FAILURE MECHANISM OF LOESS LANDSLIDES DUE TO SATURATED-UNSATURATED SEEPAGE-CASE STUDY OF GALLENTE LANDSLIDE IN ILI, XINJIANG

Ili valley of Xinjiang in large areas are covered with loess. Loess landslides occur frequently in this region. Its number accounts for 80% of all landslides in Xinjiang province. The loss caused by loess landslide is remarkable. Compared with other typical loess landslides in western China, loess landslides in Ili valley are characterized by complex slope structures and rainfall-induced unsaturated seepage instabilities. Case study of the unsaturated seepage failure mechanism for Gallente landslide is presented in this study. Slope structure model for Gallente landslide is firstly established. Based on unsaturated seepage theory, the two-dimensional unsaturated seepage field in the slope is simulated and analyzed. Then the seepage failure process and mechanism induced by rainfall are examined. The coupling seepage-stability computing method is used to analyze the destabilizing process of slope structure induced by unsaturated seepage. The unsaturated seepage failure mechanism of large-scale loess landslide in Ili valley is eventually revealed.