Rheological characteristics and seepage laws of sandstone specimens containing an inclined single fracture under three-dimensional stress

The rheological properties and seepage laws of fractured rock masses have a highly significant impact on the long-term stability of engineering rock masses. To study the rheological properties and seepage laws, rheological experiments under different loading paths were designed and conducted on sandstone samples with pre-fabricated single fractures. The results indicated that (1) as the axial stress or pore pressure increases, or the confining pressure decreases, the creep strain (both axial and radial directions) during the creep tests increases, and their stain rate decreases; (2) compared to the pore pressure, the axial stress and confining pressure have a more significant influence on the flow rate during the creep process. As the axial stress increases or the confining pressure decreases, the flow rate shows an increasing trend; (3) the higher connectivity results in higher final flow in an exponential function, indicating that the connectivity ratios can well reflect the permeability of the fractures; (4) the changes in the stress field may lead to the transition of the surrounding rock from a stable state to an unstable state, i.e., the occurrence of creep failure, or water inrush. Therefore, when the state of the surrounding rock changes, strengthened monitoring and proper preventive measures should be implemented.