Formation And Evolution Mechanism Of Loess Landslide System

Slope geological hazards frequently occur in the loess mountain zone, and one of the most typical and most frequent is the loess landslide, especially in Longxi area. Due to frequent occurrence and harmfulness of loess landslide, it is necessary not only to analyze characteristics and formation evolution mechanism of loess landslide, but also to explore characteristics and evolution mechanism of loess slope—the origin of loess landslide. As the part of loess landform system, both loess slope and loess landslide have openness, dynamic characteristic, and other system attributes. However, there is less research about characteristics and evolution mechanism of slope and landslide from the point of system.According to the system point, the loess landslide is regarded as the result of loess slope that evolves to specific stage, and on the basis of a large quantity of data obtained from in-situ observation and laboratory experiments and construction of the loess slope system, its structure, component elements, slope structure characteristics are deeply analyzed in this paper. And then evolution models and types of loess slope system under the condition of earthquake and rainfall are mainly studied; finally characteristics and formation evolution mechanism of loess landslide in the Changjiahe area in Tongwei county, Gansu provice are researched from the point of system.The main results of this research as follows.(1) Based on the system point and characteristics of loess slope, constructes the loess slope system which includes rock and soil mass, tectonic, topography and geomorphology, stress field, seepage field, temperature field; studies the subsystem’s characteristic; divides loess slope into36groups on the basis of slope structure and emphatically analyzes slope structure characteristics of common slope types by a lot examples.(2) Based on field investigation data, uses FALC3D software to emphatically study evolution models and types of loess slope system which under four different working conditions such as natural, rainfall, earthquake, rainfall and earthquake, and totally eight evolution models and six landslide types are obtained; slope structure restricts and controls evolution models, process and types of loess slope system evolving to loess landslide system. The intersected relations of the interface and slope surface plays a key role in the evolution. Specificially, it is easy for slope to slide when the interface inclines to slope surface.(3) Based on the construction of the loess landslide system, deeply analyzes characteristics of loess landslide system and slope system in the Changjiahe area; On the basis of analysis of control function of slope structure and induced function of earthquake and rainfall on formation evolution process of loess landslide system, mainly studies the formation evolution process of loess landslide that slide direction inclined to gully, and simultaneous analyzes formation evolution of loess cave in loess landslide and its effect on loess landslide.