中文摘要：

水库岸坡滑坡稳定性主要受库水位涨落的影响。由于库区水位变化可概化为二维非稳定流,地下水位变化可采用有限元模拟。三峡水库正常运行时的水位涨落速度在0.6～4.0m/d、高程145～175m之间变化,通过有限元法对库区的马家沟滑坡模拟表明：库水位和滑坡体内的地下水位同步升降,水力梯度很小,因此水位涨落对滑坡的影响主要是浮托力作用。在此条件下,采用Morgenstern-Price法对滑坡稳定性进行计算表明,随着水位上升,滑坡稳定性降低,水位上升到165m时,稳定性达到最小,水位再上升则稳定性增大,当滑坡完全淹没在水下时的稳定性高于未被淹没的情况,滑坡最终的稳定性按最小稳定系数评价。

英文摘要：

The Majiagou landslide,as a case for study,is located on the left side of the Zhaxihe River,a tributary of the Yangtze River.After the water level of the Three Gorges Reservoir rose from 95m to 135m in June 2003,the Majiagou landslide occurred including a 20m long,3～5cm wide（locally 10cm wide） fissure at its back that occurred in a time-frame of 3 months.The implication is that the reservoir impounding reactivated the landslide.The slide mass of the Majiagou landslide is composed of a thin layer of silty clay on the top with low permeability and a thick layer of angular pebbles as the main portion beneath the silty clay which has high permeability.The rate of water level fluctuation is between 0.6 m /d and 4.0m /d with regard to the altitude between 145 m and 175 m in the reservoir during its normal operational state.Under these conditions,the FEM method was applied to simulate the groundwater changes in the slide mass,coinciding with the reservoir water level fluctuation.The results suggest that the groundwater level almost changes with the reservoir water level simultaneously within the slide mass,which means that the groundwater gradient is very gentle.Therefore,the effect of the reservoir water level fluctuation on the landslide stability is mainly by the action of buoyant force.Without considering dam failure,the seepage force is so little as to be negligible.The stability of the landslide in cases of different water levels is then calculated using the Morgenstern-Price method,and the results show that the factors of safety decrease with the water level rise.As the water level increases to 165m,the factors of safety are at the minimum value,then increasing with the water level rise.The minimum value reflects that the landslide is in a critical state.