Abstract：A coupled model for anisotropic damage and permeability variation by using a micromechanical approach is presented. The damage state is represented by oriented distribution of microcracks，damage evolution in rock is defined from a crack propagation criterion；and the free entropy and constitutive law of cracked rock are obtained by using micromechanical method. It is assumed that the cracks exhibit normal aperture which is coupled with the crack growth due to asperities of crack faces. By using Darcy¢s law for macroscopic fluid flow and assuming laminar flow in microcracks，the overall permeability of RVE is obtained by a volume averaging procedure taking into account crack aperture in each orientation. An analyzing case shows that the result by the model perfectly agrees with experimental one.
