滑坡前缘开挖后滑坡变形特征分析及稳定性评价——以贵州省岑巩县大榕滑坡为例

岑巩县大榕滑坡发生后，形成堰塞湖，为了疏通河道，对滑坡前缘进行了分级开挖碾压。为掌握大榕滑坡的稳定性状况，对滑坡实施了安全监测。对监测数据进行分析发现：滑坡发生后坡体处于稳定状态；在前缘开挖及强降雨作用下，坡体出现较大变形，之后的2～3个月处于应力与状态大幅调整阶段；特定环境下强降雨或长时间连续降雨对土体的含水率的影响是有限的，含水率不随降雨强度的增大而无限增大，但孔隙水头明显与降雨强度有关，可能成为滑坡发生滑动的主要因素。监测数据及极限平衡法分析表明，该滑坡整体稳定性较好，在强降雨作用下局部处于欠稳定状态。

Deformation analysis and stability evaluation of landslide excavated in front:case of Darong Landslide in Cengong County of Guizhou Province

After Darong landslide in Cengong County occurred, a barrier lake was formed in front of the landslide. To dredge the river channel, staged excavation and rolling compaction were conducted and the monitoring measures were taken to master the landslide′s stability. The results of monitoring data analysis show that the sliding mass was still stable; the relative large deformation occurred under the strong rainfall and the landslide toe excavation, and in the following 2 to 3 months, the stress and stability state were in a large fluctuation. In a specified condition, the influence of strong rainfall or long-term continuous rainfall on soil moisture content is limited, so the soil water content would not rise infinitely along with the increase of rainfall intensity; but pore water level is related to rainfall intensity apparently, and it might be the main cause of the landslide. The monitoring data and analysis of limited equilibrium method show that the landslide is stable generally; however it might be unstable under strong rainfall condition.