The Mechanism Of Debris Flow And The Confluence Of The River And The Numerical Simulation Of Debris Flow Movement

The mechanism of confluence between debris flow and main river, which discuss reciprocity between different liquids, is a brand-new question for fluid mechanics study. It includes not only research of Newtonian fluid, but also study of non-Newtonian fluid.Based on junction phenomena over debris areas, types and features at conflux of different areas are obtained. And then, three converging modes are classed by fluid qualities. The relations of debris flow and water flow at conjunctions are discussed in this paper.When debris flows converge into river, serious hazards and complex mechanisms will be caused. The movement types of debris flow, erosion shapes, results of confluence and deposition character in the conflux are summarized in this paper. The process of debris flow converging into main river is also presented. Based on the analysis of mechanism of debris flow under water, the stress expresses of debris flow under water are worked out by considering of moving water compressive stress. Combined with movement character of debris under water, the stabilization and material translation over interface of two fluids is discussed. The critical conditions of interface stabilization are made. A new criterion for blockage of main flow is obtained by approaching to the influence factors and the modes of blockage.The confluence between viscous debris flow and river flow considered as density flow is based on the assumption that the main influence of converging into water flow is the transform of riverbed. Therefore the upper layer is water flow and the nether layer is debris flow. The moving water compressive force and the shear force of interface are taken into account. An affluence model for debris flow and river is established by using this assumption. The equations of the model are approximately applied for simplicity. The bed resistance is obtained by express of the single-fluid model for debris flow.In this paper, a model of debris flow is calculated by using the finite nodes method with triangle cells. The method is combined with FDM and FEM. Vast applications proved that it can suit for complex boundary as FEM and is efficient as FDM. Moreover, it can expediently deal with moving boundary.The method of numerical simulation visualization make it easy for calculative results. Especially, real-time graphical display and control can make higher efficiencyfor numerical simulation, which has a complicated topography and needs a great calculative time.A 2-D model for debris flow is tested by experimental data of debris flow deposition. The plane extent, maximum length and width of the alluvial fan are computed under different conditions of supply process, initial ground slope and flow density. It shows that the model has a good agreement for single-supply alluvial experiment. But the model isn't suit for multiple alluvial experiment.