project report on Effect Of LEACHATE on the engineering properties of the soil

7/30/2019 project report on Effect Of LEACHATE on the engineering properties of the soil

1/91

1

A

PROJECT REPORT

ON

EFFECT OF LEACHATE ON ENGINEERINGPROPERTIES OF THE SOIL

By

Akhil Shukla (0934800004)

Aman Juneja (0934800006)

Arvind Dixit (0934813009)

Prasoon Kumar Maurya (0934800029)

Shashank Singh (0934800048)

Shobhit Omar (0934800049)

Vishal Singh (0934800057)

Submitted to the department of civil engineering

In partial fulfillment of the requirements

For the degree of

Bachelor of Technology

In

Civil Engineering

PSITC.O.E., Kanpur

GAUTAM BUDDH TECHNICAL UNIVERSITY, LUCKNOW

APRIL , 2013


2/91

2

DECLARATION

I hereby declare that this submission is my own work and that, to the best of my

knowledge and belief, it contains no material previously published or written by

another person nor material which to a substantial extent has been accepted forthe award of any other degree or diploma of the university or other institute of

higher learning, except where due acknowledgment has been made in the text.

Akhil Shukla Aman Juneja Arvind Dixit

(0934800004) (0934800006) (0934813009)

Prasoon Kumar Maurya Shashank singh Shobhit Omar

(0934800029) (0934800048) (0934800049)

Vishal Singh

(0934800057)


3/91

3

DEPARTMENT OF CIVIL ENGINEERING

PSIT COLLEGE OF ENGINEERING

KANPUR, U.P-209305

CERTIFICATE

Certified that the project report entitled EFFECT OF LEACHATE ONTHE ENGINEERING PROPERTIES OF THE SOIL submitted by

Akhil Shukla (Roll No. 0934800004), Aman Juneja (Roll No. 0934800006 ),Arvind Dixit (Roll No. 0934813009), Prasoon Kumar Maurya (Roll No.

0934800029 ), Shashank Singh (Roll No. 0934800048), Shobhit Omar (Roll

No. 0934800049), Vishal Singh(Roll No. 0934800057) as a part of their Final

Year project for the award of the degree of Bachelor of Technology in Civil

Engineering from PSIT College Of Engineering, Kanpur, is a record of

students own work carried out by them under my guidance and supervision.

The matter embodied in this report has not been submitted for the award of any

other degree.

Place: Kanpur (ASHISH YADAV)

Date: Asst. Professor

Civil Engineering Department

PSIT COE


4/91

4

Acknowledgement

It gives us immense pleasure to present the project report on Effect OfLeachate On The Engineering Properties Of The Soil.

We feel obliged to express our sincere gratitude and thanks to our honorable

guide Ashish Yadav, Asst. Professor ,Department of Civil Engineering, PSIT

College Of Engineering, Kanpur, for his affably, erudite and worthy guidance,

supervision, consistent encouragement, cooperation, keen interest shown

through our work, without which it would have been impossible to complete

this work in a fruitful manner.

Having been able to complete our project successfully, it is the moment of great

satisfaction for us and we feel euphoric to extend our sincere thanks to all our

friends and faculty members of the Department of Civil Engineering, PSIT

College Of Engineering, Kanpur, for helping us directly or indirectly in

completion of this work.

Akhil Shukla Aman Juneja Arvind Dixit

(0934800004) (0934800006) (0934813009)

Prasoon Kumar Maurya Shashank singh Shobhit Omar(0934800029) (0934800048) (0934800049)

Vishal Singh

(0934800057)


5/91

5


6/91

6


7/91

7

ABSTRACT

The project work on THE EFFECT OF LEACHATE ON ENGINEERING

PROPERTIES OF SOIL is an effective study on the physical characterstics of

the soil after being exposed to a highly reactive and nutrient rich liquid , which

has the ability of deteorating materials like gypsum and cemet. The project

work comes under two different streams environmental engineering and

geotechnical engineering. Our work is confined to the geotechnical portion. The

physical analysis of the soil includes testing the soil for various engineering

and index properties of soil.

Solid waste open dumps are sited indiscriminately in Kanpur and are always

potential hazards to health , loss of soil nutrients and are sources of groundwater

pollution. The study investigates the effects of leachate on some engineering

properties of three different soil conditions which includes a soil site where no

dumping has been done , second site is one where dumping has been done for

past one year and the last is the site where dumping has been done for a longer

span of time around ten years. A comparative study has been done to determine

the effect of leachate . In order to determine whether there are significant

differences between the characteristics at different dump a statistical test of

hypothesis was carried out. The values of the specific gravity, liquid limit,

plasticity limit, permeability, moisture content, dry density and direct shear test

were evaluated in the soil under the dumps. The results indicate the needs for

proper site investigation before solid waste dumps are selected.

The project work comprises of a comparative analysis of three different soil

samples in order to bring out the contrast in the change in properties of theaffected soil. Vast research is being done in the field of environmental science


8/91

8

to counter the problem of leachate and to treat the affected soil. As it is known

that leachate is not any special structured chemical compound nor it is a highly

reactive nuclear waste , it is just liquid which through the leaching action collect

all the ingredients presents in that layer it passes by. It is a naturally occuring

liquid which is so reactive that it can completely deteriorate the soil and make it

barren .

The project work has been divided into 4 stages

1. Site selection

2. Sampling of soil3. Lab testing

4. Comparative analysis

1.Site selection

The selection of site has been done keeping in mind the need toevaluate the effect of leachate over the soil at the sites. For this

purpose the sites need to be old enough and must have seen atleast one

monsoon. The season of monsoon is necessary for the formation of

leachate , as leachate is formed by the percolation of water through the

layer in open garbage dumps. Sites of varying age have been selected

in order to highlight the effect of leachate. The older the site is more is

the leachate formed and more is the effect on soil. The site selected is

rich in garbage dump and the variety of refuse in it. A healthy site has

also been taken into consideration to highlight the difference between

the properties of a heathy soil and an affected one. The two affected

sites taken into consideration vary in their age, which contrasts effect

of leachate on the soil.


9/91

9

SITE 1 at PSIT, kanpur : Normal Soil Site


10/91

10

Site 2 at psit , Kanpur : Young Dumping Site


11/91

11

Site 3 at panki padao : Old Dumping Site (age more than 10 years)


12/91

12

2.Sampling of soil

Soil sampling has been done in mind the various tests to be perfomed. The

samples extracted are the disturbed samples. Soil samples have been extracted

from the at considerable depth wiz. At grass root level for the healthy site , at adepth of 1 ft. at the dumping site in PSIT, Kanpur and the depth of extraction of

soil from the site at panki padao was more than 15 ft.

The soil samples were collected from the points where the concentration of

leachate was assumed to be maximum on the basis of observed surface

moisture content.


13/91

13


14/91

14

3.Lab Testing

After collecting soil sample we tested the soil sample by performing test of

liquid limit , plastic limit , permeability , direct shear , specific gravity ,moisture

content and dry density test. We are highly thankful to our HOD , department

of civil engineering , for making us available the lab support from HBTI Kanpur

. we are thankful to Deepesh sir , Kartikeya sir , Abhishek sir and staff thatdevoted their precious time in completion of the practicals.


15/91

15

4.Comparative Analysis

The comparative analysis in the project has been done on the basis of the

result obtained from various tests performed on the soil samples. These results

clearly depict the effect of leachate over the soil samples. The tests are

performed in order to carry out a physical analysis of the soil samples. The

tests performed to get the current state of the physical properties such as

liquid limit, plastic limit, etc.


16/91

16

Table of Contents

DECLARATION.ii

CERTIFICATE...iii

ACKNOWLEDGEMENT..iv

ABSTRACTv

1.Introduction

1.1.General.191.2. More on Leachate221.3. Landfill Leachate....23

1.4. Composition of landfill leachate241.5. History of landfill leachate collection251.6. Environmental Impact251.7. Other types of leachate...261.8. Engineering Properties & Index properties....27

1.8.1. Engineering Properties .271.8.2. Index Properties27

1.9. Objective28

2.0.Site selected.30

3.1 Permeability.33

3.2. Importance of Permeability...343.3. Use of Permeability...343.4. Units of coefficient of permeability(k)..353.5. Permeability Test...35

3.6.1. Preparation of specimen...363.6.2. Procedure..383.6.3. Record of observation..393.6.4. Calculations.39

4.1Shear Strength..424.2. Shear strength in soils...444.3. Mohr-coulomb failure criteria..44

5.1. Consolidation47


17/91

17

5.2. Elastic settlement or emmediate settlement475.3. Primary consolidation settlement485.4. Secondary consolidation settlement495.5. Excess pore water pressure()..49

6.1. Soil consistency51

6.2. Cohession and adhesion..536.3. Rupture Resistance..536.4. Dry Consistency..546.5. Dry and moist consistency..546.6. Wet consistency..556.7. Stickyness Classes..556.8. Plasticity.576.9. Atterberg Limits.57

6.10. Liquid Limit..59-63

6.11.Importance of liquid limit test

6.12. Derived Limits

6.13. Liquidity Index

6.14. Plasticity Index

6.15. Activity

6.2. Test for liquid limit63-69

6.2.1. Procedure

6.2.2. Apparatus

6.2.3. Method

6.2.4. Report6.2.5. Precautions

6.3. Determination of plastic limit...70-73

6.3.1. Apparatus

6.3.2. Procedure

6.3.3. Report6.3.4. Precautions


18/91

18

7.1. Specific Gravity By Density Bottle Method74-78

7.1.1. Apparatus Required

7.1.2. Theory

7.1.3. Application

7.1.4. Procedure

7.1.5. Test Procedure

7.1.6. Observation and calculation table

7.1.7. Precautions

8.1. Density of soil By Core-Cutter Method...79-84

8.1.1. Apparatus Required

8.1.2. Theory

8.1.3. Applications

8.1.4. Procedure

8.1.5. Observation and Calculation table

8.1.6. Precaution

9.1. Determination of moisture content...85-88

9.1.1. Standard Reference

9.1.2. Significance

9.1.3. Equipments

9.1.4. Test procedure

9.1.5. Data Analysis

10. Conclusion89-90

11. References.91


19/91

19

Chapter I

1. Introduction

1.1 GENERAL:-

1.1 What is Leachate? The Secret Story of Leachate

Leachate can be any water that once it has drained through a medium takes up

chemicals and solid materials during its passage. The term leachate is most

often used in connection with landfills. Landfill leachate is contaminated 'dirty'

water that is produced when rainwater comes into contact with waste materials

on the area of the landfill. It contains a large number of different contaminants,

probably the most significant of which is ammonia.

The second most common type of leachate encountered is the black odorous

run-off from manure heaps and from so me composting facilities.

If leachate is allowed to leak from a landfill it will usually cause pollution both

locally around the waste, and it may form a plume of contamination within

groundwaters it enters and a plume of gr oundwater pollution may move away

from the landfill over time to contaminate wells and any drinking water taken

from them.


20/91

20

Leachate forms from both the combination of liquids that are dumped in a tip or

landfill, and liquids that form through decomposition of wastes, as precipitation

filters through the wastes. It is a liquid which is mostly organically

contaminated but which will also contain low levels of most of the liquids

disposed of in the landfill from which it emanates.

Sometimes leachate can be produced by a landfill, which is sealed by a low

permeability capping layer. That is normally the result of a rise in pressure on

the landfill when additional loads are placed on the landfill forcing compression

of the structure or the presence of excess water.

Leachate is produced by the percolation of precipitation through a landfill (from

rainfall and snowmelt) once it penetrates the landfill's daily, intermediate, orfinal cover. However, the quantity that penetrates a well vegetated cover is

lower than many expect, due to the evaporation from the surface, which will

include the transpiration from the leaves of the foliage on the surface . As the

water passes vertically downward through the waste mass, it comes into contact


21/91

21

with the waste, picking up chemical contaminants and biological impurities as it

goes, and the deeper the waste he stronger it gets. It also gets stronger if it

stands from a long while in the waste which is not highly surprising.

There are two main types of leachate produced in landfills which containbiological municipal solid waste (MSW). These are known as acetogenic

leachate and methanogenic leachate. The methanogenic type is often black in

color always smelly and may smell of bad eggs. Methanogenic only has only a

slight smell and is brown or golden colored.

Acetogenic leachate is the young leachate which is produced in a landfill first. It

has a very high Chemical Oxygen Demand (COD) which can be as high as

hundreds of thousands of milligrams per litre for short periods, soon after thecells of he organic waste break open or "lyse" and the complex compounds

which make up live cell tissue drain out of the cells.

The demand for oxygen in a modern quite rapidly filled landfill, is so intense

that within a few months of deposition a new cell of waste will lack oxygen


22/91

22

within the airspaces. Oxygen will be present in the waste which is then said to

be in an anoxic condition.

Over time the original oxygen in the waste and in the leachate becomes depleted

as biological fermentation proceeds, and at some point ancient bacteria whichhave always been present in airless bogs and swamps and lie dormant in our

environment multiply and take over the reaction within he waste.

These are known as methanogenic bacteria. Why are they called that? Well, it is

simple really! They produce the gas known as methane!

All that brings me around to the point where I can now define methanogenic

leachate. Yes. You have guessed it. Methanogenic leachate is the leachate that

is produce by a methane producing anaerobic landfill. By the time it hasbecome methanogenic however, the process of decomposition by fermentation

has reduced the COD to quite possibly 1/100 th of its maximum value, or even

1/1000 th.

However, the leachate is hardly any less toxic to aquatic life, because the

ammonia present in dissolved and gaseous forms remains high, and thus as we

stated earlier is one of the most important contaminants in leachate.

That is the story of leachate from young (acetogenic) to old (methanogenic)

1.2 MORE ON LEACHATE

Leachate is any liquid that, in passing through matter, extracts solutes,

suspended solids or any other component of the material through which it has

passed.

Leachate is a widely used term in the environmental sciences where it has thespecific meaning of a liquid that has dissolved or entrained environmentally

harmful substances which may then enter the environment. It is most commonly

used in the context of land-filling of putrescible or industrial waste.

In the narrow environmental context leachate is therefore any liquid material

that drains from land or stockpiled material and contains significantly elevated

concentrations of undesirable material derived from the material that it has

passed through.


23/91

23

Leachate may also be defined as a product or solution formed by leaching,

especially a solution containing contaminants picked up through the leaching of

soil.

Leachate is a water that carries salts dissolved out of materials through which ithas percolated, especially polluted water from a refuse tip.

Leachate is a solution resulting from leaching, as of soluble constituents from

soil, landfill, etc., by downward percolating ground water.

1.3 Landfill leachate

Leachate from a landfill varies widely in composition depending on the age of

the landfill and the type of waste that it contains . It can usually contain both

dissolved and suspended material. The generation of leachate is caused

principally by precipitation percolating through waste deposited in a landfill.

Once in contact with decomposing solid waste, the percolating water becomes

contaminated and if it then flows out of the waste material it is termed leachate.

Additional leachate volume is produced during this decomposition of

carbonaceous material producing a wide range of other materials including

methane, carbon dioxide and a complex mixture of organic acids, aldehydes,

alcohols and simple sugars.
http://en.wikipedia.org/wiki/Aldehydehttp://en.wikipedia.org/wiki/Aldehyde


24/91

24

The risks of leachate generation can be mitigated by properly designed and

engineered landfill sites, such as sites that are constructed on geologically

impermeable materials or sites that use impermeable liners made of

geomembranes or engineered clay. The use of linings is now mandatory within

both the United States and the European Union except where the waste is

deemed inert. In addition, most toxic and difficult materials are now specifically

excluded from landfilling. However despite much stricter statutory controls

leachates from modern sites are found to contain a range of contaminants that

may either be associated with some level of illegal activity or may reflect the

ubiquitous use of a range of difficult materials in household and domestic

products which enter the waste stream legally.

1.4 Composition of landfill leachate

When water percolates through the waste, it promotes and assists the process of

decomposition by bacteria and fungi. These processes in turn release by-

products of decomposition and rapidly use up any available oxygen creating an

anoxic environment. In actively decomposing waste the temperature rises and

the pH falls rapidly and many metal ions which are relatively insoluble atneutral pH can become dissolved in the developing leachate. The decomposition

processes themselves release further water which adds to the volume of

leachate. Leachate also reacts with materials that are not themselves prone to

decomposition such as fire ash, cement based building materials and gypsum

based materials changing the chemical composition. In sites with large volumes

of building waste, especially those containing gypsum plaster, the reaction of

leachate with the gypsum can generate large volumes of hydrogen sulfide which

may be released in the leachate and may also form a large component of thelandfill gas.

In a landfill that receives a mixture of municipal, commercial, and mixed

industrial waste, but excludes significant amounts of concentrated specific

chemical waste, landfill leachate may be characterized as a water-based solution

of four groups of contaminants; dissolved organic matter (alcohols, acids,

aldehydes, short chain sugars etc.), inorganic macro components (common

cations and anions including sulphate, chloride, iron, aluminium, zinc and
http://en.wikipedia.org/wiki/Geomembraneshttp://en.wikipedia.org/wiki/Geomembranes


25/91

25

ammonia), heavy metals (Pb, Ni, Cu, Hg), and xenobiotic organic compounds

such as halogenated organics, (PCBs, dioxins, etc.).

The physical appearance of leachate when it emerges from a typical landfill site

is a strongly odoured black, yellow or orange coloured cloudy liquid. The smellis acidic and offensive and may be very pervasive because of hydrogen,

nitrogen and sulfur rich organic species such as mercaptans.

1.5 History of landfill leachate collection

In the UK, in the late 1960s, central Government policy was to ensure newlandfill sites were being chosen with permeable underlying geological strata to

avoid the build-up of leachate. This policy was dubbed "dilute and disperse".

However, following a number of cases where this policy was seen to be failing

and an expose in "The Sunday Times" of serious environmental damage being

caused by inappropriate disposal of industrial wastes both policy and the law

was changed. The Deposit of Poisonous Wastes Act 1972 together with The

1974 Local Government Act, made local government responsible for waste

disposal and also responsible for environmental standards enforcement forwaste disposal. Proposed landfill locations also needed to be justified not only

by geography but also scientifically. Many European countries decided to select

sites in groundwater free clay geological conditions or to seal each site with an

engineered lining. In the wake of European advancements, the United States

increased its development of leachate retaining and collection systems. This

quickly led from lining in principle, into the use of multiple lining layers in all

landfills (minus those truly inert).

1.6 Environmental impact

The risks from waste leachate are due to its high organic contaminant

concentrations and high concentration of ammonia. Pathogenic microorganisms

that might be present in it are often cited as the most important, but pathogenic

organism counts reduce rapidly with time in the landfill, so this only applies to

the most fresh leachate. Toxic substances may however be present in variableconcentration and their presence is related to the nature of waste deposited.
http://en.wikipedia.org/wiki/Xenobiotichttp://en.wikipedia.org/wiki/Mercaptanshttp://en.wikipedia.org/wiki/Mercaptanshttp://en.wikipedia.org/wiki/Xenobiotic


26/91

26

Most landfills containing organic material will produce methane, some of which

dissolves in the leachate. This could in theory be released in weakly ventilated

areas in the treatment plant. All plants in Europe must now be assessed under

the EU ATEX Directive and zoned where explosion risks are identified to

prevent future accidents. The most important requirement is the prevention of

discharge of dissolved methane from untreated leachate when it is discharged

into public sewers, and most sewage treatment authorities limit the permissible

discharge concentration of dissolved methane to 0.14 mg/l, or 1/10 of the lower

explosive limit. This entails methane stripping from the leachate.

The greatest environmental risks occur in the discharges from older sites

constructed before modern engineering standards became mandatory and also

from sites in the developing world where modern standards have not beenapplied. There are also substantial risks from illegal sites and ad-hoc sites used

by criminal gangs to dispose of waste materials. Leachate streams running

directly into the aquatic environment have both an acute and chronic impact on

the environment which may be very severe and can severely diminish bio-

diversity and greatly reduce populations of sensitive species. Where toxic

metals and organics are present this can lead to chronic toxin accumulation in

both local and far distant populations. Rivers impacted by leachate are often

yellow in appearance and often support severe overgrowths of sewage fungus.

1.7 Other types of leachate

Leachate can also be produced from land that was contaminated by chemicals or

toxic materials used in industrial activities such as factories, mines or storagesites. Composting sites in high rainfall also produce leachate.

Leachate is also associated with stockpiled coal and with waste materials from

metal ore mining and other rock extraction processes, especially those in which

sulphide containing materials are exposed to air and thus to oxygen generating

acidic, sulphur-rich liquors, often with elevated metal concentrations.

In the context of civil engineering (more specifically reinforced concrete

design), leachate refers to the effluent of pavement wash-off (that may include


27/91

27

melting snow & ice with salt) that permeates through the cement paste onto the

surface of the steel reinforcement, thereby catalyzing its oxidation and

degradation. Leachates can be geotoxic in nature.

1.8 ENGINEERING PROPERTIES & INDEX PROPERTIES

1.8.1 (a)Engineering Properties-The main engineering properties of the

soil are permeability, compressibility and shear strength. Permeability indicates

the facility with which water can flow through soils. It is required for estimation

of seepage discharge through earth masses. Compressibility is related with the

deformations produced in soils when they are subjected to compressive loads.Compression characteristics are required for computation of settlement of

structures founded on soils. Shear strength of a soil is its ability to resist the

shear stresses. The shear strength determines the stability of slopes, bearing

capacity of soils and the earth pressure on retaining structures.

1.8.2 (b)Index Properties-The tests required for determination of

engineering properties are generally elaborate and time consuming. Sometimes,

the geotechnical engineer is interested to have some rough assessment of the

engineering properties without conducting elaborate tests. This is possible if

index properties are determined. The properties of soils which are not of

primary interest to the geotechnical engineer but which are indicative of the

engineering properties are called index properties. Simple tests which are

required to determine the index properties are known as classification tests. The

soils are classified and identified based on the index properties.
http://en.wikipedia.org/wiki/Genotoxicityhttp://en.wikipedia.org/wiki/Genotoxicity


28/91

28

The index properties are sometimes divided into two categories.

(1) Properties of individual particles, and

(2) Properties of soil mass, also known as aggregate properties.

The properties of individual particles can be determined from a remoulded,

disturbed sample. These depend upon the individual grains and are independentof the manner of soil formation. The soil aggregate properties depend upon the

mode of soil formation, soil history and soil structure. The properties should be

determined by undisturbed samples or preferably from in-situ tests. The most

important properties of the individual particles of coarse grained soils are the

particle size distribution and grain shape. The aggregate property of the coarse-

grained soils of great practical importance is its relative density.

The index properties give some information about engineering properties. It

is tacitly assumed that soils with like index properties have identical

engineering properties. However, the correlation between index properties and

engineering properties is not perfect. A liberal factor of safety should be

provided if the design is based only on the engineering properties. Design of

large, important structures should be done only after determination of

engineering properties.


29/91

29

1.9 OBJECTIVE

To prepare a comparative analysis report on the effect of leachate on the

engineering properties of the soils taken from three different sites. Sites are

so chosen that the waste dump on them differs in age.


30/91

30

Chapter II

2.SITE SELECTED

Site -1 : Normal soil

The Normal site is taken as the PSIT PLAY GROUND keeping in mind

that there no dumping activity is being done in past years and regularmaintenance of soil is being done for gardening. Hence we are taking this

site for comparing all the test results from the other two dumping sides.


31/91

31

Site -2 : PSIT Dumping Site

This is our another site where dumping is being done for past few years,

All the domestic waste of the organisation is been done here, hence fresh

layers of dump can be obtained . This particularly will help us in making

an easy comparison of the test results in between the normal site and other

sites of different dumping conditions.


32/91

32

SITE -3 : PANKI PADAO

This site lies in the outskirts of Kanpur city where nearly all the waste is

being dumped from past few decade .This site is of great importance in

making a healthy comparison of the test results.


33/91

33

Chapter III

3.1 Permeability

Due to the existence of the inter-connected voids, soils arepermeable. The permeable soils will allow water flow from points of

high energy to points of low energy.Permeabilityis the parameter to characterize the ability of soil to

transport water.

Permeability in fluid mechanics and the earth sciences (commonly symbolized

as , ork) is a measure of the ability of a porous material (often, a rock or

unconsolidated material) to allow fluids to pass through it.


34/91

34

3.2 Importance of permeability

1. Permeability influences the rate of settlement of a saturated soil under load.2. The design of earth dams is very much based upon the permeability of the

soils used.

3. The stability of slopes and retaining structures can be greatly affected by the

permeability of the soils involved.

4. Filters made of soils are designed based upon their permeability.

3.3 Use of Permeability

Knowledge of the permeability properties of soil is necessary to:1. Estimating the quantity of underground seepage ;2. Solving problems involving pumping seepage water from construction

excavation;

3. Stability analyses of earth structures and earth retaining walls subjected toseepage forces.


35/91

35

3.4 Units of the coefficient of Permeability k

The permeability k is in the dimension of velocity. However, in

deferent field people prefer use different units for permeability simplybecause different fields deal different scales of subsurface fluid flow. Inhydrogeology a used to be popular unit is meinzer; in geotechnical

world is cm/sec; and in petroleum engineering people just use the unit

of darcy. Here are the conversions:

1cm/sec=864 m/day

1 darcy= 1 cm3

of fluid with viscosity of 1 centiposein 1 sec, under a pressure change of 1

atm. over a length of 1 cm through a porous medium of 1 cm2in cross-

sectional area. 1 Meinzer= 1gal/day/ft2

3.5 Permeability Test

Thisstandard describes the method for determining coefficient of permeability

of granular Foils by a constant head method and under conditions of laminarflow of water. This method is suitable for disturbed granular soil containing less

than 10 percent soil passing 75-micron IS Sieve, the type of material used for

construction of embankments base courses under pavements.

Prerequisite for laminar flow of water through granular soils is that, water shall

flow below critical velocity so that there is no movement or disturbance of soil

particles; moreover, water shall flow through saturated soil voids without

having bubbles in them, and there shall be no change in soil volume nor any

change in hydraulic gradient during the performance of the test.


36/91

36

The permeameter shall have specimen cylinders with minimum diameters

approximately 8 or 12 times the maximum particle size in accordance with

Table 1. The permeameter shall be fitted with:

a) A porous disc or suitable reinforced screen at the bottom with apermeability greater than that of the soil specimen, but with openings

sufficiently small ( not larger than 10 percent of finer size of the soil to

be tested ) to prevent the movement of particles;

b) Manometer outlets for measuring the loss of head, 11. over a length,L,equivalent to at least the diameter of the cylinder; and

c)A porous disc or suitable reinforced screen with spring attached to the*top, or any other device for applying a light spring pressure of 2 to 4 kg

total load when the top plate is attached in place. This will hold the

placement density and volume of soil without significant change duringthe saturation of the specimen and the permeability testing to satisfy the

requirement that there should be no soil volume change during a test.

3.6.1 PREPARATION OF SPECIMEN

Make the following initial measurements and record on the data sheet

( Appendix A ), the inside diameter,D, of the permeameter; the length, L,

between the manometer outlets; and the depth, H1, measured at four

symmetrically spaced points from the upper surface of the top plate of thepermeability cylinder to the top of the upper porous stone or screen temporarily


37/91

37

placed on the lower porous plate or screen. This automatically deducts the

thickness of the upper porous plate or screen from the height measurements

used to determine the volume of soil placed in the permeability cylinder. A

duplicate top plate containing four large symmetrically spaced openings through

which the necessary measurements can be made, shall be employed todetermine the average value for HI. Calculate the cross sectional areaA of the

specimen.

Small portion of the sample selected as prescribed in 3.2 and 3.3 shall be taken

for water content determinations. Record the weight of the remaining air-dried

sample , 11/l, for unit weight determinations.

Place the prepared soil by one of the following procedures in uniform thinlayers approximately 15 tO 20 mm.

For soils having a maximum size of 10 mm or less, place the appropriate size offunnel, as prescribed in 2.3, in the permeability device with the spout in contact

with the lower porous plate or screen or previously formed layer, and fill the

funnel with sufficient soil to form a layer, taking soil from different areas of the

sample in the pan Lift the funnel by 15 mm or approximately the

unconsolidated layer thickness to be formed, and spread the soil with a slow

spiral motion, working from the perimeter of the device towards the centre, so

that a uniform layer is formed. Remix the soil in the pan for each successivelayer to reduce segregation caused by taking soil from the pan.

For soils with a maximum size greater than 10.00 mm, spread the soil from a

scoop. Uniform spreading can be obtained by sliding a scoopful of soil in a

nearly horizontal position down along the inside surface of the device to the

bottom or to the formed layer, then tilting the scoop and drawing it towards thecentre with a single slow motion, this allows the soil to run smoothly from the

scoop in a windrow without segregation. Turn the permeability cylinder

sufficiently for the next scoopful, thus progressing around the inside perimeter

to form a uniform compacted layer of a thickness equal to the maximum particle

size.

Compact successive layers of soil to the desired

relative density by appropriate procedure, as

follows, to a height of about 20-mm above theupper manometer outlet.Minimum Density ( Zero Percent Relative Density ) - Continue placing layers

of soil in succession by one of the procedures described in 4.4.1 until the device

is filled to the proper level.

Maximum Density ) Density ( 100 Percent relative 4.5.2.1 Compaction byvibrating tamper - each layer of soil thoroughly with the vibrating tamper,


38/91

38

distributing the light tamping action uniformly over the surface of the layer in a

regular pattern. The pressure of contact and the length of time of the vibrating

action at each spot should not cause soil to escape from beneath the edges of

the tamping foot, thus tending to loosen the layer. Make a sufficient number of

coverages to produce maximum density, as evidenced by practically novisible motion of surface particles adjacent to the edges 01 the tamping foot.Compacting with sliding weight tamper --

Compact each iayer of soil thoroughly by tamping blows uniformly distributed

over the surface of the layer. Adjust the height of drop and give sufficient

coverages to produce maximum density, depending on the coarseness and

gravel content of the soil.Compaction by other methods Compaction may be accomplished by other

approved methods, such as deposition under water, by vibratory packerequipment where care is taken to obtain a uniform specimen without

segregation of particle sizes.Relative Density Intermediate Between zero and 100 Percent - By trial in a

separate container of the same diameter as the permeability cylinder, adjust

the compaction to obtain reproducible values of relative density. Compact the

soil in the permeability cylinder by these procedures in thin layers to a height of

about 20 mm above the upper manometer outlet.

3.6.2 PROCEDURE

Open the inlet valve from the filter tank slightly for the first run, delay

measurements of quantity of flow and head until a stable head condition without

appreciable drift in water manometer level is attained. Measure and record the

time t, head h ( the difference in level in the manometers ), quantity of flow Q,and water temperature T.

Repeat the test runs at heads, increasing by 5 mm in order to establish

accurately the region of laminar flow with velocity u ( where u = Q/At ),

directly proportional to hydraulic gradient i (where i = h/L ). When departures

from the linear relation become apparent, indicating the initiation of turbulentflow conditions, 10 mm intervals, of head may be used to carry the test run

sufficiently along in the region of turbulent flow to define this regionif it is significant for field conditions.

At the completion of the permeability test, drain the specimen and inspect it to

establish whether it was essentially homogenous and isotropic in character.

Any light and dark alternating horizontal streaks 01 layers are evidence of

segregation of fines.


39/91

39

3.6.3 RECORD OF OBSERVATION

The inside diameterD of the permeamcter, the length L between manometer

outlets and depth are measured and recorded in Appendix A. For the given soil,

water content is determined and recorded. The weight W8, of air dried soil usedin preparing soil specimen is also recorded. The final height of specimen after

compression by spring, HI - Hz, is measured and recorded. Dry

unit weight and void ratio are calculated. The temperature of water, T is

measured and recorded,

During the test, observations are made of manometer readings hland h2,

quantity of flow Q collected in a graduated jar in the time t and are recorded in

columns ( 2 ) to ( 5 ) respectively. Head h ( = hl - h2 ) is calculated to column (

6 ) and gradient i ( = h/L ) is calculated and recorded in column ( 7 ). Finally,permeability k, is calculated and recorded in column ( 8 ).

3.6.4 CALCULATIONS

Permeability k Tat temperature Tis calculated

by:kT = q/(ait)

and permeability at 27C by using the expressionk27=kt-ut/u27

where

ut =Coefficient of viscosity at TC, andu27 = Coefficient of viscosity at 27C.


40/91

40

SITE 1

SITE 2


41/91

41

SITE 3


42/91

42

Chapter IV

4.1 Shear strength (soil)

Shear strength is a term used in soil mechanics to describe the magnitude of

the shear stress that a soil can sustain. The shear resistance of soil is a result of

friction and interlocking of particles, and possibly cementation or bonding at

particle contacts. Due to interlocking, particulate material may expand or

contract in volume as it is subject to shear strains. If soil expands its volume, the

density of particles will decrease and the strength will decrease; in this case, the

peak strength would be followed by a reduction of shear stress. The stress-strain

relationship levels off when the material stops expanding or contracting, and

when interparticle bonds are broken. The theoretical state at which the shear

stress and density remain constant while the shear strain increases may be

called the critical state, steady state, or residual strength. The volume change

behaviour and interparticle friction depend on the density of the particles, the

intergranular contact forces, and to a somewhat lesser extent, other factors such

as the rate of shearing and the direction of the shear stress. The average normal

intergranular contact force per unit area is called the effective stress. If water is

not allowed to flow in or out of the soil, the stress path is called an undrained


43/91

43

stress path. During undrained shear, if the particles are surrounded by a nearly

incompressible fluid such as water, then the density of the particles cannot

change without drainage, but the water pressure and effective stress will change.

On the other hand, if the fluids are allowed to freely drain out of the pores, then

the pore pressures will remain constant and the test path is called a drained

tress path. The soil is free to dilate or contract during shear if the soil is drained.

In reality, soil is partially drained, somewhere between the perfectly undrained

and drained idealized conditions. The shear strength of soil depends on the

effective stress, the drainage conditions, the density of the particles, the rate of

strain, and the direction of the strain. For undrained, constant volume shearing,

the Tresca theory may be used to predict the shear strength, but for drained

conditions, the MohrCoulomb theory may be used. Two important theories ofsoil shear are the critical state theory and the steady state theory. There are key

differences between the critical state condition and the steady state condition

and the resulting theory corresponding to each of these conditions.


44/91

44

4.2 Shear Strength in Soils

The shear strength of a soil is its resistance to shearing stresses.It is a measure of the soil resistance to deformation by continuous displacementof its individual soil particles

Shear strength in soils depends primarily on interactions between particles Shear failure occurs when the stresses between the particles are such that theyslide or roll past each other

Soil derives its shear strength from two sources:

Cohesion between particles (stress independent component)Cementation between sand grainsElectrostatic attraction between clay particles

Frictional resistance between particles (stress dependent component)

4.3 Mohr-Coulomb Failure Criteria

This theory states that a material fails because of a critical combination of

normal stress and shear stress, and not from their either maximum normal orshear stress alone.


45/91

45

where

c = cohesion;

c=effective cohesion = angle of internal friction; = effective angle of internal friction = coefficient of friction; ' = effect ivecoefficient of friction =n.


46/91

46


47/91

47

Chapter V

5.1 Consolidation

Civil Engineers build structures and the soil beneath these structures is loaded.This results in increase of stresses resulting in strain leading to settlement of

stratum. The settlement is due to decrease in volume of soil mass. When water

in the voids and soil particles are assumed as incompressible in a completely

saturated soil system then - reduction in volume takes place due to expulsion of

water from the voids. There will be rearrangement of soil particles in air voids

created by the outflow of water from the voids. This rearrangement reflects as a

volume change leading to compression of saturated fine grained soil resulting in

settlement. The rate of volume change is related to the rate at which pore watermoves out which in turn depends on the permeability of soil. Therefore the

deformation due to increase of stress depends on the Compressibility of soilsAs Civil Engineers we need to provide answers for1. Total settlement (volume change)2. Time required for the settlement of compressible layer

The total settlement consists of three components

1. Immediate settlement.2. Primary consolidation settlement

3. Secondary consolidation settlement (Creep settlement)

St = Si + Sc + Ssc

5.2 Elastic Settlement or Immediate Settlement

This settlement occurs immediately after the load is applied. This is due to

distortion (change in shape) at constant volume. There is negligible flow ofwater in less pervious soils. In case of pervious soils the flow of water is quick

at constant volume. This is determined by elastic theory.


48/91

48

5.3 Primary Consolidation Settlement

It occurs due to expulsion of pore water from the voids of a saturated soil. Incase of saturated fine grained soils, the deformation is due to squeezing of water

from the pores leading to rearrangement of soil particles. The movement of porewater depends on the permeability and dissipation of pore water pressure. With

the passage of time the pore water pressure dissipates, the rate of flow decreases

and finally the flow of water ceases. During this process there is gradual

dissipation of pore water pressure and a simultaneous increase of effective

stress as shown in Fig 1. The consolidation settlement occurs from the time

water begins move out from the pores to the time at which flow ceases from the

voids. This is also the time from which the excess pore water pressure startsreducing (effective stress increase) to the time at which complete dissipation of

excess pore water pressure (total stress equal to effective stress). This timedependent compression is called Consolidation settlement

Primary consolidation is a major component of settlement of fine grained

saturated soils and this can be estimated from the theory of consolidation.

In case of saturated soil mass the applied stress is borne by pore water alone in

the initial stages

With passage of time water starts flowing out from the voids as a result the

excess pore water pressure decreases and simultaneous increase in effective

stress will takes place. The volume change is basically due to the change in

effective stress . After considerable amount of time flow from the voids ceases

the effective stress stabilizes and will be is equal to external applied total stress

and this stage signifies the end of primary consolidation.


49/91

49

5.4 Secondary Consolidation Settlement:-

This is also called Secondary compression (Creep). It is the change in volumeof a fine grained soil due to rearrangement of soil particles (fabric) at constanteffective stress. The rate of secondary consolidation is very slow whencompared with primary consolidation.

5.5 Excess Pore water Pressure (Du)

It is the pressure in excess of the equilibrium pore water pressure. It isrepresented as Du.

Du= h gw

Where

h --- Piezometric head

gw --- Unit weight of water


50/91

50

When saturated soil mass is subjected to external load decrease in volume takes

place due to rearrangement of soil particles. Reduction in volume is due to

expulsion of water from the voids. The volume change depends on the rate at

which water is expelled and it is a function of permeability.

The total vertical deformation (Consolidation settlement) depends on

1. Magnitude of applied pressure (sD)

2. Thickness of the saturated deposit

We are concerned with_ Measurement of volume change

_ The time duration required for the volume change


51/91

51

Chapter VI

6.1 Soil Consistency

Soil consistency is defined as the relative ease with which a soil can

be deformed use the terms of soft, firm, or hard.

Consistency largely depends on soil minerals and the water

content.

Atterberg limits are the limits of water content used to define soil behavior.

The consistency of soils according to Atterberg limits gives the following

diagram.

LL: The lowest water content above

which soil behaves like liquid,normally below 100.

PL: The lowest water content at which

soil behaves like a plastic material normally below 40.

PI: The range between LL and PL.

Shrinkage limit: the water content below which soils do not decrease their

volume anymore as they continue dry out. needed in producingbricks and ceramics .


52/91

52

Soil consistence provides a means of describing the degree and kind of

cohesion and adhesion between the soil particles as related to the resistance

of the soil to deform or rupture.

Since the consistence varies with moisture content, the consistence can be

described as dry consistence, moist consistence, and wet consistence.

Consistence evaluation includes rupture resistance and stickiness.

The rupture resistance is a field measure of the ability of the soil to

withstand an applied stress or pressure as applied using the thumb and

forefinger.

Soil consistency is defined as the relative ease with which a soil can be

deformed use the terms of soft, firm, or hard.

Consistency largely depends on soil minerals and the water content.


53/91

53

6.2 Cohesion & Adhesion

Cohesion is the attraction of one water molecule to another resulting from

hydrogen bonding (water-water bond).

Adhesion is similar to cohesion except with adhesion involves the attraction of

a water molecule to a non-water molecule (water-solid bond).

When We Describe Consistency We Attempt to Describe the Following

Engineering/EnvironmentalRupture ResistanceMoist and Dry ConsistencyStickinessWet ConsistencyPlasticity-Wet ConsistencyGeophysicalManner and Type of FailurePenetration Resistance

6.3 Rupture Resistance

A measure of the strength of the soil to withstand an applied stress

Moisture content is also consideredDryMoist (field capacity)


54/91

54

6.4 Dry Consistency

6.5 Dry and Moist Consistency


55/91

55

6.5 Wet Consistency

Describe Stickiness

The capacity of soil to adhere to other objectsEstimated at moisture content that displays maximum adherence betweenthumb and fore fingerDescribe PlasticityDegree a soil can be molded or reworked causing permanent deformationwithout rupturing.

6.6 Stickiness Classes

Non-Stickylittle or no soil adheres to fingers after release of pressure

Slightly Stickysoil adheres to both fingers after release of pressure with littlestretching on separation of fingers

Moderately Stickysoil adheres to both fingers after release of pressure withsome stretching on separation of fingers

Very Sticky -soil adheres firmly to both fingers after release of pressure with

stretches greatly on separation of fingers


56/91

56

Water Content Significantly affects properties of Silty and Clayey

soils (unlike sand and gravel). Plasticity property describes the

response of a soil to change in moisture content.

Strength decreases as water content increases

Soils swell-up when water content increases

Fine-grained soils at very high water content possess properties similar toliquids

As the water content is reduced, the volume of the soil decreases and the soilsbecome plastic

If the water content is further reduced, the soil becomes semi-solid when thevolume does not change


57/91

57

6.7 Plasticity

The degree to which puddled or reworked soil can be permanently deformed

without rupturing

Evaluation done by forming a 4 cm long wire of soil at a water content where

maximum plasticity is expressed

6.8 Atterberg limits

The Atterberg limits are a basic measure of the nature of a fine-grained soil.

Depending on the water content of the soil, it may appear in four states: solid,

semi-solid, plastic and liquid. In each state, the consistency and behaviour of a

soil is different and consequently so are its engineering properties. Thus, the

boundary between each state can be defined based on a change in the soil's

behavior. The Atterberg limits can be used to distinguish between silt and clay,

and it can distinguish between different types of silts and clays. These limits

were created by Albert Atterberg, a Swedish chemist. They were later refined

by Arthur Casagrande. These distinctions in soil are used in assessing the soils

that are to have structures built on. Soils when wet retain water and some

expand in volume. The amount of expansion is related to the ability of the soil

to take in water and its structural make-up (the type of atoms present). These

tests are mainly used on clayey or silty soils since these are the soils that expand

and shrink due to moisture content. Clays and silts react with the water and thus

change sizes and have varying shear strengths. Thus these tests are used widely

in the preliminary stages of designing any structure to ensure that the soil will

have the correct amount of shear strength and not too much change in volume as

it expands and shrinks with different moisture contents.


58/91

58


59/91

59

6.9 Liquid limit

The liquid limit (LL) is the water content at which a soil changes from plastic to

liquid behavior. The original liquid limit test of Atterberg's involved mixing a

pat of clay in a round-bottomed porcelain bowl of 1012 cm diameter. A groovewas cut through the pat of clay with a spatula, and the bowl was then struck

many times against the palm of one hand. Casagrande subsequently tandardized

the apparatus and the procedures to make the measurement more repeatable.

Soil is placed into the metal cup portion of the device and a groove is made

down its center with a standardized tool of 13.5 millimetres (0.53 in) width.

The cup is repeatedly dropped 10 mm onto a hard rubber base at a rate of 120

blows per minute, during which the groove closes up gradually as a result of the

impact. The number of blows for the groove to close is recorded. The moisture

content at which it takes 25 drops of the cup to cause the groove to close over a

distance of 13.5 millimetres (0.53 in) is defined as the liquid limit. The test is

normally run at several moisture contents, and the moisture content which

requires 25 blows to close the groove is interpolated from the test results. The


60/91

60

Liquid Limit test is defined by ASTM standard test method D 4318.[3] The test

method also allows running the test at one moisture content where 20 to 30

blows are required to close the groove; then a correction factor is applied to

obtain the liquid limit

from the moisture content..

The following is when one should record the N in number of blows

needed to close this 1/2-inch gap:

The materials needed to do a liquid limit test are as follows

Casagrande cup (liquid limit device)

Grooving tool

Soil pat before test

Soil pat after test

Another method for measuring the liquid limit is the fall cone test. It is based on

the measurement of penetration into the soil of a standardized cone of specific

mass. Although the Casagrande test is widely used across North America, the


61/91

61

fall cone test is much more prevalent in Europe due to being less dependent on

the operator in determining the Liquid Limit.

6.10 Importance of liquid limit test

The importance of the liquid limit test is to classify soils. Different soils have

varying liquid limits. Also, one must use the plastic limit to determine its

plasticity index.


62/91

62

6.11 Derived limits

The values of these limits are used in a number of ways. There is also a close

relationship between the limits and properties of a soil such as compressibility,

permeability, and strength. This is thought to be very useful because as limit

determination is relatively simple, it is more difficult to determine these other

properties. Thus the Atterberg limits are not only used to identify the soil's

classification, but it allows for the use of empirical correlations for some other

engineering properties.

6.12 Liquidity index

The liquidity index (LI) is used for scaling the natural water content of a soilsample to the limits. It can be calculated as a ratio of difference between natural

water content, plastic limit, and liquid limit:

LI=(LL-PL)Where

W is the natural water content.

The effects of the water content on the strength of saturated remolded soils can

be quantified by the use of the liquidity index, LI: When the LI is 1, remoldedsoil is at the liquid limit and it has an undrained shear strength of about 2 kPa.When the soil is at the plastic limit, the LI is 0 and the undrained shear strength

is about 200 kPa.

6.13 Plasticity index

The plasticity index (PI) is a measure of the plasticity of a soil. The plasticity

index is the size of the range of water contents where the soil exhibits plasticproperties. The PI is the difference between the liquid limit and the plastic limit

(PI = LL-PL). Soils with a high PI tend to be clay, those with a lower PI tend tobe silt, and those with a PI of 0 (non-plastic) tend to have little or no silt or clay.

PI and their meanings

0 - Nonplastic

(1-5)- Slightly plastic

(5-10) - Low plasticity

(10-20) - Medium plasticity

(20-40) - High plasticity >40 Very high plasticity


63/91

63

6.14 Activity

The activity (A) of a soil is the PI divided by the percent of clay-sized particles

(less than 2 m) present. Different types of clays have different specific surface

areas which controls how much wetting is required to move a soil from onephase to another such as across the liquid limit or the plastic limit. From the

activity,one can predict the dominant clay type present in a soil sample. Highactivity signifies large volume change when wetted and large shrinkage when

dried. Soils with high activity are very reactive chemically. Normally the

activity of clay is between 0.75 and 1.25, and in this range clay is called normal.

It is assumed that the plasticity index is approximately equal to the clay fraction

(A = 1). When A is less than 0.75, it is considered inactive. When it is greater

than 1.25, it is considered active.

6.2 Test For Liquid Limit

6.2.1 Procedure

About 120 g of the soil sample passing 425-micron IS Sieve shall be mixed

thoroughly with distilled water in the evaporating dish or on the flat glass plate

to form a uniform paste. The paste shall have a consistency that will require 30to 35 drops of the cup to cause the required closure of the standard groove. In

the case of clayey soils, the soil paste shall be left to stand for a sufficient time (

24 hours ) so as to ensure uniform distribution of moisture throughout the soilmass.


64/91

64

The soil should then be re-mixed thoroughly before the test. A portion of the

paste shall be placed in the cup above the spot where the cup rests on the base,

squeezed down and spread into position shown in Fig. 1, with as few strokes of

the spatula as possible and at the same time trimmed to a depth of one

centimetre at the point of maximum thickness, returning the excess soil to thedish. The soil in the cup shall be decided by firm strokes of the grooving tool

along the diameter through the centre line of the cam follower so that a clean,

sharp groove of the proper dimensions is formed . In case where groovingtool,

Type A does not give a clear groove as in sandy soils, grooving tool Type B or

Type C should be used.

The cup shall be fitted and dropped by turning the crank at the rate

of two revolutions per second until the two halves of the soil cake comein contact with bottom of the groove along a distance of about 12 mm

. This length shall be measured with the end of the grooving tool or a ruler. The

number of drops required to cause the groove close for the length of 12 mm

shall be recorded.

A little extra of the soil mixture shall be added to the cup and mixed with the

soil in the cup. The pat shall be made in the cup and the test repeated . In no

case shall dried soil be added to the thoroughly mixed soil that is being tested.

The procedure given and in this clause shall be repeated until two consecutiveruns give the same under of drops for closure of the groove

A representative slice of soil approximately the width of the spatula, extending

from about edge to edge of the soil cake at right angle to the groove andincluding that portion of the groove in which the soil flowed together, shall be

taken iu a suitable container and its moisture content expressed as a percentage

of the oven dry weight otherwise determined as described in IS : 2720 ( Part 2 )-

1973*. The remaining soil in the cup shall be transferred to the evaporating dishand the cup and the grooving tool cleaned thoroughly. The operations specified

shall be repeated for at least three more additional trails ( minimum of four in

all ), which the soil collected in the evaporating dish or flat glass plate, to with

sufficient water has been added to bring the soil to a more fluid condition. In

each case the number of blows shall be recorded and the moisture contentdetermined as before. The specimens shall be of such consistency that the

number of drops required to close the groove shallbe not less than 15 or more than 35 and the points on the flow curve are

evenly distributed in this range. The test should proceed from the drier ( more

drops ) to the wetter ( less drops ) condition of the soil. The test may also be

conducted from the wetter to the drier condition provided drying is achieved by

kneading the wet soil and not by adding

dry soil.


65/91

65

6.2.2 APPARATUS

Casagrande apparatus confirming to IS: 9259-1979.

Grooving tool.

Balance of capacity 500 grams and sensitivity 0.01gram. Thermostatically controlled oven with capacity up to 2500 C.

Porcelain evaporating dish about 12 to 15cm in diameter.

Spatula flexible with blade about 8cm long and 2cm wide.

Palette knives with the blade about 20cm long and 3cm wide.

Wash bottle or beaker containing distilled water.

Containers airtight and non- corrodible for determination of moisture

content.

6.2.3 PROCEDURE

Take representative soil sample of approximately 120gms passingthrough 425 micron IS sieve and mix thoroughly with distilled water in

the evaporating dish to a uniform paste.

The paste shall have a consistency that will require 30 to 35 drops of thecup to cause the required closure of the standard groove.

Liquid Limit test


66/91

66

Leave the soil paste to stand for 24 hours to ensure uniform distributionof moisture throughout the soil mass.

Remix the soil thoroughly before the test.

Place a portion of the paste in the cup above the spot where the cup rests

on the base, squeeze down and spread in to position with a few strokes ofthe spatula as possible and at the same time trim to a depth of 1cm at the

point of maximum thickness.

Make a clean, sharp groove by a grooving tool along the diameterthrough the centre line of the cam follower.

Drop the cup from a height of 10 + 0.25 mm by turning the crank at the

rate of two-revolutions/ sec, until the two halves of the soil cake come in

contact with the bottom of the groove along the distance of about 12mm.

Record the number of drops required to cause the groove close for the

length of 12mm. Collect a representative slice of sample of soil approximately the width of

spatula, extending from about edge to edge of the soil cake at right angle

to the groove in to an air tight container and keep in the oven for

24hrs,maintained at a temperature of 1050 to 1100C and express itsmoisture content as the percentage of the oven dried weight.

Transfer the remaining soil in the cup to the evaporating dish and cleanthe cup and the grooving tool thoroughly.

Repeat the operation specified above for at least three more additional

trials (minimum of four in all) with soil collected in evaporating dish towhich sufficient water has been added to bring the soil to more fluid

condition.


67/91

67

In each case record the number of blows and determine the moisture

content as before.

The specimens shall be of such consistency that the number of dropsrequired to close the groove shall not be less than 15 or more than 35.


68/91

68

Observation And CalculationsSITE 1

SITE 2


69/91

69

SITE 3

6.2.4 REPORT

Plot a flow curve with the points obtained from each determination on asemi logarithmic graph representing water content on the arithmetical

scale and the no of drops on the logarithmic scale.

The flow curve is a straight line drawn as nearly as possible through thefour or more plotted points.

The moisture content corresponding to 25 drops as read from the curveshall be rounded off to the nearest second decimal and is reported as

liquid limit of the soil.

6.2.5 PRECAUTIONS

This test should proceed from the drier (more drops) to the wetter (lessdrops) condition of the soil.

This test may also be conducted from wetter to drier condition provideddrying is achieved by kneading the wet soil and not by adding dry soil.


70/91

70

6.3 DETERMINATION OF PLASTIC LIMIT

Plastic limit is defined as minimum water content at which soil remains in

plastic state

6.3.1 APPARATUS

Porcelain evaporating dish about 12cm in diameter.

Flat glass plate 10mm thick and about 45cm square or longer.

Spatula flexible with the blade about 8cm long and 2cm in wide.

Ground glass plate 20 x 15 cm.

Airtight containers.

Balance of capacity 500grams and sensitivity 0. 01gram.

Thermostatically controlled oven with capacity up to 250 0C. Rod 3mm in diameter and about 10cm long.

6.3.2 PROCEDURE

Take representative soil sample of approximately 20g from the portion ofthe material passing 425 micron IS sieve and mix thoroughly with

distilled water in an evaporating dish till the soil mass becomes plasticenough to be easily molded with fingers.

In the case of clayey soils, leave the soil mass to stand for 24 hours toensure uniform distribution of moisture throughout the soil.

Form a ball with about 8 grams of this soil mass and roll between thefingers and the glass plate as shown with just sufficient pressure to roll

the mass into a thread of uniform diameter throughout its length.

The rate of rolling shall be between 80 and 90 strokes/minute counting

the stroke as one complete motion of the hand forward and back to the

starting position again. Continue the rolling till the thread crumbles exactly at 3mm diameter.

If the soil thread doesnt crumble exactly at 3mm knead the soil togetherto a uniform mass and roll it again.

Continue this process of alternate rolling and kneading until the thread

crumbles under the pressure exactly at 3mm diameter.

Collect the pieces of crumbled soil thread in an airtight container anddetermine its moisture content


71/91

71

Determine the plastic limit for at least two points of the soil passing 425 micronIS sieve

SITE 1


72/91

72

SITE 2

SITE 3


73/91

73

6.3.3 REPORT

Report the individual and the mean of the results as the plastic limit of the

soil to the nearest second decimal.

6.3.4 PRECAUTIONS

At no time shall an attempt be made to produce failure at exactly 3mm

diameter by allowing the thread to reach 3mm then reducing the rate of

rolling or pressure or both and continuing the rolling without further

deformation until the thread falls apart.


74/91

74

Chapter VII

7.1 Specific Gravity Method by Density Bottle Method

Specific gravity is the ratio of the density of a substance compared to the

density (mass of the same unit volume) of a reference substance.Apparent

specific gravity is the ratio of the weight of a volume of the substance to the

weight of an equal volume of the reference substance. The reference substance

is nearly always water for liquids or air for gases. Temperature and pressure

must be specified for both the sample and the reference. Pressure is nearly

always 1 atm equal to 101.325 kPa. Temperatures for both sample and reference

vary from industry to industry. In British brewing practice the specific gravity

as specified above is multiplied by 1000. Specific gravity is commonly used in

industry as a simple means of obtaining information about the concentration of

solutions ofvarious materials such as brines, hydrocarbons, sugar solutions

(syrups, juices, honeys, brewers wort, must etc.) and acids.

To determine the Specific Gravity of soil a particle passing through 4.75 mm IS

sieve using Density bottle.

7.1.1 APPARATUS REQUIRED:-

i. Density bottle of 100 mm capacity.

ii. Desiccators.

iii. Balance with sensitivity of 0.01 gm.

7.1.2 THEORY:-

Specific Gravity is the ratio of the mass in air of given volume of dry soil

solids to the mass of equal volume of distilled water at 4o

C. Or ratio of unit

weight of soil solids to that of water. Let, in the figure
http://en.wikipedia.org/wiki/Atmosphere_%28unit%29http://en.wikipedia.org/wiki/Worthttp://en.wikipedia.org/wiki/Musthttp://en.wikipedia.org/wiki/Musthttp://en.wikipedia.org/wiki/Worthttp://en.wikipedia.org/wiki/Atmosphere_%28unit%29


75/91

75

M1 = Mass of empty density bottle.

M2 = Mass of density bottle + Soil grains.

M3 = Mass of empty density bottle + Soil grains + water.

M4 = Mass of empty density bottle + water.

The value of specific gravity depends on the temperature hence its value

is reported as standard temperature of 27o

C.

G (at 27oC) = G (at t

oC) * (SG of water at t

oC / SG of water at 27

oC)

7.1.3 APPLICATION:

Specific gravity of the soil grains is an important property and is used to

determine the voids ratio, porosity, and degree of saturation if density and water

content are known.

Its value helps to some extent in identification and classification of solids.It gives an idea about the stability of soil as a construction material; higher

value of specific gravity gives more strength for roads and foundation. It is used

in comparing the soil particle size by means of hydrometer analysis. It is also

used in estimation of critical hydraulic gradient in soil when sand boiling

condition is being studied and in zero air void calculation in the compaction

theory of solids.

Its value ranges as follows:

i. Coarse grained soils: 2.6 to 2.7

ii. Fine grained soil: 2.7 to 2.8

iii. Organic soil: 2.3 to 2.5


76/91

76

7.1.4 PROCEDURE:

i. Take the Weight of clean and dry density bottle.

ii. Keep about 1015 gm of oven dried cool soil in bottle and weight (M2).

iii. Cover the soil with air free distilled water from the plastic wash bottle.Give some time of socking. A gentle heating may be required to dispel

any air inside the soil. Gently stir the soil in the density bottle by clean

glass rod. Observed the temperature of the contents (o

C) in the bottle and

record. Insert the stopper in the density bottle, wipe and weight (M3)

iv. Empty the content of bottle, rinse thoroughly, fill it with distilled water at

the same temperature, insert the stopper, wipe dry from outside and

weight it (M4).

v. Note the ridings as given in Table and at least three such observation andCalculate the Specific Gravity using stated equation.

7.1.5 TEST PROCEDURE:

i. Select the size of density bottle.

ii. Empty bottle is appearing on the screen, and note the mass (M1).

iii. Select the type and mass of soil.

iv. Bottle with some amount of soil with close lead will appear on the

screen and note the mass (M2).v. Click arrow, some amount of water is added in the bottle and wait for

some time (till the soil is completely saturated) mostly around 30 min

to 2 hr.

vi. Then add again water in bottle till the bottle is full and give some stare

for removing the air from bottle and close the lead.

vii. Bottle with some soil and full of water is appearing on the screen and

note the mass (M3).

viii. Click arrow, Empty the bottle and fill completely with distal waterand note the mass (M4).

ix. Then run the experiment specific gravity of soil will appear.


77/91

77

7.1.6 OBSERVATION AND CALCULATION TABLE:

SITE 1

SITE 2


78/91

78

SITE 3

7.1.7 PRECAUTIONS:

i. The soil grains whose specific gravity is to be determined should be

completely dry.

ii. Inaccuracies in weighting and failure to eliminate the entrapped air are

the main source of error. Both should be avoided by careful working.iii. If pycnometer is used, the cap of the pycnometer should be screwed up to

the same mark for each test.


79/91

79

Chapter VIII

8.1 DENSITY OF SOIL BY CORE CUTTER METHOD

To determine the field or in-situ density or unit weight of soil by core cutter

method

8.1.1 Apparatus Required:

a) Special:

i. Cylindrical core cutter

ii. Steel rammer

iii. Steel dolly

b) General:

i. Balance of capacity5 Kg and sensitivity 1 gm.

ii. Balance of capacity 200gms and sensitivity 0.01 gms.

iii. Scaleiv. Spade or pickaxe or crowbar

v. Trimming Knife

vi. Oven

vii. Water content containersviii. Desiccator.


80/91

80

8.1.2 Theory:

Field density is defined as weight of unit volume of soil present in site. That is

= W

V

=Density of soilW = Total weight of soil

V = Total volume of soil

The soil weight consists of three phase system that is solids, water and air. The

voids may be filled up with both water and air, or only with air, or only with

water. Consequently the soil may be dry, saturated or partially saturated.

In soils, mass of air is considered to be negligible, and therefore thesaturated density is maximum, dry density is minimum and wet density is

in between the two.Dry density of the soil is calculated by using equation,

d= /(1+w)

Where, d=dry density of soil =Wet density of soil

w = moisture content of soil.

Density or unit weight of soils may be determined by using the followingmethod:

i. Core cutter method

ii. Sand replacement test

iii. Rubber balloon test

iv. Water displacement methodv. Gamma ray method

Hear we use core cutter method, the equipment arrangement is shown as

follows


81/91

81


82/91

82

8.1.3 Application:

Field density is used in calculating the stress in the soil due to its overburden

pressure it is needed in estimating the bearing capacity of soil foundation

system, settlement of footing earth pressures behind the retaining walls andembankments. Stability of natural slopes, dams, embankments and cuts is

checked with the help of density of those soils. It is the density that controls the

field compaction of soils. Permeability of soils depends upon its density.

Relative density of cohesionless soils is determined by knowing the dry density

of soil in natural, loosest and densest states. Void ratio, porosity and degree of

saturation need the help of density of soil. Core cutter method in particular, is

suitable for soft to medium cohesive soils, in which the cutter can be driven. It

is not possible to drive the cutter into hard, boulder or murrumy soils. In suchcase other methods are adopted.

8.1.4 Procedure:

i. Measure the height and internal diameter of the core cutter.ii. Weight the clean core cutter.

iii. Clean and level the ground where the density is to be determined.

iv. Press the cylindrical cutter into the soil to its full depth with the help of steelrammer.

v. Remove the soil around the cutter by spade.

vi. Lift up the cutter.

vii. Trim the top and bottom surfaces of the sample carefully.viii. Clean the outside surface of the cutter.

ix. Weight the core cutter with the soil.

x. Remove the soil core from the cutter and take the representative sample in the

water content containers to determine the moisture content


83/91

83

8.1.5 Observation and Calculation Table:

SITE 1

SITE 2


84/91

84

SITE 3

8.1.6 Precautions:

i. Steel dolly should be placed on the top of the cutter b

Documents

project report on Effect Of LEACHATE on the engineering properties of the soil