Influence of coarse and giant particles enrichment position on rainfall infiltration of accumulation body

A rainfall model test was carried out indoors with regard to the enrichment of local coarse and giant particles at different development positions, the middle and the foot of the slope of the accumulation body in Dongxing County. By observing the changes in pore water pressure, matric suction, volume water content, and wetting front migration, the effect of coarse and large particles’ local enrichment in the middle and at the foot of the slope in the course of rainfall infiltration was analyzed. The research indicates: (1) The hollow parts caused by the enrichment of local coarse and giant particles from the middle of the slope (Group A) and the foot of the slope (Group B) led to the formation of a dominant rainwater infiltration channel during the rainfall, and the infiltration rate under the enrichment area was apparently faster than that around homogeneous soil. (2) The filtration rate on the right side of the accumulation in Group B was faster than that of Group A while the left side was slower than that of Group A. (3) With stronger overall seepage, the wetting front migration of Group B was the first to hit the bottom, 72 hours earlier than Group A. (4) The wetting front migration pattern of the accumulations in Group A showed a gentle concave infiltration in the early stage, which was wider than the concave infiltration on the right in Group B; later they showed smooth arc infiltration, while the infiltration area of the accumulations in Group B was larger. Group A was smaller. (5) The rainfall infiltration in Group A and B could divided into vertical infiltration stage and lateral infiltration stage, but there were obvious differences: in Group A, the vertical infiltration rate was faster than the lateral one, while the former was slower than the latter in Group B.