A Micromechanical Model for Time Dependent Behavior Related to Subcritical Damage in Quasi Brittle Rocks

Abstract

In France, an underground research laboratory is constructed in a clay formation, called Callovo-Oxfordian argillites. In order to evaluate quantitatively the structure durability, it is necessary to achieve a good understanding of the long-term behavior of the material. Subcritical crack growth is one of main causes of time-dependent behavior in rock. In order to rigorous modeling of the time-dependent behavior of studied material, a micromechanical model incorporated subcritical damage propagation is proposed for Callovo-Oxfordian argillites in this paper. In the proposed constitutive model, the argillite is considered as a two phase composite: the clay matrix and the mineral inclusion. Based on experimental observations [1], the clay matrix is described by a time-dependent damage model and the mineral inclusions are described by a linear elastic model. The passage from the micro-scale to the macro-scale is done through different homogenization schemes for studying their influences on the subcritical propagation of cracks.