泥石流局部阻塞大河的特点及判据研究(英文)

Characteristic and Criteria of Debris Flow Partially Blocking Big River

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 the Minjiang River basin, there are lots of barrier dams which generated by debris flows partially block the main rive. Considering this conditions, the large-scale indoor flume experiment was conducted to reproduce the course that the high-density debris flows run into the main river when the intersection angle was 90 degrees. The experimental results show that the thrust force of the follow-up debris flow is the major dynamic force driving the debris flow into the main river; the total volume of debris flows has important effects on river blocking. And the more total volume increase, the more serious blocking generate. In the process of debris flow blocking river, when damming coefficient R increases, velocity of main river firstly increases and then decreases： when R is less than 0.8, little material of debris flow is lost （washed away） , and head- water level increases linearly; when R is equal to or more than 0.8, the serious amount of material of debris flow is lost （washed away）, and head-water level increases exponentially. Based on water and sediment dynamic process, as well as the dynamic equation of debris flow at different slopes, the interaction between barrier dam and the flow of the main river was analyzed, and the formula to calculate the run-out distance of debris flow in the main river was established. In view of the phenomenon that the material erosion is serious when debris flow blocking big river, the erosion coefficient is obtained ac- cording to the test data of flume experiment. On the basis of the formula to work out the total amount of debris flow blocking the main river proposed by Zhou Bifan, the relevant conditions amended in the light of the erosion coefficient is presented. And the criteria of debris flow partially blocking big river is proposed in terms of the formula of dynamic process and total a- mount of material.