Dynamic Characteristics Of Debris Flow And Its Numerical Simulation

Debris flow is one of the common mountain hazards which seriously threaten human lives and belongings and affect humain normal life, and therefore, it becomes an important factor restricting the development of mountain area. With the development of scientific technology, the numerical simulation combining with the dynamic model equation of debris flow has become a main method to study debris flow. In this way, we can not only know more about debris flow through the inversion and reappearance of the happening of these disasters, but also predict debris flow in order to provide an appropriate design for the prevention of disasters. The research on debris flow is paid great attention by different fields and certain achievements have been obtained. However, due to its complexe components and mechanical mechanism, the study of debris flow remains a hot and difficult subject in home and abroad engineering field.In this paper, the dynamic model equation of debris flow is analysed, the characteristics of static and dynamic resistance of debris flow are dicussed, by modifying the shear resistance term at bottom surface under static conditions, the model equation which has the uniform characteristic of static and dynamic is obtained, and the return of dynamic equation to static equation under static conditions is realized, and thus, the theory of model equation is perfected. On the basis of these analyses and with the static analysis method, the accumulation state curve of debris flow is obtained by deducting the static equation. Futhermore, the accumulation sate under different boundary conditions and different composing material conditions is also discussed.Based on the approximate Riemann solver of HLL scheme, the numerical discretization of dynamic model equation on unstructured triangular meshes is achieved with finite volume method. By use of space MUSCL linear reconstruction and time two-step Rung-Kutta, the format of space-time second order accuracy is obtained. The numerical validation of concrete example shows that the numerical scheme has higher precision and resolution, and proves its stability and effectivity.With the established theoretical model and numerical methods, the numerical simulation of dynamic process of debris flow under different conditions is achieved. The influence of different conditions on dynamic process of debris flow and the included regularities and characteristics as those of energy process, the influence of bottom surface resistance conditions, erosion conditions and obstacles on dynamic process, and so on are also discussed.Finally, through the numerical inversion and calculative analysis of two concrete disaster cases, the dynamic development process reappears with the numerical simulation methods. Comparing these obtained disaster-caused areas with the real ones, it can be seen from the discussion and analysis on the phenomenon happened during the dynamic process that basal water pressure and erosion play important roles during the occurrence process of disasters.