Study on the Seepage Mechanism of Rainwater on Granite Residual Soil Cut Slopes

In order to study the seepage process of rainwater on granite residual soil cut slopes, a numerical model for seepage analysis of granite residual soil cut slopes was established. Then, by applying the rainfall boundary condition, the seepage path of rainwater on the slope was analyzed under the condition of rainfall infiltration. Finally, during rainwater seepage, the volumetric water content and pore-water pressure change characteristics inside the slope were analyzed, and the seepage mechanism of rainwater in the granite residual soil slope was revealed. The results show that, under the condition of rainfall infiltration, the surface area of the slope gradually forms a saturated area in a temporary stable state. As the saturated area in the temporary stable state gradually extends to the inside of the slope, the area gradually increases and a groundwater level recharge area is gradually formed at the foot of the slope. Rainwater infiltration changes the original stable state of the slope, causing the granite residual soil slope to change from the two original distribution states of the unsaturated area and saturated area to the three distribution states of the temporarily stable saturated area, unsaturated area, and saturated area from top to bottom. The volumetric moisture content of slope-monitoring points increased gradually with an increase in the duration, and the overall distribution showed an "S" shape. The infiltration of rainwater causes the pore-water pressure of the granite residual soil to increase gradually, and matric suction gradually disappears. In particular, the disappearance of the matric suction at the foot of the slope will lead to the gradual weakening of the shear strength of the slope soil, thus affecting the slope stability.