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A SHORT COURSE INSOIL AND ROCKSLOPE ENGINEERING
NOEL SIMONS, BRUCE MENZIES and MARCUS MATTHEWS
Published by Thomas Telford Publishing, Thomas Telford Ltd, 1 Heron Quay,
London E14 4JD.
URL: http://www.thomastelford.com
Distributors for Thomas Telford books are
USA: ASCE Press, 1801 Alexander Bell Drive, Reston, VA 20191-4400, USA
Japan: Maruzen Co. Ltd, Book Department, 310 Nihonbashi 2-chome, Chuo-ku,
Tokyo 103
Australia: DA Books and Journals, 648 Whitehorse Road, Mitcham 3132, Victoria
First published 2001
Reprinted 2005, 2007
A catalogue record for this book is available from the British Library
ISBN: 978-07277-2871-5
# Noel Simons, Bruce Menzies, Marcus Matthews and Thomas Telford Limited 2001.
All rights, including translation, reserved. Except as permitted by the Copyright,
Designs and Patents Act 1988, no part of this publication may be reproduced, stored in
a retrieval system or transmitted in any form or by any means, electronic, mechanical,
photocopying or otherwise, without the prior written permission of the Publishing
Director, Thomas Telford Publishing, Thomas Telford Ltd, 1 Heron Quay,
London E14 4JD.
This book is published on the understanding that the authors are solely responsible for
the statements made and opinions expressed in it and that its publication does not
necessarily imply that such statements and/or opinions are or reflect the views or
opinions of the publishers. While every effort has been made to ensure that the
statements made and the opinions expressed in this publication provide a safe and
accurate guide, no liability or responsibility can be accepted in this respect by the
authors or publishers.
Typeset by Academic Technical, BristolPrinted and bound in Great Britain by MPG Books, Bodmin
Cover photograph
Photograph of a landslide pushing over an apartment building in Kuala Lumpur, by kind
permission of Bruce Mitchell.
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Dedication
Professor Noel Simons FREng, 19312006
Noel Simons, who developed the University of Surrey into one of the UKs
leading centres of geotechnical learning and research, and who inspired
the Short Course Series of geotechnical books, died on August 10th
2006. He was aged 75.
He was not only a wonderful teacher, mentor, colleague and co-author,
but was also a dear friend. This book is dedicated to his memory.
viii
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measured in the direct shear test
SHORT COURSE IN SOIL AND ROCK SLOPE ENGINEERING
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Slip II (5 May 1957)
Slip I (24 April 1957)
N
16 April 1957
19 April 1957
23 April 1957
Date of excavation to 945 m O.D
Groundlevel+ 183 m O.D.
Excavated to 701 m O.D.by 14 April 1957
0 10 20 30 m
Scale
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Originalground level
Excavation to 091 mon 1 April
Excavation to 701 mon 14 April
Excavation completed19 April
Note:Slip surfacesnor surveyed
BlueLondon clay
BrownLondon clay
Marsh clay
Clay fill
25 April2 p.m.
24 April9 p.m.
24 April5 p.m.
1:1
1:1
:1
366 m
183 m
1478
m
854
m
945 m
+533 m
+183 m
091 m
+091 m
823 m
O.D.
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BrownLondon clay
:1
Fill
Marsh claysu = 15 kPa
73
m
35
m2
7 m
85
m
Pw
Case
Londonclay
Strength for F = 10 suMeasured strength su
su in kPa
su / su
1 2 3 4 5527
958055
537
958056
508
1053048
594
1149052
685
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2330
25
28
29
26
24
2119
CBA
5
5
10
15
15
20
5
5
10
10
0 50 100 m
Scale
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Ovre Storgate
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Reduced level+ 30 m
Dep
th: m
Sam
ple
No.
Soil type
Sandy rockFILLMediumSAND
Very soft to soft greysilty CLAYwith verythin seamsof silt andfine sand
Water content: %
20 30 40 50 2010 30 40 50 2010 302010 30 40 50
Boring 30
Salt content: g/lClay content: %Plasticity index: %
Unit weight: kN/m3
Shear strength: kPa
St.
Undisturbed
Remoulded
ClaySalt P.I.
St.
1510
5 Unconfined compression test,showing failure strain in %Cone testVane testSensitivity
Boring log for boring 30
% 9! ) #$%,&
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= 95
= 90
= 85
= 185
= 95
= 90
= 85
= 185
= 95
= 90
= 85
= 185G.W.L.
G.W.L.
G.W.L.
15
14
13
12
11
Fact
or o
f saf
ety
16
15
14
13
12
Fact
or o
f saf
ety
13
12
11
10 Fact
or o
f saf
ety
c : kPa, : kN/m3
Profile A
Profile B
+5
0
5
10
Elev
atio
n: m
Profile C
+5
0
5
10
Elev
atio
n: m
+5
0
5
10
15
Elev
atio
n: m
L.W.L. 10
L.W.L. 10
L.W.L. 10
Timber pilesat 1 m ccs
c = 1 = 32
c = 2 = 32
c = 3 = 32
c = 0 = 32
Slightly over-consolidated clayNormally-consolidated clay
c = 1 = 32
c = 3 = 32
c = 0 = 32
Slightly over-consolidated clayNormally-consolidated clay
Critical circle
Critical circle
Critical circle
c = 2 = 32
c = 1 = 32
c = 3 = 32
c = 4 = 32
c = 0 = 32
Slightly over-consolidated clay Normally-consolidated clay
c = 2 = 32
Profile after slip
0 " 9! )
#$%,&
"# $ " "#
++
0908
07
06 Fact
or o
f saf
ety
06
05
04 Fact
or o
f saf
ety
07
08
06
05 Fact
or o
f saf
ety
= 95
= 90
= 85
= 185
: kN/m3Profile A
+5
0
5
10
Elev
atio
n: m L.W.L. 10
Timber pilesat 1 m ccs
Critical circle
= 95
= 90
= 85
= 185
Profile C5
0
10
15
Elev
atio
n: m
L.W.L. 10
Critical circle
= 95
= 90
= 85
= 185
Profile B
0
5
10
15
Elev
atio
n: m
L.W.L. 10
Critical circle
Profile after slipProfile before slip
3025
2015
10 kPa
2015
10 kPa
20
25
30
1510 kPa
Undrained shear strength
6 # 8& 9! )#$%,&
! !
+,
15 19 255 9Borehole
25
20
15
10
50 1000
0 50 1000 50 100 1500 50 100 1500 50 100 2001500
5
Dep
th b
elow
gro
un
d su
rface
: m
Pore pressure: kPa
Measuredpore pressure
Level +74 +30 +225 +30 +28
$ *5 9! ) #$%,&
21 3
F = 101
F = 105Actual slip circlesafety factor 107
Critical slip circlesafety factor 100
30
20
10
2468
101214
0 4 8
4
12 16
8
20 m
Scale
Curves of equal pore pressure
12 16 metres of water
Measured pore pressure
02468
101214
metres
SectionNo.
Safety factorsc , analysis (Bishop 1955)
123
110100110
Weighted average safety factor for the whole slide F = 106
c = 10 kPa = 27
8 " ' ) #$%&
"# $ " "#
+$
( ,1:; = A C 0
0 )C
,11
,1=
!
%
9 7
( 1 = 5 1=
!
,-3-
" 1# &
4 .,, ' 1-
,1,
/ 5 '
7
4
1 " % #
" ./# 7
1
4'& * %27 L 8 9 7
5 ' 4 .,
G
,2 5
! ,-..
,2./
8 G
7
G
" ,67 /68 ,6 .6#
! !
+2
0
(
2/8 1 "#D 1 2 "# >
0 )C
,1 " 1-- ,,3 G
#
1/- " 4 .,#
G
21 3
0 5 10 m
Scale
SectionNo.
Safety factors = 0
123
097093135
10095
Actual slip circlesafety factor F = 117
Critical slip circlesafety factor F = 093
30
4050607080
70
80
60
50
40 kPa
20
10
Curves of equalshear strength
# 8& ' ) #$%&
"# $ " "#
+
!
G >
@ 5 ",-=#
0
0 5 10 15 m
Scale
Sandstone and shaleSandstone
Limestone
Fractured shaleLowercarboniferous
Boulderclay
Alluvial gravelRiver Lune
128
m
Typicalslip circle
Average inclinationof slope = 28
Boulder clay w = 12LL = 26PL = 13
Clay fraction = 25%
, ) ) )+
#$%&
60
60
40
20
200
0
Shea
r stre
ngth
: kPa
Effective pressure: kPa
w = 12LL = 26PL = 13
matrix
" %
$ % * &
! &
*
4
B
? 7 ,-,
,-3, 13. " 4
.,3# )
,/8
+
,-/
! ! &
7
&
75
50
25
0
cm Observations startedFailure after29 years
194119291912
Wall built
Forward movement of wall with time
North
BrownLondonClay
Blue London ClayLondon and North Western Railway
18361875
6 m
Ballast
2 ) 9 : 4 )+ #$00&
"# $ " "#
+%
&
! 0
4 .,.
(
! !
' * ,-== 8 0
: 0 H
4 +
&&0 '&9 '0 8 4%7'
7 + ,-/3
,-=
,-= 1=. ,-=. 1/ " 5
# > 4 .,/
'
8
) 7
,, E ,@
,-./
, 8
,-=. 1,. ,-
1 ,. "4 .,=#
150
125
100
75
50
25
00
c re
quire
d fo
r st
abilit
y: kP
a Wembley Hill
Uxbridge
Northolt
Wood Green
Upper HollowayKensal Green
Sudbury Hill
Mill Lane
Park Village East
10 20 30 40 50 60 70 80 90 100Age at failure: years
Analysis by circlesAnalysis by planesDenotes there is reason tobelieve point should bemoved in direction shown
; ' #$0&
! !
,)
7 & 31 .1
& "4 .,2# %
! 7 .=
.= 3( ,
,1 3 ( , &
.=
,1 11 4 .,2 +
1. 1. 4 .,-
CL
South
17 m
0 10 20 m
Scale
Hendon Motorway (M1)
North
Brown LondonClay
Blue London Clay4:1
1964
56
123
Piez.ru
1973 197512356
017022101105
+0090320809505
Mean ru values1973 (9yrs) = 0751975 (11yrs) = 062
% " )+ #$00&
11 m
Great Northern Railway
EastWest
Brown Londonclay
Blue London clay
4:1
3:1
3:1185018501956
54
12 9
8
11 10
Piez. ru
0061254
018021009
Piez. ru
03189
1110
034031032
Mean ru = 015
Mean ru = 032
Old SideNew Side
Piezometer readings 1975
Old Side (125 yrs)
New Side (19 yrs)
0 * )+ #$00&
"# $ " "#
,
! ! (
,8 1
18 17
7 (
,38 1
=8 1 ".1 #
7
(
,38 ,
04
02
02
04
0r u 20 40 60 80 100 120Time: years
6
4 .1
! 7
& A C A C
0 *
!
30
30 40 50 60
20
20
10
100
0
Shea
r stre
ngth
s: k
Pa
Effective pressure : kPa
West Acton Crews Hill
Grange Hill
Sudbury Hill Hadley Wood
First time slides, older than 45 years, depth 5 to 12 m
ru =035 03 025
c = 1 kPa = 20
$ " ' )+ #$00&
30
30 40 50 60
20
20
10
100
0
Shea
r stre
ngth
s: k
Pa
Effective pressure : kN/m2
Peak 38 m
m samples
Peak 250
mm dia. sa
mples
Back-anal
ysis first-sl
ides
= fully s
oftened
c 14
7 kPa
14 kPa
14 kPa
20
20
20
13
Residual
,8 " '
)+ #$00&
"# $ " "#
,+
0 7 8 0
7 ! ( ,8 1
A C
"* !#
,
! 7
&D
31 .1
' & 1 0 ",-=3#
>
7
( ,1 1 ,.8 1 .2
&
G
.2 & &
G
0 1 10 . : 09
!
",-31#
6 =>
' 3 )+ #$02&
E ( 0
, ,( ,
/ ( ,
,( ,
! !
,,
? "
! # ",-.1#
& " .1 #",-=1 #D
& $ % ;': 4'& %2,7 ,-. F! 0
9 0 )D
*
0 G "
) #
7 ? +
,-.1
,-.,
4 ,-. %
0
*
! )
,2 " 4 .,#
!
! />2
"4 .# "
,1# . ,=1 ,-.;.
1/
' /8 ,-8 % . /
,,8 . 5
!
4
"# $ " "#
,$
,-
/8 318 18
) "
#
,-8
NRiver Severn
B
E
F
GD
C
A
River bankafter slide
River bankbefore slide
Road before slide
Road after slide
Railway (maintained in position)
Approximateboundary ofmain slide
Secondary slide
0 50 100 m
Scale
Original positionof housePosition of houseafter slideHousedemolished
, * @+1 )+ #$%2&
Scarp ofmain slide
CoalportBeds
Fault
Probable limit ofweathering
Railway
1951 1952Road
183 m
Slip surfaceobserved
0 25 50 m
River Severn
Inclination of slope = 10
w = 21LL = 44 PL = 22
,, ) @+1 )+ #$%2&
! !
,2
& ,- - ,, - ! ,1 " 4 .#
+
F!
1/ " ,116
,1# <
,- ,,6
. 4 %27$ *
5
G
,. 1'
+
, 1
60
100
50
25
500
0
Shea
r stre
ngth
: kPa
Effective pressure: kPa
w = 21LL = 44PL = 22
1 ,.1
5
G
0
2. ,0 -.
G
& 2. -.
! &
G ,18 ,
2
- G 7 G
% &'( & *0 G
+
" #
&
!
10 4'& %2,7' ,-3- 7
0 E
0
" #
5 ! ,-./
" 4 .3#
,1 $ H>8
(
-8 28 &
,33 " "0 ,-/3# ,. 1# ' 7 , 0 E ,18 ,<
0 E ",-/-#
4 5 5C 5 0 5 9 ) @
"# $ " "#
,%
' !
% % &
' &
4 !
4
! &
" #
0
!
7 !
"
# F !
Typical slip circle
Piezometric line
Piezometric level
Piezometer
1900
Section after slip(surveyed 1956)
7 m
0 5 10 m
Scale
3:1
Brown LondonClay
w = 31LL = 82 PL = 28
Slip occurred after 49 years
Analysis of sectionafter slipc = 0 = 15
,2 ) ) = #$2$& )+
#$%2&
! !
$)
!
!
G
4
7
& 31 .1
"# $ " "#
$
!"
# ! $% #& '% ( ()
* (+ (+ ! ) (
,% (# #& # #+ #+ % -
%
% "
. ,%/ "
% "
0
0 1
%% % % %
2 %
%
% %
'
% %
' % % "
% % %
" 3 % % *
% % -
" %
4 % %
" %
2
% " 0 %%
% - % % %
2 % -
" % %
%
. %
% %
0
" % %-%
% 0 % "
%% " %
% - '
" %
5%-
% % 6 0
% %-
% -
" %7% 2
%- 68
" %
%
4 %
9
* 4% %
5% 8
% %
%
% %
0 % 8
%
2 %
8
" %
%
0
%
2
, : -
%
%
0 7%
% % %
! "
!
% % %
% %%
4 % %
% ;
) % 2 % %%
% % %
3 0
." )( " % "
3 "
" # 4
% %
9
5" % % %
9 5 0 9 - ? 3%
@
0 , %% 9 5
% 9 5 8 % % 5
% %% % )
2
% 8% 9 5
5 9 5
53
%
- % "
%
;% ? %% 9 5
"
! "# $ !
%% ! $ $ !
! ! $ ! & ! !
! "
.1 0 % %
0 % %%
% %
" % %
% % "3 -
A % " % %
% 6 % %
% 0
%
% -
%
% 7%"
%
2 B C ) >>
&>> " %
% %
. %
2 ' )) 8
4 ! 5
' * ,% %
' ! "" ! !
$ ! ! ! ! !!
$ %& #$ "! !!!
9 !% &> &>+ .-
4 5 ! ' % %
%
2 ) ( +>>
% " 4 +&
8 %
" %%% 9 -
% %7% %
2
% % % -
-3
0 %%
% 9 5
= #++ % -3 %
% 9 5
9 5 4 %
,
205
204412
180
190
200
220
230
250240
210
Toe
D
C
B
ABackscarp
0 10 20 30 40 50 mScale
BatterseaCourt
111 101102
104402403
103404
405
406
106105107
108
109110
112
401
Library
AC AB
AA
Lecturetheatres
413410411203
202 206408
407201
419
Trialdrain
250240
230
220
210
200
190
180
170
160
170
SurreyCourt
414
416415
417
N
Deep drainage trenches
( ! ) $ *
! "
(
4
;%
% %
9 % %
% ( ". 8 % % %
% 0" % 8
% %
% #) ".
2 ' ) %
D% )) . 2 -
% % %
%
2 ) "
>>>
E >>>
@8 %
E>> >>>
0 E)> >>>
0 E( >> E> >>>
7% % %
7%
" 9 5
% %
8% % % >
#) (
0 %
% %
%
% %-
2 %-
9 5 % % 3
P205 P201 P104 P107 P102
31
m
47
m
77
m
135
m81
m
16
m
04
m
182
m
104
m
Readings taken on4 January 1966prior to effects ofdrainage measures
# ,-% ! .
30
30
60
90
O.D.
m
Water levelin the Chalk
1820 1843 1878 1895 1911 1936
Drift and gravel
London Clay
Woolwich and Reading bedsThanet Sand
Chalk
/ ! !0 1 /
)"(*
! "
*
% %
%
%
% 9
!% (& 2
9
%
"
%
%%
2
3 0
' ) ; )( 3
- % 2 %
% - %
% % 8 % A
%
;% %
% 9
%
0 %
% %-
%
% % %-
% )
%
;% )#
-
5 % +>+
% % 2
%
% %
% &( 2
% )
+&F G 0
% %
1965 1966N D J F M A M J J A S O N D
0
1
2
3
Dep
th b
elow
gro
un
d su
rface
: m Piezometer P106Depth 61 m24 m from of drainDrains installedMarch / June 1966
LC
4 2
$ %& #$ "! !!!
+
% ;% )
%
+>+ %
;% )> %
%
% -
3
% 4
% *
% %%
=%
%
8 9
!%" (+
%
%
0 %
%
% %
19701969M A M J J A S O N D J F M A M J J
0
1
2
3
Dep
th b
elow
gro
un
d su
rface
: m Outside drained areaPiezometer CDepth unknown
Inside drained areaPiezometer 404Depth 57 m
5 % -% ,(6(
2
3
Dep
th b
elow
surfa
ce: m
1969 1970 1971 1972 1973 1974 1975 1976
Piezometer P404 21 m from centre line of drain
" 7 -% (6(
! "
*" ) % "
9 %
%
& %
0 % %
-%
6 % % % % 6
4 3 %
-
6
,% (# ! #+
' > >
> > &>
, 9 1 0 %
% ? = ,
% 9 4 5%
%%
I%/
2 D% #> J % J 5
= , % 9 "
% 0 %
% %
" % &) 0
% 0 % 8 >
0
&> ? 8 %
%
*" - %
%
;% #+
?
"
% 6
%
%
0
" %
8 % % % %
8 %
-
" 6 0 %
; )
" -
8 % + %
% 0 %
! "
!
9 %% .
% %
8 % > %
0 % 8 %
% 2 % %
% %
0 5 10 15 20 25 m
Scale
N
P10
P15
P14P13
P2
P6
P8P9
P7
P3(S)
P11(S)P12(D)
P4(D)
P1
I4 I5I8
I27
I14
I21
I12I10
I17
I2
3339 Victoria Crescent(under construction)
Existing rear retaining wall
Phase 2Counterfort drains
Lateral extentof slip
Y
X
Dow
nsl
ope
dire
ctio
nInclinometerreadingdirections
Lateral extentof slip
Phase 1 piles
Access RoadSite Boundary
Existing 3 storey block of flats
600 mm dia. bored pilecontaining 305 305 118 UCInclinometer and numberPiezometer and numberShallowDeep
(S)(D)
Note: Reinforced concrete retaining walls and associated works omitted for clarity
9 )""*
$ %& #$ "! !!!
'
4 %-% %
%%
2 >
2 % %
% % %7% % %
4 %
! #) 0 % %
% % 0
+ %
>
2
%
%
B %7% 0
% 8%
( -
%
P1 Piezometer tip and number
3339 Victoria Crescent
1
1
2
2
3
3
4
4
Flats
Access
Spur drain
Outline of counterfort
P1P10
P12P15
P9
P11
P4
P2P3P5P6
P7P8P13P14
Existing retaining wall
Original ground level
Final ground levelPost-slip ground level
Rows of piles
!! 9 )""*
! "
0 -
& % ;
% %
-
% &>
0 -- -
%%
0
% % 3 -
0
%
?
% %% 3
%
3 -
"
" , ." &>>> @%
&>>> C 9 &>>>
- - 4 8
%
. # 0 % 4# %%
%- ; 2 %
% 8% +> 0 %
%
% % % "
%
' % &
% %
0
% %%
" %
4
% % %-
% #> &>F %-
2 " -
%
2 % 8
" %
%
% % 0
% %
%
$ %& #$ "! !!!
%
%
" D &>>>
&>>>
: 0 %%
%
#K 0
( 0 )> >> %
0 7%"
%
%% 2
%
1% 7 ; 9 %
* '
-
4% "
%% 5
" % /
2 % % #)> .
%% @ 5 %
> .
%
% %
. %
%
% &> % 3 %
0
? 7% %
5
5%
0 9 @ 2 *
' ' 5% >
" %
/
%
%
%
0 %
" .
" % ? % 9
* ' ' 5% %
%
%
"
! "
(
0
" "
1
%% % 8
0 9
% %
; &>>> ! % %
I%/ % 3-
0
" %-
% -
9 @
5 0 %
7% % % % -
% % 0 ?
%
3-
8 % %
2 % % 7%
%% 1
0 % 7% 8% 6 %% ? % 8 %-
6 %
0 % 3 6 -3
%
4 % %3
%-
% 3
2 -
% %
% %
0 % % 3
2 % %
% - %
0 %
9 7%
% 9 -
" %
$ %& #$ "! !!!
)
;% ) %
; &>>> % %
% % .%
% %
%-
4 %
9
0 %
% %%
" 9 .
3%
; )+ 2
%
% ; )
#% % & %
% 1
6 % ; )) %
% %
0 10 m
Scale
Fish Bed
Grey Ledge
Table Ledge
Seacliff
Seawall
Beach
Mudslide
Loading at headfrom landslide above
1998 clifftop postion
1995 clifftop postion
Active slip surface observedapprox. 2 m above Grey Ledgein exposure above seawall
Denotes moving landslidePosition of shear surfaceconfirmed by inclinometeror visual observation
' % 1% 7 )666*
! "
*
45 40 35 30 25 20
Elevation mAOD
45 40 35 30 25 20
Elevation mAOD
45 40 35 30 25 20
Elevation mAOD
P2P3 P
6P4
P5
P1
Sect
ion
A
Sect
ion
D
Sect
ion
F
ND
rain
dril
led
to g
rou
nd
surfa
ce
Dra
in te
rmin
ates
with
in th
e gr
ou
nd
Not
e: dr
ain
leng
ths
and
posit
ions
are
pro
visi
onal
Birc
hi B
edEx
istin
g pi
ezo
me
ter.
(Prop
osed
addit
ional
piez
om
ete
rs n
ot s
how
n)
Prop
osed
loca
tions
of p
neum
atic
piez
om
ete
r
D
C
E
F
B
A
(,
1%7)%
/;;
9!.,7*
$ %& #$ "! !!!
(+
* 6
% % % ; )( ,%-
(# # #+
* % 3 %
% ,%-
(# % ;% )# % 8 4 3
2 %
3
%
2 % %
8 % % 2
% 3 %
# ; $.!- 7$ 9 ! / ; ;
*
Removal of soil
Toe, berm preferably free draining
? % $
! "
(
5 6
%
% " %
= % " %
2 % % 3
-
% ; )
4 - 8 %
% ;" * % @ ,
% % ; * *
7% * ; @8 3
J-! 4%
F F
Centre of slip circle
Removal of soil
Deep seated circular slip surface
4 % .
9! )"5' "5($*
Fills always advantageous
Fills always unfavourableFills adverse in
short term, butbeneficial in long term
Centre of rotation
Drained neutral point = mobilized
Undrained neutral point of landslide = , immediately under centre of rotation
5 ! ! 9! )"45*
$ %& #$ "! !!!
(
!
% '' 3 %% 3
2
%% %%
% %
" %% %
0 0 %
%% %
%
0 % %% % 5%
" " 5 ,"
! (( 2 #& 9? (( =
&>>> : &>>> D% ,% &>>>
(' %.-: 9 5 % - -
->
%
5 +( & 2
- % % -
% 8
4 %
%
;% )&>
% 0 6 %
@ & 4 %
-
0 - %-
% 5 !?%
)( 8
- % %
C 7%" 8
% + % %
0 4L % > " % B
B? 0 %
; )& -
; )&& 0 %
8
) ". 2
% !?% @ )
% -
7%"
0 -
%
> % ) % >
&& % >) 2 >
%
&>> &
C % 8
8 % % %
%
8
% %
0
+
-
% ! % % -
% % %
Cathode, can be a perforated tube
Original water table
Anode, usually a steel rod
Water flows from anode to cathode
6 %? .%
$ %& #$ "! !!!
('
% ; )&
%
4 -
%
0
'% 8
%
% (F
0 % % > >>> "*
+ 4 >>
8 % % &>>> ( "*
&& "
0
; )&+ %
% % % >>
% 4 &
%
Dep
th: m Descrip-
tion of soil
Water content: %
10 20 30 40
Unitweight:kN/m3
Shear strength: kPa
10 20
Sensi-tivity
Vertical effective stress: kPa
50 100Weath-eredcrust
5
Quickclay
10
15
wPw
w = Water contentwL = Liquid limitwP = Plastic limit
wL
193
196
200
195
195
Vane boring I50
80
80
7070
10
>100
>100
>100
Effective pressure
Vane boringUnconfined compression testCone test
Pre-consolidation pressure observed in consolidation test
! .% @ =A%
)"4*
! "
(
10+
8+
6+
4+
2+
1
3
5
7
9
Electrode row no:
N
+
B
P12P14P11
P13
P10P2 P4P1 P5
P3P6P8
P9P7
S1S2S3
S4
Brook
Excavation
BV7
V3V4V1V5V6
V2
I5
67
8910
1112
Section BB
S1
S4
S3
P6
P12
P13
P14
P7 P9
P11 P10 P1 P2P3
P4
P8
P5
0 5 10 m
Scale
Bedrock 28 m
Excavation
5 67 89101112
Weatheredcrust
Quick clay
Piezometer installations P1P14Precision settlement gauge S1Borros settlement gauge S2S12Vane boring I before electro-osmosisVane borings V1V5 after 30 days ofelectro-osmosisVane borings V6V7 after 103 days ofelectro-osmosis
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