唐家山堰塞湖大水沟泥石流发育特征及堵江危害性评价

 大水沟位于唐家山上游侧，“5.12”地震前为一条小山洪冲沟，震后由于沟域内崩塌、滑坡发育，形成极为丰富的松散物源，具备发生泥石流的所有条件，也成为唐家山堰塞湖成功泄水处理后，仍对堰塞湖正常利用起控制作用的严重地质灾害隐患点之一。通过现场实地调查，在查明沟域内松散物源分布及稳定性基础上，结合6.14泥石流发育状况，系统对大水沟泥石流发育特征及其动力学特性，尤其对在不同降雨频率下可能形成的泥石流规模进行分析研究，并对唐家山堰塞湖泄水口部位堵江规模、持续时间、溃决方式及其可能带来的危害性进行评价。分析计算结果已被2008年9月24日发生的百年一遇的泥石流所证实。

DEVELOPMENTAL FEATURES AND EVALUATION OF BLOCKING DANGERS OF DASHUI DITCH DEBRIS FLOW IN TANGJIASHAN DAMMED LAKE

Dashui Ditch is located in the upstream side of Tangjiashan Mountain. It was a gully before the May 12 earthquake，however，extremely rich loose sources were formed with all conditions of the occurrence of a debris flow due to the collapses and landslides after the earthquake. It became one of the serious potential dangers of geological disasters after successful discharge of Tangjiashan dammed lake，which controlled the normal operation of Tangjiashan dammed lake as well. Through in-situ investigation，the developmental and dynamic features of Dashui Ditch debris flow was analyzed systematically combining with the developmental situation of debris flow on June 14 on the basis of identifying the distribution and stability of the groove loose sources. In particular，the possible sizes of the debris flow under different rain frequencies were studied，and the possible blocking size，duration and outburst forms were evaluated. The results were confirmed by the once in 100-year debris flow on September 24，2008.