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| Research on deformation characteristics and instability mechanisms of large monoclinal layered bedrock landslides：a case study of the Longjing landslide in Shizhu county，Chongqing |
| ZHU Sainan1，WEI Yingjuan2，WANG Ping3，ZHANG Zhihua3，WU Xiaobin3，WANG Wenpei1，YANG Liu3 |
| (1. China Institute of Geo-environment Monitoring，Beijing 100081，China；2. Land Satellite Remote Sensing Application Center，MNR，Beijing 100081，China；3. Hydrogeology and Engineering Team 208，Chongqing Bureau of Geological Exploration，Chongqing Reconnaissance and Design Academy of Geological Disasters Prevention and Treatment Engineering，Chongqing 400714，China) |
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Abstract Taking Longjing landslide as an example，the deformation characteristics，genetic mechanisms and three-dimensional stability of the landslide are analyzed in detail by means of field survey and mapping，satellite remote sensing interpretation，UAV survey，engineering geological drilling，deep displacement monitoring，and field and laboratory tests. The landslide about 142.83×104 m3 is a large monoclinal layered rock landslide with complex failure characteristics. The elevation difference between the front and the rear margins is about 50 m. The leading edge shear outlet is near a precipice，which provides potential energy for the high shear of the landslide. Two groups of dominant structural fractures and weak interlayers in the slope cut the medium-thick bedrock into fragmentation blocks，which makes the rock mass has good dispersion and provides favorable conditions for the long run-out landslide. After long-term evolutionary creep，the shear strength of the soft interlayer decreases gradually，forming a sliding zone，which provides the mechanical conditions for the landslide. The three-dimensional static analysis is carried out by using the method of mechanical vector solution. When the saturated residual shear strength is adopted，the safety factor of the landslide is 0.93. The slip body will creep along the true trend direction of the soft interlayer along the strata，and will slip in the SE direction at a small angle after being blocked by the stable mountain in the west. In this paper，the deformation characteristics and instability mechanisms of Longjing landslide are analyzed comprehensively by various means，which can provide useful reference for the early identification and instability mode judgment of wedge landslides with blocked steering.
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2021, Vol. 40 
