现阶段滑坡稳定计算大多采用拟静力方法中的极限平衡法,也是现行规范中推荐采用的计算方法。对于大多数滑坡持久工况和短暂工况该方法计算结果与地质理论评价结果基本一致,但对地震工况下的多数计算结果则与实际地质分析结果相差甚远。金江滑坡是白鹤滩水电站近坝区的一个巨型滑坡,在对该滑坡进行极限平衡法分析计算时,首先根据《水工建筑物抗震设计规范》(DL5073-2000)土石坝抗震稳定计算中对地震效应的处理方法,计算出滑坡体不同高度上的动态分布系数及相应高度上的水平向地震力和动态分布系数等效值,进而求解出地震力作用于整个滑坡体上的水平加速度折减值,然后再利用该水平加速度折减值进行稳定性计算。结果表明:在地震工况下金江滑坡整体稳定,稳定性系数为1.23~1.45,与实际地质理论分析结果具有较高的一致性,避免了完全按拟静力法计算结果与地质理论分析结果不符的问题出现。
The limit equilibrium method from mimetic statics numeric method,a recommended method in current specifications,is adopted at present in most calculations to the stability of landslide.To most permanent and transient operating conditions in landslides,the result calculated with this method is in accordance with the result evaluated by geologic theory;but to the operating conditions in earthquakes,most results are quite different with each other.The Jinjiang landslide is a giant one near the dam of the Baihetan power plant.In the calculations to the slide with limit equilibrium method,3 steps are adopted in the study.Firstly,based on the calculation ways for anti-seismic stability of the earth-rock dam specified by "The Seismic Design of Hydraulic Structure DL5073-2000",values such as the dynamic distribution coefficients at different heights and the horizontal seismic force component and the dynamic distribution coefficient at the corresponding heights are figured out by means of the handling method to earthquake effect.Secondly,the horizontal acceleration value of the earthquake force that acting on the whole landslide mass is solved.Lastly,the stability calculation is done with the horizontal acceleration value.The results prove that,under seismic operating conditions,the Jinjiang slide is stable as a whole with the stability coefficient being 1.23~1.45,which is not only quite in accordance with the results by geologic analysis,but also avoids the discrepancy between the mimetic statics numeric method calculating results and practical geologic analysis results.