粗、巨颗粒富集位置对堆积体降雨入渗的影响

针对某堆积体局部粗、巨颗粒于坡中、坡脚不同发育位置富集现象展开室内降雨模型试验，通过孔隙水压力、基质吸力、体积含水率及湿润锋迁移形态的变化情况，探讨粗、巨颗粒于堆积体坡中、坡脚位置局部富集在降雨入渗过程中的差异性影响。研究表明:（1）坡中（A组）、坡脚（B组）局部粗、巨颗粒富集导致的架空现象致使降雨过程中形成雨水优势入渗通道，富集区下方的入渗速率明显快于周围均质土体；（2）B组堆积体右侧入渗速率比A组堆积体更快，而左侧入渗速率不及A组堆积体；（3）B组堆积体的整体渗流特性更强，其湿润锋运移率先触底，比A组堆积体提前72 h；（4）A组堆积体湿润锋迁移形态先期中部呈平缓凹形下渗，较B组右侧凹形下渗范围更宽；后期均呈平滑弧形入渗，而B组堆积体浸润面积较A组更小。（5）A、B组堆积体降雨入渗可划分为竖向入渗阶段和侧向入渗阶段，但存在明显差异，A组堆积体竖向入渗快于侧渗，而B组堆积体竖向入渗慢于侧渗。

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.