Study On The Influence Of Active Fault On Slope Hazards In Ningqiang County

The active fault in Ningqiang County is very developed,and have an important influence on the occurrence of slope hazards.Mianxian-Yangpingguan fault is the most important active fault in Ningqiang County,and it is of great theoretical and practical significance to study the influence of this fault on slope hazards.Based on the analysis of the development characteristics of slope disasters in the study area,the information method is used to study the influence of various related factors on slope disasters,and it is considered that the fault structure has a significant influence on the formation of slope disasters.Combined with remote sensing interpretation,field investigation and previous research results,the movement characteristics of dextral strike-slip of active faults are analyzed from the aspects of tectonic geomorphology,fault characteristics of water system and fault outcrop,and the relationship between active faults and slope disasters in the study area is further clarified.On this basis,a three-dimensional geological model of the study area is established by using FLAC3D numerical simulation software,the influence of Mianxian-Yangpingguan active fault on slope disaster in Ningqiang County is simulated and analyzed,and the influence of active fault on regional slope stability is analyzed from the aspects of stress,displacement,plastic failure area and so on.The results show that the maximum principal stress is concentrated at the end of the fault,the turning point,the intersection of the fault and the southeast shale area,the minimum principal stress on both sides of the fault changes obviously,and the stress value of the lower wall is greater than that of the upper wall.a strong differential stress is formed on both sides of the fault zone,which adversely affects the rock mass structure of the slope and provides internal force conditions for the formation of slope disasters.Obvious displacement dislocation occurred along the Mianxian-Yangpingguan fault and its secondary faults,the displacement difference between the two sides of the fault gradually decreased from SW to NE,and the displacement of the hanging wall was larger than that of the footwall,changing the slope slope and aspect on both sides of the fault and other factors affecting the formation of slope disasters.The surface plastic failure area is mainly developed along the fault strike,and the surface shear failure mainly occurs,especially the surface plastic failure of the Mianxian-Yangpingguan fault develops in a band along the fault strike,and the plastic failure range of the upper surface is larger than that of the footwall.In the southeast shale area,the plastic damage is serious,the rock weathering degree is serious,and the slope height difference is large,which is prone to slope disasters induced by rainfall.Based on the analysis of the influence of active fault on regional slope disaster,taking Fenghuangjie landslide in Ningqiang County as an example,the influence of active fault on the stability of single landslide is studied.The results show that when the fault is active,the stress is concentrated at the fault,the stress direction is obviously deflected,and the safety factor of landslide is obviously reduced.At the same time,the stability of the landslide under the earthquake is analyzed,and it is found that the displacement of the landslide increases,the tensile stress on the surface of the landslide increases,and the stability of the landslide decreases.