四川美姑河牛牛坝水电站库区泥石流成因分析

Analysis on the formation of debris flow in the reservoir zone of Niuniuba Hydropower Station in Meigu River,Sichuan Province

牛牛坝水电站是美姑河流域“一库五级开发方案”的龙头电站。牛牛坝库区为泥石流多发段。泥石流具有规模较大、分布范围广、发育密度大(1.33条/km)、发生频率高、致灾作用强烈的特点。泥石流灾害是库区重大地质灾害之一。通过系统分析工程区陡峻的地貌条件、发育的区域构造、软硬相间的岩层、广泛分布的堆积体、降雨集中的气候条件及不合理的人类活动等因素对泥石流的影响,揭示了美姑河牛牛坝水电站库区泥石流的成因。

Niuniuba hydropower station is a head hydropower station of ＂exploitation project of five-step hydropower stations in one river＂. There frequently occur debris flows in the reservoir zone of the hydropower station. The debris flows present such features as large scale, wide range, dense distribution （ 1.33pieces/km）, high frequency and strong hazard. Debris flow hazard is one of grave geological hazards in the reservoir zone of the hydropower station. The paper systermatically analyzed the impact of high and precipitous geomorphology, complex geologic structure, interbedded strata of incompetent bed and competent bed, wide distribution of deposits, intense rainfall climate and illogical human activity upon debris flow. Based on the analysis, the paper indicates the reasons causing debris flows in the reservoir zone of the hydropower station.