(1991 Duncan & Wright) Slope stability during rapid drawdown

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£

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Sl Stblty   

Sl Stblty   

J   h  Wh

J   h  Wh  ;  W

 ;  W

INTRODTION

INTRODTION

The wters had he gea plesur of wong th Pofessor Seed on the eseh The wters had he gea plesur of wong th Pofessor Seed on the eseh erd n ths a.

erd n ths a. He He plyd n cive plyd n cive le in te sudle in te sudies ies whih we gunwhih we gun in the ey

in the ey 1980s1980s _{(Wong, Duncn ad Seed(Wong, Duncn ad Seed} 8383 _{d contnued late unde ad contnued late unde a}

ntat fo the

ntat fo the





S Ay Cps of Engnees Wgh nd DuncanS Ay Cps of Engnees Wgh nd Duncan 187187 _ee



 _{leased t akwedge leased t akwedge rofes Seed's grofes Seed's gt t nuence on nuence on d onbutin tod onbutin to}

ths work ad to dedate ths pa o his memo ths work ad to dedate ths pa o his memo

AID DRADON LOP BILIT PROBL

AID DRADON LOP BILIT PROBL

hen

hen the wate leve outsdethe wate leve outsde  so dops, th sablzing nuence so dops, th sablzing nuence of the waterof the water res

ressue sue n the slon the slope s pe s los los If he we If he we eve subsdeseve subsdes  _{pdy th the epdy th the e}

ressues withn the slo do no hv tme

ressues withn the slo do no hv tme  _{chnge n equibum wth the dropchnge n equibum wth the drop}

n exel wte evel the slo s de less sble n exel wte evel the slo s de less sble

Many filures of dm slopes n nu sopes hve cued dung d Many filures of dm slopes n nu sopes hve cued dung d 

don don heshese ncude fo epe ncude fo eple Pilos le Pilos D u oD u of S Fnciscf S Fnciscoo





A WeA We

&&

AssAss 77 _{Wle Bouldn D n  (Witeside,Wle Bouldn D n  (Witeside,} 176

176 _{d  num of ed  num of e} kk sos ong  Ro ono n Pe ee dsos ong  Ro ono n Pe ee d uncn,

uncn, 7575 _{Rpd ddon imss ve ve odng on slos nd isRpd ddon imss ve ve odng on slos nd is}

uenly

uenly te desgn ondiote desgn ondio  c  css





seepss ofseepss of





upsm slos ofupsm slos of ams

ams Anlysis of pd ddon s heefoe  m consdeon frAnlysis of pd ddon s heefoe  m consdeon fr esgn of dms, nd fo desgn of he slos t wll  submeged d subject esgn of dms, nd fo desgn of he slos t wll  submeged d subject t dwdwn

t dwdwn



UniverslY Dinguh ofe. Vgn Poyhc InUniverslY Dinguh ofe. Vgn Poyhc In d S Unrty d S Unrty Bakb, V

Bakb, VAA



AshleyAshley



Pidy Cnnnl ProPidy Cnnnl Pro



CC



_{Eng Eng r. r. UnvrtUnvrt}



_{Txa, AusnTxa, Ausn}







AA Poe o C EnPoe o C Enn Ny Tnonsu ngn Ny Tnonsu ng







Dun�nDun�n W&h a W W&h a W nn

at

at  of hgh aby can  dring pid drado but teas of hgh aby can  dring pid drado but teas





clay cnten ca

clay cnten ca T aalyze T aalyze sably during pid sably during pid radow it s radow it s ecssecss 

di

di whch teal ll drain an whch teal ll drain an hich will no. hich will no. In doubtful c it In doubtful c it mumu

b

b a tat dina eihr ill or ill nt cu whhver ill reslt ina tat dina eihr ill or ill nt cu whhver ill reslt in  low

low





n withn h picul on withn h picul o  th lowest facto of fety fth lowest facto of fety f th lo

th lo F

F  da d aOn rom a high or lvel  da d aOn rom a high or lvel s an is an imprabe evetmprabe evet n nt

n nt  _{ee loing caee loing ca  h da ith da it i aroat to }i aroat to  lo  

lo  f y f f y f h rapid drh rapid drawn con awn con For other For other dada otabl otabl 







t jtS, epi of pid down c quntly, and het jtS, epi of pid down c quntly, and he n

n  _{ul ul otioti  conditioconditio  In hIn h ca  ca i ii i} to ruito rui

MTHOD OF

MTHOD OF

AAY

AAY

ili dn pid aon has e analy in o bcally fferen wa: ili dn pid aon has e analy in o bcally fferen wa:

I

I

usin effctiv sress mhs, adusin effctiv sress mhs, ad (2)(2) usng totl ses s  hch husng totl ses s  hch h unind h sreh of he soil  relaed o th conolato presures in  unind h sreh of he soil  relaed o th conolato presures in 

ll Boh Boh mehs at fmehs at f inig  inig marials in he samarials in he sa way.

way.

  o ffctiv sress analyes s th it is latively e to vluat te   o ffctiv sress analyes s th it is latively e to vluat te

q h sngth p

q h sngth pt t   ffcv ffcv ss sh sngth  sh sngth ptptererss fo 

fo 





rdily dtind b mans of ioopicaly coldatd ndrirdily dtind b mans of ioopicaly coldatd ndri (C-U

(C-U  t  t with  reur rnt with  reur rnt Thi ty of te i wThi ty of te i wllll 

 tt _{}

o  

o  

_{chnchnc c lala}



 e  e f f ctiv ctiv e e aly aly is is that that i i i i dicult dicult to to esimat esimat wiwitt



 y y 





ru tha will exit withi one drang tels dru tha will exit withi one drang tels d dn

dn

T

T

 ressur change urin rawdown end on th change ressur change urin rawdown end on th change in

in ss ss tha ul fm th changin waer loads on th slo ad th unaitha ul fm th changin waer loads on th slo ad th unai r f t il within th lo

r f t il within th lo o h chgs o h chgs in load in load Whil he chanWhil he chanee in 

in  c c _bb simae wit aablaccucy aicully a shallo desimae wit aablaccucy aicully a shallo de nat t ue of the slo th undain s of th sol is much haer nat t ue of the slo th undain s of th sol is much haer to

to tt. . T T chaechaes i s i re presure re presure oud  oud  xcted txcted to  cosieralo  cosieral diffren

diffren fo teifo teils h tend ls h tend o date ui shear an os h o date ui shear an os h o o o o WhiWhiee n

n cipl it i ssie o esime hse r pssures us kmpo'scipl it i ssie o esime hse r pssures us kmpo's 

prss

prss tsts popo

9

9



p

p

s s us s u In st caes efe  

In st caes efe  

ff

 dugdug rpd ao haverpd ao have used he sumpo  por

used he sumpo  por susu h r sue y shph r sue y shp 195 and ler us b Mo

195 and ler us b Mo 11969633 hee asumpos hav ehee asumpos hav e

aproate aproate

hih  of fty factor fo th dawdown conition a

hih  of fty factor fo th dawdown conition a othr dsigothr dsig c   hih pbilie

c   hih pbilie





cccc forfor



 t t adon adon

Te r

Te r trnghs  aed   of efeiv sreses a  s ssumtrnghs  aed   of efeiv sreses a  s ssum that  e prssurs hn hm  hrosc

that  e prssurs hn hm  hrosc

Ef Ef









 

 

SS

SS

justi on e i of e f t t

justi on e i of e f t t





 cve   cs  cve   cs y hvey hve 

n foud to ult   vu of f of fet f d tht uffern foud to ult   vu of f of fet f d tht uffer pid

pid dwwn flu  dwwn flu W W ee





183)183) f   vs of set fctorf   vs of set fctor

lculted using Mrgnste ui w

lculted using Mrgnste ui w FF  1.21.2 f Pilitof Pilito DD   FF :

: 1010 fo Wter Bouldn D  of whh flfo Wter Bouldn D  of whh fl

t sms liy th Bisop nd Morgenses supions for pore pressures t sms liy th Bisop nd Morgenses supions for pore pressures uring

uring dw dwown my own my b b re re ururte te for for silsil h   h  not tenot tend nd o o dildil  durngdurng sh

sh th for hos th th for hos th do e t dilte do e t dilte u, ug  u, ug  sumptions sumptions mymy   hohoww rle  rle coecoee e wt wt fl fl of of lo lo n n mtimtis  s  e e notnot

nl

nl  co coct ct d d     



 dl  dl dung dung s s tete





lkel o blkel o b ndu conve fo

ndu conve fo    t to dlte dung   t to dlte dung  h

 he e s s of of efefffii 

u wouu wou gh nd P

gh nd P (1967)(1967) suggs suggs 





resse dung wdown in wllresse dung wdown in wll

 c coompcted mpcted sily sily sndsnds s could could b b eett  ung ung ow ow nt nt everl everl invesigtorsinvesigtors rowzin,

rowzin, 19611961 Brhm dBrhm d HH 1963; 1963; Newlin nd Rossier,Newlin nd Rossier, 196;196; Desi ndDesi nd

han,

han, 1919 sa,sa, 22  1977)1977) u htcl ths to nlyz thu htcl ths to nlyz th

on

onsad sad low low conditions conditions follofollowing wing drwdown drwdown iik the k the ishishop op andand orgnstern re pressure ssutions tese meths o not consider he orgnstern re pressure ssutions tese meths o not consider he hvior of the ol wit gd o diltnc, nd e tu not caple of hvior of the ol wit gd o diltnc, nd e tu not caple of presentng all of te n fctors t conrl the re pressures during presentng all of te n fctors t conrl the re pressures during rawdown

rawdown

ano nd Nord

ano nd Nord (197)(197) nd Wg nd Duncnnd Wg nd Duncn (1987)(1987) used prurs forused prurs for

sng

sng





ppss dg dwdwn t ss dg dwdwn t t t  ue ue of dily of dily

 re pr

 re pressu chessu changs angs vvo nd o nd No u wo-stage sility anlys No u wo-stage sility anlys  irat to hiee nsistey bwn t clcul ftor of set  e es irat to hiee nsistey bwn t clcul ftor of set  e es f he  pssures

f he  pssures

rghi d Pk

rghi d Pk (196)(196) sumz the prolems in estiming re prssurssumz the prolems in estiming re prssurs

urng drwdown in tse words urng drwdown in tse words

" "  i in order n order to deterto determin min the pore pressure conditions fr tthe pore pressure conditions fr tee  drwdown

 drwdown stte stte all all he he following following facfactortors s nd nd o o b b known known thethe lation f te undies btwen mterials with signicanly lation f te undies btwen mterials with signicanly  d

 diiffererenent t prpropoperertitiss; ; he he pepermrmeeiiiiy y nd nd ccononsosolldadaioionn  ch

 charaaractctririsisics cs o o ch ch of of hese hese matmaterierialsals  nd nd the the antianticipacipa mxim

mximm ram ra    drwdown drwdown n n dition he dition he pore prssurspore prssurs inc y e chngs in h sheing sss thmsels  inc y e chngs in h sheing sss thmsels 

n o

n o  n ino n ino consconsidetionidetion



 ngineng practice,  ngineng practice, fw ofw o

thse

thse facors cfacors cn n b relily b relily deteined deteined TheThe gps n he vailagps n he vaila

br-cpe br-cpe

v

v  e o e Bs d Morgenste o e Bs d Morgenst









ll  s s

 p

 p

esu dungesu dung ngly he g ngly he gtt al al ss ms ms  w  w wdn gdl of w we  wdn gdl of w we 





  w  w d d



 dt dung dt dung





Wght

Wght nd Du us nie elent nyses to smend Du us nie elent nyses to sme e sess chnge durng

e sess chnge durng ketons r pressure pmers oketons r pressure pmers o l

lculcule te re ressure e te re ressure e wdow .wdow .e te indte indce  ce t it it it i  ssile to estissile to estimm alistic  pressures for ecv s , ut it

alistic  pressures for ecv s , ut it



 cubo cubo





icult t using tot sss s s de





c, Wi_{c, Wieeht d W}ht d Wee

By  ,

By  ,





e anale a ei i the folloing ioe anale a ei i the folloing io y f

y f _pbpb





iat withiat with _etiveetive s s

y

y





 av av  tete 

 v by

 v by impimp

e 

e  (( gngn 1970)1970)



a ttagea ttage





T

T   nt vaent vae (( hehe





d ed e

a

a

eteinedeteined    t

t





-U-U g eveg eve   how how 

F

F

11 At w s, wheAt w s, whe _   enve ie ae the eeve 

  enve ie ae the eeve 





n ghn gh   envelope i  to etene engths (r the   envelope i  to etene engths (r the y y , ,









:

:





Either drained or Either drained or





 UU

enelope s used. whiheer enelope s used. whiheer ges lor strength

ges lor strength

Normal stress

Normal stress  effect e effect e strstr

n bae of slie before n bae of slie before drawdown

drawdown

Normal Stess

Normal Stess







F

F



 Srh Evelop Used in Cops ofSrh Evelop Used in Cops of

Er Mtod Er Mtod

T

T

jj _((  _di engh evel alow e i o avoidi engh evel alow e i o avoi y 

y 





h tha h tha  _negavenegave

p

p

u, hih oulu, hih oul 

tating

tating  pp



 o(o( p dwp dw tabity aalstabity aals





C o e C o e

Ei

Eit t Cos Cos o( o( p e

p e age, hih azs s fo awn i uage, hih azs s fo awn i u



dee

deee e p p fafae e TheThe





fl fl

ve

ves s of of onoliatio pre aoonoliatio pre aon e n e ii d ps

d ps

a

a

 to e  he g value to e  he g value

 

 e s wh the  w we s wh the  w w

v , v ,    c c





Rapid Dro Rapid Dro

cause the effectve al sess us to determe te she sength is the cause the effectve al sess us to determe te she sength is the fctive sess foe rawdw. which is wer tha the effective sess after fctive sess foe rawdw. which is wer tha the effective sess after awdow eve when it is ssud that e re pressres after dawdown awdow eve when it is ssud that e re pressres after dawdown  yd

ydrosttic rosttic As a As a result the Corresult the Corps f ps f Engieers methEngieers metho o is unnis unnecessecesslyly nseatve

nseatve e 

e ooss _{   nees meth nees meth avds the avds the pblemspblems f  f estimatinestimating changes ng changes n } esse d dwdwn by usng urin stregths t aayze stabty after esse d dwdwn by usng urin stregths t aayze stabty after adw

adwn n By By snsng g ndrained stegths this ndrained stegths this prepredure accdure accuts uts fr fr thethe ndecy f e eal to dlate  compss dug sh

ndecy f e eal to dlate  compss dug sh

While the  of the ttal sss IC-U evelo is quitively cot. it cot  While the  of the ttal sss IC-U evelo is quitively cot. it cot  jstie

jstie in detail in detail Te cirles f Te cirles f se u to eel te total se u to eel te total sess evelosess evelo mbie te efftive s ng colio wit

mbie te efftive s ng colio wit  devi  devi se a se a filufilurere





 d nt  d nt pret  pret  state of sss state of sss i i e il e il t t y y gien gien   rr_{ e e} ay that the sesses o e sli se

ay that the sesses o e sli se

a

a

 relat  relat to to e e ICU ICU eveo eveo is is  sisten

sistent wit te wy the t wit te wy the eelo is lo eelo is lo lough e ers resutglough e ers resutg





tese icnsistecies re ot exemey ge in os cses te se o an tese icnsistecies re ot exemey ge in os cses te se o an icosistent a illogical met

icosistent a illogical met





lg se s lg se s to lo pressuto lo pressu is

is undeundesirable sirable As dsAs dscusse i sube ios ttecusse i sube ios tter pes fr r pes fr relagrelag shear stength t consolitio pressre ve e develpe by Lowe a shear stength t consolitio pressre ve e develpe by Lowe a araath (

araath (119)9)

ike the Crps  Egineers meth Lowe an araaths meth uses a two ike the Crps  Egineers meth Lowe an araaths meth uses a two sge alysis rere. and ses uae sregs or alysis o stability sge alysis rere. and ses uae sregs or alysis o stability urng

urng rawdrawdww s shw in Fig,

s shw in Fig, 2,2, _{we and Karafaths meth us eves that are mrewe and Karafaths meth us eves that are mre} gcal than the tta stess C-U envelo for eang unin shear sengths t gcal than the tta stess C-U envelo for eang unin shear sengths t ndation pressures ndation pressures The hortal aThe hortal ais is is is the effetive sethe effetive sess on the ss on the failurefailure lane urng cosoliati (

lane urng cosoliati (fcfc)  the veic axis is te shea sess o the)  the veic axis is te shea sess o the ailu

ailu



lane at failure (_{lane at failure (  ff ff ))}

we and Karaath shwe tht the ndained seng of soils when ptted as we and Karaath shwe tht the ndained seng of soils when ptted as





_{vsvs 0'0'fcfc vaes with the efie pcil sess tio dung conlidatin  vaes with the efie pcil sess tio dung conlidatin  c c}



 _{llcc " "33 c c  The value o The value o this this ratio ca vay ratio ca vay rm uity (fr cosolidatio rm uity (fr cosolidatio underunder}

istropic stresses t K

istropic stresses t Kf f  the vaue of 0' the vaue of 0'1/1/0'0'33 at failueat failue As the value of KAs the value of K c c nncreases. the ndrcreases. the ndraineained d strengt incrstrengt increases eases Fr ay materl there is Fr ay materl there is a amly oa amly o nda

ndane strengtne strength envelos coesnding to h envelos coesnding to dffedfferent rent values of values of _{ c c varying}varying









t t K_{Kf f }

e maner f repeseting uai sength suggested by Lwe and Kafath, e maner f repeseting uai sength suggested by Lwe and Kafath, hih is shwn in Fg

hih is shwn in Fg 2.2. _{is is lgica ad lgica ad accute accute e testing e testing ruire o establishruire o establish} hese

hese strength envepestrength envepes however s however is is diffcdiffcult ult Test Test specinspecin 

Le an Karaatb' Meh Le an Karaatb' Meh

S

S

Dc. WriDc. Wrieehl  Wonhl  Won

us onderble t d carful tteto cu the ree mut us onderble t d carful tteto cu the ree mut



nc slwy t vod the poblt tht the

nc slwy t vod the poblt tht the wll l durgwll l durg .

.

 

 





 vue vue





K_{K c c. th}. th e e mm re re aa

e 

e      t t t t  wl  wl l dn l dn cld cld FeFe 

  _{exenc  exenc  orn orn  l l}



_{, nd t , nd t  }





 empl empl





Lw  KLw  K t t 

u

u

. . + +uu

C

C

_

_{ }

_--





_

�

�





  ++

0

0

_{ u}

_u

O

OC

C

















_

_



_{-- }

--









Effecive ess on the Fue Plne

Effecive ess on the Fue Plne

Dng

Consoldn-Dng Consoldn-

C;c

C;c







 Srh Elop Usd  Low adSrh Elop Usd  Low ad

Krfh'

Krfh' MethMeth U 

U 





  E  Eerers t s t te Lwe d Krte Lwe d Krt th t th u thu thee ni sn evelopes t low tree ere he udred treth ni sn evelopes t low tree ere he udred treth vel l ave

vel l ave ee   enelo enelo

T

T

th tu  ot llth tu  ot ll 

         O O bb sb to blzsb to blz





ll ndre tth nll ndre tth n 

w w 



  





 cv cv  _{ee}

VALUATIG TT FO PD DWDOW LE VALUATIG TT FO PD DWDOW LE

A

A





e e t t  reptn ur reptn ure e ent p_{ent p  }   Lw Lw   ecimens ecimens tt    s s ppuu   cy

cy  o o 





 

  ww _{ll}

prvously prvously

d

d  s c d ccrte, bu eblsn the vto  s c d ccrte, bu eblsn the vto 





& wt coldton ure ole dcult d enve& wt coldton ure ole dcult d enve





re

re

Rad Dawown

Rad Dawown

Bau

Bau o  dfio  dfi ivvivv



ng ACUng ACU ailail s a num ofs a num of suggstd   esmang

suggstd   esmang  rlrl oo ACU tesSACU tesS ICU es

ICU es





 oo _{n abe n abe }





_hishis









 _{  e}e









oo _{y uny un}

D  d, 

D  d,  au yau y





DD





 pp i a snge pp i a snge

c

c

,,yy





ooen, ACU sg en, ACU sg   ul o ul o IU IU 

 

 



 



 

-- 





eeby Tayby Tay

(18)

(18)

rlrl

  

  

oo te AC

te AC

l  

l  

cc u u itit �irs ph�irs ph











  



ngng





ur  f y sgsur  f y sgs dung

dung 







-- ththe me meteth h susuggggeseseded we and Kaaiath (96) esultswe and Kaaiath (96) esults 



mmoo nh envels fnh envels f





vs ofvs of





  t sue by  t sue by   yy





rsu nrsu n





ableable AU sngh enve

AU sngh enve

T

T _{sties d by g esties d by g e}





983)

983)

_{ss}

 

 

_{is al ssibeis al ssibe}





e AC-U ng enve

e AC-U ng enve





CU sn CU sn  rul rul   





ntelntelaon aon e e envelenvel ccosngosng





 _ cc ll

1.

1.

n F,n F,

22

isis    ICUICU

nvelo an

nvelo an   



bhedbhed





plOn plOn 

 

 

_{ ''  cc}





enveenve sndin to  

sndin to  cc   K_Kff



siy hesiy he ee     sss sngh envelsss sngh envel tlis 

tlis  plgplg val oval o _{11 VV}

C

C

_{   }   ll o ll o  ru ru





( _{( 1 1   }

C

C

_{f f cc}

n

n





 n  n   ompompuud d mm hh rsusrsus oo  IC-U IC-U axilaxil tes ith etes ith e ur

ur sun sun EnvelEnvel  f f val val of of   ininae nae n

.

.





K_{K }    estals  estals y iny ing l tg l t envelsenvels ((  

10  K

10  K    KK    . . is is ur ur es es tt





of AC ngs mh easeof AC ngs mh ease

 

 

l u i liesl u i lies ee sysy

o

o

in&  in&  ccut A·ut A· 

 Aon Aon  s  s rth rth AC-U nels AC-U nels of of t t ty swn nty swn n



 22  etlh  lin etlh  lin nce sig hence sig he sulsuloo C-U tesC-U tes

EW MTHOD FOR VALUATIG STABILTY DURG EW MTHOD FOR VALUATIG STABILTY DURG PID A

PID A WDO WDO 

 h un stte ofh un stte of 





oo anazn stabiliy un d dwwn it isanazn stabiliy un d dwwn it is

vp vp havehave





rsusrsus oo I- I-  T s T s cc T T





ss he he





a a





bj bj

  

  



n n





lili

  

  

r.r. sgt sgt





 T Taayy





(18)

(18)

  

  

(1)

(1)





NN





yy T T

 

 

s by W,s by W,







(1983)

(1983)

wi twi t (19S). (19S).    





by by AC-U AC-U





Duc, Wrht d WgDuc, Wrht d Wg

 Lke Lke he C he C o ngneeo ngnee h a e  h a e n Kth' n Kth' 



 ew t us unned he ngths to aod the omlew t us unned he ngths to aod the oml





ccces invlve n etimtn uaned  reue urccces invlve n etimtn uaned  reue ur dww

dww

 Lke e a Karh' met t  e moe ue_{Lke e a Karh' met t  e moe ue  v}v

_

_

ene th AC-U ngth ng th te al o K

ene th AC-U ngth ng th te al o Kcc

 Fw t s  W_{Fw t s  W e }e 

(13)

(13)

the AC-U trengtsthe AC-U trengts 

emd   ilan u  sus o ICU s emd   ilan u  sus o ICU s

 oo vv _{uned sn hJ} uned sn h_{J her  n snth hi}her  n snth hi



_  ee   _{di sengthdi sength} 





 

e ew

e ew  s e t  the t ee o e ts e t  the t ee o e t IIhaha



    vsy  vsy  lyss  rd wdw lyss  rd wdw tabltabl  I dtio I dtio  ce 

ce   eew w eaeass: : II) t ) t smsmlele  hhe ask e ask   esesmmnn  AC-AC- S

S by usn e ntelationby usn e ntelation adad 2)2) t us t us   crate a le crate a le



  f cn  f cn _ible ruon of uane engts tible ruon of uane engts t  p

 ps ds d



vain o dingevain o dinge





sc eps ivolesc eps ivole  te mtte mt  hehe

(1)

(1) Dteie or eah  i te cton hethe drange ll Dteie or eah  i te cton hethe drange ll  d dwdw.

d dwdw.

T

T

s ll ans f mn tis etenato iss ll ans f mn tis etenato is tt

e  v  he dmesoe  or

e  v  he dmesoe  or  gve by he ollwgve by he ollw ex

ex

(1)

(1)

 wc

 wc

 •

 •

ccie f oldton tccie f oldton t    ro n  ro n



 lengtlengt



  p  p  the  the ccccuateuated d vvlue lue of of T s T s reatreate te tha ha r r equaequa  toto _{0 0 } ds

ds oo excsexcs  ssue durin wn ll ssue durin wn ll   ee ee  



   e  e



a te mtia a lly ia te mtia a lly i V

V oo





cc  lculated i dta  he t rte o ontio rilculated i dta  he t rte o ontio ri





 pxe vaues or vaous spxe vaues or vaous s





omed lsomed ls eeltedlted



 1  1 us us mz mz f cvi f cvi

u weeve ey e sme   nde u weeve ey e sme   nde p i de fm p i de fm _ .  .  _  oo  wi he  wi he s.  s.  w i w i sr nth. sr nth.  vv  e C  vv  e C E

E Me Me _ eecve sts eecve sts     f f EiEi eve s

eve s ev loev lo



dww  eteie 

dww  eteie     new pred he eecve ss

new pred he eecve ss





w s uw s u  Ue

 Ue oo_{ eve ss e dww ru eve ss e dww ru}II

ys

yss s e rs e rs w staew staes re s re he she s  s hs he Lwee Lwe





meh

meh   h h thrd thrd ae  draied ae  draied sh  sd sh  sd 





stst

Kah Kah

 of the l sue where the draed sen  sller tha  of the l sue where the draed sen  sller tha  nh.





pd rwdow pd rwdow

al

al 11 _{Apoxie Valus oApoxie Valus o}





_{o Vous Soilso Vous Soils}

Ty o

Ty o SoilSoil Co sand Co sand Fine snd Fine snd Sily sand Sily sand Silt Silt Cpt clay Cpt clay Sot clay Sot clay soc socvv > >_{10 10 22 /day /day} 1 to 10  1 to 10  /day /day 10 to 10 to

X

X

tt /day /day  05  05 to to 1 1  /dY /dY  005  005 t 5 t 5  /day /day < < _{0 022 tt22 /day /day}

I the vale o T cacuat using quaio

I the vale o T cacuat using quaio

I

I

is ess than 30. the undranis ess than 30. the undran trength s

trength should b hould b consiee consiee The ollowing The ollowing ses ssure tses ssure t the  the undranedundraned n

ngth used in gth used in e e staistaiity ays wity ays w





b ge t e b ge t e de de sngth sngth  is thus conative to assu th he mtei is unin in tho cases where is thus conative to assu th he mtei is unin in tho cases where e is dot whet

e is dot whet   ot c dge wot c dge wuu

((22) ) Estaish Estaish the the sength sength nveonveos s qued qued o o the the analyses analyses oror ateas that ain dun awdown. oy the ane strength enveope is ateas that ain dun awdown. oy the ane strength enveope is quired

quired or mteals thaor mteals tha

a

a

undrined ing drawdow. thundrined ing drawdow. th te drainedte drained

 e

 ennvv e ell o op_{p ((ttf f f f ss aa''f f f f )) an}an d  d thethe ndrndrined nined nvelop (_{velop (f f f vsf vs ''fcfc) re re}) re re quired.  quired. ThTh e e

qu nlops or alus o K

qu nlops or alus o K c c bwen 1 and Kbwen 1 and K can can   een  een yy

li

linn     nnerer  lalatiotion,n, aas ds d cu cussss ed ed p p v vioiosslyly..

(3)

(3) For a lete sFor a lete sip ip sfe ccuate e actor o ety sfe ccuate e actor o ety ar drwdownar drwdown y

y a 3ste u:a 3ste u: (i)

(i) Pero Pero  ysi ysis s of sity bo drwdown usng of sity bo drwdown usng in sengtin sengt paraters

paraters or l mes o deteine he eve no sssor l mes o deteine he eve no sss



_cc))  on

 on he ae ohe ae of ach slice. nd the value o K_{f ach slice. nd the value o K c c o} o each sliceach slice e Values Values o o K_K c c re

re deeine  deeine n n the mner the mner sggest sggest y y Lowe Lowe and and rath. rath. aed aed onon the assumption

the assumption of  of no eieto of no eieto of prncipprncip sess duingsess duing drwdown drwdown These values

These values  e  e sed sed t t deemne deemne undrained undrained sength sength vaues vaues or or hehe mar

marials thaials thatt do n  do n dn dn y dung y dung wdowwdownn (ii)

(ii) Pero an anaysis of staility ae dwdown using undrandPero an anaysis of staility ae dwdown using undrand sengths o mates ha do not ain reey.