库水和降雨作用下黄土坡临江Ⅰ号滑坡可靠度研究

Study on Reliability of Riverside Ⅰ Landslide on Loess Slope under Reservoir Water and Rainfall

三峡水库蓄水改变了库区原有的地质环境,诱使大量库岸滑坡复活甚至失稳,严重威胁库区安全。为研究库水和降雨作用对库岸滑坡稳定性的影响,该文以黄土坡临江Ⅰ号滑坡为例,对库水位波动下滑坡渗流场进行了模拟计算,同时考虑滑带强度参数的不确定性,采用Monte Carlo方法对滑坡进行了可靠度分析。选取计算所得最危险的三种库水位工况,叠加不同重现期的降雨量,计算了12种工况下滑坡的破坏概率。研究表明:在库水位波动下,滑坡内渗流场变动相应滞后,滑坡的破坏概率变化明显。在库水位下降及低水位时,临江Ⅰ号的深层和浅层滑坡均逐步进入欠稳定状态。在库水和降雨联合作用时,滑坡破坏概率更高,且随降雨重现期(强度)的增大而升高,浅层滑坡更易受库水和降雨的影响。

The impoundment of the Three Gorges Reservoir changes the original geological environment of the reservoir area, induces a large number of landslides to revive or even lose stability, and seriously threatens the safety of the reservoir area. In order to study the influence of reservoir water and rainfall on the stability of reservoir bank landslide, in this paper, taking the riverside Ⅰ# landslide on loess slope as an example, the seepage field of landslide under reservoir water level fluctuation is simulated, and considering the uncertainty of strength parameters of sliding zone, the reliability of landslide is analyzed by Monte Carlo method. Three most dangerous reservoir water level conditions are selected, and the rainfall of different return periods is superimposed to calculate the failure probability of landslide under 12 conditions. The results show that: under the fluctuation of reservoir water level, the change of seepage field lags behind, and the failure probability of landslide changes obviously. The deep and shallow landslides of riverside Ⅰ# gradually enter into an unstable state when the reservoir water level drops and the water level is low. Under the combined action of reservoir water and rainfall, the failure probability of landslide is higher, and increases with the increase of rainfall return period(intensity). The shallow landslide is more susceptible to reservoir water and rainfall.