| With the characteristics of regional distribution, group～occurring, and multiple～ occurrence, landslides extremely threat people’s life and property and destroy geological environment. Shexian country, located in the mid～east region of southern mountainous area in southern Anhui province, with complicated engineering geological conditions, is the most serious landslide hazard area in Anhui province. During annual flood season, heavy rainfall inevitably induces various degrees of landslides. These landslides raised serious safety concerns of local residents. Based on a typical landslides survey in mountainous area (southern Anhui province) and a detailed geohazards survey in Shexian, this paper comprehensively studied the development of characteristics of landslides, such as spatial and temporal distribution, forming conditions and stability influence factors, analyzed deformation and failure modes, and carried out monitoring and early warning research on some typical representative landslides. The main achievements are as follows:(1) The engineering geological conditions of landslides in Shexian region was analyzed from several aspects, such as physical geography, meteorology, geomorphology, formation lithology and tectonics.(2) Spatial and temporal distribution law was obtained by analyzing large number of landslides in Shexian area. In the spatial distribution, with the influence of mountain chain and geotectonic condition, landslides mainly show banded distribution at a regional altitude from 400m to 800m. In the time distribution, affected by heavy rainfall in flood season, landslides intensively develop from May to September.(3) The classification principles of landslides in Shexian area were established. This paper proposed comprehensive classification system containing material composition, structure characteristics and hazard～formation mechanism. According to this system, this paper also classified all landslides in Shexian area.(4) Based on field survey and analysis, combined with physical and numerical modeling, formation mechanism and mode of landslides in Shexian area was obtained. The formation mechanism and mode mainly includes the following aspects:① Taking henghen landslide as a typical case, according to the morphological characteristics, slope structure and deformation evidence, this paper established the slide-tension mode in Shexian area. After evaluating the stability of the sliding mass, this paper suggested that it should be unstable under heavy rainfall.② Taking Niaoqueping landslide as a typical case, this paper established the slide～ bend mode and proposed key control factors for this kind landslide. Discrete element method (DEM) was used to simulate the deformation process of this landslide. After analyzing and evaluating the current deformation characteristics, this paper concluded that local instability of the upper slope would be triggered under heavy rainfall.(5) Taking Waidongshan landslide as a typical case, this paper analyzed and evaluated deformation mechanism of gravelly soil landslides in Shexian area. Based on field survey and used Particle Follow Code (PFC) numerical modeling, this paper analyzed deformation and failure modes of Waidongshan landslide and established creep～ cracking mode in the area. After studying deformation and movement characteristics under different moisture content, the critical moisture content for gravelly soil slope was specified.(6) Systematically studied monitoring technology for a single landslide. Taking the most common gravelly soil landslides as research objects and Hefeng landslide as an exemplary case, this paper carried out a series of monitoring work, including the displacement of deep slope, pore-water pressure and rainfall, and finally established the exemplary base of landslide monitoring and early warning, which would provide support for geological disaster forecast in the area. |
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