金沙江白鹤滩水电站小红岩沟泥石流危险性评价

Evaluation of debris-flow risk in XiaohongyanGully of Baihetan Hydropower Station on the Jinsha River

泥石流地质灾害为我国山区城镇常见的一种地质灾害,尤其频发于我国西南山区,对这一地区的梯级水电站建设和安全运营构成了极大的危害。以金沙江白鹤滩水电站小红岩沟泥石流为研究对象,通过地质调查系统地分析了泥石流形成的地形及物源条件,结合室内试验,分析泥石流的容重、流速、流量、一次泥石流总量、一次固体物质总量及冲击力等运动参数,预测泥石流发展趋势,评价泥石流对工程建设的影响并提出防治建议。研究表明:小红岩泥石流沟具备发生泥石流的地形、物源及降雨条件,沟内共计有松散固体物源量218.14×104m3,可能参与泥石流活动的不稳定物源量为26.46×104m3,为沟谷降雨型低频大型稀性泥石流。小红岩沟泥石流沟50年一遇主要参数为:泥石流容重为1.52 t/m3,泥石流流速为3.71 m/s,泥石流峰值流量为173.63 m3/s,一次泥石流总量和固体物质含量分别为5.50万m3和1.72万m3,流体整体的冲击力为2.83 kPa。

Debris-flows are common geological disasters that strike the southern mountainous areas in China frequently,posing harms to the construction and safe operation of cascade hydropower stations.In this study,we conduct a geological survey to analyze the topographic conditions for debris-flow triggering at the Xiaohongyan Gully of Baihetan Hydropower Station,Jinsha River.Then,we continue with a laboratory test and analyze the bulk density,speed,volume,impact force of debris flows as well as the total volume of a debris flow and the total solid material content.Finally,we predict how a debris flow develops and how it affects engineering construction,thereby proposing suggestions on how to effectively control and prevent debris flows.The results revealed that debris flows in Xiaohongyan gully met the topographic,material source and rainfall conditions.The total volume of loose solid material sources in this gully was 218.14×104 m 3,among which the volume of unstable material sources that might participate in debris flow activities was 26.46×104 m 3,in dicating a gully rainfall-induced low-frequency large-scale diluted debris flow.The main parameters of Xiaohongyan debris flow gully with a 50-year return period were as follows:bulk density(1.52 t/m 3),speed(3.71 m/s)and peak volume(173.63 m 3/s)of debris flows,total volume of a debris flow(55000 m 3),solid material content(17200 m 3)and overall impact force(2.83 kPa)of the fluid.The study results provide beneficial reference for evaluating,preventing and controlling debris flow disasters in major engineering construction areas.