降雨对黄土裸坡坡面形态影响的室内模型试验

Indoor Model Experiment for Rainfall Effects on Bare Loess Slope Shape

黄土高原坡面的侵蚀主要发生在降雨集中的6—9月,坡面会遭到严重破坏,更甚者造成滑坡。建立了黄土裸坡的室内模型并模拟人工降雨,通过综合监测来观察降雨过程中坡面形态的变化并分析降水入渗对黄土滑坡的影响。试验结果表明:(1)降水入渗速率由快到慢;径流量/入渗量的值随时间先增长,再减小,最后稳定;坡顶的降水入渗速率始终大于坡面;(2)坡顶首先产生贯通的拉裂缝,然后坡体内部产生局部微小竖向裂缝,位移方向为坡顶下方竖直向下,坡面下方略大于45°;(3)坡面侵蚀经历了"片蚀—沟蚀—沟间坡面面蚀向深切和侧蚀发展"的过程,最终沟岸发生崩塌,坡面因受侵蚀呈整体下降趋势;(4)坡面崩滑从坡趾处自下而上发展。

Soil erosion on the Loess Plateau mainly occurs from June to September during which high intensity rainfall occurs correspondingly, which always leads to severe damages to slope surface and even causes land- slides. In this study, an indoor model of bare slope was established and the artificial rainfall device was set up over the slope. The changes of slope shape were observed and the effects of water infiltration on the loess landslides were analyzed through comprehensive monitoring. Results show that： （1） the water infiltration rate was low and the ratio of runoff to infiltration first increased and then dropped to a steady level with the increased time. Water infiltration rate at slope top was always greater than that on the slope surface. （2） After tensile cracks were generated at slope top, small vertical cracks were created locally inside the slope. The displacement directions were vertical below the slope top and slightly greater than 45~ on the low slope section. （3） Eerosion on the slope experienced the process of ＂sheer erosion--gully erosion--deep and lateral erosion in the slope of ditch＂, and ultimately the gully bank collapsed. The whole slope moved downwards due to the erosion on the slope surface. （4） The landslide developed from the toe of the slope to the top.