ANISOTROPY OF COMPACTED CLAY IN SHEAR

DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS

FOR THE DEGREE OF

Master of Science (Engineering) IN

Building Engineering

BY

Chandra \/\r Gupta

:i.K-,

DEPARTMENT OF CIVIL ENGINEERING Z. H. COLLEGE OF ENGG. & TECH.

ALIGARH MUSLIM UNIVERSITY ALIGARH-INDIA

March, 1981

• » * *

•A * . '• ' ' ^'

X.'.**--,

; D3 7 3I ., J..Kt 'i-

DS731

Certified that the dissertation entitiiKS "Al^utPMY

Qi' CO FACi i S CiM lU CIUAH* which i s being sialMtted tjy

hir* Chandra Vir Gupta t in partial foifiiment of the require*

mento for the awar<3 of degree of Iksaiiter of 'Jclsnee (Bf^ineerii^)

in 3uii(3ing iingimering of AXigarh dmlim ^ilniversity* .^Ugarh

Is record of the ©tudenta, ourn orK carried oat hy hiai iHjder

ray eupervieion and ©aidenee. The reBults embodied in this

dissertation have not tseen suteiitted for the ai ard of arsy

other Degree or DiploEa*

^hi© i^ further to certify that ijr. Chandra Vir Quptat

worked for a ^riod of e i s months • fror, £et cotober* i980 to

3l9t tjarch 1981 for preparation of this »orl:»

( Qr« r.ohd. Haroon ) l^^ofessor of /3oil i^echanics

ALXa 'ill ar^ Foundation r n&ineering Department of Oivil £ngin«erif^

ritedi 3lst liarch-lQSi ^•^^* College of n ;,-;. s I'ech., iateai i i s t i.arcn,X9i5i Ali;,'arh .iuslim University,

Aligarh

In the proparatlon of this dissertation t?» autho?

urieties to express his heart fftit (pratitude to iir* lohd {!aro(m

Professor of 3oiI iechanios and Fouf mtion iingineering*

i^partnent of Civil :>n^ii»ering» Aiigarh t' osiie; Universitsr*

Ali^i^ for his oonslstent oai ^ ^ cet :^u|)ervisiont encoiHpage-

ment and valuable tiis© so freely given throughout the ccmree

of this work.

Thanto are also due to Prof* i ,ti, ATmwtit the present

Hea6» Departr^nt of Civil li;ni:inscring» oxnA rrof. ihaiais 4hiii;adi»

forcier Head* Departi^nt of Civil nnglneering. for providing

al l f&oilitiee &nA for hie encouragojient during the progress

of this «c»rk*

Thsml are also due to iir» ;:iasood llusain* Jr« lab*

Assistant* Joil LahoratcHry for his help in experig^ntal set­

up ana to those who helped €lr©otl2r or in<3ireotly in the

present work*

3i9t t aroht i9Bi ( Chmndra Vir Uupta )

In nature th© so l i I® consolidated Bnisotropicall.y

as the horliontsl and imrtioal stresses &Mn^ with th©

&9pth \»Xcm grouud ievei . In order to iRveBtl^te th® aid-

sotropy of c^^apaotefi eluy In shear• the imthtyp resorted to

laboratory! ntudies* fhe so i l wae ecs^paoted in a box a t

optiiaum fviolstura content and samples were taken in different

directions (0°, 3©®t 0® and 90° fv<m horizmiistXi fvcm the

bos. Triaslal te'Jts ^ere cons!i20ted on tnifsa aaiaplos tit

different confining f^^jsures of 1^ k^cs^# 1*5 fcg/ea^ and

8*0 feg/cB • In th is dissertat ion t!\9 s t ress -s t ra ln ohaimc<»

terifstios* peak strengttis, polar Glsp'at;^^ are dlsewHsed and

related to t!ie directions of tlie sj^cipiens tested• I t i s

conoladed that t^haviour of thio ccMapactedir Jol l in shear

le anisotropic and thle ie l»cau8e of the crlentat ian of ao i l

par t ic les paral lel to tiie plan© in whicii ccMpiitlve effcrte is

applied during compaction*

C Q ;j T K,.II f 3

PagB

m&Fmi - III

3.1 frlaxlal ^hear 4|ipanitiffl -j

3.2 L«ma and Defonnatlon wasurliag j , .

3»3 Sols, lisea aiuS i t s p»oj»rti«© 11,

3«« Preparation of soil anfi s aap l i ^ l-v-

3«5 ^©st Frccedor© ,*

^•l i-'-tJ^ss-stPaln oharaoterlstlcsi

^•2 Gheaf Stpcngtij paras^teps

^#3 Polar diatiPais for etiaar strengtli

XI

APFL'iliDIX «> IX

AFKIIIDIX • 111

M J S OF FIOUKO

U^!I' OF SABLCS

34

isif

m

m

In conirentional triaxial eaemr t@st@» the ^mjor

prlriolpai stress is lo vertical dlrdoticist fh« oriental

tlon ©f prlnoipal stress e^stts should not influence tlie

©trenntfi oharacterleties of Isotropio soil©. Hofeever*

most of tfte soils tjotft msn-«sde car m.turmll^ ocotiriwg have

anisotropic ©traoturet and hence there eiist® anisolapopy

of Bh^BT strength in almoet a l l ©oils* fhie r an® usual

isfcoratcrir tests are not able to oorreotljf predict the

l^ftavlour of soils for ostieating the @taMlit^ of Bn mx"

fefiiife;':©nt or feeoring capacity of founc \tionstsince s l l s ta-

bllitgr prot>leE3, assuin® reasonafele rupture siarface oM the

eriantaticn of prinelpal etres© ©jratem along the assussd

failure eurfases change from one point to another as &hmn

in l-'is3 i»l mv& 1»2*

In order to investigate the anieotpopy of oo»i5meted

ela^^ in shear* the aat cap s^aerted to Im'baratoi^ studies*

.aiisarh elasr wae ©oEpaoted at optimum ©oisture content la

a tsox. .:oil spnpies for tr lsxial teste were ttiken at 0®

(horisontal), 30°* 6Q^ wM 90® (vertioal) aireotion froij the

horizontal with the help of thin tube saripler* b i a x i a l tests

were oonduoted on these seiaples at confining pressures of

fe^cm^ ana 2.0 kg/em^» The results of

///^aoAv^

VT (MAJOR PRINCIPAL 1 STRESS)

SLOPE

'HEIGHT OF EMBANKMENT

N A T U R A L S O I L

FIG.n ORIENTATION OF MAJOR PRINCIPAL STRESS ALONG AN ASSUMED FAILURE PLANE IN AN EMBANKMENT.

GROUND /f/WI 7m 7!TO^

D i

B FOOTING

SURFACE TTTO TfyHr-

SURCHARGE=yD

'45-'ty2 II \ " ^ #^5-^/2

• ^ ^ ^ ^ ^

FIG.1.2 ORIENTATION OF MAJOR PRINCIPAL STRESS ALONG AN ASSUMED FAILURE PLANE IN A BEARING CAPACITY PROBLEM.

labopatca^ trlaxial test® show thnt th© undrals^d shear

etrersgth psr«2»t«F8 ©f oo©|sicted el&y of 4llgarf5i varies

mpendin^ en the direction alou^ %hicn tU© clay Is brou^t

to failtiff©# SThe ®ti?tss strain charsct^rintles* peals

©trengthas, poljir aiai^ras'S ar© tllscucsefl ajitS rtlated to tin©

dir@otlon of s^ole^n tested*

Vh@ iiivestl^atloa presents th© (5©gr®© of strei^th

?iJ5isotrox^ of B CQsipaotea clsy. I t is expeetsfi thpX 1Kb©

tf^iaS will 'd© smm Cov a l l o l a ^ , altliou^.' the .':.agiiit«<t©

of t 'i© strengt!.! dlffereno© .::sy vars" fira:s otm ola^? to amcther*

An attempt hm% tsoon I2*J4© hsr^ to ntxk^.f as to hoer imch le

tri© na piitttc!© of etapongtn difference &>M to orieutatloa of

th© pric^ipnl stross ej^stes.

5

In natur® tit« horlKorital and vertical effective

8tre»s®f! a*ian3© %:ith tli© <^-gth aolow <|rouiiKl levtX* The

effective vertical prensur© aJUiO ia not tli© aawe as th«

horlsontal affeotiv© prebsui*© at luiy 6«|)th» I'hua In natur©

also tUB uoil i© consolidated atilsotroplcmlly* ior taa?*-

{fififl© ©FJth ©sfeanEr- int® ttie soil Is GempF.ct«a In Xa ei

«git!i application of vertical pressures# the horlssontal

prec'.fTsa?© almost does not exist. '2huB r aafmd© earth embank-

imntn are aiilsotroplcally ocmpRQtm6* I t has therefcar©

l)88!i reeoiXilsed t f vai*louB r:©searcherQ that the behaviour

of coh©Ji:5sr« sel l In Ehear Is anlBOtrtiplOt

Bishop (19^8) studies th© aideotoopy In shear of

London Clayt vertical mvA Inollmd eauploa w©r© tal^sn for

teiJt In Gheart frosi the naturally occurlng X«ondon Clay» I t

ras otmervsd that the strength of th© inclined samples «s r©

aboat 28','' less tf -an the stre3a§th of th© vertical isauples.

i Mj pton (195^) has also inveetlsated the strength of

Inclined find vertical eartples of natural London t»lay and ob­

served that the strength of Inclined eanplee from shallow

depth ¥^re 2S;' less thjin the etrength of vertical sacsples,

fsherea© the strength of Inclined smsples froa greater depth

were only i^ lese than the e t re i^h of vertloul sasiples*

s

ThvsB i t api^ar that at cheater oonaolidatioxi px^nstira

anlsotropy Ifi shear does not play a E;aJor r&ie.

Jaootjsen (1955) etadied the .mlsotropie toh&vloap

of poot»gl30ial Eiarii» oXay of Sweden in &lt«ar« iiat saspl©s

froa th© mturally coctarlng olay at a depth of 3 a baloi^

th© r^aanSi levcil war© takan at vartical Inclined aw2 feori-

aontal slOi'^o, Th© greatest averas© difference Imtween

any t9ro types of cas-iples ras iftf., Jaoo^sen also ccnioluded

that the swedlah poFt glaoipil earir^ olay wiys almost isotrcpie,

ilenon (i9B0) has recently reported that the U3idrai!^d

Bfeoar etrensth of Uong rii oo-Mao olay vm?ies within &ld« llidLt

denetalins on th© dlreotioa along ^>idch the clay ia lai'ouiiht

to failui^* ior anieotropio coil , the strength will 6©

p ftaaotion of orlentatltm of the epeoir en axis r i ih resj®ot

to th© prinolpal asio direotloji*

Hvor^lev (19^0) 1® probably the f i rs t • investia^ator

to etudy th© anisotropic Lehavlour of coiisoliCated remoulded

5p©ciE am of O1B;^» II© uaed vienns arid l i t t l e - i e l t clay

and taated trimmed v©ptioal» Xnelined and hoFisontal sarplcs.

He obf orvod thi t th© verticil emcples haim hi^.er strength

thBji th© inellnsd or horiecnf*! sarjples.

I t i2 aJU'-ost octfiblloh©d faot tU^t nstijrally aocariRg

oohoaive coil are anisotropic as re.:^rda the Ghear strength

though anisotropy In shear stren^tti does not play a mfijor

rol© at greater cc!isoll<lation pr©sstjrt®» I t appears fro®

the proo«sa of ocupaotlcn of so i l for trailing ciin1im!L":ent of

roads I (3nL:s arai leveea that thB s e l l of ouch a com true t Ion

wi l l also havo rmlsotroplo behaviour in ehear t)soau30 i t

i9 visu:ali£!e<3 that uurinii the cc^s^ction procesa the so i l

pnrtleloo :30t oriented f:\rallel to the pltm© en v*hicli the

major principal otreas acts during coi^ipaction. .->iiic© the

ccmpaotion io aohievea ^ applying v e r t i c i l co^jpactiw

effort to a layor of s o i l , the so i l part icles j et (oriented

in horinontal dirootion. I t lo therefore postulated that

the ccKsp. cted ooheaive aoil wil l have difi'ercnt shear strength

i f the 3nF::jles nr© ts^en in dlffere:it (directions* I t mas r i t h

thlB in t^n lon that the attar.jrt «ts fid© to stufy the ani»

Gotr-cpy of ecs:nacted so i l in Bh©ar»

a

CHAFT a • III

friexial shear test in oarried out in a tria3U.al

cell whic!i co^nsisto of a perspex cyllnaer fitted t)etirtefi

a tissBB mt^ a top cap* It oon^lsts of loatllrig s»ohif$B oM

X(mjA and deflection tmmnrinz devices. PUotograph of the

triaxi'ii shear test set up is Ehcrnn in Fig«3*|» The

descripticm of the apparattxs is given beIo» i

Triaxial call have thr@© preesura coisnectione throu^

the baseI ceil fluid inlet* pore water out let from botto©

of 6peoit:«n and drainage outlet tttm top of specimen* water^

under pressure is ueually used for buildins up confining

pressure in the cell* In the top cap there is an air release

valve which is kept o^n daring the filling of the cell

with water* A etTLinleee steel piston nrniiir^ throu^ the

centre of the top cap apfli®® the vertical oompreijeive load

(deviator stress) on the speoiisen under test* fhe vertical

load fr&rr the piston acta en a pressure cap resting over

the top of the apeolr^n*

?h© cpeoirsn is enclosed in a rubliar-sesljran© at>out

0*1 or 0*2 £Es In thlcfemss* jopondins won th& drainage

eondltiores of the test* solid ncnpcrous dises or end caps

or poroi^ dlses ore placed on top and botto® end on the

JO

opeoisaen atwS th® rub^r m0m"brf jit 1® sealed on to these

end cans ^ rubt«r rinpt. The effect of the rubber m&m»

Wnrm i s to ellghtly increase the apparent strei^th of

the speclf-^n.

^ e length of the si«cltien is kept fv(m about ^o

t© tfe'O BM a telf tlses i t s dlanKJter. -ih® diajsieter of the

epecliaen ie 'oeln^ Itept to be 3*3 cm and the length of the

8|»oli!»n &e 8«5 en*

the vertical load on the speclEwn is applied ^rmflaa-

l ly train a etmined con^olled loading swohine* The load

is i^asured from th© deflection of n callbp^^ted proving

ring reotins on the piston of the cell* the vertical strain

of the s|ieoiEien is meaeared fr<^ the dowjsrard Rovei tent of

the piston as IntSloated tsy another dial ^tis» fixed to the

top cap of triaxie.1 cell*

2t ie usually deeii^^le to tsaintain the cell pressure

constant duping the test . I^pessape la ^ i l t up in i?ater air

reservoir witier byasjotor driven oompreesor or by a tyrepusp.

3.8 LomC.amd Mformtionre^^

5he vertical lead applied on the epecif^en i t aeasured

fros the deflection of a calibrated proving r i i ^ resting on

the piston of the ce l l . Immt count of the proving ring io

11

I divif^ion • •0001* and the deflection of I dlvisloa on

tne ring develops a Xo&d on the epeoSxian «qmal to Z ib«

?he defoHiiation of the speoie^en under the Xtmdlng

%mB sacaswrea tjy dial gauge f IxeS to the tap cap of e

triaxlal cell* Least ooimt of the dlfil fsawge was 1 dlvlalon

• .001"•

3*3 ;M ,..P9f ,J^n^ ,|^9,,fiFppeir^^^

? ?h0 properties of the cohesiiro KOII ussfl In thl©

®taf!y are as folios® i

X) Atterberg 2«liQlt8 •

Uqald Uialt. i | « 28f»

Plaatlo lAaltt*'*p • 21^

rieatlolty Zn<lextl_»^a

Frcn the plpstlolty chnrt 8ho?;n in iis«3.2 (I.iil^98»

1959) • the above eoll lo clsisclfled m Oh soil* ihe gstiln

olse al6tribatlcn of the EOII ucea li; also given in ris«3«3»

XI} Sompaotion test •

Utanusra rroctor test mm perforF.ed and the results

are as nn^r i

^%ax» " '*4ixl®uiL Dry Itnsit^? « l»9 t^mP

(-•»£•€.• optliscuBt ^:oi8tlaro Content « %!^

15

U) (9

IU<t

s.

N oeiii

Z 3

T-tr

z "3 ^

3 : \ u N

\

D y « \ UJZ o<t =!9\o2:<i Z ^ 0 3 Z C I <t^ «nC <tuju

111 00 (A

3 0 : w

2 J

O t - -

Z < t j

Q W U .

1 1

z o o

\ I

u

u

\

2 o 0

\ (TO

i'fll|;-\'> • m l - ' A

o o

o

o CO

o

I-

0 2

U OQ.

O-J

3

z o

in in

u

o in

Ok in o»

T

in

o o o o o o tv ^ m <9 n (M

lN33a3d-X30NI AXOUSVld

O UJ m

H GC <t X 3 u > u in <I J 0.

in

6 iZ

18

o z <t in

5

5 U

•0

ID

IT

U

5

z iZ

in

<l o o z 5 ^.

Ui 2

z o

u

in m <I J U

->•

->•

•V

, V, V

• - ^

'

o o

t

E E

w o u> o Z

o

o o o

o in

(J

z I-u. o > C D U z o

OQ

in 5 UJ N In

O

6

o o to o o o O o

J.H9I9M AQ il3NlJ lN3Dii3<i

u

Th9 moistare • fiiry dejisity rolatiuimlilp is ehtrnn

in Flg93»<»«

3«^ ^r9mrmtim of aoil Ana uaaplina

Goll used In this study was sslxed thorooj-i laf «ith

optisram moisture content (G«r;«0») determim^ by standard

l^ootor t«9t« After adxlngt th« soil %m ootspacted In

layers in t!ie wooden b«» of sie© 50 « 50 x 25 cm* fh« l>ox

waa filled vith the well oiixed soil in sis Is^^rs and cois*

pating each layer with 800 !>lo«f3 es detercdiwd in proportion

to the etanfiard Frcctor test.

¥rcm the Ixm. the sasples ¥iere taken at an inclina­

tion of 0°, JQ^t 60° end 90*^ froia the horleontal with the

help of eac^ler* ?ne Ba.mpleB were ta'^en IToie the cot^paoted

©oil at a distance of t out 10 cm centres to avoid filst«r-

bEuee to tne st^iples* All tue saoi^les were tested in about

one mBQks tioe to avoid thixotropio effects in the @oil*

-j.S geet rrocedure

(InconBclidnted • undrained trlajcial shear tests were

carried cut cm renoulded ear pies taken from tlie box. In

this test* tlie 8peoi:.en enclosed in th@ rubber ise&ibrane is

placed between eolid (non«porou3) end caj^» '*»ater un«!er

pressure ii; used for buildl!^«up confining pressure in the

cell* ^ e (iiamcter of t^e ai^oinen was 3*3 oa aftd the hei^t

15

2 0

15 20 25 MOISTURE CONTENT, V.

30

FJG.3.4 LABORATORY MDISTURE-OENS/TY TEST RESULTS

je

of th« epecimea was 8.5 os« the !»p80ir.8n W«FO t«st«d at

different confining prassures (^3 ) of 1.0 ku/cas^,

I #5 fes^QJa^ ana 2.0 kg/ca^ la^ the lomd waB aispUsd at a

strain rata of O^Q^ sm/miimtt* After applying tlie desired

confining i^^ssure (cell pres ure)» the speoli!»n Is failed

by Increasing axial devlator strain i^ % • ^ 3 )• Hach

test lasted for a perl a! ranslr^ fposi atJOttt 30 to ^5 lalnutes,

17

A series of unconsolidated undrained trlajEiiil. Mh»@r

tests vere conducted on soil speolriins t a ^ n fros a cj^pac^

ted sollt sampled at 0®, 30®, 60® and 90° direetioi;® to the

horisontal* ?he ceil presi;iire ( c(^tfinline presstire* 3 }

adopted ware l.O, 1.5 and 2.0 fej/crs^. The trlsxiiil tests

«ere cajrrled*out s t a strain rate of 0*89 tm/t'Afmt9* omim&ry

of ^ e results of t r las ia l te^^ts are c lven in table A - I ,

A - II* A - III BM A - IV of Appendix • I I I . ^he aversse

of tiro sataples tested at sime oonflning preaeore was tal:en

for ealoaintion*

Geviator stress ( V | • ^ 5 ) varous percentage axial

Btraln for sariples taicon at different directions ( 6®i 30^,

60^ and 90® froo horitontal ) are plotted In Fijj. ^ . i for

ccnfiRin3 precsare of 1.0 kg/ca^t In i'lg» ^.2 for confining

pressure of l»5 ka/ca and in Fig. ^.3 for confinl?^ preD..iire

of 2.0 kg/cB • flie stress - strain curves resulting from

the failur© of horieontjil and Inclir^d sa^iiples stioR pronoun-

ced peaks. I t lo evident ffom tlie8s-ri::fjrey tJiat nnicotropic

effect leads to tlie hi:f:?ier fctllare stress as the inclir^tion

of eas^les increases from ^ e horif»ontal» The failure deflator

stresses versus Inollnation of saisples «lth horizontal i s also

JS

AXIAL STRAIN,%

FIG.^.1 STRESS-STRAIN CURVES FOR. SAMPLES UNDER V3 =1-0 Kg/cm'

TT^

U 8 12 16 AXIAL S T R A I N , %

FIG-/; .2 STRESS-STRAIN CURVES F O R . SAMPLES UNDER V3 =1.5Kg/cm?

2f)

/; 8 12 AXIAL STRAIN,%

FIG-4.3 STRESS-STRAIN CURVES FOR . SAMPLES UNDER 73=20Kg/cm'

21

plotted In rtgt 4.4 for different confining isressures

( ^ 3 ) . Ilhe deviate ::tre8a C "^i • ^ 3 J at failure

lnore3S@3 aliiaiit linsfiriy a® t>tt inollnation of the sample

inoremsee from the horisontal* I t can also l;e inferred

t!mt as the cojifinisis iwnaui'e iiioreasres tlie failure stre*

cseo ^Iiio Insrease for a l l the um-plj^B*

2he oaslmim strain at failure « versus incllimtion

of sanples ^ith horiEontal are depicted in Fig. 4 .5 . I t

can t)© concluded that the failtare etre3S occore at sjsalier

Btrains c© the Inolunation of sar»ples inoreasee frcaa the

horizontal, fine effect of increase in confining pressore

I0 to further reduce the etrains at failure.

I t Q-n t3@ thus deduced that g^nei:^!!^ stress-strain

characteristics of compacted soils tre dependent on the

direction of opeoii-.en tested, ^his in true for different

confining iirescures also.

Che ohservatloa of maxlaum failure stress In the 90**

( i^rtioal } direction esipS^s and mini&ua at 0* (horizontal)

direction samples taKen ft ou ooiopaoted cc^eslve i^oil m^ tm

attri^tesS to a certain dei:T8® of orientation of the soil

particles in 'iho dlreotioa periJcmlictalar to tlie cotai^active

force.

"fe 8 §•

LK)

in UJ

» -

a.

z X <

6 -

4 -

1.

^3=20 Kg/cnjl.

X

P2

0" 30" 60° 90" iNCLfNATION OF SAMPLES WfTH HORIZONTAL

F/G.4-4 MAXIMUM DEVIATOR STRESS VS INCLINATION OF SAMPLES WITH HORIZONTAL.

0" 30" 60" 90" INCLINATION OF SAMPLES WITH HORIZONTAL

FIG.4-5 MAXIMUM STRAIN AT FAILURE VS INCLINATION OF SAMPLES WITH HORIZONTAL.

23

^•2 P.ftffir ''t|:fr|^^ FfTitiflffyf

OtiXieia^ tlie aevlator stresseo at failurei smjor

wnA minor principal stresses {^i and ^ 3 respectively )

«;ere obtained for vertioml aiid horieontaX caiiple8« and

saisplee ta^n at 30° ana 60** irtm horisontaX. Aversge of

tKO saspliffi tested at tlie 6a»ae oonfinii^ laressur© wis talent

fjie sai pXes *?ere tested st three confining:: ppe::sure8« Tear

the four t pes of saiipXes i*e* verticmXf h&risontal aM

Bm^l99 ta2:en at 30® end 60< frcM the horizontalt Kc Jr

GireXes are pXotted in Fig. ^.S, fe.7t ^«8 and ^.9 respecti­

vely* Faiiure envelopes are shourn In these figures* 2he

shear etreng^ p^raiseters •ti* and *0* derived ffron t.ohr

Circles sre giwsn In fable-I. Jhear strength p?xaiaeteitj

of 30** and 60° easiples are alm«Mit sarte. It appears fPGm

the results, that the sajor part of the atrength is derived

6x19 to cohesion for horizontal saapXss* 5?lie faajor chanse

in stref^tht however• id £ue to inoreast in angle of internal

friction '0* tot vertical sacples.

QO

30°

60°

90°

6

6

6

6

•a' (/ig/cmS)

1.40

1.05

i.OD

Oi,90

•^« (ee^pee

16

21

22

26

24

6\-

tfi

Dry Denslry, rdr 177gm/cm^ Molsfupe Contents 16-2%

Foilure Envelope

^•r10Kg/cnrj2

^=1-5Kg/cm^

Vj =20 Kg/cm?

NORMAL STRESS, V- Kg/cm^

FIG.46 MOHR CYCLES FOR VERTICAL SAMPLES

Cr1-40 Kg/cm2

Dry Dcnsily>rd=1-77gm/cfn3 Moisture ConlentslfiVo

T

s1 0 Kg/cnr

rl-SKg/cm^

p 2 0 Kg cm?

NORMAL STRESS, 7" Kg/cm*

FIG.4.7MOHR CIRCLES FOR HORIZONTAL SAMPLES.

25

u Dry Dcnsiry, rd-1-76gm/cm^ Moisfurc Confen^-16-2Vo

Failure Envelope

2 4 6 8 NORMAL STRESS^V- Kg/cm^

FIG. 4f lMOHR CIRCLES FOR 30° (INCLINATION FROM HORIZONTAL) SAMPLES-

E Q\ 6

< UJ

z

i Crl-Oj, Kg/criTl

2 -

j<

Dry Dcnsil"//rd-1-76gm/cm Moisture Conrcnf-16-4Vo

Failure Envelope

NORMAL STRESS, V - Kgfcm^

FIG. 4-9 MOHR CIRCLES FOR 60°(INCLINATION FROM HORIZONTAL) SAMPLES.

2B

flhear strengtli of ai^ so i l l3 given fey i:ohr*cclotiis1)

T f • C • u- tan ^ ( I )

wh®r« T f " ^^®^* atrengt!5 l a Itg/c®

G » Unit cohesion In k^cs?

cTis r^onual strecs a t fctiiurs plu.TJtSt \s/^

0 • Angle of Interasil fr ict ion In dtgree

Equation (1) i s aleo the equation for strength envelope*

The otrength envelope for the horisontalt ver t ica l ana inclined

O'inples of th is pert icalar so i l wil l be as un&mt •

Horieontal sauple •

TfQ « i.«> • ^ r t a n 16® (2)

30® inclined ssusple t

TfjO • 1.05 • ^ tan 2l<> (3)

60® inclined eaiiple •

"^feo • l.OO •'T-tan 22° W

9@o I.e. vertioal ssmple >

'Tf9o • 0,90 •^rt?».n 26° •••••• (5)

^he above strength envelopes are plotted in Fig* 4*10•

It is concluded froa this figure that cohesion predor-iiimtcs

for horlBontfii saisples for 'T-< 2«5 fe^c©^ &M the strength

27

0 1 2 3 ^ 0 5 NORMAL STRESS v; Kg/cm^

FIG. -10 STRENGTH ENVELOPES FOR HORIZONTAL,VERTICAL,30°AND 6Cf INCLINED SAMPLES.

28*

of the hori«ontiii etu^pXe 1@ mot9 than the vertleai saesplo*

ilowevtrt for *^>2«5 ^g/cs^ t!ie intargraitidar strength is

higher thafi cohesion and so strength of vertieal eajrple is

nore than the horisontai smipie* It is also concluded Sttm

this fii^ore that the strength of the horieontal sample for

^T~< 3.5 kg/cm^ ana ''' < 3.0 kg/eia^ is ©ore thun the strensth

of 30** and r>0® inolinecS saEple respectively* Hoirevert the

strength of 30® ana 60° inclined samples are acre thmn the

horisontal f;a^le for '=»"> 3»S feg/cm^ and 'T-> 3 « 0 kg/os?

respectively.

^•3 Polar diagram for ihear :;tgength

Osing ;:ohr^oloumb equations (2)»i3hW and (5)» the

shear strengths for samples of inolination d°t 33®• 69** ai*3

90** froE horisontal were ccKiputed for ^ « 1»0 3£g/cR^, 2.0

feg/cB^, 3»0 kg/ca^ and 4.0 Icg/cia « The saar e is plotted in

FoL«ir dia r^H shewn In Fig. 4.11. A ociaparision tjetireen hori*

sontal shear strsnsl^ ( ^ ) and vertical shear strength ( f^)

is also given in the polar dl^graB. fhe ra.tio in almost one at

'r • 2.0 ks/cffi?, however for '" 8.0 Iq^/cm^ the strength of

horizontal eaiaples ore sore %h:m the vertical samples and for

'3-> 2.0 &g/cni2 the etren:|th of vertical sassples art sore than

the strength of the horisontal samples. The s^ner^l treraS is

observed to b© that as ratio 'y f ^ t g <29creases with the

Increase in noraal etresa • • •

29

<

>

|^=1.24,For\r=10Kg/cm^

2!}=l.06,Forr-=20Kg/cm^

?l3=0-95,For 7-=30Kg/cm^ Tfv ""

|!3=o.88.Forr=40Kg/cm^

30

HORIZONTAL

SHEAR STRENGTH Tf, Kg/cm^

FIG./;.11 TRIAXIAL SHEAR STRENGTH POLAR DIAGRAM FOR DIFFERENT NORMAL STRESSES.

30

i* th9 triaxlaX t«ist results of soil samplts ta]c«n team

ccjupacttd clay of Allgarli» at four different t^lreotlons

(0®» 30 f 60° and 90** Irom horizontal) t shcm that ttio

etress strrtln characteristics of the soil are related

to the direction of the Fpeoli-iSn. ^he devlator stress

at failure of the eanples increases as the direction of

sample Increasee from the horlsontal.

a, The ccffiTacted dm under Investlcmtlon Is finlsotropic tsfith

respect to ghssr ©trt!^h pfiraT?mt-ers 'C* nrv& *0** The

epscl'-en t^r^sa at different Inclinations show different

strrnsth pnr0i!M>t8rs* Thin kin0 of vsrrliitlen In shear

s t r c r^h paranetere of ocmpacted clay fjidlcate that the

ctmvcnticnsl Rsethod of i»ng.ljrsln£, the atability of ©ansade

CBbap^ent or bearing capacity probleia on staMllsed soils

are of^f.tisfaotory and aneoonomlcal.

3» The cohesion prertomirKites for hurl?,ontal aaaplee for ^< &S

l::l/cs^ KM the strength of the horizontal saaples are sore

tnan the stren^sth of the vertloftl aaisplee* lloiiever* for

^r-> g,5 kg/cffi the Intergranat-ir str8n£;th Is h l ^ r

thtn cohsaicm and ao stren,ith of the vertical samples are

more than the otrength of the horiaontal samples.

^« ^he ratio of horiaontal shear strength and vertical shear

31

strenf^h ( Tfj j / T iv ) ^as foa vl to vary wltfe • <3r •

normal stress at failare plant, ^ e increase in ncsKiiil

strecB teiifjs to decr«as© the i^tlo ( Tfh/Tfv )•

S* Ih© in^mstlcatloa presents th@ (fe r®^ of ntrength £nl»

BQtrcrj oi Ali::arh cor'!i)aot9(! olay ciily. I t ir> egpected

tii"t th© tit;n<2 will c® r.iiallar for other c l a ^ elsoi

ft'cyi-: on© oloy to anot!ier.

32

1* A, Senon. Dar Al '/ianflauah (1980), "Onfirali»di .*h«ar

3taren||t^ Anlaotroi^ of Clays*', Intepaatlonal .^yi^oslua

cm XmM 'lldeBt Hew^Belhl, /ol*!, pp»l.09*ii2«

2« :)u-noan, J.::» ana 3e®a H. ^iotton (19^6;, *Anlsotro|^

sjidi rJtF®ss-r®or®ntat.ton in Clay*, ^Joisrnal of th© >;« .«

and Foii!Vtatlor« Divlsjlon, AsGr„ Voi.92,2lo.j«I;..5 Froc.

i-aptr 4903 pp. 2i»50.

3, >Jccnptoa» ^••u.(i9^)# "wli® r-melreaauro Uosf^Tioi^nts

A ai^ ^t aotjtaciii'iiqut, 2mt. ef Ciir. ^ r \ ^# Isandon

^ . Hansen, ty»ij» araa Gibson, :i»K» (I9 9)»**11n«3raine<! :ii«ar

':trength of Aniootropically Gonsoli<!at«d Gl^ys" G«ote«

chnlquo, I r^t . of Civ, iJn^ps. tontlon, l^ol.l, *io.3 pp#

l89-20^«

5. Jacotsen, B, (195S)» * Isotropy of Ola^" C#soteclmique,

Irmt* of Civ, :;o<^?3, LoiitJoii, Vol.S, :*o,i, pp. 23-28.

6. 2»o, /..Y. (Juljr 1965)1 • -^tRtJlUty of i/lopes In Anlso*

tropic Joll" tJoamal of tii® ^oll neshanlcs KnA fotiRdatlon

Jlvision, iiu€£, Vol.911 1*0. . L.i*, Froo. h'mpsr 4^05 pp.

65»io6.

33

?• Harasen, J.li. (1952) • •• A Oftntral Pla»tiolty theory

for Clay* Oeotechnlqua, Irsat. of Civ» L:i^rs» liOndoii*

Vol.3, r^o,4, pp. I5tj*i64.

8# 3is!jop, A«v:« (19^8), * Jon© F-iCtore Involved In the

Oeslp i of a Iarg9 llarth Tins? in the Thames Valley",

Ppoceedln^, 2ns!l International Uonfereiica on ^oil

lechonice and Foondatloi^* Hotterdasi, Vol*2*p«l3«

9» Hvorelevt L.J» (t96d}, " l^yslcal Corsponents of the

Jhoar Jtrengtii of saturated Clays", k.l&B Kesearch

Conl rerK»» on t^e ^h9W^ strength of Cdlieslve .^iolls,

Cenver, Colo*, pi* 169-273,

10, Cl?.^clflcstf.cn aiitfi Idsntifloat!en of .ells ft p General

:'nziTXtrir^ Forprses", Indian :tr?idarfi i 1 '98 • 1959•

I-il, 'let; t^lhl*

31

APFEIIDZX - It

c~ • Nomial Btr«83 ftt Failor* Flsno* Kg/c»^

^l • fiajop FriR0li»a2. 3trt8s, kg/tm^

^3 - Confining l¥©88ur«, kg/bis^

Ti^-^j . Dtviator Jtrtss, kg/cia^

C . unit Coh.Bion. ks/oo^

^ • Ai^e of Xnttmal Friction in &9gt99

^f • Shear Jtr«ngt!i. kg/cBi

Tfh,Tfo» Kopieontal ihear strength, ke/cs?

^tv Tfofl- *' *'®*^ -hear v)trtngtli» kg/es^

rrf30 • Shear Strength of 30** Znolined (frcac horisontal)

Tfgo • 3hear strength of 60® Xnolined ifrm& horisontal)

sasiplee* kg/ct?

V^ • Dry Densltyt ga/ca^

Tfd ot* laxisjua Dry Density, ^ja/cs^

a»ig«C« optistiB iSoistnre contentt^

W| • Uqiiid U@it, ^

^p • Plastic Liidti^

Ip • Pl^ifiticity Index,

D • Depth of i ounflationi a

B • fcldth of Foun(!iition» m

Qf - Oltioate bearing capacity /

35

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1*1 (^ientation of itajor PriiKsipal 2

3tres3 along an asuured fmllur*

plane In uxi embankment •

Flg« 1*2 Orientation of i lajor Prinolpal -

otrtss alor^ an assucied failur«

plane in a Hearing Capaoi^ prol>Iea

i*ig» 3«i Fhotograph of tlio trlEixial Jhsar »

test Get*upt

Fig* 3»^ Plnstioity Chiart Used in ^oll

Classification (I~i 11^98-1959)

Pig. 3.3 Grain aise aistriliution Ciirvm of

the Goil.

Fig. 3»^ Laboratory f^oisturt-Density test

Heeults.

12

13

IS

Fig. ^.1 iitress-Jtrain Curves fc^ ^miplee under ,„

" 3 • ItO kg/^

Fig. 4.2 3tre©s-wtrain Carvea for .ajaplea under 19

3 " 1»S lig/ca ^ 1 m, * H t . n . / » M 2

41

Pa§t

[m ^•3 U^es8«^)train Curves for . aEples ^

Pig. ^.^ giaxiao^ Devlator -itrass Verstis 22

Inclination of wamplns with horl-

sontal*

Fig. ^mS hlsMimm strain at I-oiluara Vs In-

olination of iaaplea ??lth hrarisontal

Fig. ^.6 EoIiT Circles for Vertical 3aspl«8

Pis. 4.7 i ofiT Circles for Horisontal

3ojsple8

Fig. 4.0 iCohr Circles for 30®(inclined; froa

horlsontal) isunplee.

rig. 4.9 Hoiir uircles for 60^ (Inclined fror.

horleoBtal) Sanples.

Fig. 4.10 -.tren^th envelopea for horlsontal

Verticalt 30^ imd 50° Inclined

Japples.

Pig. 4.11 Trlaxlal -hear -^trenstfi lolar

dlai ram for aifferent fSormal

.stresses.

22

24

24

2S

2S

27

29

AFFEK0IIC • V

xji^'s m '2ABm:^

42

1?&t>l« • A«I 3\ii;3&@r of t r l as la i « h«8r ?«st

H«@ul.t8 for 0^<horlsont&l)

SflSlpI«8»

^uEsaary of frlsxlal wfwiar T»st

Hesulta for 30^ (Xnoilmd fr<m

horleontal.} i:at<,pie8«

fat>l« • A-III StBsaErjf of friesJlal jihesr T#at

BemtXts for 60® C InoUntd flrero

horlsontaX) l^as^les*

Ta&U • A*ZX

3&

. /

3a

Ta^it • A-IV jusaa^ry of Triaxlal ^hoer ^©st

HestiXts for 90° ( Vertical )