库水位周期性变化对簸箕石滑坡的影响评价

摘要

库区水位变化对于控制库岸斜坡的稳定性具有十分重要的作用,以簸箕石滑坡为研究对象,分析库水位周期性变化对坡体变形的影响.簸箕石滑坡常年受到周期性水位调节的影响,水位的波动比水面平稳时对坡体前缘所造成的侵蚀更严重,坡体的变形也更加复杂化.基于簸箕石滑坡实地巡查,利用FLAC3D软件进行渗流-力学耦合计算,分析了库水位涨落过程中,滑坡体的剪应变及滑动位移规律.结果表明:蓄水之后水位变化对剪应变增量的影响不明显,但剪应变增量集中程度较蓄水之前有所增强;蓄水之后,滑坡的滑动位移随着水位的下降而增大,而水位上升过程中,位移值虽然较下降之后的值有所减小,但上升到一定水位高度之后,滑动位移继续增加.该研究成果对于簸箕石滑坡及此类滑坡灾害的预测预报具有重要的现实意义.%Variation of reservoir water level plays a crucial role in triggering and controlling the stability problem of reservoir bank slope.In the present research, the influence of cyclic variation of reservoir water level on a slope deformation is analyzed.Located in the Three Gorges Reservoir area, Bojishi landslide is affected by cyclical water level variation.Compared with smooth water surface, water level fluctuation is much more erosive to the toe of the landslide and leads to more complex slope deformation.According to field investigation result, the shear strain and sliding displacement of the landslide mass during reservoir water level fluctuation are analyzed by coupled hydro-mechanical module FLAC3Dsoftware.Results reveal that water level variation has no obvious influence on shear strain increment, but leads to more concentrated strain increment than that before impoundment.Moreover, after impoundment, the sliding displacement, which increases with the drawdown of water level and alleviates with the rising of water level, will keep increasing when water level reaches a certain value.