四川都江堰龙池八一沟泥石流成因、特征及危险性评价

Causes, Characteristics and Hazard Assessment of the Bayi Gully, Longchi, Dujiangyan of Sichuan Province

摘要: 2010年8月13日都江堰龙池八一沟在降雨量75 mm/h下暴发大型泥石流，冲毁各支沟内的拦挡坝，形成规模巨大的过渡性泥石流，造成重大的生命财产损失。本文在通过对八一沟泥石流灾害的现场调查的基础上，首先对形成泥石流的地形、水源、物源三个基本条件进行了论述认为物源和降雨是激发本次泥石流的主要原因；其次分析了八一沟泥石流的特征：形成区物源丰富，流通区沟蚀明显、冲刷切割沟道深，堆积区淤埋范围长、厚度大；再次计算了泥石流的动静力学参数：八一沟为50 a一遇泥石流，容重在1.88 g·cm3左右，泥石流的洪峰流量达1082 m3/s，一次泥石流泥石流固体总量为106.6 ×104 m3；最后采用MFCAM模型对八一沟进行危险性评价认为八一沟及其支沟危险度为中高度以上并提出防治建议。

Abstract: A large-scale debris flow outbreaks in Long Chi, Dujiangyan, on August 13, 2010.The recorded rainfall was 75 mm/h hour from PM 16:00 to 17:00, which caused powerful flood in the catchments, triggered material sources and destroyed prevention dams in the Bayi gully. The present study indicates that the rainfall and sediment source are the principal factors for triggering the landslide basing field investigation and analysis of the formation conditions of the debris flow, such as topography, water source and sediment source; The elaborated characteristics of debris flow, for instance, rich material sources, obvious gully erosion, deep cutting channel and accumulation zone buried long range in thickness, are then analyzed. Thirdly, the dynamic parameters calculation shows that the density and the discharge are1.88g/cm3 and1082 m3/s, respectively. The total volume of sediment in debris flows was estimated at 106.6 ×104 m3; Finally, the hazard assessment suggests that the debris flow in the Bayi Gully and its branches might be above moderate using the MFCAM model, which provides a corresponding hazard prediction there.