A micromechanical model for the elasto-viscoplastic and damage behavior of a cohesive geomaterial

A Hill type incremental homogenization method was recently proposed by Abou-Chakra Guéry et al. [Abou-Chakra Guéry, et al., 2008. A micromechanical model of elasto-plastic and damage behavior of a cohesive geomaterial. Int. J. Solid. Struct., 45(5), 1406–1429] for the elasto-plastic damage behavior of a cohesive geomaterial, the Callovo–Oxfordian argillite. The aim of this paper is then to extend the homogenization method to its time-dependent behavior. The argillite is now seen as a three phase composite with an elasto-viscoplasticity matrix and elastic damaged calcite grains and elastic quartz grains. Considering that the incremental formulation of Hill cannot rigorously be used, we proposed a new modified incremental method. A validation of its predictions against experimental data is then conducted.