| Landslide hazard is sudden and destructive.Landslides are affected by topography,geological conditions,hydrological climate and external precipitating factors,and mostly develop in mountainous areas,causing great harm to society.With social development,more and more underdeveloped areas have begun to promote the construction of comprehensive,coordinated and sustainable economic and ecological development.The prevention and control of geological disasters is the basis for the stable development of the region,so it is particularly important to conduct research on regional geological disasters.Qiubei County is located in the southeastern slope of the Yunnan Plateau,which is affected by various climates and has abundant precipitation.The area of mountainous area in the territory accounts for 82.1%,which belongs to mountainous counties.Qiubei County’s abundant precipitation and complex geological and geomorphological characteristics have caused frequent landslide disasters in the area,which are very easy to cause social property losses and threaten people’s lives and safety.In view of the above situation,this thesis takes Qiubei County as the research area,and uses remote sensing,spatial analysis and slope unit analysis methods to study the formation conditions,developmental characteristics and susceptibility of landslides in Qiubei County.This thesis not only has a comprehensive understanding of landslide disasters in Qiubei County,provides a theoretical basis for the prevention and control of landslide disasters in this area,but also provides an effective technical method for the study of landslide susceptibility in mountainous counties.The conclusions of this thesis are as follows:(1)Established the Qiubei County Landslide Remote Sensing Interpretation Mark and Catalog Database.Using high-resolution remote sensing data and historical landslide hazard data,landslide interpretation signs were established.Through remote sensing interpretation and field verification,70 landslides in Qiubei County were identified and a landslide catalog database was established.(2)The developmental characteristics of landslides in Qiubei County were identified.From the characteristics of spatial distribution,development type,dispersion and aggregation,the development characteristics of landslide disasters in Qiubei County were analyzed.○1 From the perspective of spatial distribution characteristics,Shuanglongying Town has the largest number of landslide disasters and the highest disaster density,Shede Township has the largest total landslide volume;And from west to east,the landslide area shows a trend from large to small.○2 From the characteristics of development types,small landslides accounted for 67.1%of all landslide types,tongue-shaped landslides accounted for 80%of all landslide types,and soil landslides accounted for 79%of all landslides.○3 From the point of view of dispersion and agglomeration,the distribution of landslides in Qiubei County is dispersive;in terms of disaster scale,threatened objects and spatial distribution,Qiubei County landslides are characterized by clustering.(3)The formation conditions and deformation characteristics of typical landslides are analyzed.Through the analysis of two typical landslides,it is found that the landslide in the west of Chongtou Village has a plane shape of"circle chair shape"and a cross section shape of"step shape".The sliding body is about 95 m long,50 m wide and 3～15m thick,the volume is 30000 m~3,it is a small shallow traction soil landslide.The light yellow Quaternary overlying soil and the brown-yellow residual slope contain gravel clay,and the sliding surface is the interface between the residual slope and the strongly weathered mudstone.The landslide in the east of Chongtou Village has a vertical shape in plan and a"stepped shape"in section.The sliding body is about 200 m long,60～110m wide and 3～15 m thick,the volume is 160000 m~3,it is a medium-sized shallow traction soil landslide.The sliding body is a residual slope with gravel-bearing clay layer and strongly weathered mudstone,and the sliding surface is a strongly-weakly weathered mudstone interface.(4)The evaluation factor of landslide susceptibility in Qiubei County was established.Using the slope unit as the mapping unit,the study area is divided into 56999units.From the perspective of topography and geomorphology,select elevation,undulation,slope,slope aspect,and slope shape;from the perspective of geology,select the type of rock and soil and the distance from fault;from the perspective of hydrogeology,select the distance from the water system,terrain humidity index,and runoff intensity index;The land use type,rainfall and vegetation coverage are selected as evaluation indicators,and quantify and grade the above evaluation indicators respectively.Use the relative density method to calculate the information content model,and carry out the correlation test between the evaluation indicators.After eliminating the runoff intensity index,a total of 12 indicators were established,including elevation,undulation,slope,slope aspect,slope shape,geotechnical type,distance from fault,distance from water system,terrain moisture index,land use type,rainfall and vegetation coverage.The evaluation factor of landslide susceptibility in Qiubei County composed of indicators.(5)The susceptibility evaluation of landslide geological disasters in Qiubei County was carried out.Using logistic regression model to evaluate the susceptibility of landslide geological hazards in Qiubei County.By setting up 140 sample data for logistic regression model operation,and then calculating the information amount of each evaluation factor,the susceptibility of landslide geological disasters in Qiubei County is obtained.The landslide susceptibility grading map in Qiubei County was made,and the susceptibility zoning study was carried out. |
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