Centrifuge model test study on key hazard-inducing factors of deep toppling deformation and disaster patterns of counter-tilt layered rock slopes

Taking the toppling deformation body in front of the dam of Gushui hydropower station as the research object, the physical model of the slope is established on the basis of geological cognitions and similarity theory, and the process of valley cutting is simulated by prefabricated modules and graded excavation. Five-stage centrifuge model test is carried out and the key hazard-inducing factors of deep toppling deformation and the disaster patterns of the counter-tilt layered rock slope under gravity are studied. The results show that the occurrence, development and failure of deep toppling deformation of counter-tilt layered rock slopes go through a long geological history time when energy and deformation accumulate, and that the sharp increase of rock deformation is closely related to external conditions such as excavation and earthquake, etc.. Lithological conditions(relatively weak rock mass), structural conditions(appropriate layer thickness and dip angle) and external conditions(undercutting of river valleys or excavation of slopes) are key factors for deep toppling deformation, while free face condition is the key hazard factor for deep toppling damage. Repeated valley incisions or multi-level excavations result in several bending belts with different depths inside the slope, and development and penetration of the bending belt gradually from the foot to the top of the slope result in the overall shear failure of the slope along the bending belt. © 2019, Science Press. All right reserved.