Multi-scale permeability evolution model for layered rocks

A damage constitutive model and a multi-scale permeability tensor model for layered rocks based on a two-step homogenization technique are proposed considering the characteristics of multi-scale structures (i.e., bedding planes and microcracks). With the homogenization technique, the proposed models wells account for the influences of anisotropic damage growth and mobilized dilatancy behavior of microcracks, mobilized degradation and shear dilatancy of bedding planes, and interaction between bedding planes and microcracks. The effects of structures with different scales on the variation of permeability are better addressed. Numerical simulations are performed on an underground cavern in layered rock masses to investigate the changes in multi-scale hydraulic conductivities under excavation, which are influenced by the anisotropic strength characteristics of layered rocks and inclination angles of bedding planes. The results may provide a helpful reference for better understanding the coupled hydro-mechanical behaviours of deep rocks.