Deformation characteristics and failure mechanism of large-scale obliquely dip rock landslide in the Three Gorges Reservoir Region

In recent years, the tangential rock landslides occurred frequently in the urban area of the Three Gorges Reservoir region. Therefore, it is of great significance to study the deformation and failure characteristics and failure mechanism for the prevention and control of the tangential rock landslides. In this paper, taking the Baiyangwan landslide in Wushan Town as a case study, the deformation characteristics and failure mechanism are studied in detail, by field investigation, drilling works and in-situ comprehensive monitoring systerm. The stratum of the landslide is mudstone in the second member of the Badong Formation, with abundant groundwater and broken rock mass. The rock layer incline to the right boundary, which is cut by a fault, and the multi-layered weak interlayer forms a multi-stage slip zone. Therefore, wedge-shaped sliding surface was easily developed. The volume of the landslide is about 320×10⁴ m³, and the angle between the sliding direction and the rock formation attitude is 60°. Affected by human engineering activities, such as slope excavation and construction loading, the significant deformation began in July 2019, and the displacement velocities in the middle part reached to 2～5 mm/day. In September 2019, the emergency anti-slide pile project was set at the toe part of the landslide, after that the deforamtion velocities of the landslide slow down to 0～0.5 mm/day. The Baiyangwan landslide seriously threaten to the Jinke community, and the prevention and control measures of "relocation avoidance + project management + professional monitoring" were recommended to adopt to the landslide. The research results of this paper are of great significance for guiding the prevention of tangential rock landslides in the Three Gorges reservoir area and landslides induced by excavation.