Numerical Simulation of Debris Flow Disaster in Yunnan Mountainous Areas Guided by Discrete Element Tracing Method

Abstract

Abstract The purpose of this study is to accurately predict and evaluate the occurrence, development, and impact of debris flow disasters, and to further improve the accuracy of debris flow disaster prediction by comparing the simulation results of high-performance algorithms with the measured data and other numerical simulation methods. Discrete Element Tracking Method (DETM) is adopted as a numerical simulation method. Debris flow is regarded as a non-Newtonian fluid composed of many discrete particles, and the motion state and deformation characteristics of debris flow are calculated by tracking the position, velocity, and force of each particle. This study takes a typical debris flow channel in Yunnan Province as an example. Firstly, a three-dimensional (3D) terrain model is established, including the length, width, slope, and curvature of the channel. Secondly, according to the physical characteristics of debris flow, the initial conditions of debris flow are set. Finally, the movement process of debris flow is simulated by DETM, and the position, speed, and force of each particle in the process of debris flow movement are tracked. The numerical simulation results are compared with those of the Finite Element Difference Method (FEDM), and the simulation results are checked with the data in the national debris flow database. It is found that the coincidence degree of debris flow deposition range guided by DETM and debris flow database is 0.89 (FEDM is 0.76). The root mean square error (RMSE) of debris flow deposition thickness and debris flow database is 0.04 (FEDM is 0.23). The relative error of debris flow deposition volume and debris flow database is 0.06 (FEDM is 0.15). The relative error of debris flow movement time and debris flow database is 0.03 (FEDM is 0.19). These results show that DETM can well predict the actual situation of debris flow disasters in mountainous areas of Yunnan. This study not only provides a new tool and basis for the prediction and prevention of debris flow disasters, but also provides a new idea and method for the application of DETM in simulating other non-Newtonian fluids.