Instability mechanism of massive oblique bedding rock landslide in the Three-Gorges Reservoir: A case study of the Longjing landslide in Shizhu County of Chongqing City

The Three Gorges Reservoir is located in the transition zone of the second and third terrains in China. Taking the Longjing landslide in Chongqing as an example, this paper analyzes in detail the deformation characteristics, formation mechanism and failure pattern of the oblique bedding slope, and calculates the stability of the slope under four working conditions by using the limit equilibrium method. The results show that: (1) Longjing landslide is located in the northwest wing of the syncline of the stone pillar of the Yangtze platform, with a volume of 142.83×10⁴ m³ and the main sliding direction of 162°. (2) Under the influence of topographical features, stratigraphic structure, groundwater, rainfall and other factors, the slope is currently in the stage of creep deformation. The deformation pattern are mainly tensile fractures, shear fractures and local bulging deformation. (3) The slope is under the sliding conditions of rainstorm and leading secondary landslide at the same time, and its stability factor is 1.03, so it is in an under-stable state. The slope is prone to overall sliding failure along the weak intercalated layer.