Numerical simulation for formation of Jiweishan landslide in Wulong County, Chongqing City of China

Because of the gently-inclined rock in the hill sliding source area and the lack of the effective free surface and sliding space, there were a series of complicated dynamic behaviors during the process of Jiweishan landslide in Wulong County, Chongqing City of China in 2009, such as compression deformation, bottom shear sliding, trailing edge rupture and lateral cutting and sliding of the leading key blocks (karst zone). There exists a remarkable transition and transformation from continuous deformation to discontinuous one. It is difficult to obtain good results simply by using the finite elements of continuous media or the discrete elements of discrete media. The instability process and formation mechanism of Jiweishan landslide are simulated by use of the large numerical simulation software CDEM with the organic coupling continuous-discontinuous elements. The results show that the bottom sliding surface is cut through and the shearing creep occurs along the bottom surface in the process of the formation of landslide. The stresses on the slope concentrate towards the "easy compression zone" at the leading edge of the slope, and they are slope stress automatically adjusted. The slope along the "easy compression zone" creeps, and the second fracture face perpendicular to the slope (cliff) is formed. Finally, the karst rock is cut to induce instant instability of land slide and high-speed remote debris flows. The numerical results reveal the “quasi free surface provided by soft foundation effects” in karst zone in the viewpoint of apparent dip distribution, and the disaster-causing mechanism of “creep-crack-