Capacity FactorsCu Undrained Cohesionqu Ultimate Bearing Capacityqnu Net Ultimate Bearing Capacityqns Net Safe Bearing Capacityqs Safe Bearing Capacity

SPECIFICATIONS

1. Grade of Concrete M 252. Grade of Steel Fe 415

3. Unit Weight of Materials used(a) R.C.C 25 kN/m3

(b) Brick Work 19 kN/m3

(c) Floor (C.C.) 17 kN/m3

(d) Mud Phuska 16 kN/m3

(e) Lime Concrete 19.5 kN/m3

1. Thickness of Mud Phuska/Tile work = 70 mm2. Height of Parapet Wall = 1.0m3. Size of Column = 400mm X 400mm4. Slab Thickness = 150mm5. Thickness of Tile =50mm6. Thickness of Flooring =25mm7. Floor to Floor Height =3.0m8. Depth of Brick Work Below Plinth Level =0.85m9. Dimensions of Beam:

a. Depth = 600mmb. Width = 300mm

CONTENTSChapter No. Title Page No.

1 Introduction

2 Load Calculations

3 Field Test

(Standard Penetration Test)4 Laboratory Test

(a) Density Bottle

(b) Consistency Limits

(c) Grain Size Analysis

(d) Triaxial Compression Test

(e) Standard Proctor Compaction test

5 Results and Discussion

6 Recommendations as Per I.S. Code of Practice

7 Design of Foundation

8 References

Introduction

INTRODUCTION

This project deals with the determination of various soil properties including grain

size analysis, index properties, specific gravity, shear strength and bearing capacity

etc. of the soil and design of foundation for college building.

A foundation is the supporting base of the structure that transmits the load from the

super structure to the natural ground and hence a foundation becomes the basic

necessary element in any structure.

The bearing capacity of the soil is the load carrying capacity, which it can carry

without any excessive settlement or shear failure. Thus for a safe design of a

foundation to know the value of bearing capacity in advance is a prerequisite.

The design of foundation has to be such that the soil should not be over stressed

which may eventually lead to the failure of the super structure due to shear or

settlement.

The investigation of the site is an essential prerequisite to the construction of all

civil engineering works with a view to assess the suitability of the site for the

proposed work as well as adequate and economic design.

The investigation of the site should be carried out in accordance with the principles

set in IS: 1892- 1979. It is usually advisable to collect basic information related to

the site in preliminary survey, before commencing detailed investigations. The

investigation of the sites for the important structure requires exploration and

sampling of all the strata, likely to be affected by the structural loads. The extent of

exploration will depend upon the type of site and type of structure. In any case,

particular attention shall be paid to the groundwater level, underground water

courses, old drains, pits, wells, old foundation, etc. Presence of excessive sulphates

or other deleterious compound in the ground water and soil should also be

monitored. The site should also be explored in detail, wherever necessary, to

ascertain the consistency of soil distribution, thickness and dip of the strata.

As a part of site investigation works both the field tests as well as lab tests were

carried out. The former included the Standard Penetration Test (SPT) and Plate

Load Test and the later comprised of Particle Size Analysis, Atterberg’s Limits,

Triaxial Shear Test, Determination of in-situ Density and Specific Gravity of the

soil particles.

The SPT is done in accordance with IS: 2131-1981. For this purpose bore holes are

made up to 7.5m depth and the samples are collected at intervals of 1.5m and are

retained for lab soil investigation.

The Plate Load Test as carried out in accordance with IS: 1888-1982 to determine

the bearing capacity of soil. Seating load of 1 ton was applied through the

hydraulic loading system over 300mm X 300mm size plate which was placed in a

square pit whose depth was taken approximately equal to that of the proposed

foundation and the width was equal to five times the size of plate.

The Grain Size Distribution, Liquid Limit, Plastic Limit, Shear Strength and

Specific Gravity and in- situ density were found out from the above failure plane

of the soil.

Of the above tests performed, the field tests are more reliable than the laboratory

test as they deal with the actual condition of the site where the soil is in its natural,

undisturbed condition. Laboratory tests on the other hand make use of samples

collected from the site and thus their reliability depends on so called “undisturbed”

samples. It is a common practice that laboratory tests are relied more in case of

cohesive soils, because the field tests are of short duration and often fail to yield

meaningful data such as consolidation, settlement etc. while field tests are favored

where the soil is essentially of non- cohesive character.

The various foundation types considered are Isolated or Continuous footing, Mat

or Raft foundation and Deep foundation. Of these foundations isolated footing was

adopted because of its effectiveness in reducing the differential settlements. The

deep foundations have been discarded the soil at the site has adequate bearing

capacity for the safe design of the rafts.

LOAD CALCULATION

COLUMN NO. 26

Load on Terrace

Load due to parapet wall = (1.613x0.115) x 1.0 x 19.5

= 3.62 KN

Load due to roof terracing = (2.818 x 1.613) x 0.1 x 19.5

= 8.83 KN

Live load on terrace = (2.818 x 1.613) x 1.2

= 5.45 KN

Load due to slab weight = (2.818 x 1.613) x 0.12 x 25

= 13.64 KN

Self weight of beam = 0.23 x 0.3 x (2.818 + 1.613) x 25

= 7.64 KN

Total = 39.18 KN

Load on 7 th Floor

Load due to floor finish = (2.818 x 1.613) x 0.045 x 24

= 4.91 KN


= 13.64 KN

Load due to beam = (2.818 + 1.613) x 0.23 x 0.3 x 25

= 7.64 KN

Load due to brickwork = (2.818 + 1.613) x 0.23 x (3.0-0.3) x 19.5

= 53.66 KN

Live load = (2.819 x 1.613) x 1.2

= 5.45 KN

Total = 85.30 KN

Load on 6 th Floor


= 4.91 KN


= 13.64 KN


= 7.64 KN


= 53.66 KN

Live load = (2.819 x 1.613) x 1.2

= 5.45 KN

Total = 85.30 KN

Load on 5 th Floor


= 4.91 KN


= 13.64 KN


= 7.64 KN


= 53.66 KN

Live load = (2.819 x 1.613) x 1.2

= 5.45 KN

Total = 85.30 KN

Load on 4 th Floor


= 4.91 KN


= 13.64 KN


= 7.64 KN


= 53.66 KN

Live load = (2.819 x 1.613) x 1.4

= 6.36 KN

Total = 86.21 KN

Load on 3 rd Floor


= 4.91 KN


= 13.64 KN


= 7.64 KN


= 53.66 KN

Live load = (2.819 x 1.613) x 1.6

= 7.27 KN

Total = 87.12 KN

Load on 2 nd Floor


= 4.91 KN


= 13.64 KN


= 7.64 KN


= 53.66 KN

Live load = (2.819 x 1.613) x 1.8

= 8.18 KN

Total = 88.03 KN

Load on 1 st Floor


= 4.91 KN


= 13.64 KN


= 7.64 KN


= 53.66 KN

Live load = (2.819 x 1.613) x 2.0

= 9.09 KN

Total = 89.75 KN

Load on Ground Floor

Load due to plinth beam = (2.818 + 1.613) x 0.3 x 0.45 x 25

= 14.95 KN

Load due to total ht of column = (8 x 3 + 2) x 0.3 x 0.6 x 25

= 117 KN

Total load on top of the footing = 39.18 + (85.3 x 3) + 86.21 + 87.12 + 88.03 + 89.75 + 14.95 + 117

= 778.14 KN

Field Tests

Standard Penetration Test

The standard penetration test (SPT) is used to assess essentially the In-situ

properties and density index of a soil deposit. The test involves the measurement

of the resistance to penetration of a sampling spoon under dynamic loadings. The

test is performed in a cased bore hole of 60 to 75 mm diameter. A split tube

sampler of 50 mm outer diameter and about 650 mm length attached to a string of

drill rods is lowered to the bottom of the hole for extraction of undisturbed

samples. To evaluate subsurface soil conditions and to measure In-situ soil

resistance at different depths, soil samples were collected at every 1.5m

interval or at change in strata in the bore hole in order to record ‘N’ values

per 30cm of sinking of a split spoon sampler into the ground after 15 cm of

initial seating drive under the impact of 65 kg hammer having a free fall of 75cm.

Results of standard penetration tests plotted as shown in Figures 2, 3 and 4 show

that the top 1.5m strata is cohesive, exihibiting plasticity and lying in loose state of

compactness. From 1.5m to 15.0m depth the sub-soil layers are silts with fine

sands, silts and sand mixture, silty sand and and poorly graded fine sand lying in

medium to dense state of compactness.

Observations

The soil strata obtained from various depths at three bore hole locations (Fig. A)

followed by laboratory analysis of soil samples. All the three bore holes show

almost similar strata. The bore whole records reveal that the initial soil stretch (0.0

– 1.5m) is a mixture of low compressible silt and clay and clay of low

compressibility (CL–ML and CL) consist of silt (64-68%), sand (13-14%) and clay

(19-22%). The soil strata from 1.5m – 7.5m in all the three bore holes show silty

sand (SM), exhibiting nil plasticity and lying in low to dense state of compactness.

The soil in this stretch consist of silt (14 to 25%) and sand (74 – 86 %). The stretch

from 7.5m to 15m comprises of poorly graded sand lying in low state of

compactness. In all three bore holes water table was encountered at depth of 6.0m

from ground level. On the basis of least number of blows in SPT test, the Bore

Hole #1 is taken as the critical bore hole.

Soil Types

Following types of soils were found in three bore holes during Standard

Penetration Test (SPT).

CL Silty clays

CL-ML Silts and very fine sands with traces of clay

SM Silty sands

SP Poorly graded sands

Standard Penetration Test Method

Corrected Value of N for Critical Bore Hole, BH1 at Depth 1.5 m

D = 1.50m, N = 14

σ = Overburden pressure, D = 18.6 × 1.5 = 27.9 kN/m2

D = depth in m

Overburden Correction:

Nc =Adjusted SPT values

Nc = Cn × N

N = Recorded SPT values

Cn = Correction factor

Cn = 0.77 log10 (2000 / σ)

Cn = 1.42

Adjusted SPT values Nc = 21

Diletency Correction:

If Nc > 15, then

Nc’=15+0.5(Nc-15)

Nc’=15+0.5(21-15)

Nc’=18

Corrected Value of N for Critical Bore Hole, BH1 at Depth 3.0 m

D = 3.0m, N = 6

Overburden Correction:

Nc = Cn × N

Cn = 0.77 log10 (2000 / σ)

Cn = 1.20

Adjusted SPT values Nc = 7

STANDARD PENETRATION TEST VALUES

DEPTH (d)m γ(KN/m2) Nobs NC NC’

1.5m 18.6 14 21 18

3.0m 18.2 6 7 7

4.5m 19.8 7 7 7

6.0m 19.1 6 5 5

7.5m 19.2 12 10 10

9.0m 18.3 9 7 7

10.5m 19.3 15 11 11

12.0m 18.0 6 4 4

13.5m 17.5 10 7 7

15.0m 17.3 12 8 8

16.5m 17.4 13 9 9

18.0m 17.6 10 7 7

19.5m 17.5 12 8 8

21.0m 17.8 16 11 11

22.5m 17.8 7 5 5

LABORATORYTests

Proctor Compaction Test

To determine the Optimum Moisture Content (OMC) and Maximum Dry Density

by Proctor Compaction Test.

Theory

Compaction is defined as the process of packing the soil grains by reducing the air

voids by means of mechanical methods. The mechanical methods for compaction

may include rollers, vibrators, rammers, etc. Short duration respective loading is

the real requirement for compaction, and this really makes it different from

consolidation, which is a process of long duration loading, resulting in removal of

water from the pores of a saturated soil, and causing its consolidation by reduction

in volume. The compaction of a soil by rolling etc. can be best performed, if we

add a certain particular amount of water during compaction. Less than that or more

than that quantity will not help us to achieve maximum compaction, or maximum

dry density in the compacted soil. This most beneficial water content is known as

optimum moisture content (OMC), and the max value of dry density which can be

produced by compaction is known as maximum dry density, denoted as d (max).

The OMC and d (max) can be determined in the laboratory by performing a

standard test, which was designed by Proctor in 1911. The test consists of filling

wet soil in a cylindrical mould of a standard size, and filling and compacting the

wet soil in the mould in 3 layers, each layer being compacted with certain standard

amount of compaction by falling hammer. The achieved dry density in the

compacted soil in the mould is then determined by computing the water content of

the soil (), as:

γd=( Mass of moist soil in the mouldVolume of the mould )[ 1

1+ω ]The achieved dry density at various water contents can, thus, be determined by

repeating the test at different water contents (gradually increasing), and then

plotting a curve between water content and achieved dry density. The obtained

curve shows an initial rise in the dry density with the increase in moisture content

and after the dry density peaks a particular value, it again falls down with any

further increase in moisture content. This max value of dry density is d (max).

The apparatus used to were out dry density some includes IS mould 100 mm

diameter, 127.3 mm height, with a volume of 1000 cm3, as shown in Fig. 2.

Alternately, the mould will be 150 mm in dia, 127.3 mm in height with a volume

of 2250 cm3. The 100 mm dia mould is to be used when soil fraction retained on

4.75 mm sieve is less than 20% ; and 150 mm dia mould is to be used when soil is

coarser, having soil fraction retained on 4.75 mm sieve to be more than 20%. For

light or ordinary compaction, the rammer should have a mass of 2.6 kg, and should

fall from a height of 310 mm. The soil is to be compacted in 3 layers, with each

layer given 25 blows for 10 cm dia mould, and 56 blows for 15 cm dia mould;

blows to be distributed evenly on its surface, as in Proctor's test. However, for

heavier compaction, rammer will have a mass of 4.89 kg and free fall ht. of 450

mm, compacting in five layers.

1. Proctor mould with a detachable collar assembly and base plate.

2. Manual rammer weighing 2.5 kg and

equipped to provide a height of drop to a

free fall of 30cm.

3. Sample extruder.

4. A sensitive balance.

5. Straight edge knife.

6. Squeeze bottle

7. Mixing tools such as mixing pan, spoon, spatula etc.

8. Moisture cans.

9. Drying oven

Procedure

1. Obtain approximately (4.5 kg) of air-dried soil in the mixing pan, break all

the lumps so that it passes No. 4 sieve.

2. Add approximate amount of water to increase the moisture content by

about 5%.

3. Determine the weight of empty proctor mould without the base plate and

the collar. W1, (kg).

4. Fix the collar and base plate.

5. Place the first portion of the soil in the Proctor mould and compact the layer

applying 25 blows.

6. Scratch the layer with a spatula forming a grid to ensure uniformity in

distribution of compaction energy to the subsequent layer. Place the

second layer, apply 25 blows, place the last portion and apply 25 blows.

7. The final layer should ensure that the compacted soil is just above the

rim of the compaction mould when the collar is still attached.

8. Detach the collar carefully without disturbing the compacted soil inside the mould and using a straight edge knife trim the excess soil leveling to the mould.

9. Determine the weight of the mould with the moist soil W2, (kg). Extrude the

sample and break it to collect the sample for water content determination

preferably from the middle of the specimen.

10.Weight an empty moisture can, W3, (g) and weigh again with the moist soil

obtained from the extruded sample in step 9, W4, (g). Keep this can in the

oven for water content determination.

11.Break the rest of the compacted soil with hand. Add more water to increase r

the moisture content by 2%.

12.Repeat steps 4 to 11. During this process the weight W2 increases for some

time with the increase in moisture and drops suddenly. Take two moisture

increments after the weights starts reducing. After 24 hrs recover the sample

from oven and determine the weight W5, (g).

Observations & Graphs

Weight of Mould ‘W’ = 4.164 kg

Diameter of Mould = 10cm.

Height of Mould = 11.5 cm

Volume of Mould ‘V’ = (π4 )×102×11. 5=903. 21 cm3

Proctor Compaction Test for Sample 1(a) Dry Density

Moisture Content (%)

Weight of Mould +

Compacted Soil

(kg) 'Wl'

Weight of Compacted Soil

(kg) 'W2' = 'W' - 'Wl'

Bulk Density (KN/m3)

Dry Density (KN/m3)

d = b /(l + )

12 6.116 1.95 21.6 19.3

14 6.194 2.03 22.5 19.7

16 6.210 2.05 22.7 19.5

18 6.200 2.04 22.6 19.1

(b) Water Content

S. No. Determination 1 2 3 4

1. Percentage of Water (%) 12 14 16 18

2. Wt. of Container (gm) 14.9 18.7 19.3 22.6

3. Wt. of Container + Wet Soil (gm) 44.1 45.7 38.3 41.2

4. Wt. of Container + Dry Soil (gm) 40.9 42.3 35.6 38.4

5. Wt. of Water (gm) 3.2 3.4 2.3 2.8

6. Wt. of Dry Soil (gm) 26.0 23.6 16.3 15.8

7. Water Content ‘’ % = [(5)/(6)] × 100 12.31 14.41 16.56 17.72

Proctor Compaction Test for Sample No. 2

(a) Density


Weight of Mould +

Compacted Soil

(kg) 'Wl'


(kg) 'W2' = 'W' - 'Wl'

Bulk Density, b

(KN/m3)Dry Density

(KN/m3)d = b /(l + )

12 6.122 1.95 21.6 19.3

14 6.220 2.05 22.7 19.9

16 6.218 2.05 22.7 19.6

(b) Water Content

S. No. Determination 1 2 3

1. Percentage of Water (%) 12 14 16

2. Wt. of Container (gm) 22.5 14.4 19.1

3. Wt. of Container + Wet Soil (gm) 45.0 36.4 30.9

4. Wt. of Container + Dry Soil (gm) 42.5 33.7 29.3

5. Wt. of Water (gm) 2.5 2.7 1.6

6. Wt. of Dry Soil (gm) 20.0 19.3 10.2

7. Water Content ‘’ % = [(5)/(6)] × 100 12.5 13.99 15.69

Proctor Compaction Test for Sample N0. 3

(a) Density


Weight of Mould +

Compacted Soil

(kg) 'Wl'


(kg) 'W2' = 'W' - 'Wl'

Bulk Density , b

(KN/m3)

Dry Density (KN/m3)

d = b /(l + )

12 6.030 1.84 20.4 18.2

14 6.222 2.04 22.6 19.8

16 6.188 2.00 22.1 19.1

(b) Water Content

S. No. Determination 1 2 3

1. Percentage of Water (%) 12 14 16

2. Wt. of Container (gm) 32.9 19.7 21.5

3. Wt. of Container + Wet Soil (gm) 43.3 48.5 58.1

4. Wt. of Container + Dry Soil (gm) 42.2 45.0 53.3

5. Wt. of Water (gm) 1.1 3.5 4.8

6. Wt. of Dry Soil (gm) 9.3 25.3 31.8

7. Water Content ‘’ % = [(5)/(6)] × 100 11.83 13.83 15.09

Specific Gravity Test

To determine the specific gravity of fine-grained soil by density bottle method as per IS: 2720 (Part Ill/Sec 1) - 1980. Specific gravity is the ratio of the weight in air of given volume of a material at a standard temperature to the weight in air of an equal volume of distilled water at the same stated temperature.

Theory

Specific gravity 'G' of a soil is expressed as:

' G '= Density of dry soil (solids)Mass per unit of water

' G '= Mass of unit of dry soil ( solids )Mass per unit of water

' G '= Mass of dry soil of a given volume VMass per water of same volume V

The specific gravity (G) of a soil is, thus, defined as the mass (in air) of a given volume of dry soil (solids) to the mass of equal volume of water (distilled water) at 20oC (or sometimes 27°, only in India).

To perform the test, the density bottle is first cleaned and weighed. Oven dried, sample of about 20 gm is poured into the density bottle, and weighed (let its mass be M2). The density bottle containing soil is then filled with water and weighed again (let this mass be M3). The density bottle is then emptied and filled with water and weighed (let this mass be M4). We can then easily write:

Mass of density bottle = M1

Mass of density bottle + mass of dry soil = M2

Mass of density bottle + mass of dry soil + mass of water=M3

Mass of density bottle + mass of water = M4

' G '= M 2−M 1(M 4−M 1)−( M 3−M 1 )

The value of G obtained in the above test will be the G value at the given temperature (T° C) at which the test is performed, and hence may be indicated as G To C

Necessity of Computation of G Value

Specific gravity of soil grains (G) is an important property of a soil and is used for calculating void ration, porosity, degree of saturation; if the density or unit wt. and water content are known. The value of G is also used in computing the soil particle size by means of hydrometer analysis. The value of G for various types of soils may range as shown in the table below:

G values for different Types of Soils

S.No. Type of soil Range of G value

1. Sands 2.65-2.67

2. Silty Sands 2.67-2.70

3. Inorganic Clays 2.70-2.80

4. Soils with mica or iron 2.75-2.90

5. Organic Soils Quite variable, as low as 2.2

Apparatus Used

1. Two density bottles of approximately50ml capacity along with stoppers.

2. Constant temperature water bath (27.0+ 0.2°C)

3. Vacuum desiccators

4. Oven, capable of maintaining a temperature of 105 to 110 °C.

5. Weighing balance, with an accuracy of 0.001g

6. Spatula

Procedure

1. The density bottle along with the stopper, should be dried at a temperature of 105 to 110°C, cooled in the desiccators and weighed to the nearest 0.001g (Wl).

2. The sub-sample, which had been oven-dried, should be transferred to the density bottle directly from the desiccators in which it was cooled. The bottles and contents together with the stopper should be weighed to the nearest 0.001g (W2).

3. Cover the soil with air-free distilled water from the glass wash bottle and leave for a period of 2 to 3hrs for soaking. Add water to fill the bottle to about half.

4. Entrapped air can be removed by heating the density bottle on a water bath or a sand bath.

5. Keep the bottle without the stopper in vacuum desiccators for about 1 to 2 hrs until there is no further loss of air.

6. Gently stir the soil in the density bottle with a clean glass rod, carefully wash off the adhering particles from the rod with some drops of distilled water and see that no more soil particles are lost.

7. Repeat the process till no more air bubbles are observed in the soil-water mixture.

8. Observe the constant temperature in the bottle and record.

9. Insert the stopper in the density bottle, wipe and weigh (W3).

10. Now empty the bottle, clean thoroughly and fill the density bottle with distilled water at the same temperature. Insert the stopper in the bottle, wipe dry from the outside and weigh (W4).

11. Take at least two such observations for the same soil.

Observations(Depth: 1.5m)

Specific Gravity test for Sample 1

S.No. Determination 1

1. Wt. of Dry & Clean Bottle 'Wl' (gm) 29.90

2. Wt. of Bottle + Dry Soil 'W2' (gm) 48.0

3. Wt. of Bottle + Dry Soil + Water 'W3' (gm)

91.10

4. Wt. of Bottle + Water 'W4' (gm) 79.80

5. Specific Gravity of Soil ‘G’

[ w2−w1

(w2−w1 )−( w3−w4) ]2.66






92.4



[ w2−w1

(w2−w1 )−( w3−w4) ]2.68






93.3



[ w2−w1

(w2−w1 )−( w3−w4) ]2.67

SPECIFIC GARVITY AT DIFFERENT DEPTHS

DEPTH (m) AVERAGE SPECIFIC GRAVITY(G)

3.0 2.65

4.5 2.68

6.0 2.61

7.5 2.66

9.0 2.70

10.5 2.67

12.0 2.68

13.5 2.66

15.0 2.63

16.5 2.66

18.0 2.70

19.5 2.69

21.0 2.67

22.5 2.75

AVERAGE SPECIIC GRAVITY= 2.67

SIEVE ANALYSIS

A sieve analysis (or gradation test) is a practice or procedure used (commonly used in civil engineering) to assess the particle size distribution (also called gradation) of a granular material.The size distribution is often of critical importance to the way the material performs in use. A sieve analysis can be performed on any type of non-organic or organic granular materials including sands, crushed rock, clays, feldspars, coal, soil, a wide range of manufactured powders, grain and seeds, down to a minimum size depending on the exact method. Being such a simple technique of particle sizing, it is probably the most common.

Theory

As per provisions of IS 460-1972 (revised), soils having particles of size larger than 75 micron (0.075 mm) are termed as coarse grain soils. Thus, sand, gravel, cobble and boulder do fall within the definition of coarse grained soils. The size range of different types of these soils, is as under:

I. Boulder-more than 300 mm

II. Cobble-80 mm to 300 mm

III. Gravel-4.75 mm to 80 mm

IV. Sand - 0.075 mm-4.75 mm

Soils finer than 0.075 mm (75) are classified as silts and clays; and hence are called fine grained soils. The coarse grained soils will contain varying percentages of different sized coarse particles

http://en.wikipedia.org/wiki/Particle_size_distribution

http://en.wikipedia.org/wiki/Particle_size_distribution

http://en.wikipedia.org/wiki/Civil_engineering

and very small amount of fines (silt and clay sizes). In order to determine the percentage of various coarse sizes (0.075 mm to 300 mm), the given soil is usually sieved through a set of sieves, having different sizes, each placed successively below the larger sized sieve. The IS sieves in coarse size range are available in the following two sets:

1. First set, containing sieves of size 300 mm, 80 mm, 40 mm, 20 mm, 10 and 4.75 mm.

2. Second set, containing sieves of size 2 mm, 0.850 mm (850), 0.600 mm (600 ), 0.425 mm (425), 0.300 mm (300), 0.212 mm (212 ), 0.150 mm (150) and 0.075 mm (75 ).

The given coarse soil is successively sieved through the above mentioned two sets of sieves to determine the percentage finer than the different sieve sizes, and grain size distribution curve is plotted. From the grain size distribution curve, it becomes feasible to read the percentage presence of different types of coarse soils, such as percentages of boulder, gravel, and sand. Percentages of course sand, medium sand and fine sand can also be read out. The value of coefficient of curvature (Cc) and the of uniformity coefficient (Cu) can also be evaluated by using their appropriate equations.

When the given coarse soil contains less than 5% of fines (silt and clay sizes), it is analyzed by dry sieving; but when it contains fine soil exceeding 5%; it is analyzed by wet sieving. Wetting is

adopted to break the cohesive bond between fine soil particles and the coarse soil particles.

Apparatus Used

1. Stack of Sieves including pan and cover

2. Balance (with accuracy to 0.01 g)

3. Rubber pestle and Mortar (for crushing the soil if lumped or conglomerated)

4. Mechanical sieve shaker

5. Oven

6. Brush

Procedure

1. Take a representative oven dried sample of soil that weighs about 500 g. (this is normally used for soil samples the greatest particle size of which is 4.75 mm).

2. If soil particles are lumped or conglomerated crush the lumps and not the particles using the pestle and mortar.

3. Determine the mass of sample accurately. Wt (g).

4. Prepare a stack of sieves. Sieves having larger opening sizes (i.e. lower I numbers) are placed above the ones having smaller opening sizes (i.e. higher I numbers). The very last sieve is #200 and a pan is placed under it to collect the portion of soil passing #200 sieve.

5. Make sure sieves are clean; if many soil particles are stuck in the openings try to poke them out using brush.

6. Weigh all sieves and the pan separately.

7. Pour the soil from step 3 into the stack of sieves from the top and place the cover, put the stack in the sieve shaker and fix the clamps, adjust the time on 10 to 15 minutes and get the shaker going.

8. Stop the sieve shaker and measure the mass of retained soil.

Observation and Graph (Sieve Analysis Test)

(a) Sieve Analysis Test Given soil sample 1”-Mass of the soil sample taken = 500 gm Sieve Analysis Test for sample 1 (1.5m)

S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained

Cumulative % Weight Retained

% Finer

1. 600 5 1 1 99

2. 425 0 0 1 99

3. 300 16.1 3.2 4.2 95.8

4. 212 27.1 5.4 9.6 90.4

5. 150 36.5 7.3 16.9 83.1

6. 75 75.5 15.1 32.0 68.0

7. Pan 339.8 68 100 0

=500

Sieve Analysis Test for sample 2 (3.0m)

S. No.

I.S. Sieve Size ()

Weight Retained

(gm)

% weight Retained


% Finer

1. 600 10 2 2 98

2. 425 0 0 2 98

3. 300 2 0.4 2.4 97.6

4. 212 5.5 1.1 3.5 96.5

5. 150 30.5 6.1 9.6 90.4

6. 75 62.1 12.4 22.0 78.0

7. Pan 389.9 78.0 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 0 0 0 100

3. 300 0 0 0 100

4. 212 1.1 0.2 0.2 99.8

5. 150 3.4 0.7 0.9 99.1

6. 75 10.5 2.1 3.0 97.0

7. Pan 485 97.0 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 0 0 0 100

3. 300 10.5 2.1 2.1 97.9

4. 212 21.5 4.3 6.4 93.6

5. 150 15.5 3.1 9.5 90.5

6. 75 83.0 16.6 26.1 73.9

7. Pan 369.5 73.9 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 3.0 0.6 0.6 99.4

3. 300 10.5 2.1 2.7 97.3

4. 212 16.4 3.3 6.0 94.0

5. 150 26.1 5.2 11.2 88.8

6. 75 78.5 15.7 26.9 73.1

7. Pan 365.5 73.1 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 1.5 0.3 0.3 99.7

3. 300 10.5 2.1 2.4 97.6

4. 212 12.0 2.4 4.8 95.2

5. 150 26.5 5.3 10.1 89.9

6. 75 54.5 10.9 21.0 79.0

7. Pan 395 79.0 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 1.0 0.2 0.2 99.8

3. 300 4.4 0.9 1.1 98.9

4. 212 11.6 2.3 3.4 96.6

5. 150 14.0 2.8 6.2 93.8

6. 75 49.0 9.8 16.0 84.0

7. Pan 420 84.0 100 0

=500


S. No.

I.S. Sieve

Weight Retained

% weight

Cumulative % Weight

% Finer

Size () (gm) Retained Retained1. 600 0 0 0 100

2. 425 0 0 0 100

3. 300 14.5 2.9 2.9 97.1

4. 212 26.5 5.3 8.2 91.8

5. 150 53.5 10.7 10.9 89.1

6. 75 105.5 21.1 40.0 60.0

7. Pan 300 60.0 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 3.5 0.7 0.7 99.3

3. 300 43.5 8.7 9.4 90.6

4. 212 51.0 10.2 19.6 80.4

5. 150 151.5 30.3 49.9 50.1

6. 75 130.5 26.1 76.0 24.0

7. Pan 120 24.0 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 4.0 0.8 0.8 99.2

3. 300 25.5 5.1 5.9 94.1

4. 212 50.5 10.1 16.0 84.0

5. 150 141.5 28.3 44.3 55.7

6. 75 178.5 35.7 80.0 20.0

7. Pan 100 20.0 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 13.5 2.7 2.7 97.3

3. 300 15.5 3.1 5.8 94.2

4. 212 31.0 6.2 12.0 88.0

5. 150 141.5 28.3 40.3 59.7

6. 75 208.5 41.7 82.0 18.0

7. Pan 90.0 18.0 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 11.0 2.2 2.2 97.8

3. 300 25.5 5.1 7.3 92.7

4. 212 45.5 9.1 16.4 83.6

5. 150 143.5 28.7 45.1 54.9

6. 75 179.5 35.9 81.0 19.0

7. Pan 95 19.0 100 0

=500


S. No.

I.S. Sieve

Weight Retained

% weight

Cumulative % Weight

% Finer

Size () (gm) Retained Retained1. 600 0 0 0 100

2. 425 0 0 0 100

3. 300 8.5 1.7 1.7 98.3

4. 212 56.5 11.3 13.0 87.0

5. 150 145.5 29.1 42.1 57.9

6. 75 199.5 39.9 82.0 18.0

7. Pan 90.0 18.0 100 0

=500


S. No.

I.S. Sieve

Size ()

Weight Retained

(gm)

% weight

Retained


% Finer

1. 600 0 0 0 100

2. 425 21.0 4.2 4.2 95.8

3. 300 41.5 8.3 12.5 87.5

4. 212 80.5 16.1 28.6 71.4

5. 150 127.5 25.5 54.1 45.9

6. 75 149.5 29.9 84.0 16.0

7. Pan 80.0 16.0 100 0

=500

0.001 0.01 0.1 1 100

10

20

30

40

50

60

70

80

90

100

Fig. 1 Grain Size Distribution of Soil at Depth 1.5m from G.L

Grain Size Diameter (mm)

Perc

ent F

iner

by

Wei

ght

0.001 0.01 0.1 1 100

10

20

30

40

50

60

70

80

90

100

Fig. 2 Grain Size Distribution of Soil at Depth 3.0m from G.LGrain Size Diameter (mm)

Perc

ent F

iner

by

Wei

ght

0.001 0.01 0.1 1 100

10

20

30

40

50

60

70

80

90

100

Fig. 4 Grain Size Distribution of Soil at Depth 6.0m from G.L

Grain Size Diameter (mm)

Perc

ent F

iner

by

Wei

ght

0.001 0.01 0.1 1 100

10

20

30

40

50

60

70

80

90

100

Fig. 5 Grain Size Distribution of Soil at Depth 7.5m from G.LGrain Size Diameter (mm)

Perc

ent F

iner

by

Wei

ght

Liquid Limit Test

This test is done to determine the liquid limit of soil as per IS: 2720 (Part 5) - 1985. The liquid limit of fine-grained soil is the water content at which soil behaves practically like a liquid, but has small shear strength. Its flow closes the groove in just 25 blows in Casagrande’s liquid limit device.

Theory

When enough and sufficient water is added to a fine soil, it achieves a liquid state; i.e. the soil behaves like a liquid without having any shear strength. However, when we reduce the water content of the soil gradually, the soil changes from the liquid state of the plastic state. In the plastic state, the soil gains a lot of shear strength. A plastic soil (i.e. a soil in plastic state) is a sticky soil and can be moulded into different shapes and hence used for making clay toys, etc.

The water content at which the soil just changes from the liquid state to the plastic state, is known as the liquid limit of the soil, and is usually represented by L and L.L In physical terms, it can be defined as that water content, at which a soil passes from zero shear strength to a very small (infinitesimal) shear strength. For laboratory determination of liquid limit of a soil is that water content at which the soil has such a small shear strength that it flows to close a groove of standard dimensions when jarred under an impact of 25 blows in a standard liquid limit apparatus.

Application

The value of liquid limit of a soil coupled with the value of plastic limit is directly for classifying the fine grained soils.

Apparatus Used

1. Casagrande's liquid limit device.

2. Grooving tools of both standard and ASTM types

3. Oven

4. Evaporating dish

5. Spatula

6. IS Sieve of size 425

7. Weighing balance, with 0.01g accuracy

8. Wash bottle

9. Air-tight and non-corrodible container for determination of moisture content

Procedure

1. Air-dry the soil sample and break the clods. Remove the organic matter like tree roots, pieces of bark, etc.

2. About 100g of the specimen passing through 425m IS Sieve is mixed thoroughly with distilled water in the evaporating dish and left for 24hrs. for soaking.

3. Place a portion of the paste in the cup of the liquid limit device.

4. Level the mix so as to have a maximum depth of 1cm.

5. Draw the grooving tool through the sample along the symmetrical axis of the cup, holding the tool perpendicular to the cup.

6. For normal fine grained soil: The Casagrande's tool is used to cut a groove 2mm wide at the bottom, 11mm wide at the top and 8mm deep.

7. For sandy soil: The ASTM tool is used to cut a groove 2mm wide at the bottom, 13.6mm wide at the top and 10mm deep.

8. After the soil pat has been cut by a proper grooving tool, the handle is rotated at the rate of about 2 revolutions per

second and the no. of blows counted, till the two parts of the soil sample come into contact for about 10mm length.

9. Take about 10g of soil near the closed groove and determine its water content.

10. The soil of the cup is transferred to the dish containing the soil paste and mixed thoroughly after adding a little more water. Repeat the test.

11. By altering the water content of the soil and repeating the foregoing operations, obtain at least 5 readings in the range of 15 to 35 blows. Don't mix dry soil to change its consistency.

12. Liquid limit is determined by plotting a 'flow curve' on a semi-log graph, with no. of blows as abscissa (log scale) and the water content as ordinate and drawing the best straight line through the plotted points.

Plastic Limit Test

This test is done to determine the plastic limit of soil as per IS: 2720 (Part 5) 1985 the plastic limit of fine-grained soil is the water content of the soil below which it ceases to be plastic. It begins to crumble when rolled into threads of 3mm dia.

Theory

When we reduce the moisture content of the soil gradually, the soil changes from the liquid state to the plastic state. In plastic state,

the soil gains a lot of shear strength, and become sticky and liable to be molded into different shapes. When the moisture content is further reduced, the soil goes into a semi-solid state before going into a solid state. In semi solid state, the soil loses its molding capacity and begins to crumble when we try to mould it into an arbitrary shape. The boundary limit moisture content between the plastic state and semi solid state is called the plastic limit. The plastic limit may hence be defined as the water content (p) at which the soil sample first loses its full plasticity, and begins to crumble when molded. For the purpose of laboratory determination, the plastic limit is defined as the water content at which a soil will just begin to crumble when rolled into a thread of 3 mm in diameter.

The range of water content between liquid limit (L) and Plastic limit (p) represents the range in which a soil behaves like a plastic material. This range is hence called the plasticity index (Ip). Soils with a high IP are called plastic soils, because they behave like plastic material for a large range of water contents.

Application

The value of liquid limit of a soil coupled with the value of plastic limit is directly used for classifying the fine grained soils.

Apparatus Used

1. Porcelain evaporating dishes about 120mm dia.

2. Spatula

3. Container to determine moisture content

4. Balance, with an accuracy of 0.01g

5. Oven

6. Ground glass plate -20cm x 15cm.

7. Rod-3mm dia. and about 10cm long.

Procedure

1. Take out 30g of air-dried soil from a thoroughly mixed sample of the soil passing through 425m IS Sieve. Mix the soil with distilled water in an evaporating dish and leave the soil mass for nurturing. This period may be up to 24 hrs.

2. Take about 8g of the soil and roll it with fingers on a glass plate. The rate of rolling should be between 80 to 90 strokes per minute to form a 3mm dia.

3. If the dia. of the threads can be reduced to less than 3mm, without any cracks appearing, it means that

the water content is more than its plastic limit. Knead the soil to reduce the water content and roll it into a thread again.

4. Repeat the process of alternate rolling and kneading until the thread crumbles.

5. Collect and keep the pieces of crumbled soil thread in the container used to determine the moisture content.

6. Repeat the process at least twice more with fresh samples of plastic soil each time.

Observation & Graphs (Liquid Limit & Plastic Limit Test)

Liquid Limit Test for Sample 1 (1.5m)

S.No. Determination No. 1 2 3

1. No. of blows 28 16 25

2. Wt. of saturated soil (gm) 14 9.9 6.7

3. Wt. of dry soil (gm) 11.4 7.33 4.64. Wt. of water (gm) 2.6 2.57 1.15. Water content in % 22.81 25.98 23.91



1. No. of blows 13 28 35





1. No. of blows 27 19 15

2. Wt. of saturated soil (gm) 11.30 9.80 6.55




1. No. of blows 28 16 24


3. Wt. of dry soil (gm) 11.4 6.9 4.64. Wt. of water (gm) 2.6 2 1.15. Water content in % 22.81 28.98 23.91



1. No. of blows 35 27 20

2. Wt. of saturated soil (gm) 32.3 22.5 20.7

3. Wt. of dry soil (gm) 24.55 16.43 14.94. Wt. of water (gm) 7.75 6.07 5.85. Water content in % 24 27 28

Plastic Limit Test for Sample 1 (1.5m)

S.No. Determination No. Test 1 Test 2 Test 31. Container No. 1 2 32. Wt. of Container 20.3 33.9 36.8

3. Wt. of Cont. + Wet Soil (gm) 21.65 35.42 38.36

4. Wt. of Cont. + Dry Soil (gm) 21.43 35.17 38.1

5. Wt. of Water (Ww) (gm) 0.22 0.25 0.266. Wt. of solids (gm) 1.13 1.27 1.307. Water content in % 19.35 19.69 19.92















5. Wt. of Water (Ww) (gm) 0.2 0.2 0.1

6. Wt. of solids (gm) 1.00 1.05 0.557. Water content in % 20.00 19.04 18.18

Plasticity Indices at Different Depths

Depth Below

Ground Level

Liquid LimitWL

Plastic LimitWp

Plasticity Index

Ip

m % % %

1.5 27 23 4

3.0 25 22 3

4.5 26 22 4

6.0 2 19 6

7.5 26 19 7

9.0 -----NON-PLASTIC-----

10.5 31 21 10

12.0 -------NON – PLASTIC------

13.5 -------NON – PLASTIC------

15.0 -------NON – PLASTIC------16.5 -------NON PLASTIC------

18 -------NON – PLASTIC------

19.5 -------NON – PLASTIC------

21.0 ------NON- PLASTIC------

22.5 -------NON – PLASTIC------

WL = 24 %

WL = 22 %

WL = 36 %

WL = 25 %

MEASUREMENT OF SHEARING RESISTANCE BY TRIAXIAL TESTS

The triaxial compression test is the most widely used technique to determine the shear strength of the soils. The apparatus is shown diagrammatically in figure. The sample, which is cylindrical, is tested inside a Perspex cylinder filled with water under pressure. The sample under test is enclosed in a thin rubber membrane to seal it from the surrounding water. The pressure in the cell is raised to the desired value, and the sample is then brought to failure by applying an additional vertical stress.

One of the major advantages of the triaxial apparatus is the control provided over drainage from the sample. When no drainage is required (i.e. in undrained tests), solid end caps are used. When drainage is required, the end caps are used. When drainage is required, the end caps are provided with porous plates and drainage channels. It is also possible to monitor pore water pressures during the test. Full details of the basic apparatus and refinements, and procedures for a wide range of tests in the triaxial apparatus, are given by Bishop and Henkel.

For cohesive soils, the size of sample normally used in the triaxial apparatus is 38mm diameter and 76 mm long. When gravel is present, for example in boulder clay, larger samples may be used, the most common being 100 mm diameter and 200 mm long. For coarse gravelly soils, rock fill and artificially prepared granular material such as railway ballast, even larger samples are required if realistic values of the shearing strength are to be

obtained. This is also true for fissured cohesive soils, where the sample tested must be of sufficient size to contain a truly representative collection of all the structural features which may affect the shear strength.

To obtain the shear strength parameters of the soil, a number of specimens (normally at least three) are tested at different values of cell pressure. For each test, the vertical stress σ3 at failure are determined and are used to plot a Mohr Circle. The envelop to these circles then defines the shear strength parameters.

It is important that the values of the shear strength parameters c’ and Φ’ are obtained from the Mohr’s circles obtained by tests on similar material. In markedly heterogeneous materials, it may be difficult to obtain sufficient samples for testing, and the technique of ‘multi stage ‘testing may be employed. This form of test is normally perforated on 100 mm diameter samples. The sample is initially tested at a particular cell pressure and the vertical stress is increased, and the shearing resume until failure is again approached under the new cell pressure. The process is repeated a number of times. There has been some criticism of this type of test, but it does appear to give reasonably acceptable results if the test id performed with care.

TRIAXIAL SHEAR TEST

The shear strength of the soil i.e. shear strength parameters namely the cohesion and the angle of shearing resistance are determined in the laboratory by triaxial test.

In this test the soil sample which is generally circular in cross section is subjected to compressive stress in three direction and shear stress are induced due to applied compressive stresses.

METHOD

This test is performed on a soil specimen which is cylindrical in shape which is subjected to a particular lateral pressure (also called as chamber pressure). This pressure is applied in all the directions of the sample. This chamber pressure is denoted by σ3. The sample is filled in the test apparatus as per directions given by Casagrande and Karl Terzaghi in 1936-37. In addition to the chamber pressure, additional axial pressure is applied till the sample fails. This additional axial pressure is called as Deviator Stress. The additional axial pressure is applied by loading the sample. The sample is loaded at a constant rate through a proving ring with the help of mechanically operated load frame until the sample fails or required range of stress is achieved. The deviator stress is recorded on the proving ring dial. Another dial measures the vertical deformation of the sample during testing.

A particular confining pressure σ3 is applied during one observation giving the value of other stress w, at failure. A Mohr’s circle corresponding to this set (σ1, σ3) can be drawn. Various Mohr’s circle thus can be plotted by varying the confining the pressure and corresponding stress σ at failure. A line tangential to these circles gives failure envelope for the soil from which c and Φ can be obtained.

For the test on dry sand, calculating the corrected area using the equation

Ac = Ao1−ϵ

Where,

Ac= corrected area

Ao= initial area

=π/4 x (4)2

= 12.56 cm2

Strain ϵ= ∆ LLo

Where, Lo= original length

Depth σ3 σd σ1 c φ

1.5m50 67.46 117

17 12100 93.11 193150 118.75 268

3.0m100 135.5 235.5

14 19200 231.2 431.2300 327.2 627.2

4.5m100 132.05 232.05

38 10200 173.66 373.66300 215.27 515.27

6.0m100 150.25 250.25

16 20200 254.74 454.74300 359.23 659.23

7.5m100 143.6 243.6

17 19200 239.6 439.6300 335.6 635.6

9.0m100 141.6 241.6

13 20200 246.1 446.1300 350.6 650.6

10.5m100 160.0 260.0

35 15200 229.0 429.0300 298.0 598.0

12.0m100 126.0 226.0

14 18200 213.6 413.6300 301.4 601.4

13.5m100 66.0 166.0

0 28200 132.0 332.0300 198.0 498.0

15.0m100 69.0 169.0

0 29200 138.0 338.0300 207.0 507.0

16.5m100 212.2 312.2

0 31200 424.0 624.0300 636.6 936.6

18.0m100 199.3 299.3

0 30200 398.6 598.6300 597.9 897.9

19.5m100 212.3 312.3

0 31200 423.7 623.7300 634.9 934.9

21.0m100 224.0 324.0

0 32200 448.0 648.0300 672.0 972.0

22.5m100 224.4 324.4

0 32200 449.3 649.3300 673.8 973.8

CALCULATION FOR BEARING CAPACITY

Take a square footing of size 2.5m x 2.5m

Breadth=2.5m , Length =2.5m

Df=3.5m, γ=18.5kN/m3 , c= 15.0KN/m2, ø =20°

(CL-ML)

Since,ø<26° ,i.e local shear failure occurs.

C’=2/3c=2/3*15=10KN/m2

C’= 10KN/m2

tan ø’=2/3 tan ø =2/3 tan 20°

ø’=13.6°

Now,use c’& ø’ instead of c & ø

Nq=[tan2(45°+ ø’/2)].(e tan ø’)

=3.42

Nc=(Nq-1)cot ø’=[3.42-1].cot(13.6)=9.99

Ny=2[Nq+1]. tan ø’=2[3.42+1].tan 13.6=2.14

The assumed footing is square

Therefore Sc =1.3, Sq=1.2, Sr =0.8

Now depth corrective section .

Dc=1+0.2 Df/B tan(45°+ ø’/2)

= 1+0.2x3.5/2.5 tan(45+13.6/2)

=1.356

Therefore ø’>10°

dq=d γ = 1+0.1. Df/B tan(45°+ ø’/2)

= 1+0.1 3.5/2.5 tan(45+13.6/2)

= dq=d γ =1.178

Since,the load is vertical & there is no water table

ic = iq = iγ = 1

Therefore Net ultimate bearing capacity.

qnf = [C. Nc. Sc. dc. Ie + γ Df(Nq-1).Sq.dq.iq+1/2 γB.N γ.S γ.d γ.i γ.Rw]

=10x9.99x1.3x1.356x1+18.5x3.5x(3.42-

1)x1.2x1.178x1+1/2x18.5x2.5x2.14x0.8x1.178x1x1

= 345 KN/M2

Net safe bearing capacity

qns = qnf / FOS

= 345 / 3

= 115 KN/M2

DESIGN OF FOUNDATION

DESIGN OF FOUNDATION

DESIGN OF RAFT

Total vertical load due to all column on raft P = 6844 kN

Self weight of raft =611 kN

Gross load W = 6720 kN

Bearing capacity=153 kN/m2

Area of strip = 6720/110

13 x b = 61.09 m2

b = 4.7 m

Net upward pressure = 6109/(13 x 4.7) =100 kN/m2

Pressure per m length of the strip,q= 100 x 4.7

= 470 kN/ m2

CALCULATION OF SHEAR FORCE

AT C- 27

S.F. just before C/L of C-27 = (-470 x 0.5) = -235 kN

S.F. just after C/L of C-27 = (-235 + 1060) = 825 kN

AT C- 30

S.F. just before C/L of C-30 = (-470 x 3.5 + 1060) = -585 kN


AT C- 30’

S.F. just before C/L of C-30’ = (-470 x 9.5 + 1060 + 1937) = -1468 kN

S.F. just after C/L of C-30’ = (-1468 + 1937) = 469 kN

AT C- 33

S.F just before C/L of C-33 = (-470 x 13 + 1060 + 1937 x 2) = -941 kN


POSITION OF POINT OF ZERO S.F (using similar triangles)

B/W C-27 & C-30 X1/ (3-X1) = 825 / 585

X1= 1.76 m

B/W C-30 & C-30’ X2/ (6-X2) = 1352 / 1468

X2 = 2.88 m

B/W C-30’ & C-33 X3/ (3-X3) = 469 / 941

X3 = 0.99 m

CALCULATION OF BENDING MOMENTS

B.M. under C-27 = 470 X (0.5)2 / 2 = 59 kN-m

B.M. at 1.76 m from C-27 = 470 X (0.5 + 1.76)2 / 2 – 1060 x 1.76 = - 665 kN-m

B.M. under C-30 = 470 X (3.5)2 / 2 – 1060 x 3 = -301.25 kN-m

B.M. at 2.88 m from C-30 = 470 X (3.5 + 2.88)2 / 2 – 1060 x 5.88 – 1937 x 2.88 = - 2245 kN-m

B.M . under C-30’ = 470 X (9.5)2 / 2 – 1060 x 9 – 1937 x 6 = 46.75 kN-m

B.M . at 0.99 m from C-30’ = 470 X (9.5 + 0.99)2 / 2 – 1060 x 9.99 – 1937 x 6.99 – 1937 x 0.99 = - 187.23 kN-m

B.M. under C-33 = 470 X (0.5)2 / 2 = 59 kN-m

CALCULATION FOR DEPTH OF RAFT

MAXIMUM B.M = 2245 kN-m

Taking , fck = 25 N/mm2

Width of raft b = 4.7 m

B.M = 0.138 fck b d2

2245x106 = 0.138 x 25 x 4700 x d2

d = 375 mm

Adopting overall depth D = 600 mm and effective cover = 100 mm

Effective depth d = 500 mm

CALCULATION FOR STEEL

B.M = 0.87fy Ast [ d- (Ast fy) / (fck b)

2245 x 106 = 0.87 x 415 Ast [ 500 – Ast 415 / 25 x 4700 ]

Ast = 15430 mm2

Check for max.m steel = 0.04 x 4700 x 600 = 112800 mm2 > 15430 mm2

Check for mim.m steel = 0.85 x 4700 x 500 / 415 = 4813 mm2 < 15430 mm2

Ast in per m width = 15430 / 4.7 = 3283 mm2

Using, 25 mm dia. Bar. Area of each bar = 3.14 x 252 / 4 = 491 mm2

c/c spacing = (1000 x 491) / 3283 = 150 mm

providing 25 mm dia. Bar @ 140 mm c/c spacing in each direction at top & bottom.

CALCULATION OF BENDING MOMENT AT SUPPORT

(B.M)A =0 kN-m

(B.M)B = R Ax7.885-qx7.8852/2 kN-m

=2454.52x7.885-559.2 x7.8852/2

=1970.26 kN-m

(B.M)C = R Ax18.936+R Bx11.051-qx18.9362/2 kN-m

=2454.52x18.936+5159.79x11.051-559.2 x7.8852/2

=3242.87kN-m

(B.M)D = R Ax30.944+R Bx23.059 +R Cx12.008-qx30.9442/2 kN-m

=2454.52x30.944+5159.79x23.059 +6261.64x12.008-559.2x18.9362/2 kN-m

= 2654.37kN-m

(B.M)E = R Ax37.915+R Bx30.03 +R Cx18.979+R Dx6.971-qx37.9152/2 kN-m

= 2454.52x37.915+5159.79x30.03 +6261.74x18.979+5142.62x6.971-qx37.9152/2 kN-m

=762.28 kN-m

(B.M)F =0 kN-m

CALCULATION OF MAXIMUM BENDING MOMENT AT SPAN

For Span AB

(B.M.)X=2454.52xX-559.2xX2/2

For maximum moment d(B.M)/dx =0

On solving,

X=4.39 m

On putting this value in equation,

(B.M.) max =13965.41 kN-m

For Span BC

(B.M.)X=2454.52x(7.885+X)+5159.79xX-559.2x(7.885+X)2/2


On solving,

X=5.73 m


(B.M.) max =11154.53 KN-m

For Span CD

(B.M.)X=2454.52x(18.936+X)+5159.79x(11.051+X)+6261.4xX-559.2x(18.936+X)2/2


On solving,

X=5.88 m


(B.M.) max =12903.07 kN-m

For Span DE

(B.M.)X=2454.52x(30.944+X)+5159.79x(23.06+X)+6261.4x(12.008+X)+5142.62xX-559.2x(18.936+X)2/2

For maximum moment d(B.M)/dx = 0

On solving,

X = 3.07 m


(B.M.) max = 5030.07 kN-m

For Span EF

(B.M.)X = 2454.52 x (37.915+X) + 5159.79 x (30.03+X) + 6261.4 x (18.978+X) +

5142.62 x (6.971+X) + 3999.28 x X-559.2 x (37.915+X)2/2

For maximum moment d(B.M)/dx = 0

On solving,

X = 3.25 m

On putting this value in equation, (B.M.) max = 3711.42 kN-m

CALCULATION FOR AREA OF STEEL

The depth of the raft shall be governed by two way shear at one of the exterior column. In case location of critical shear is not obvious, it may be necessary to check all possible location.

Shear strength of concrete , τc’ = 0.25(√fck)

= 0.25 √20 = 1.118For a corner columnPerimeter, bo = 2(d/2 + 900)

= d + 1800τv = Vu/b0d1.118 = 1.5 x 1755.29 x 1000/ (d + 1800)dd = 879 mmFor side column other than cornerPerimeter, bo = 2(d/2 + 900) + (d + 600)

= d + 1800 + d + 600

= 2d + 2400τv = Vu/b0d1.118 = 1.5 x 3631.97 x 1000/ (2d + 2400)dd = 1072 mmMaximum Bending Moment,M = 13965.41 kN-m

Area of steel, Ast = 0.5 fckfy (1-(√1− 4.6 M

σck . b . d2 )= 34885.98 mm2

Area of steel per meter length = 4360.75 mm2

Provide 25 mm ∅ bars @ 110 mm c/c (Astprovided = 4460 mm2) at top and bottom in both directions.

SUMMARYa) Residential building.

Site : Residential flat (G+7) Storied building,Ramghat Road,Aligarh

Type of Foundation : Raft Foundation

Width of Foundation : 14.50 x 39.0 m

Depth of foundation below G.L. : 3.5 m

Safe Allowable Bearing Capacity qa : 11.5 t/m2

As the soil below 1.5m depth from G.L was found sandy and water table

encountererd at

shallow depth of 7.5m, therefore it is better to provide annular raft cum pile

foundation.

However, the designer may adopt any other type of foundation and values for

depths and widths of foundation according to his discretion and judgment, keeping

in view the characteristics of the strata at site.

REFERENCES

1. I.S. Code 2720 (Part IV) 1985 : Particle Size Distribution

2. I.S. Code 2720 (Part V) 1985 : Determination of Liquid and

Plastic Limits

3. I.S. Code 2720 (Part XII) 1982 : Determination of Shear Strength

Parameters in Triaxial Compress-

-ion Test

4. I.S. Code 2720 (Part XV) 1986 : Determination of Consolidation

Properties

5. I.S. Code 1904 1978 : Coed of Practice for Structural

Safety of Buildings: Foundations

6. I.S. Code 6403 1981 : Code of Practice for Determination

of Bearing Capacity of Shallow

Foundations

7. I.S. Code 1892 1983 : Code of Practice for Sub-Surface .

Investigations for Foundations

8. I.S. Code 1498 1970 : Identification and Classification of

Soils for General Engineering

Purposes

9. I.S. Code 2131 1981 : Method of Standard Penetration Tests

for Soils

10. I.S. Code 2911 (Part-IV) 1984 : Code of Practice for Design and

Construction of Pile Foundation

11. Alam Singh 2nd edition 1990 : Modern Geotechnical Engineering

12. Gopal Ranjan, 2nd edition 1999 : Basic and Applied Soil Mechanics

13. B.C. Punmia, 13th Edition 2000 : Soil Mechanics and Foundations

Engineering

TABLE 1: SOIL PROPERTIES OCCURING AT THE SITE OF PROPOSED

FOUNDATION OF RESIDENTIAL BUILDING, NEAR RAMGHAT ROAD , ALIGARH

BORE HOLE # 1

Depth

Below

Ground Level

Grain Size

Distribution

Unit

Weight

( γ )

Plasticity Indices

I.S. Soil

Classification

Shear parameters

Silt Clay Sand kankar Liquid Limit

WL

Plastic Limit

Wp

Plasticity Index

Ip

Cohesion

(c)

Angle of Shearing

Resistance

(ø)

m % % % % kN/m3 % % % kN/m2 Degrees

1.5 66 20 14 - 19.0 32 20 12 CL 35 15.0

3.0 26 - 74 - 20.138 23 15

CI 43 10.0

4.5 31 - 69 - 18.525 19 06

CL-ML 15 20.0

6.0 22 - 78 - 18.2 -------NON – PLASTIC------

ML 14 18.0

-------NON –

7.5 12 - 88 - 18.6 PLASTIC------ ML 15 19.0

9.0 11 - 89 - 19.131 21 10

CL 36 16.0

10.5 10 - 90 - 18.2 -------NON – PLASTIC------

ML 14 17

12.0 08 - 92 - 17.2 -------NON – PLASTIC------

SM-SP 0 27.0

13.5 07 - 93 - 17.5 -------NON – PLASTIC------

SM-SP 0 28.0

15.0 08 - 92 - 17.8 -------NON – PLASTIC------

SM 0 30.0

16.507 - 93 -

17.4

-------NON – PLASTIC------ SM 0 31.0

18 09 - 93 - 17.6

-------NON – PLASTIC------ SM 0 30.0

20 08 - 92 - 17.5

-------NON – PLASTIC------ SM 0 32.0

Complete Project ISRAR

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