Geoscience Reference
In-Depth Information
278
Multiscale Geomechanics
Stiffness
State
Hardening
Elasticity
(
V
s
,
V
p
)
φ
pp
,
ψ
Directly measurable
(
G
,
K
)
γ
el
,
γ
hys
(
E
,
ν
)
d
n
e
p
c0
or
σ
c0
Plasticity
β
r
ela
,
r
hys
,
r
mbl
,
γ
mbl
Not directly measurable
a
1
,
a
2
b
n
p
,
m
p
r
iso
,
c
,
c
cyc
Table 9.2.
Classification of the ECP's constitutive model parameters
I) parameters independent of the assembly of grains:
1) geometric parameters:
a) granulometric description:
d
10
,
d
60
/d
10
and
F
(% < 0.8 mm),
···
b) shape of grains: angular or rounded,
c) texture of grain surface;
2) mechanical parameters (independent of loading history):
a) perfect plasticity:
φ
pp
, one point and the slope of critical state line in
the (
e − log p
) plane: (
C
c
and
Γ(p
Γ
)
) or two points of the line: (
e
max
,p
c
max
)
and (
e
min
,p
c
min
),
b) normally consolidated behavior:
C
c
and
C
d
(slope of a
p
=cst test in
(
e − log q
)) plane;
II) parameters depending on the grain assembly:
1) geometrical arrangement:
e
and the tangent planes of contact between
grains;
2) history of loading:
a) normally consolidated:
σ
c
(
p
ic
isotrope,
σ
vc
oedometer),
b) overconsolidated: OCR.
In addition to these parameters, which describe the state of a soil, the state
of anisotropy and the applied stresses should be mentioned.
The parameters of unsaturated behavior depend mostly on the arrangement and are
classified in the latter category. We present the strategy developed for both clays and
sands:
1) case of clays: Atterberg limits are parameters that are very easy to obtain and
they have great significance in the behavior of clayey soils [BIA 72, BAR 97, LAM 79].
Therefore, the limit of liquidity (
w
L
) and plasticity index (
I
p
= w
L
− w
P
)
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