Study On The Relationship Between Geological Structure And Large Landslide In Wulong Area Of The Eastern Sichuan Block-chuan EYu Qian Block

Since the Mesozoic,the Yangtze block has experienced the Early Mesozoic Indosinian movement,late Mesozoic Yanshan movement and Cenozoic Himalayan movement,and developed strong intraplate tectonic deformation,under the control of the Tethys structural domain and the Pacific structural domain.During the complex geological moment,the Yangtze block is divided by faults in different directions,and the basement is broken to form several sub-blocks with different structural styles.The study area is located in Wulong area in the lower Wujiang River at the junction of the eastern Sichuan block and the Chuan EYu Qian blocks,which is the intersection area of the eastern Sichuan thin-skin fold structural belt and the Chuan EYu Qian thick-skin fold structural belt.It belongs to the transition zone between The Sichuan Basin and Yunnan-Guizhou Plateau in geomorphology,and the huge thick carbonate strata are widely exposed.The complicated geological structure background makes the geological landslide disaster in Wulong area frequently occur,widely distributed and harmful,seriously restrict the development of society and threatening the safety of human settlements.Based on detailed field investigation and DEM data processing,we analyze the geometric,kinematic and dynamic characteristics of structural deformation,summarize the distribution and strike data of drainage system,linear structure and slope in Wulong area.On the basis of this,we discuss the relationship between the geological structure and the response of large geological landslide in Wulong karst mountainous area.The main progresses of the thesis are as following:1.The giant thick carbonate rocks deposited under the background of continental and Marine advance and retreat under the control of large-scale tectonic movement from Paleozoic to early Mesozoic laid the lithologic material foundation for the study area.The mud shale and coal seam sandwiched by carbonate rock provide a good shear sliding surface for geological landslide,which accelerates the development of rock fissures and causes rock mass instability to trigger geological landslide.2.The dominant structural plane of large-scale geological landslide is mainly controlled by fracture and joint structural plane and other structural foliation.The yanshan movement in Mesozoic established the basic geological structure of the study area,which was modified under the stress field of the Himalayan movement in Cenozoic.The original shear joints were transformed into tracing-tension joints.The interconnecting and stretching of the mutually closed structural planes destroyed the stability of the rock mass and controlled the development boundary of the landslide.3.Under the effect of three tectonic uplifts of Cenozoic Himalayan movement,the wulong area developed three level planation planes(corrosion surface),which greatly changed the elevation of erosion base level and controlled the development of karst pipeline and karst cave system.With strong physical erosion and chemical erosion,the water network developed along the geological structure traces rapidly erodes and cuts the rock,forming steep walls and slopes at the edge of the planation surface(corrosion surface),providing favorable space conditions for the development of geological landslides,which in turn controlling the distribution position and sliding direction of geological landslides and other characteristics.4.The frequent seismic activity in the study area have a non-negligible impact on the stability of rock mass and is conducive to the development of geological landslides.