In this study, the discrete element method numerical software program 3DEC 5.2 was applied to simulate
and analyze the effects of rainfall infiltration on the failure process of rock slopes and the pore pressure variation in the plane of weakness during the failure process. This study constructed two sets of rock-slope numerical models using 3DEC. The first numerical model had a simplified dip slope of approximately 10 m in length and width and 15° in dip angle. The tension crack at the top of the slope was assumed to provide a starting point for rainfall infiltration.In the second numerical model, a plane of weakness with a dip angle of 75° was added to the first model, allowing the rainfall to evenly infiltrate into the slope. In the model, rocks were assumed to be elastic, and the Mohr-Coulomb joint constitutive model was used. This study set water pressure at the crown of the slope or slope surface as the starting point of rainfall infiltration and then used a two-way coupling method for simulation. The simulation results indicate that surface water infiltrates from the top, and that pore pressure accumulates inside the rock slope and the rock slope fails when the water pressure reaches a certain value. The expanded plane of weakness after failure allows the pore pressure to dissipate, and the pore pressure changes during the continual deformation of the rock and sliding, which may eventually cause a large-scale rock slide.
Key Words: infiltration, rock slope, numerical model, pore pressure, rock slide