2种雨型的黄土坡面侵蚀室内试验

Laboratory Experiment of Rainfall-induced Erosion on Loess Slopes Under Two Rainfall Patterns

为研究黄土边坡在连续与间断2种雨型下坡面侵蚀动态变化过程,进行室内人工降雨试验。采用三维激光扫描获取坡面点云并生成DEM,分析坡面侵蚀特征。结果表明:三维激光扫描生成的DEM可直观重现坡面侵蚀的动态过程,采用自然邻点插值法生成的DEM误差最小;间断降雨模式下距坡面5 cm处体积含水率出现与降雨周期一致的波动;2种降雨模式下土壤流失总量在土壤饱和后呈线性增加,间断降雨产生的土壤流失总量(0.035 6 m^3)大于连续降雨产生的土壤流失总量(0.024 9 m^3);间断降雨土壤流失过程可看作多个连续降雨土壤流失过程的组合;2种雨型下,土壤流失速率在空间上分布不均,由前缘至后缘逐渐降低;间断降雨坡面变化区域为中部至前缘区域,其过程为前缘下切→中前缘下切→前缘及中部下切;连续降雨坡面变化区域集中于前缘,表现为前缘逐渐后退。

In order to study the dynamic process of erosion on the loess slope in both continuous and intermittent rainfall patterns, we carried out a laboratory rainfall experiment. We used the 3D laser scanning to acquire the point cloud of the slope and generated DEM to analyze the erosion characteristics of the slope. The results showed that the DEM generated by 3D laser scanning could visually reproduce the dynamic process of slope erosion. The error of DEM generated by natural neighbor interpolation method was the smallest. At the location of 5 cm from the slope surface, the fluctuation of volumetric water content under the intermittent rainfall mode was consistent with the rainfall period. The total amount of soil loss under two rainfall patterns increased linearly after soil was saturated. The total amount of soil loss caused by intermittent rainfall (0.035 6 m^3) was greater than that caused by continuous rainfall (0.024 9 m^3). The soil loss process of intermittent rainfall could be seen as a combination of multiple continuous soil loss processes. Under the two rainfall patterns, the soil loss rate was unevenly distributed in space, and gradually decreased from the front to the trailing edge. Under the intermittent rainfall, the slope surface changed from the central to the front, and the process was: the front cutting → the mid-front cutting → the front and central cutting. Under continuous rainfall, the change of slope surface concentrated on the front, which was characterized by the gradual retreat of the front.