A Multiscale Microstructural Model of Damage and Permeability in Fractured Solids

Deterioration of mechanical and hydraulic properties of rock masses and subsequent problems are closely related to changes in the stress state, formation of new cracks, and increase of permeability in porous media saturated with freely moving fluids. We describe a coupled approach to model damage induced by hydro-mechanical processes in low permeability solids. We consider the solid as an anisotropic brittle material where deterioration is characterized by the formation of nested microstructures in the form of equi-distant parallel faults characterized by distinct orientation and spacing. The particular geometry of the faults allows for the analytical derivation of the porosity and of the anisotropic permeability of the solid. The approach can be used for a wide range of engineering problems, including the prevention of water or gas outburst in underground mines and the prediction of the integrity of reservoirs for underground CO2 sequestration or hazardous waste storage.