3. Visco-elasto-plasticity of geomaterials

We now return to the general case of visco-elasto-plastic behavior, recalling that there are three main dissipation mechanisms in geomaterials: plasticity, damage and viscosity. For plastic behaviors, we have seen that physical time does not exist (only a chronology of events can be introduced) and that these behaviors are therefore independent of stress velocities. This is also true in the case of damage, which is very present in brittle geomaterials (overconsolidated clays, rocks and concretes), and the formalism specific to damage can be treated in a framework very close to that of plasticity. We won't distinguish between them here. Viscous behaviors, on the other hand, differ drastically in their dependence on time, and therefore on loading velocities.

Visco-elasto-plastic formalisms are based on the assumption that incremental deformation can be broken down...