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This command makes it possible to calculate the value of a criterion \({r}_{u}\) evaluating the liquefaction zones in a geotechnical structure, modelled by a saturated porous medium. Four formulas are available to calculate this criterion:

• DP_SIGV_REF: the criterion is based on the values at any material point of the pore pressure at the moment in question, of the pore pressure at the reference moment and of the component of the effective stress field at the reference moment, according to the direction of gravity, associated with the weight of the land. It is accepted that when the value of the criterion exceeds 0.8, a risk of local liquefaction is deduced.

• DP_SIGM_REF: the criterion is calculated from the values at any material point of the interstitial pressure at the time in question, of the interstitial pressure at the reference moment and of the effective mean stress at the reference moment.

• DP: it is a difference in interstitial pressure between an instant \(t\) and a reference moment.

• P_ SIGM: the criterion is calculated from the interstitial pressure and the mean effective stress at time \(t\).

This post-treatment calculation is independent of the mechanical behavior model of the porous medium in question.

As input, we give:

• the concept result EVOL_NOLI of the simulation of the structure at the moment in question;

• the axis along which gravity applies;

• For criteria DP_SIGV_REF/DP_SIGM_REF /DP:

  • • • a concept resulting EVOL_NOLI as a « reference » for simulating the work;

      • the reference moment.

As an output, we obtain a result concept EVOL_NOLI which contains in a field at Gauss points of type “ELGA_SIEF_R” the value of the criterion, in the variable SIPXX or SIPYY or SIPZZ depending on the direction of gravity in the mesh.