溃坝泥石流起动过程及其动力学特征

溃坝泥石流是由于滑坡、地震等自然灾害或不当的人为堆土弃渣产生大量固体物质淤堵沟道或河流后,在遭遇暴雨或汇流冲刷作用下致使淤堵体突然溃决而形成的一种特殊固液两相流。本文采用自制泥石流模拟变坡水槽,实施了24组溃坝泥石流模拟实验,按照溃决方式和相对剪切力将溃坝泥石流划分为局部型和整体型两类,并分析了这两类溃坝型泥石流的成因,揭示其在起动过程中孔隙水压和水沙因子动力学特征。结果表明,小流量、小坡度下更容易形成局部溃坝型泥石流,否则更容易形成整体溃坝型泥石流,而且后者相对剪切驱动力大于前者,研究成果对于溃坝泥石流防治工程的规划设计以及提高泥石流防灾减灾水平具有重要意义。

Starting processes and dynamic characteristics of dam-break debris flow

Dam-break debris flow is a special solid-liquid two-phase flow formed when a large amount of collapsed materials generated by landslides or earthquakes,etc. fill up the valley or river and then sudden-ly break out under the scouring action of rainfall runoff. In this paper,twenty-four groups of dam-break de-bris flow simulation experiments were carried out by using the self-made multi-functional flume at Dongch-uan Debris Flow Observation and Research Station of the Chinese Academy of Sciences in Yunnan Prov-ince. According to the patterns of dam-break and relative shear force, the dam-break debris flow is divid-ed into two types:part-type and integral-type. Firstly, the formation reasons of these two types of dam-break debris flows are analyzed, and the dynamical characteristics of pore water pressure and wa-ter-sediment factors during the starting processes of them are revealed. The results show that the part-type dam-break debris flow is easier to form under small flow and small slope; otherwise it is easier to form a kind of integral-type dam-break debris flow. And the shear driving force of the integral-type is greater than that of the part-type. The research results are of great significance for the planning and design of pre-vention and control projects of the dam-break debris flow and the improvement of the level of debris flow disaster prevention and mitigation.