汶川震区窄陡沟道型泥石流动力学特性及堵江分析--以都汶高速沿线磨子沟为例

摘要

在汶川震区沟道型泥石流中，普遍存在一种窄陡沟道类型，窄陡沟道型泥石流具有沟道纵坡陡、平均宽度窄、流域面积小的地形特点，在震区容易瞬间汇流形成大规模突发性泥石流灾害。结合四川省都汶高速沿线2013年“7·10”特大群发性泥石流，重点以窄陡沟道型的磨子沟泥石流为实例，针对该泥石流对都汶高速、岷江等造成的冲击淤埋及堵塞问题，通过现场调查泥石流形成条件和发育特征，采用大型流体动力学计算软件CFX模拟再现50年一遇暴雨频率下此类窄陡型泥石流的动力学过程，分析其危险范围、评价其冲击都汶高速桥梁，堵塞岷江，淹没岷江两岸居民安置点的破坏性影响，为提出针对性的泥石流防治工程措施提供依据。%The debris flow with narrow-steep channels is very common in gully debris flow in Wenchuan earthquake region.High longitudinal slope and narrow average width of the gully and little drainage basin area are observed in this kind of debris flows.Thus,the debris flows with large scale is easily happened due to the quickly converge of the rainfall in earthquake area.In particular,extra-large group debris flows occurred on July 1 0,201 3along Duwen freeway in Sichuan province.This paper concentrates on the phenomenon of the impaction,burying,blockage of Duwen freeway and Minjiang River caused by the debris flow.Through the field investigation of the debris flows, the formation conditions and development characteristics are identified.Using of CFX hydrodynamic calculation software,a simulation of the dynamical process of narrow-steep channels featured debris flow during 50-year storm conditions is set up.The paper makes a prediction of the hazardous region,evaluates the destructive effects on the Duwen freeway,Minjiang River and residents of settlements,which can provide the evidence of the prevention measures design of the debris flow.