Study on the Destruction Process of Piers by Debris Flow Impact Using SPH-FEM Adaptive Coupling Method

Debris flows represent a prevalent natural disaster in mountainous regions, frequently devastating roads, bridges, and other vital transportation infrastructures due to their abrupt onset and immense destructive power. This study introduces a three-dimensional numerical model that employs the SPH-FEM adaptive coupling algorithm to examine the destruction process of bridge piers under the influence of debris flows. It conducts flume experiments to assess the effectiveness of this approach. The findings indicated that the coupled SPH-FEM method, combined with a cross-rheological model, effectively captures the dynamic progression of debris flows and accurately calculates the impact forces exerted on a pier. The process is subsequently simulated in the LS-DYNA software by analyzing the destruction of the Liziyida Bridge in Sichuan Province, China, as a case study. The research proposes an empirical model for estimating the impact force of debris flows on piers derived from the numerical simulations and additional flow tests around piers. These results offer theoretical insights and a design framework for debris flow disaster prevention and mitigation projects.