降雨及库水位联合作用下秭归八字门滑坡稳定性预测

针对三峡库区库水位调控方案和极端降雨情况，对秭归县八字门滑坡稳定性分析设置了10种计算工况，采用SEEP/W软件模拟该滑坡在降雨入渗及库水位联合作用下的暂态渗流场，并利用SLOPE/W软件，将暂态孔隙水压力分布用于该滑坡的极限平衡分析中，确定不同工况下（不同降雨强度）的滑坡稳定性系数，据此采用降雨量对该滑坡进行失稳预测。研究认为：150 mm/d以上的降雨量对该滑坡影响较大，降雨入渗具有滞后性；在相同的降雨量情况下，1 d的降雨强度比5 d的连续降雨对滑坡体的稳定性影响更明显；在水位从175 m降至145 m的过程中，临界雨量为100 mm/d时，滑坡就可能失稳；水位从145 m升至175 m的过程中和175 mm稳定水位时，当临界雨量为200 mm/d时，滑坡才可能失稳，即水位骤降过程中滑坡失稳概率大。不同工况下的滑坡土体含水率分析结果表明，降雨影响的主要是上部土体，下部土体含水率受控于地下水位，即降雨更容易引起浅层滑坡与局部滑坡

Stability prediction for Bazimen landslide of Zigui County under the associative action of reservoir water lever fluctuations and rainfall infiltration

Aimed at regulated scheme of Three Gorges Reservoir and extreme rainfall events, 10 working conditions were set for stability analysis of bazimen landslide of Zigui county. Transit seepage due to associative action of reservoir water lever fluctuations from 175 to 145 and rainfall infiltration was simulated adopted by SEEP/W software. And by using SLOPE/W software, the computed transit pore water pressures were used for limit equilibrium analysis of this landslide, then the landslide stability factors of different work conditions (different rainfall intensity) were decided and the rainfall could be used to predict landslide at last. The stability study showed it would have a great influence on landslide stability when the rainfall is greater than 150 mm/d, and rainfall infiltration had time delay. In the same condition of rainfall, the influence of one day’s rainfall intensity on landslide stability had greater than five day’s rainfall intensity. During the process of water lever descending from 175 m to 145 m, the landslide would be instability when the critical rainfall was 100 mm/d. That is to say, the landslide failure probability was high during the rapid drawdown. During the process of water lever ascending from 145 m to 175 m and the stable water lever of 175 mm, the landslide would be instability while the critical rainfall was reach to 200 mm/d, that means the landslide failure probability was low under the above two conditions. The results of moisture analysis on landslide showed that it mainly influenced upper soil by rainfall, and lower soil’s moisture was controlled by underground water, which indicated rainfall was accessible to cause shallow slope and local slope