ANALYSIS OF FAILURE MECHANISM OF YANGUAN LANDSLIDE IN THREE GORGES RESERVOIR AREA BASED ON THE CHANGE OF PORE PRESSURE

Yanguan landslide was on the right bank of Xiangxi River in Guizhou Town,Zigui County and suffered from overall damage on October 30,2017. It became one of few failed landslides in the Three Gorges reservoir area in recent years. According to the site emergency investigation,the landslide went through the process of early warning to complete destruction in less than three days. In this paper,we use module SEEP/W in the finite element geotechnical simulation software Geo-Studio to simulate the seepage field of Yanguan landslide under the boundary conditions of actual rainfall infiltration and reservoir water level value. Next,we calculate the change of pore water pressure value with time. Then,we apply the results to another module Slope/W to calculate the curve of safe of factor. We propose the mode of landslide instability and failure under the condition of pore water pressure change rate combining with the principle of effective stress and take Yanguan landslide as an example to analyze the influence of pore pressure on landslide failure. Then,we verify the cause of failure that the pore water pressure soars after the soil inside the landslide is saturated under the action of combined effect,rainfall and high reservoir water level.