Investigating Toppling Failure Mechanism of Anti-dip Layered Slope due to Excavation by Physical Modelling

The failure mechanism of anti-dip layered slopes is essentially different from that of dip layered slopes. Therefore, it is important to investigate the failure mechanism of anti-dip slopes due to excavations. In this study, slope instability induced by mining excavation at the Changshanhao open-pit mine in Neimenggu province, China, was used as a case study. Based on the similarity ratio theory, a physical model was built to investigate the failure mechanism of the anti-dip layered slope under excavation. The physical model was monitored by various monitoring equipment including static strain data acquisition equipment, infrared thermal camera, and digital speckle displacement field measurement equipment. The evolution characteristics of the multi-physics fields including displacement field, strain field and temperature field of the physical model during the excavation were comprehensively obtained. According to the deformation characteristics of the anti-dip layered slope during excavation test, the failure mechanism can be divided into four stages: initial compression stage, crack generation stage, crack propagation stage and formation of sliding surface stage. The deformation characteristics of the slope at each stage were analyzed and compared with those of the anti-dip slope in the field. The comparison verified the rationality and accuracy of the physical model experiment, and provided a deeper understanding of the failure mechanism of anti-dip layered slope under excavation through the comprehensive monitoring data. The results of this work can be used as a reference for the follow-up reinforcement and treatment of similar anti-dip layered slopes.