The effects of water content and fracture angle on rock creep and crack behavior under impact conditions

Deep mining rock masses often contain numerous fractures and significant water content, making them highly susceptible to instability and failure under external disturbances such as mining and blasting. This study investigates the effects of water content and fracture angle on the creep behavior and crack evolution of sandstone. Uniaxial compression and creep disturbance experiments were conducted on sandstone samples with varying fracture angles (0 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees) and water contents (0%, 50%, 100%), with DIC-2D technology employed to monitor failure modes and crack propagation. Results show that fracture angle significantly influences the compressive strength, which decreases with increasing angle, and transitions failure modes from tension-dominated to shear-dominated. Higher water content prolongs creep failure time, particularly for fully saturated samples with 45 degrees and 30 degrees fractures, which did not fail during testing. DIC analysis reveals that 45 degrees fractures exhibit the highest shear stress concentration, leading to localized crack propagation and coalescence. However, high water content accelerates crack growth, causing rapid failure. These findings provide insights into the complex creep behavior of sandstone under combined fracture and water conditions, offering guidance for improving the stability of deep engineering projects.