A coupled SPH-DEM-FEM model for fluid-particle-structure interaction and a case study of Wenjia gully debris flow impact estimation

Abstract

Debris flows are rapid gravity-driven unsteady flows of highly concentrated mixtures of water and solid particle material, destroying numerous mountain building structures and traffic facilities. The investigation of debris flows is thus of significance to hazard prevention and mitigation. This paper aims to provide a numerical model capable of reproducing debris flow impact estimation by accounting for the complicated fluid-particle-structure interaction (FPSI) using a coupled smoothed particles hydrodynamics (SPH), discrete element method (DEM), and finite element method (FEM) approach. The fluid phase is represented by SPH. The solid phase consists of physical particle(s) and is represented by the DEM, and the deformable structure is represented by the FEM. The interaction forces among the fluid, solid particles, and structure are computed using the penalty function method. The proposed model is capable of simultaneously simulating a fluid-particle interaction (FPI), particle-structure interaction (PSI), and fluid-structure interaction (FSI), with good agreement between the complicated hybrid numerical and experimental results. Finally, a Wenjia gully debris flow is carried out to demonstrate the capability of the coupled model in simulating the FPSI as an application of debris flow impact simulations. When compared with the actual situation, the propagation of the debris flow and destruction of the structures were predicted accurately. Additionally, the Wenjia gully debris flow was treated, and the treatment measure was analyzed from the impact evolution (e.g., interception by dams, impact force, and destruction of dams). The developed method will contribute to a better understanding of the FPSI and is a promising tool for hazard analysis and mitigation.