Dynamic Response Study of Impulsive Force of Debris Flow Evaluation and Flexible Retaining Structure Based on SPH-DEM-FEM Coupling

Flexible retaining structure is demonstrated to be an effective measure for debris flow prevention in mountainous areas, which can effectively separate water and stone, reduce particle mass, and dissipate kinetic energy. In order to explore the impulsive force and dynamic response of flexible retaining structure impacted by solid-liquid two-phase debris flow, a complex dynamic interaction model of particle-fluid-structure has been established by employing the SPH-DEM-FEM coupling numerical analysis method. In the present study, the process, impulse force, and dynamic response of a flexible retaining structure subjected to debris flow under different slopes were investigated, respectively. The numerical results are compared with those of the calculation formula of the peak impulsive force of the semiempirical debris flow. Meanwhile, the effectiveness of the coupling numerical simulation is verified. The simulation results show that the coupled SPH-DEM-FEM numerical analysis method can visualise the impact of the solid-liquid two-phase debris flow on the flexible retaining structure, reproducing the impact, retaining, water-stone separation, climbing, silting, and deposition process of debris flow. The dynamic time-history curve of the coupling numerical analysis method for the flexible retaining structure is consistent with the results of the existing literature. The debris flow evaluation results of flexible retaining structure impacted by solid-liquid two-phase debris flow are in an order of magnitude with the empirical formula results. Moreover, the results are reliable. The obtained results have a certain reference value for the study on the impulsive force and dynamic response of the flexible retaining structure impacted by solid-liquid two-phase debris flow and the engineering design of the flexible retaining structure.