Analysis of the fluidization process of the high-position and long-runout landslide in Shuicheng, Liupanshui, Guizhou Province

High-position and long-runout landslide is a kind of common geological disaster in the southwestern mountainous area of China. It always exists with impact disintegration effect,then converts to avalanche debris or debris flow with the characteristics of fluidization movement and accumulation. The Jichang landslide,occurred in Shuicheng County,Liupanshui City,Guizhou Province,China on July 23,2019, is a typical high-position and long-runout fluidized landslide. The position difference between toe and crown is 430 m,the horizontal movement distance is 1340 m,and the volume of accumulation body is 200×10⁴ m³,which caused 21 houses being buried and 51 people being killed. Based on the detailed field investigation and the comparison of the topography before and after the landslide,the whole process of the movement and accumulation of the landslide is simulated and analyzed by using DAN-W. (1) The maximum thickness of the accumulation body in the source area and accumulation area of the Shuicheng landslide is 27 m and 15 m respectively,the maximum velocity is 27 m/s in the front of debris flow,and the maximum kinetic energy is 6.57×10⁶ J. (2) Due to the conversion of potential energy into kinetic energy,the landslide quickly reaches the peak velocity and scrapes the loose soil layer on the surface. (3) Due to heavy rainfall,the main body moves at high speed so that the pore water of the basement can't be discharged in time,which leads to the decrease of the friction of the basement and reduces the energy loss; Disintegration of the main body promotes fluidization of particles,then reduces friction,which is also an important reason for the long-runout movement of landslide.