Deformation characteristics and failure mechanisms induced by rainfall of the Zhoujia landslide in southwestern China

Abstract The Zhoujia landslide, which has a potential risk of instability due to the complex engineering geological conditions, is located near the dam site of the Kala Hydropower Station and poses a significant threat to the safety of the power station. In this paper, a comprehensive assessment of the deformation characteristics and failure mechanisms of the Zhoujia landslide is conducted through field investigations, in situ monitoring data, and numerical simulations. The results indicate that the Zhoujia landslide is a giant ancient accumulation-landslide currently in the creep stage. Deformations of the landslide are characterized by frontal traction and rearward tearing. Deformations are concentrated mainly in Zone B1, with no signs of convergence yet, while Zones A and B2 show smaller and converging deformations. It is found that, through correlation analysis, rainfall is the primary triggering factor for landslide deformations, with a time delay of 1–2 months. Preliminary results from numerical simulations of plastic zones of the landslide indicate a layered failure pattern for the Zhoujia landslide. Three potential failure patterns are identified: sliding along the shallow gravel silt layer in Zone B1, sliding along the deep gravel silt layer in Zone B1, and overall sliding along the bottom sliding zone in Zone B1. The results in this paper will provide guidelines for early warning and engineering control of the Zhoujia landslide during the construction and after the completion of the Kala Hydropower Station project.