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针对岷江流域泥石流多半是以堰塞坝形式局部阻塞主河的现象,运用大型室内水槽试验再现交汇角为90°时高容重泥石流入汇主河的过程。试验结果表明:泥石流入汇主河的运动过程是后续泥石流逐步推移龙头运动的过程;泥石流总量对堵河有重要的影响,总量越大堵河越严重;在泥石流堵河过程中,主河的流速随堵塞系数R先增大后减小,当R<0.8时,堰塞坝的物质流失量少,当R≥0.8时,堰塞坝的物质流失量严重。基于水沙动力过程,以泥石流在坡度变化沟道内的运动方程为基础,考虑堰塞坝和主河水流的相互作用,给出了泥石流在主河中运移距离的计算公式;鉴于泥石流堵塞大河过程中物质流失严重的现象,根据水槽实验数据确定了流失系数;以周必凡提出的泥石流堵断主河总量的计算公式为基础,提出了按流失系数加以修正的泥石流阻塞大河物质总量条件。建立了基于动力学方程、物质总量的泥石流局部阻塞大河判据。
In view of the fact that the debris flow in the Minjiang River Basin is partially obstructed by the main dam in the form of barrier dam, the large-scale indoor tank test is used to reproduce the process that the high-volume and heavy debris flows into the main river when the crossing angle is 90 °. The test results show that the movement process of debris flow into the main river is the process of follow-up debris flow gradually leading the faucet movement. The total amount of debris flow has an important impact on the blocking of the river. The more the total amount, the more serious the blockage of the river. In the process of blockage of debris flow, The flow rate increases first and then decreases with the blockage coefficient R. When R <0.8, the material loss of the dam is small, and when R≥0.8, the material loss of the dam is serious. Based on the movement equation of debris flow in slope change channel, considering the interaction between dam and main river flow, the formula for calculating the migration distance of debris flow in the main river is given based on the process of water and sediment movement. The material loss is serious, and the loss coefficient is determined according to the experimental data of the sink. Based on the calculation formula of the total amount of the main river blocked by the debris flow proposed by Zhou Beifan, the debris flow obstruction of the total mass of the river is proposed. Based on the kinetic equation, the total debris flow debris obstruction of the river criterion is established.