唐家山堰塞坝“9·24”泥石流堵江及溃决模式  

Analyses of River-Blocking and Breaking Mode of "9·24" Debris Flow near Tangjiashan Barrier Dam

作　　者：胡卸文[1,2] 吕小平[1] 黄润秋[2] 任晓明 汪雪瑞[1] 刘娟[1] 

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]成都理工大学地质灾害防治与地质灾害保护国家重点实验室,四川成都610059 [3]绵阳市水务局,四川绵阳621000

出　　处：《西南交通大学学报》2009年第3期312-320,326,共10页Journal of Southwest Jiaotong University

基　　金：国家自然科学基金资助项目(40772175;40841025);地质灾害防治与地质灾害保护国家重点实验室“科技减灾、重建家园”开放基金资助项目(DZKJ-08012);西南交通大学科学研究基金资助(2008-A01)

摘　　要："5·12"汶川地震导致唐家山高速滑坡堵江,形成唐家山堰塞湖.经过6月10日正常泄流后,堰塞坝体右岸还存在唐家山残留山体稳定性以及附近大水沟、小水沟泥石流等潜在危害.现场实地调查显示,受地震影响,大水沟、小水沟及无名沟沟域内崩塌和滑坡发育,形成了极为丰富的松散物源,具备发生坡面和沟谷泥石流的所有条件,也成为唐家山堰塞湖成功泄水后,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,"6·14"和"9·24"2次大规模泥石流又导致通口河分别堵江断流4和17h.在查明唐家山堰塞体右岸3条冲沟内松散物源分布及稳定性的基础上,重点结合"9·24"泥石流发育状况,对大水沟、小水沟和无名沟泥石流的发育特征及其动力学特性,尤其是在不同降雨频率下一次冲出泥石流时唐家山堰塞坝体泄水槽的堵江状况及溃决模式进行了系统分析.分析结果表明:3条冲沟形成泥石流堵江后,一次全溃决的可能性很小,其溃决模式为"扇缘部位首先过流→水流挤压左岸并淘刷左岸堰塞体→逐级冲开堆积扇".这一模式对震后地震灾区泥石流的研究具有指导和借鉴意义.＂5.12＂ Wenchuan earthquake caused a high-speed landslide on the Tangjiashan mountain to block the Tongkou fiver to form the Tangjiashan dammed lake. After a normal discharge on June 10, 2008, there were potential hazards of stability loss of remnant Tangjashan mountain body and debris flows in Dashui and Xiaoshui ditches on the fight bank of Tangjashan barrier dam. Through an on-the- spot investigation, due to the effect of the earthquake collapses and landslides developed in Dashui, Xiaoshui and Wuming ditches to form extremely rich loose sources, having all conditions of slope and valley debris flows. That become one of the potential serious dangers of geological disasters after the Tangjiashan dammed lake had been successfully discharged and controlled the normal use of the Tangjiashan dammed lake. ＂6＂ 14＂ and ＂9＂24＂ debris flows, two large-scale debris flows occurring respectively on June 14 and September 24, 2008, made the Tongkou fiver blocked respectively for 4 and 17 h. Based on identifying the distribution and stability of loose sources in the three ditches on the right bank of the Tangjiashan barrier dam and importantly by combining the developmental situation of ＂9·24＂ debris flow, the developmental and dynamic features of the three ditches, especially the river- blocking situation at discharge spout of the Tangjiashan barrier dam and breaking mode when the three ditches break out debris flows at the same time under different rain frequencies, were analyzed systematically. The research result shows that the possibility that debris fans break once completely is very small after debris flows block the river, and the breaking mode is that firstly flood flows over the edge of debris fans, secondly crushes and scours the left of the barrier body, finally rushes out debris fans gradually. This mode provides a guidance and reference for the research on debris flow in the disaster areas after the Wenehuan earthquake.

关 键 词：唐家山堰塞湖 泥石流 堵江 溃决 

分 类 号：P642.23[天文地球—工程地质学]