Study On Slope Structure And Deformation Failure Model In Qin-Ba Mountain Area

Qin-Ba mountain area is one of the most serious disaster areas in China,because of its strong geological structure,obvious topographic relief,complex and diverse structural types of rock and soil,developed joint fissures,serious weathering,abundant rainfall,active human engineering activities and frequent disasters.Metamorphic rock slope and sedimentary rock slope are widely distributed in the area,and the lithology is mainly slate,phyllite,schist,limestone sandstone,etc.Under the influence of geological process and human engineering activities,the geological disasters mainly including landslides and collapses occur frequently in the study area,which have a great impact on the local economic development and people's life safety.Therefore,it is of great significance to understand the relationship between the slope structure and its deformation and failure model for the prevention and control of landslide disaster in Qin-Ba mountain area.In this paper,the slope structure and slope deformation and failure model in Qin-Ba mountain area are the main research contents.By consulting the literature and combining with the field investigation,the engineering geological rock group,rock soil structure type and slope structure in the study area are divided,and the slope structure type and development characteristics are summarized and analyzed.On this basis,combined with the discrete element software 3DEC and the finite difference software FLAC3 D are used to simulate the different types of slope structures,analyze the displacement change rule in the deformation and failure process,reveal the failure mechanism of different slope structures under the action of gravity,and summarize the deformation and failure characteristics and failure model of slopes.The main contents are as follows:(1)Find out the landform,geological structure,formation lithology,hydrogeology and other engineering geological conditions of the study area and the influencing factors of human engineering activities.According to the characteristics of rock formation assemblage,the exposed strata in the study area are divided into four types: loose accumulation,sedimentary rock formation,metamorphic rock formation and magmatic rock formation,and on this basis,they are divided into seven sub types.According to the characteristics of structural plane and structure body and the characteristics of their mutual arrangement and combination,the rock mass structure in the study area is divided into four categories,which are: loose structure? layered structure?fragmentation structure and block mosaic structure.(2)The slope types in the study area can be divided into four types: soil slope,rock slope,rock soil composite slope and colluvial accumulation slope.According to the angle between the original production state and the slope direction of the slope rock,the rock slope can be divided into five types: along slope,along slope,transverse slope,reverse slope and reverse slope.Combined with the engineering geological rock group,rock mass structure and rock slope structure type,the slope structure in the area is further divided into: loose accumulation slope structure,bedding slope structure,oblique bedding slope structure,reverse bedding slope structure,steep vertical bedding slope structure,cataclastic slope structure,block mosaic slope structure,slope deposit bedrock dual slope structure.(3)In this paper,3DEC discrete element software is used to simulate the rock slopes with different slope structures in the area.The deformation and failure process of slopes under the action of gravity is discussed,and the law of displacement movement is analyzed.It is concluded that different types of slope deformation and failure are easy to occur in the form of "creeping-pulling gradual" failure in the bedding structure slope,in the form of "bending-breaking" failure in the bedding structure slope,in the form of "pulling and sliding in the bedding structure plane" in the bedding structure slope and in the form of inclined bedding structure slope,and in the form of "pulling and sliding in the bedding structure plane" in the opposite direction It is stable and not easy to be damaged.The slope of middle thin layer structure with reverse steep dip is easy to be damaged in the form of "bending,pulling and sliding",and the slope of middle thick layer structure with reverse steep dip is easy to be damaged in the form of "bending and toppling".(4)The finite difference software FALC3 D is used to simulate the slope with dual structure of slope deposit and bedrock and the slope with loose accumulation structure.When the thickness of slope deposit is large,the slope with dual structure of slope deposit and bedrock has arc sliding failure inside the slope body,and the failure mechanism is the same as that of loose accumulation slope.If the slope deposit is thin,the bedding failure will occur along the contact surface between the slope deposit and the bedrock.(5)In this paper,the different types of slope structure in Qin Ba mountain area are comprehensively classified,and the relationship between the types of slope structure and the deformation and failure mode is concluded.