Shear Characteristics and Failure Evolution Process of the Cantilever Anti-Floating Ledge in Rock Strata: A Case Study of Guangzhou Metro Stations

Based on the high strength and superior deformation control capabilities of rock strata, a novel cantilever anti-floating ledge has been proposed to resist the floating of underground structures in rock strata. To explore the actual anti-floating effect and working performance of the structure, laboratory shear tests were designed based on the actual project. The shear characteristics and failure evolution process were then discussed using the Particle Flow Code (PFC) numerical simulation. The main conclusions are as follows. The shear stress–shear displacement curve of the cantilever anti-floating ledge can be described as six stages according to the different states of stress and deformation. With the increase in groundwater buoyancy, the damage to the cantilever anti-floating ledge occurs successively from the ledge, the concrete–rock interface, the connection between the ledge and the side wall, and the connection between the ledge and the bottom plate. Local damage and delamination of the interface do not affect the structural strength, but structural cracks should be prevented from continuing to form and connect. It is necessary to pay attention to the stress and deformation state of the crack-prone area mentioned above, improve the reinforcement ratio in the crack-prone area, and strengthen the bond between the concrete and the rock.