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 <«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 )