Force and energy equilibrium-based analytical method for progressive failure analysis of translational rockslides: formulation and comparative study

Massive rockslides are recognized as one of the most catastrophic hazards due to their rapid sliding velocity and high destructiveness. This study focuses on the progressive failure analysis of translational rockslides (PFTRs) on a cataclinal dip slope, whose shear failure develops mainly along the bedding plane of the underlying strata from the head to the toe of the rockslide. A force and energy equilibrium-based analytical method (FEE) is proposed, combining shear failure propagation and strength degradation, to analyse the stability based on static equilibrium and displacement based on energy equilibrium. A representative translational rockslide, the Shanshucao landslide in the Three Gorges Reservoir, China, is used as a case study. The results of the FEE are validated by comparison with the revised rigid limit equilibrium method (RLEM) and numerical simulation (NS). According to the RLEM and NS, when the shear failure of the slide surface develops to a position with a horizontal distance of approximately 225 m, the rockslide steps into the critical state from partial progressive deformation to failure of the entire rockslide. The FEE obtains a similar result, and the corresponding horizontal distance is 200 m. The rockslide displacement calculated by the FEE agrees well with the results of the NS. Before the critical state, the rockslide displacement is less than 0.05 m; afterwards, the displacement of the entire rockslide obviously increases. In addition, it is proven that the hydrostatic pressure in subvertical tension cracks and the post-failure shear surfaces are the primary impetus for accelerated deformation of rockslides and further development of failure surfaces. The validated results indicate that the FEE is a straightforward and effective method to analyse both the stability and displacement of PFTR, which is significant for rockslide early warning and risk mitigation. In addition, the FEE still has limitations with regard to generalization of the landslide geo-mechanical model and the method validation with observational data of historical events.

Automated summary

This study investigates the progressive failure mechanism of translational rockslides and proposes an analytical method based on force and energy equilibrium to evaluate their stability and displacement. The method is validated using a real case study and it is found that hydrostatic pressure and shear surfaces are the primary impetus for accelerated deformation and failure development.