Numerical Modeling: An Efficient Tool for Analyzing the Behavior of Constructions - Multiscale Geomechanics: From Soil to Engineering Projects - page 285

290 Multiscale Geomechanics

Figure 9.14. Correlations obtained by Lopez-Caballero [LOP 03a]

tan φ pp
a

for E p = fitting G modulus and D damping - γ given by Vucetic and Dobry [VUC 91]

9.4.3.3. Domain of behavior

These parameters have to be calibrated by curve fitting by using modulus variation
with strain or pore pressure variation with strain in cyclic tests.

9.4.4. Parameters defining the initial state

Generally speaking, the initial state is represented by the void ratio, the stress state,
and the maximum stress to which the material has been historically subjected (that is to
say, OCR ). In the framework of the constitutive model, they are defined by σ 0 ( σ c0 ,γ p ,
r h , τ h )for the generic model and ( p c0 , r 0 , T h

k , t h k ) for the multimechanism model. In

the case of an isotropic monotonous behavior, the initial state can be represented by
both the initial stresses or its position with respect to the critical state. Therefore,
the unique parameter ( p 0 /p c0 ) which takes into account the relative density and the
overconsolidation (see Figure 9.15) can be used. In the case of an anisotropic stress
state, we should verify that the yield surface has not been overstepped (it should be
plastically admissible). This will be done by an adapted initialization of the degree of
mobilization of the mechanisms. If the vertical stresses can be estimated fairly easily,