摘要
2010-07-27凌晨,四川省汉源县万工集镇后山因持续暴雨而突发高位高速远程滑坡-碎屑流,最大滑程约1.4 km,启动时滑坡体约48×104m3,沿线裹挟和铲刮沟谷及其两侧边坡松散体,到达坡脚部位滑坡碎屑流体积增大至100×104m3,最终导致沿沟的双合村一组5户20名村民失踪及下游万工集镇部分房屋被掩埋而倾倒破坏。滑坡启动区发育于万工集镇后侧二蛮山大沟内,沟左侧为二叠系灰岩(P1y),顺坡倾向沟内;右侧为强风化的二叠系峨眉山玄武岩(P2β),节理极发育;沟内早期堆积物丰富,特别是沟上游还存在一大型古滑坡体;这些不稳定物源在有利地形条件及降雨诱发下极易形成滑坡。原始沟谷上游高位陡峭地形导致山体具备高位潜在势能,具备形成高位高速远程滑坡-碎屑流的地形条件。2010-07-24—26的降雨是触发此起特大灾害的主要原因,累计降雨量达163 mm,在水的作用下启程剧动并高速下滑。采用将今论古的地质方法,从地质构造、地层序列、岩体坡体结构及坡体变形等角度研究了二蛮山滑坡孕育的地质演化史,再现了滑坡区域历史时期中重要的地质活动过程。
At wee hours of July 27,2010,a landslide-debris flow occurred on the back hill of Wangong town of Hanyuan city in Sichuan province of China because of heavy rainstorm.It started in high position and moved at a high speed to long distance（about 1.4 km）.The whole volume was about 48 million m3when it started,entraining and scraping loose material accumulated in the gully bed and on both sides of slopes,then it increased to 100 million m3,which eventually led to five households 20 villagers of first group of Shuanghe village disappeared and some houses in Wangong town titling down.The landslide developed in the gully of Ermanshan behind the town.The bedrock on the left of the gully was limestone（P1y）,dipping to the gully and easily sliding along the overburden interface;while on the right side is Emeishan basalt（ P2β） with highly developed joints;there were rich deposits in the gully and a large ancient landslide existing upstream;All of these unstable loose materials easily slid with favorable terrain conditions and under rainfall.The steep terrain of original valley provided the rock mass with high potential energy,easy to form a high-position high-speed long-run out landslide-debris flow.The heavy rainfall of July 24～ 26 up to 163 mm was the main factor triggering the major disaster starting and sliding down at a high speed under the action of the water.This paper studied the basic characteristics and forming conditions of the landslide-debris flow based on the detailed investigation in field.Then the geological evolution history of the landslide was also studied by analyzing the geological structure,strata sequence,the slope structure and deformation process of slope,using the method of The Present The Key To The Past,to replay the important geological events of the landslide area during the history process.Such the research results have important significance in predicting and preventing the occurrence of similar large high-speed landslide.
出处
《山地学报》
CSCD
北大核心
2014年第5期568-578,共11页
Mountain Research
基金
国家自然科学基金项目(41372293)
NSFC-云南联合基金重点项目(U1033601)
2013年西南交通大学博士研究生创新基金~~
关键词
碎屑流
高速远程
基本特征
形成条件
地质演化
debris flow
high-speed and long-run out
basic characteristics
forming condition
geological evolution
