The Formation Mechanism And Evolution Process Of Loess-Red Beds Interface Landslide In Tianshui Area

Loess landslide widely developed in the Loess Plateau and different from other types of landslide caused serious hidden dangers to the economic development and people’s lives and property in Northwest China. Therefore, it is significant to research the loess landslide for weakening the risk.Based on engineering geology analysis and numerical simulation technology, the landslide mechanism and progress of formation and evolution of a landslide in Tianshui are explored from the dynamic perspective. The survey found that the landslide is a interface landslide, and the paper focuses on the interface landslide mechanism and reproducing the progress of formation and evolution, which aims to provide reference for engineering design and researching interface landslide.Following are the main research results:(1) The reason why landslide slide is that the landslide possess the formation lithology covered in the top of Neogene red clay, the slope structure of Double heterogeneous, and condition of abundance in groundwater during the rainy season. Another essential reason is the existence of various predisposing factors that the abundant rainfall in the rainy season, erosion of the temporary river on the leading edge of the landslide and the local frequent earthquakes.(2) Creeping liquefaction of soil layer near the interface causes the layer to be weak layer and be evolved to the mid-front sliding zone, moreover, the creeping of sliding in the mid-front of the slide body drag the vertical fracture in back loss layer and make it evolve to the steeply segment in the back of landslide. The formation of complete sliding zone and continuous reduction in shear strength eventually led to landslide. Various effects in progress of landslide movement reveals the reason why the landslide move slowly.(3) In creep stage, the landslide presents progressive type deformation, and the sliding mass creep toward to free face by traction, and the plastic zone of potential sliding zone stretch from the back of landslide to front in a progressive type, while in movement stage, landslide is characterized as sliding in a collapsed type along with the interface of loss-red layer, and sliding mass is divided into several secondary sliding mass that slide in different sliding speed, sliding direction and sliding track.