火后泥石流成灾特点及研究现状

摘要

The post-fire debris flow is another special type of debris flows that closely related to forest fire and generate in burned area. Obvious difference in term of the initiation mechanism has been find between post-fire debris flows and general debris flows. Fire combusts the surface vegetation and furtherly destroys the texture of underlying soil for the high temperature of fire. The unit weight, pore porosity, permeability and other physical and hydrological properties of the fire-infected soil are changed dramatically in fire, and abundant residual ash layer and loose debris accumulated on the slope after fire. Therefore, post-fire debris flows usually have the characteristics of high unit weight and viscosity. A review of research on the generation mode, kinetic mechanism, influence factors, debris flow forecasting and mitigation measures of this kind of debris flows is put forward, referring to relevant literature at home and abroad. Post-fire debris flows are first studied in 1936, detailed study on which is mostly conducted in America, Australian and Spain. But few can been find in China, except the researches inagroforestry, in which the study are mainly about water and soil loss, vegetation combust and recovery. As another special type of debris flow hazards, systematic study of post-fire debris flows has not attracted enough attention in China, which reflects the poor study of this kind of debris flows. Based on the key problem mentioned above, some suggestions are came up with to enhance the research on the generation and spatial-temporal evolution mechanism and effective protection of post-fire debris flows.%火后泥石流是指林火发生后火烧迹地附近发生的、与林火紧密联系的泥石流.作为泥石流地质灾害的另一特殊类别,因林火高温燃烧植被进而影响表部土壤结构,导致土壤影响层内密度、孔隙比、渗透性等物理水理性质发生剧烈改变,而出现大量灰烬层和松散泥沙,形成的泥石流常表现出高容重、大黏度流体特征,其成灾机理与普通泥石流具有显著差异.通过对国内外有关火后泥石流启动成灾机理及动力学特性研究的相关文献查阅,并从火后泥石流的启动类型及运动学特征、影响因素以及预测预报、防控措施等进行了综述,显示火后泥石流国外从1936年开始研究,且以美国、澳大利亚和西班牙的研究成果较为全面和系统,而国内除了林业系统有所涉及、且也主要从水土流失、植被恢复等方面考虑外,火后泥石流的研究还没引起我国学者的广泛关注,作为泥石流地质灾害的另一特殊类别基本上尚未进行系统深入的研究,也很少查到国内对火后泥石流方面的研究成果,可以说我国的火后泥石流研究目前尚属空白.针对国内外研究现状,结合我国山区频发森林大火形成泥石流造成的危害性,提出了未来应加强对火后泥石流的成灾机理、时空演化机制及有效防控方法的系统研究.