断裂构造对金沙江巧家至蒙姑段泥石流发育影响研究

Influence of fault structure on debris flow in Qiaojia and Menggu section of the Jinsha River

金沙江下游巧家到蒙姑段位于青藏高原东缘,区域断裂发育,地质环境复杂,泥石流灾害严重,历史上曾多次爆发泥石流并堵断金沙江。本文利用RS与GIS技术,结合野外考察资料,提出"泥石流规模指数"和"流域断层密度"两个指标,定量分析了断裂构造对泥石流规模的影响。结果表明,活动断裂和断层穿越泥石流沟的形成区和流通区时,造成沟道两岸岩土体破碎强烈,易触发崩塌滑坡,为泥石流提供丰富的物源条件;泥石流规模指数与流域断层密度呈指数关系,且当泥石流流域面积离散程度减少时,其相关性越高。

The Qiaojia to Menggu in lower reach of the Jinsha River located on the eastern margin of the Tibetan Plateau. Owing to the developed regional fault structure and complicate geological environment,this region sufferes serious debris flow hazards,which blocked Jinsha River several times. In this paper,we used RS and GIS techniques and combined with field survey to analyze the influence of active tectonic on geomorphology,slope and relief. Two indexes（ ＂debris flow scale index＂and ＂watershed fault density＂） were defined to quantify the relationship between debris flow scale and fault. The results showed that Xiaojiang fracture controlled the topography of the study area. Active fracture and faults make rock mass on sides of the gully broken and trigger rock collapses and landslides,which resulted in plentiful mass for debris flows. The debris flow scale index is exponentially related to the watershed fault density,and the correlation become higher when the standard deviation of the debris flow gully area is reduced.