西南岩溶山区特大滑坡成灾类型及动力学分析

An analysis of disaster types and dynamics of landslides in the southwest karst mountain areas

我国西南岩溶山区位于上扬子地台,经过多期构造运动,形成了特有的强烈褶皱地貌形态,特大型滑坡灾害频发。通过资料收集、现场调查以及统计分析,讨论了岩溶山区典型滑坡后破坏的成灾模式和形成条件,并得出以下结论:(1)我国西南岩溶山区普遍呈现上陡下缓的地形地貌特征和上硬下软的地层结构特征,岩溶地貌和溶蚀岩体结构加剧了滑坡后破坏的成灾规模;(2)研究区的滑坡成灾模式主要分为岩质崩塌、高位远程滑坡-碎屑流和高位远程滑坡-泥石流三种类型;(3)岩质崩塌灾害类型剪出口高差通常小于50 m,等效摩擦系数通常大于0.6,堆积体破碎比在5~20之间;高位远程滑坡-碎屑流灾害类型剪出口高差通常在50~200 m之间,等效摩擦系数通常在0.33~0.60之间,堆积体破碎比在20~100之间;高位远程滑坡-泥石流灾害类型剪出口高差通常大于200 m,等效摩擦系数通常小于0.33,堆积体破碎比区间大于100;(4)西南岩溶山区的“高位滑坡”剪出口高差通常大于50 m,具有高速远程运动特征,运动过程中具有冲击铲刮、破碎解体、气垫和流化四种动力学效应。滑坡后破坏成灾模式的提出,可以为滑坡运动动力学机理和成灾反演预测研究提供重要分析模型。

The karst mountain area in southwest China is located on the Upper Yangtze Platform.After multi-period tectonic movements,the unique strong fold landform has formed in this area and the large-scale landslide disasters occurred frequently.Based on the data collection,field investigation and statistical analysis,this paper discusses the disaster mode and formation conditions of typical landslides in karst mountainous areas.The research results show that(1)the karst mountain area in southwest China are generally characterized by topography and landform with steep top and gentle bottom,and strata structure with hard top and soft bottom,and the karst landform and the structure of the eroded rock mass aggravate the disaster scale of the landslide.(2)The landslide disaster modes in the study area are mainly divided into three types:rock avalanche,high-position landslide-debris avalanche and high position and long-runout landslide-debris flow.(3)According to statistical analyses,the elevation difference of the toe of surface of rupture of rock avalanche disaster type is usually less than 50 m,the equivalent friction coefficient is usually greater than 0.6,and the disintegration ratio of accumulation body ranges between 5 and 20;the elevation difference of toe of surface of rupture of high-position landslide-debris avalanche type is usually between 100 and 200 m,the equivalent friction coefficient is usually between 0.33 and 0.6,and the disintegration ratio of accumulation body is between 20 and 100;the elevation difference of high position and long-runout landslide-debris flow type is usually greater than 200 m,the equivalent friction coefficient is usually less than 0.33,and the range of the disintegration ratio of accumulation body is greater than 100.(4)The elevation difference of the“high-position landslide”toe of surface of rupture in the southwest karst mountain area is usually geater than 50 m,which is of the characteristics of rapid and long-runout.There are four dynamic effects in the process of movement,namely entrainment,disintegration,air cushion and fluidization.The post failure disaster mode can provide an important analysis model for the study of landslide dynamic mechanism and disaster-forming inversion prediction.