A progressive damage and permeability evolution model for brittle rocks

A model for progressive damage and permeability evolution in brittle rocks, accounting for inherent heterogeneity of rocks, has been developed. This model has been incorporated into a comprehensive three-dimensional coupled numerical framework for investigating stress-permeability dynamics throughout the rock fracturing process. Comparative analysis between simulations and experimental results validated the efficacy of the model. Subsequently, the study delved into the damage and failure mechanisms of rock specimens under uniaxial and triaxial compression, exploring the influence of confining pressure on failure plane orientation and the progressive alterations in permeability during damage and fracturing of rock. The findings show that the permeability evolution during fracturing hinges on the initiation, propagation, and coalescence of micro-fractures within rock. Initially, under loading, permeability reduction ensued due to micro-fracture compaction. Subsequent micro-fracture propagation led to a gradual permeability rise until unstable failure, prompting a sharp increase in permeability, denoting macroscopic fracture surface emergence. Furthermore, the mechanical attributes of rock specimens, fracture surface inclination, and permeability shifts were intricately inked to confining pressure: heightened confining pressure correlated with elevated compressive strength, reduced fracture angle, initial permeability levels, and alterations in permeability during macroscopic failure stages in rock samples.