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Multiscale Geomechanics
Figure 9.22.
Cyclic shear test simulations obtained with the three sets of parameters
PA01: J1 set with A = 1,300;
PA02: J1 set with A = 70; and
PA07: J2 set with A = 1,300
The critical state parameters (M and
λ
) are chosen through an analysis of the final
points of the tests. We have noticed that the tests with the same confining pressure reach
the same point for large strains in (
e − log p
) plane, which is in accordance with the
critical state concept.
C
c
=0.05
is positioned within the range given by Hicher and
Rahma (relation [9.83]) [HIC 94]. On the other hand, it is different from the values
given by Biarez and Hicher [BIA 94]. Kokusho [KOK 82] suggests using
A =1,300
,
n
e
=0.6
and
b =2.17
for parameters of relation [9.9] for the elastic modulus of
rounded gravels. This value is used for a first set of parameters (J1: see Table A.1,
section 9.8). We should note, however, that if this choice is satisfactory for simulating
drained tests, this is not the case for undrained tests. A value of
A =70
improves the
results of both drained and undrained tests. However, this last set of parameters results in
an incoherent response for liquefaction tests. Furthermore, the
G−γ
and
D−γ
curves,
obtained with this last set of parameters, are outside of the zone currently used. (Figure
9.22). A third set of parameters is recommended using the guidelines produced by
Kikoshu (
A =1,300
) but by refinement of the values of
p
c0
. Hence, a set of parameters
with acceptable precision for the response of all drained, undrained, monotonous and
cyclic triaxial tests is obtained. This set of parameters is given in Table A.1 in the
appendix (section 9.8).
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