辽西黄土陡坡的冲刷破坏机制

以70°辽西黄土陡坡为例，在降雨强度为2.7 mm/min条件下对边坡坡面冲刷破坏特征进行了室内物理试验模拟。试验发现：随着降雨的持续坡面水流能量不断增加，致使侵蚀强度增强；边坡的侵蚀方式从试验初期的片蚀，到中期的细沟侵蚀，最后演化为坡顶部的切沟侵蚀和坍塌。基于试验成果，采用SEEP/W程序对降雨条件下边坡降雨入渗规律进行数值模拟，发现在降雨过程中坡顶部所产生的水头压力最大，随高度降低呈减小趋势；运用PFC2D颗粒流软件从微观角度对坡体土颗粒运动情况进行模拟，结果发现位于坡顶的颗粒最先被径流冲刷带走，且下落速度很快。经对比表明：数值模拟结果和物理模拟试验现象基本一致，可为进一步研究黄土边坡冲刷破坏规律提供参考。

Mechanism of Steep Loess Slope Rainfall Erosion in Western Liaoning

A series of physical simulation experiments of slope rainfall erosion were conducted in laboratory on steep loess slope of 70° in Western Liaoning under a rainfall intensity of 2.7 mm/min.  It was found that as the rainfall lasted, the energy and erosion intensity of water flow increased. The erosion pattern verified from splash and sheet erosion to rill erosion, and finally evolved into gully erosion and collapse on top of the slope. Based on the experiment, the distribution of rainfall seepage in the slope was simulated by SEEP/W. Results showed that the water pressure on top of the slope was the highest, and it reduced as the height decreased. The microcosmic motion of soil particle was also simulated by PFC2D, it was found that particles on top of the slope were firstly washed off by water flow, and rapidly fell down. The simulation results are consistent with the indoor model experiment, which provide a reference for research on rainfall erosion properties of loess slope.