Formation and catastrophic evolution of giant landslides in the alpine canyon area of western China

Objective Most hydroelectric projects in western China are located in alpine canyons. The intricate geological engineering conditions in this area have contributed to the widespread distribution of landslide disasters across the reservoir banks of hydroelectric projects. Methods Based on the engineering geological characteristics of western alpine canyons, correlations between topography, geological structure, landslide material, slope structure, hydrogeological conditions, and the formation and progression of landslides were analyzed. We also delineated the types and features of landslide development in the western region, as well as the mechanisms governing the evolution of typical landslide disasters. Results Results indicate that the landslides were characterized by slopes ranging from 30° to 50°, elevations exceeding 1000 m, and volumes surpassing one million cubic meters. Triassic, Ordovician, and Silurian strata were identified as the principal slippery strata in this area. Rainfall and reservoir impoundment significantly influenced landslide stability, leading to erosion, datum uplift, and range expansion. Water level fluctuations resulted in diminished rock and soil properties along the leading edge of advancing landslides. Conclusion The most frequent landslides in the western alpine region included accumulated landslides dominated by traction, thrust, and composite mechanisms and rock landslides dominated by bedding, buckling, anti-dip, and seating mechanisms. Significance This study elucidates landslide disaster mechanisms under varying evolutionary and mechanical failure processes, providing significant guidance for the identification, monitoring, early warning, and prevention of landslide disasters in the western region.