Simulation of interactions between debris flow and check dams on three-dimensional terrain

Abstract

Debris flows are rapid gravity-driven flows of sediment-water mixture, which can be greatly destructive due to its huge volume, high velocity and large impact force. Check dam is essential protective structure for controlling debris flow. However, it is a challenging work to assess the interactions between debris flow and check dam, especially when involving complex topography and dam destruction. A numerical method was developed in this study to investigate the interactions between debris flow and check dam on three-dimensional terrain. The debris flow and check dam were simulated by Smoothed Particle Hydrodynamics (SPH) method and Finite Element Method (FEM), respectively. The method was validated by a dam break problem and a granular flow flume test. An actual debris flow event originated from failure of tailings dams on 19 July 1985 in Stava, Italy was simulated as an example. The results indicate that the proposed method is a practical tool to simulate the runout characteristics of debris flow (e.g., flow velocity, flow depth, impact area) and interactions between debris flow and check dam (e.g., impact force, destruction of check dam, interception by check dam). Given similar total dam volume, increasing the number of dams will improve the hazard mitigation effect. Moreover, it is recommended to construct dams in downstream area with straight channel. This study will contribute to a better understanding of the flow-structure interaction and is helpful for rational design of check dams.