Investigation into the evolutionary mechanisms of catastrophic bedding rock landslides in deeply incised canyon regions: a case study of the Zhisi Mountain landslide

The Hengduan Mountain region was geologically complex and climatically variable, making it highly susceptible to landslides, especially those occurring along major rivers, which posed significant threats to infrastructure. Numerous studies have examined the characteristics of landslides during specific climatic periods. However, research on the interaction between climatic cycles and landslide initiation remained limited. This paper investigated the Zhisi Mountain landslide in the upper reaches of the Jinsha River as a case study, combining field surveys and historical data analysis to explore the role of river stage undercut induced by glacial-interglacial cycles in landslide occurrence. Utilizing optimized discrete element method and discrete fracture network models, we simulated the dynamic evolution of the landslide disaster. The findings indicated that slow river undercutting during glacial periods resulted in the formation of multiple weak layers, while rapid erosion during interglacial periods led to an exacerbation of slope instability, ultimately precipitating the disaster. The study emphasized the importance of optimizing discrete fracture network models to enhance the computational efficiency of large-scale landslide simulations. This research provided novel insights into the impact of climatic fluctuations and river erosion on landslide mechanics, which were critical for disaster risk assessment in mountainous regions.