Micromechanical study of damage growth and permeability variation in brittle rocks
Résumé
This paper presents a coupled model for anisotropic damage and permeability evolution by using a micro-macro approach. The damage state is represented by a space distribution of microcrack density. The evolution of damage is directly linked to the propagation condition of microcracks. The macroscopic free enthalpy function of cracked material is obtained by using micromechanical considerations. It is assumed that the microcracks exhibit normal aperture which is associated with the crack growth due to the asperity of crack faces. By using Darcy's law for macroscopic fluid flow and assuming laminar flow in microcracks, the overall permeability of the representative volume element is obtained by an averaging procedure taking into account the contribution of crack aperture in each orientation.