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The main point of this paper discusses the relationship between the geometry shape of the up surface of the river from the debis-control dam and the impact force of the debris flow. By the indoor, simulation controlled by the rectangle channel . We can observe the different situation of the impact force and a pile of gravel in front of the dam made by three different kinds of debris flow dams .In this way, we could find out the best geometry shape of the surface of debis-control dam which will decrease the impact force of the debris flow and increase the efficiency of the debis-control dam.
Firstly, we can get the theory mode of impact force of debris flow by moment conservation equation. According to the theory, we know that the force of debis-control dam include static pressure effect, kinetic pressure effect , gravity effect and friction effect. What’s more, analysis of experimental data, we find the intensity of the force will be changed obviously with different heights of dam when different debis-control dams are impacted by debris flow. In 2H/6,3H/6,4H/6 of dam, both force of slanted surface and curved surface are less than vertical surface; In H/6 of dam, slanted surface is less than vertical surface, but curved surface is more than vertical surface at first. This is because curved surface influenced by the pressure of covered soil. However the force will be decreased gradually because fluid will take soil away with the increasing flow; In 5H/6 of dam, slanted surface is less than vertical surface with the increasing flow, and the force of curved surface is over vertical surface extremely. This means that the top of curved surface is subjected to the largest force.
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