甘肃南部典型小流域泥石流灾变链预测研究

Study on Hazards Chain Prediction in Typical Small Basin in Southern Gansu

基于前人对灾害链的研究及实地勘察,分析山地灾害链的发育类型与结构,采用SINMAP斜坡稳定性分析模型,进行小流域斜坡稳定性数值模拟,分析流域内不稳定区域分布特征。利用多重灾种链式演化模式中的聚焦型模型,分析典型小流域泥石流沟汉林沟链首地质灾害发育特征,结果表明其链首灾种为地裂缝、崩塌、滑坡、坡面泥石流及沟谷泥石流。由于汉林沟沟口相对狭窄,沟道的排导能力较弱,在极端降雨或其他地球外营力下形成的大型沟谷泥石流,极易形成堰塞湖,堰塞湖坝体在无法承受巨大的泥石流体冲击时,极易发生坝体溃决,形成大型山洪灾害,因此汉林沟流域发生泥石流灾害后最终形成的灾害链为山洪灾变链。

Based on previous research and field investigation of the hazards chain,this paper analyzed the development type and structure of mountain hazards chain,using SINMAP slope stability analysis model to do numerical simulation of small watershed slope stability and analyze the regional distribution characteristics of instability in the basin. Using the focused model in the multiple hazards chain evolution model,it analyzed the development characteristics of geological hazards chain in the typical debris flow gully of small watershed—the Hanlin gully.The results show that the hazard types of chain head are ground fissure,collapse,landslide,slope debris flow and gully debris flow. Due to the relatively narrow opening of Hanlin gully and the channel drainage capacity is weak,large-scale gully debris flow is formed by extreme rainfall or other extrasolar forces,so a barrier lake is easily formed. Once barrier lake dam can’t withstand the impact of huge debris flow,dam collapse is very likely to form major mountain flood disasters. Therefore,the mountain flood hazards chain forms the finally hazards chain after the debris flow hazard occurred in the Hanlin gully.