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7/27/2019 ascife.27510.0002
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Soil particle
Shear surface
Relative displacement
of soil in the mass
Interparticle force
normal to shear surface
N
F
Load platenN(applied normal load)
P(shear force)
Soil specimen
Induced
shear surface
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vuf/ w
Failure
zone
su
uo/ w
Excess pore
pressure at
failure
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v
Failure
zone
sd
uo/ w
No excess pore
pressure
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vol
vcrit
v
P
C Initially dense
Initially loose
Initially dense
Initially loose
(a)
(b)
(c)
c
pDilation
Compression
Critical specific
volume
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Peak
strength
envelope
12
34
0
0
Critical state line
= tan crit
(a)
(b)
c
Actual
peak strength
over estimated
at low
p= c + tan tgt
tgt
crit
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n
f
O-C peak
N-C peak
N-C peak
O-C peak
Residual
ResidualShearstress:
Displacement:
Effective stress normal to
shear plane
c r
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Remote
transducer
Digital
control
circuit
steps
Stepper motor
and gearbox
Linear bearing
Analogue feedback
Pressure
cylinderPiston
Pressure
outlet
Pressure
transducerDeaired water
(b)
(a)
Axial load
Ram in rotating
bushing
Top cap
Water-filled cell
Top platen
Rubber O-ring
Soil specimen enclosed
in rubber membrane
Clear acrylic tube
Saturated porous disc
Base pedestal
To pore pressure
transducer
Saturated
pore-water ductsValve open during
drainage
Cell pressure
Back pressure
Captiveball nut
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f=c+(
u)tan
c
Drained (back-
pressure zero)
Consolidated-
undrained
Unconfined
compression
Unconfined
compression
u
Drained
uf
(13)f = su
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0
0 0
0 0
0
50/w 50 /w 50 /w
550/w
555/w
355/w
155/w
350/w
150/w
600
600
400200
200 400
680480280
400200 600
(c)
(b)
(a)
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:kPa
:k
Pa
c
u
(1)
cu (1) cu (2) cu (3)(u): kPa
cu (2)
cu (3)
ud (1)
ud (1,2,3)
ud (2) ud (3)
155355
555
235155
200
280
390
480
400
680
600
730
1080: kPa
22
70
10
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200 400 600
600
600
1080
400
400
200
390 730
200
100/w100/w100/w
155/w235/w
70/w
(a)
(b)
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200 400 600
600
600
1230
400
400
200
350 785
200
100/w 100/w100/w
100/w 100/w100/w
(a)
(b)
:kPa
f=10
+0404
(u)k
N/m2
10
100 250 300 500 685 1130
22
u: kPa
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:kPa
:kPa
(u): kPa
: kPa
ud
ud
cd d
cu d
785730480400355
155
10022
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(1+3) / 2
(1
3
)/2
(1
3
)/2
Failure line
Failure line
(a)
(1+3) / 2
(b)
max
=(
13
)/2
(u)
3 1
1 +3/ 2
c
K
Failure envelope
Failure line
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0 050 50 100
Undrained shear strength : sukPa
LL=75
PL=24LL=80
PL=25
Heavily over-consolidated
clay
Normally
consolidated
clay
10
8
6
4
2
0
Depthbelowgroundsurface:m
Su
p = 03
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050
040
030
020
010
0
su
/pratio
0 10 20 30 40 50 60 70
Plasticity index: PI
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Torque
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00
5
100 200 300 600
Shear strength: kPa
10
15
Depthbelow
groundlevel:m
865 mm dia. plate tests
38 mm dia. triaxial
98 mm dia. triaxial
Penetration tests
Sand and gravel
Soft brown clay
Brown and grey
mottled clay
Stiff grey clay
865 mm dia.
plate tests
400 500
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100
100
100
100
80
80
80
80
60
60
60
60
40
40
40
40
20
20
20
20
0
00
0
%o
fstrengthwith=90
%o
fsu
with
=90
100
120
140
160
80
60
40
20
0
%o
fsu
with
=90
% of suwith = 90
% of strength with = 90
100
100
80
80
60
60
40
40
20
20
0
0
%o
fstrengthwith
=9
0
% of strength with = 90(c)
Circle, centre origin
Ellipse fitted
at axes
Cubical triaxial cell (after Arthur and Menzies, 1971)
Modified conventional triaxial cell (after Arthur and
Philips, 1973)
(a)
(b)
100806040200
% of suwith = 90(d)
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Direct shear
Compression
Extension
Circle
Ellipse fitted at axes
140
140 160
120
120
100
100
80
80
60
60
40
40
20
200 0
%o
ftriaxialcompress
ionsu
withbeddinghorizontal
% of tr iaxial compression suwith bedding horizontal
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12
10
08
06
04
Correctionfac
tork
v
su(field) =su(vane)kv
0 20 40 60 80 100 120
Plasticity index: %
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25
001 05
20
15
10
05
0
25
20
15
10
05
0
(
13)max(kg/cm
2)
10 min 1 hour 1 day 1 week 1 month5 10 50 100 1000500
(a)
(b)
c= 10 kg/cm2
c= 20 kg/cm2
c= 40 kg/cm2
Time to failure: hours
Porepressureparam
eter:A
f
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