Abstract Understanding the permeability characteristics of deep rock masses is highly valuable for the study of underground resource development. As important components of rock masses, fractures significantly affect their seepage capacity. To clarify the hydraulic conductivity evolution of rough fractured sandstone under varying effective confining pressures, a series of studies were carried out using laboratory tests and three-dimensional (3D) numerical simulations based on the coupled discrete element method and computational fluid dynamics (DEM-CFD). Fractured sandstone samples were prepared using Brazilian tests. Shear-seepage tests were then conducted under varying effective confining pressures using a shear-seepage apparatus. The results show that increasing effective confining pressure reduces fracture permeability and transmissivity. Under effective confining pressures of 10 and 13 MPa, the fracture transmissivity continues to decrease with increasing shear displacement. Numerical simulations were first conducted to calibrate the microparameters of the DEM model against uniaxial compression and shear tests. The proposed coupled DEM-CFD method was then applied to simulate shear-seepage tests, revealing the microscopic mechanism of fracture permeability evolution. The results validated the applicability of the cubic law for fracture permeability during shearing. Further analysis examined the evolution of fracture aperture distribution, connectivity, and roughness. The roughness was quantified using an improved algorithm for the joint roughness coefficient (JRC) and root mean square (RMS). The methods presented here provided a reference for future research on the shear-seepage behavior of fractured rock.
Li et al. (Tue,) studied this question.