降雨入渗对三峡库区堆积层滑坡稳定性的影响

基于三峡水库库水位调控方案和极端降雨情况,笔者利用有限元模拟库水位在175~145m波动和降雨时红石包滑坡Ⅲ的暂态渗流场,将计算得到的暂态孔隙水压力分布用于滑坡的极限平衡分析,并考虑基吸力对非饱和土抗剪强度的影响。探讨降雨强度对滑坡稳定性的影响,并考虑暴雨与库水位骤降共同作用下滑坡的稳定性。研究表明:滑坡稳定性的影响受控于滑坡土的入渗能力和滑坡结构形态;当暴雨强度为300mm/d时,红石包滑坡Ⅲ的临界降速1m/d。其成果将为库区滑坡治理提供科学依据。

Effects of Rainfall Infiltrati on Landslide Stability of Accumulation Horizon at Three Gorges Reservoir Area

Based on adjustment preparedness of reservoir water table and extreme rainfall in Three-Gorges reservoir, transient seepage due to descending of the reservoir water table from 175～145 m and rainstorm infiltration is computed using the finite element method. The computed transient pore water pressures are then used for limit equilibrium analyses of landslides. Effects of suction on shear strength of unsaturated soils are taken into account. Effects of various rainfall events are discussed. The analytical results of stability show that the stability of landslides is dependent on coefficient of the permeability and structure of landslides. The critical declining velocity of Hongshibao Landslide Ⅲ is 1m/d when the rainfall intensity is 100mm/d. The achievement would provide scientific criteria for the treatment of landslide at Three Gorges reservoir area.