Post-failure analysis of landslide in strongly weathered slopes using the DDA-SPH method

This study proposes a novel strongly weathered slope (SWS) numerical model based on the coupled discontinuous deformation analysis (DDA)-smoothed particle hydrodynamics (SPH) method for simulating SWSs. A post-failure analysis of a typical landslide is conducted using this model to validate its effectiveness. The geology-driven model incorporates depth-dependent weathering parameters via a depth-stratified non-uniform Voronoi tessellation algorithm coupled with a gradient-controlled block dissolution technique, generating depth-constrained rock block assemblies and weathering-governed fractures. By using the DDA method to simulate irregular rock blocks and the SPH method to model soil components, the numerical model establishes a stratified structure in SWSs, characterized by “residual soil – soil–rock mixture – bedrock” layers. Validation via the Donghekou landslide case shows that the SWS model successfully reproduces the slope’s failure pattern featuring “rear tension cracking and front shear failure” and interlayer differential dynamic characteristics. The simulation further reveals an energy-driven debris sorting mechanism. Compared with conventional homogeneous models, the weathering-gradient-controlled SWS model exhibits higher accuracy in characterizing instability development, failure modes, kinematic behavior, and landslide deposition morphology of SWSs, maintaining better consistency with field observations. This research provides a reference for understanding the catastrophic mechanisms in weathered slope systems.