泰宁县芦蓭坑沟“5.8”特大泥石流成因和特性分析

Characteristics and causes of Luankeng Gully debris flow in May 8, 2016

通过对2016年5月8日泰宁芦蓭坑沟泥石流灾害的现场调查,分析了芦蓭坑沟泥石流形成的物源、地形和水源条件,采用现场调查与模型计算相结合的方法分析了泥石流灾害的特征与形成演化过程。分析结果表明:本次泥石流为低频黏性暴雨型沟谷泥石流,沟口处泥石流流速达到11.7 m/s,泥石流流量达到721.7 m^3/s;极端雷暴雨是本次泥石流的激发因素,沟道复杂的地形地貌特征和丰富的松散坡积物为泥石流提供了演化条件;沟道内多处卡口和大石块堵塞放大了本次泥石流的规模和速度,沿途固体物质补给使泥石流容重逐步增大。通过分析芦蓭坑沟泥石流形成与演化特征,为类似低频泥石流灾害形成与演化提供一定的理论与技术支撑。

Debris flow formation conditions of source,terrain and water were analyzed according to field investigation at Luankeng gully.The characteristics and evolution process of debris flow are studied by field investigation and model calculation.Results show that this is a low frequency and viscous type debris flow.The largest velocity reached to 11.7 m/s and the discharge of debris flow was as large as 721.7 m^3/s at the gully mouth.Combination of high frequency thunder and heavy precipitation were the motivating factor of this debris flow.The complicated topographic of the channel and abundant loose slope deposits provide the evolutionary condition for the debris flow.Scale and speed of the debris flow were magnified by disturbed cross sections and large stones.Solid material supply along the route made the density of debris flow increase gradually.This study provides an example of formation and evolution of this kind of debris flow.