中文摘要：

八一沟位于地震极重灾区四川省都江堰市龙池镇云华村，历史上多次发生过大规模泥石流。通过对现有的粒度分析方法进行了总结，采用矩法和标度法分析了八一沟内松散堆积体（坡积物、沟床沉积物、泥石流沉积物）的粒度特征，最后对比分析了现有粒度分析方法。结果表明，八一沟上游为泥石流的主要物源和流动区，对颗粒沉积的影响较小，而下游的堆积区则对颗粒级配的改造较大。标度法可以通过幂指函数对松散堆积体的级配进行统一描述，八一沟中上游堆积土体的特征粒径D-主要分布在10左右，这与该颗粒级配主要形成低密度泥石流的预测和八一沟已发生的泥石流密度（1．7—1．8g／cm2）一致，说明在强降雨条件下，八一沟上游会再次诱发低密度泥石流。因此利用不同的土体粒度分析方法，可以推测松散堆积体的沉积环境及未来的活动特征。

英文摘要：

Bayi Gully is located at extreme major earthquake disaster region--Yunhua Village, Longchi Town, Du- jiangyan City, Siehuan Province and triggered several large scale debris flows in history. Through summarizing the current grain-size analysis methods, moment method and general form method were chosen to analyze the grain-size characteristics of loose deposit in Bayi Gully. And the two exsisting methods were also compared in the end. Results indicate that the upstream of the gully is main debris flow source and flow region, which has little influence on grain deposit. And the downstream has large influence on the change of grain-size gradation. General form method may make a unified description of loose deposite gradation by use of a exponent function. The chanacteristic grain