Modeling the mechanical properties of rock at different pore and confining pressures using the grain-based stress corrosion model

A grain-based stress corrosion model is built from 3DEC-GBM (i.e. a 3-D discrete element grain-based model). The model employs the effective stress law and stress corrosion theory to study the time-dependent and time-independent deformation at the mesoscale of the sandstone with varying confining and pore pressures. The simulations adequately explain complex macroscopic time-independent behaviour in terms of the mesoscale interaction of grains, and tension cracks were the dominant crack propagation pattern in the simulation for different confining and pore pressures. The traditional creep behaviour observed in laboratory brittle creep experiments could also be accurately reproduced by the proposed model. The simulations show that the percentage of tension cracks in rock fractures decreases with increasing confining pressure and pore pressures. Increasing the applied differential stress and reducing the effective pressure can shorten time-to-failure and increase the creep strain rate, respectively. We conclude that the proposed model is an appropriate tool to analyse the deformation behaviour of sandstone under coupled hydromechanical loading in both the short and long term.