3D-SPH-DEM coupling simulation for the large deformation failure process of check dams under debris flow impact incorporating the nonlinear collision-constraint bond model

Computational analysis of debris flow dynamics and its impact on structures, including check dams, is a long-standing problem for hazard prevention. It's a complex issue involving two-phase interaction between fluid mass and solid structure, as well as the large deformation failure of check dams, therefore, three-dimensional simulation of this process remains a scientific challenge. In this paper, a 3D-SPH-DEM coupling model is proposed by incorporating a nonlinear collision-constraint bond model. The model first builds upon our previous 3D-SPH model based on Herschel-Bulkley-Papanastasiou (HBP) rheology to describe the fluid behavior within the debris flow process. Secondly, a constituent particle-based DEM block representation method is integrated to model check dams, and the fluid-solid interaction force between debris flow particles and DEM blocks is obtained. Additionally, a nonlinear collision-constraint bond model with a predefined coefficient α is incorporated to simulate the solid interaction between DEM blocks and characterize the different strength levels of check dams. To verify the proposed model, a well-documented pier cubes failure experiment in a previous study is used, wherein the simulation results well reproduce the failure process as observed in the experiment from the quantitative perspective. The 2010 Yohutagawa debris flow event is selected as the case study. Results show that the proposed model well simulates the fluid-solid interaction phenomenon and can effectively explore the large deformation failure process of check dams under debris flow impact.