Anisotropic permeability evolution model of rock in the process of deformation and failure

The rock permeability is an important parameter in the studies of seepage and stress coupling. The micro-cracks and pores can initiate and grow on a small scale and coalesce to form large-scale fractures and faults under compressive stresses, which would change the hydraulic conductivity of the rock, and therefore, the rock permeability. The rock permeability is, therefore, closely related with the micro-cracking growing, coalescence, and macro new fracture formation. This article proposes a conceptual model of rock permeability evolution and a micro kinematics mechanism of micro-cracking on the basis of the basic theory of micromechanics. The applicability of the established model is verified through numerical simulations of in situ tests and laboratory tests. The simulation results show that the model can accurately forecast the peak permeability evolution of brittle rock, and can well describe the macro-experimental phenomenon before the peak permeability evolution of brittle rock on a macro-scale.