Ground Deformation Monitoring Along High-speed Railway With High Resolution SAR Image

Due to the rapid running speed of high speed trains,the demand is proposed for geographical conditions and geological conditions along the high-speed railway.However,the influence of human or natural factors leads to varying degrees of deformation along the high-speed railway,which affects the safe operation of high speed trains.Therefore,with the area along the high-speed railway as the research object,this thesis uses high resolution TerraSAR-X image,Sentinel-1 A image and Permanent Scatterer Interferometric Synthetic Aperture Radar to monitor the temporal deformation of the study area.Considering the problem that the existing digital elevation model is not accurate in the process of Differential Interferometric Synthetic Aperture Radar,this thesis proposed an iterative fusion DEM reconstruction method,using the cover along the Beijing-Shanghai High-speed Railway in Nanjing area of two high-resolution TerraSAR-X images,combined with AW3D30 digital elevation model to obtain the high accuracy and high efficiency digital elevation model of research area.This paper also introduces the AW3D30,ASTER and SRTM DEM data for comparison,the results show that the experimental DEM has high precision,for the sparse distribution of large single building,can restore the 3D information better;for high altitude hilly areas,good for the other DEM;however,for the building distribution in a relatively dense region,due to the height of the building is not consistent and dense,resulting in serious geometric distortion and phase unwrapping error,leading to elevation recovered error,affecting the accuracy of digital elevation model generation.In order to effectively monitoring the temporal deformation of the Beijing-Shanghai High-speed Railway in the route of Nanjing area,this thesis uses a total of 23 Sentinel-1 A SAR image which covers the Nanjing region and time span from April 2015 to January 2017 by PSInSAR teclhnology to interference,location,structure,modeling and adjustment,finally obtained the temporal and spatial distribution of regional surface deformation rate.The results show that the deformation velocity of LOS in the study area is-30?15 mm/yr.Considering the complexity of surface deformation,in order to verify the accuracy of the results obtained by PSInSAR,this thesis uses SBAS technology to monitor the deformation of Nanjing area along the Beijing-Shanghai High-speed Railway.Comparison analysis with the results obtained by PSInSAR method shows that the two results are basically consistent with each other,although there are slight differences in the magnitude of the total settlement,but overall speaking,the consistency of regional deformation obtained by two methods is good.The area subsidence and large amount of engineering construction have jointly led to the destruction of surrounding rock stress,which has a direct impact on the land subsidence in the vicinity,the subsidence concentration is distributed mainly in Nanjing District of Yuhuatai,the Yangtze River and Qinhuai New River intersection zone,which the maximum sedimentation rate reached-30 mm/yr,cumulative settlement reached 47 mm.