Insights from indoor testing and numerical simulations of the Lanniqing Landslide in Zhaotong, Yunnan Province, China

Rainfall-induced landslides are a prevalent phenomenon in the mountainous regions of southwestern China, attracting significant research interest regarding their processes and mechanisms. Field investigations and laboratory tests yield crucial data on the physical and mechanical properties of the landslide material and the deformation of slope movement. Furthermore, numerical simulations create a feedback mechanism with field and lab findings, enhancing our comprehensive understanding of the occurrence processes and mechanisms underlying rainfall-induced landslides. This paper focuses on the Lanniqing landslide, located in Zhaotong City, Yunnan Province, Southwest China. It employs field investigations and laboratory tests to examine the physical, shear, and compression mechanical properties of the sliding-zone soil. Additionally, numerical models are developed to analyze the deformation characteristics and slope stability conditions under various conditions. The results indicate that the soils from the sliding zone of the landslide have high fine grain content, primarily consisting of low liquid limit clay. These soils exhibit high cohesion and low friction angle, classifying them as medium-high compressibility based on the compression test results. Additionally, their poor shear and compression mechanical properties serve as a critical factor contributing to the occurrence of landslides. Under natural and rainfall conditions, the slope generally remains stable; however, slope cutting has a significant impact on stability, leading to an unstable state. The coupling of multiple factors leads to a substantial increase in shear strain and slope deformation. Furthermore, the continuous load from the Shan-ma road at the trailing edge exacerbates the slope's instability. These findings are crucial for understanding the formation of similar rainfall-induced landslides in Southwest China and offer valuable insights for the prevention and management of slope disasters influenced by various factors.