Geoscience Reference
In-Depth Information
5.6.1.
Simplified Roscoe formula for undrained consolidated soils
The Roscoe surface [5.15] at constant volume becomes:
1/2
1
q=p'M
−
1
[5.23]
CC
/
(p'/p' )
c
d
0
This equation defines the bell-shaped curve in the (
q/p'
ic
- p'/p'
ic
) plane in Figure
5.12 and the coordinates for the peak are:
p'
=−
CC
1/ 2
CC
d
d
p'
ic
[5.24]
1/2
q
C
CC
η
=
= M
pic
p'
2
−
d
pic
where
C
c
= 0.2 and
C
d
= 0.33 (see section 5.4.2 and 5.4.3).
Hence, the soils present a maximum under the perfect plasticity only if
η
peak
< M
, that is to say
C
c
< C
d
.
q/p'
c
1.0
1
(p/p
0
)
-1
q = p'.M'.
0.8
Cc/Cd
M=1.3
0.6
Seed 1966
p'0 = 3 MPa
0.4
M = 1.3
Cc = 0.2
Cd = 1/3
P'
PP
= 1.15 MPa
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
p'/p'
c
Mekkaoui-qp'c-4839
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