贵州望谟县姚家湾沟泥石流成因及力学特征和易发性

Characteristics and Formation of Debris Flow of Yaojiawan Gully in Wangmo,Guizhou

2011年6月6日姚家湾沟流域内波树滑坡在强降雨下滑动解体形成碎屑流随后转化成泥石流冲出沟道,冲毁房屋7户,掩埋农田数亩。为了查明泥石流的成因和静动力学特征,更好地提高泥石流防治和预测预警水平。通过实地调查和理论计算,分析了泥石流的成因和静动力学特征并对易发性做了预测。结果表明:本次泥石流的发生,滑坡提供了物源,而超100 a一遇的降雨是泥石流发生的激发因素;泥石流容重为1.84 g/cm^3,平均流速为6.62 m/s,峰值流量为86 m^3/s,一次固体物质冲出量约为4×10^4m^3。屈服应力在3 500 Pa以上,整体冲击力为110 kN,最大石块冲击力为55.6 kN;通过定性和定量两种方法预测姚家湾沟今后发生泥石流的可能性小。

The rainstorms triggered debris flows in Yaojiawan gully on June 6,2011.During the hazards,seven houses were seriously destroyed,and farmland were buried.In order to improve the result accuracy of the forecasting and early warning system,based on field investigation and analysis,formation and dynamic characteristics of debris flows were analyzed.The results reveal the following aspects.The tense outbreak of debris flow is an inevitable coupling result of material sources and rainstorms,but the rainfall breaking the 100 year record is the main factor for the outbreak of those debris flows.The dynamic characteristics of debris flows are calculated,which are the density of 1.84 g/cm ^3,velocity of 6.62 m/s,discharge of 86 m^3/s,and yield stress of debris flows more than 3 500 Pa.The total volume of sediment in debris flows are estimated at 4×10^4m^3.The overall impact of the debris flow is 110 kN,and the maximum rock impact is 55.6 kN.the development trend of the debris flows are predicted by qualitative and quantitative methods,which indicates the susceptibility is small.