Experimental study on the rainfall infiltration process in the accumulation with two interlayers

In order to study the influence of interlayer of different components on rainfall infiltration, the differential movement and distribution characteristics of rainwater in the accumulation body were studied. In this research, a detailed field investigation was carried out on two types of intercalation: clay intercalation and fragmentary stone intercalation developed in the deep deposits in Jiuxiang area of Han Yuan, Sichuan Province. By designing two indoor rainfall experiments of gravel interlayer and clay interlayer to monitor the changes of moisture content, matrix suction, pore water pressure and wetting front in the accumulation, the influence of the two types of interlayers on the infiltration process of rainfall in the accumulation was deeply studied. The results show that: (1) Due to the different particle composition of the interlayer, the permeability, wetting front migration morphology, infiltration rate, and the soaking time of the entire stack are ultimately significantly different. (2) There are significant differences in rainwater infiltration between the two groups of sandwich tests. The infiltration effect of the gravel group is stronger than the lateral diffusion, and the infiltration rate at the interlayer is significantly faster than that on both sides, while the lateral diffusion of the clay group is stronger than the infiltration, and the infiltration rate at the interlayer tends to zero, which is significantly lower than that on both sides. (3) The pore pressure at the foot of the slope in the clay group increases cumulatively, while the pore pressure in the gravel group dissipates rapidly, and the water is mainly distributed in the deeper layers of the accumulation, so the overall stability of the clay interlayer accumulation is lower than that of the gravel interlayer accumulation. The research results can provide a basis for analyzing the influence of subsequent rainfall on the stability of slope with weak interlayer.