Research on the deformation and failure mechanism of soft-hard interbedded composite slopes based on centrifuge model test: an example of the Zhoujia landslide in Sichuan province, China

Abstract

Anti-dip slopes are prone to toppling failure, whereas bedding slopes are susceptible to sliding-bending and sliding-shearing failures. However, a composite slope containing both an anti-dip rock mass (ADRM) and a bedding rock mass (BRM) may experience multiple failure modes simultaneously. To investigate the deformation and failure mechanisms of composite slopes, field investigations were conducted on the Zhoujia landslide. The formation of the composite slope structure was influenced by both tectonic movements and subsequent geological processes. The Zhoujia landslide was simplified, and a centrifuge model test was carried out. Artificial rock slabs were prepared using quartz sand, cement, baryte powder, gypsum, and water. Displacement gauges, earth pressure gauges, and particle image velocimetry (PIV) were employed to monitor the deformation and failure processes of the model during acceleration from 0 to 60 g. The test results indicate that the deformation and failure process of the slope model can be divided into five stages, with three failure modes occurring simultaneously: sliding-bending failure and sliding-shearing failure in the BRM, and flexural toppling failure in the ADRM. On the basis of the change in acceleration, the displacement and earth pressure curves can be divided into six stages. Analysis reveals that structural differences in slopes are the key factors leading to variations in deformation and failure characteristics, which also influence reactivation deformation. The interactions between the components of the composite slope during the experiment affect the failure process. Once failure occurs at the toe of the slope model, it will accelerate slope instability.