Experimental and Numerical Validation of an Effective Stress-Sensitive Permeability Model Under Hydromechanical Interactions

Abstract

Water seepage in rocks, in geotechnical engineering such as the hydrofracturing of hard rocks, excavation of underground chambers, and prevention of mine water disasters, is a common problem. According to rock mechanics theory, the deformation and stress of rocks influence seepage behavior. In this study, a modified permeability model of argillaceous sandstone under coupled hydromechanical conditions was established to reveal the relationship between permeability and effective stress, including external stress and internal water pressure. The modeling results indicate a negative exponential relationship between the argillaceous sandstone permeability and the effective stress. The proposed effective stress-sensitive permeability model was validated by conducting two sets of seepage experiments based on controlling the water pressure and external stress, with the results obtained considered satisfactory. Based on the proposed permeability model, a fully coupled multifield model of the water seepage and rock deformation was developed. Fully coupled scenario-based numerical simulations were conducted in a finite element environment to investigate water seepage evolution and rock deformation. The experimental and numerical results show that the trends in the evolution of the entire compressive stress–strain and permeability curves are reversed, and the maximum value of the permeability was not consistent with the failure of argillaceous sandstone. This model and corresponding numerical simulations can provide insights for water seepage research and serve as a reliable theoretical basis for evaluating roof water injection and hydraulic fracturing in rock and mining engineering.