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

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