Application Research Of Time Series InSAR Technique In Urban Surface Deformation Monitoring

It is a universal geographical phenomenon that land subsidence all over the world.With the accumulation of subsidence,it will eventually cause fatal harm to human beings.At present,there are various methods used to monitor the land surface subsidence.The traditional methods are leveling and GPS surveying technology,which is used for smallscale monitoring.However,in consideration of time and cost problems,these methods are not suitable for large-scale urban land surface subsidence monitoring.Time-series radar differential interferometry technology has the advantages of all-weather,large area,high resolution and high precision in the large-scale land subsidence monitoring.In order to study application value and reliability of time-series In SAR technology in surface deformation monitoring,the experiment was carried out combined with Sentinel-1A satellite data,SRTM DEM data,POD precision orbit data and so on,and the results are as follows:(1)The paper discussed interference phase components of In SAR technique,the theory of height measured by In SAR,the land subsidence deformation principle of D-In SAR,and the basic elementary of PS-In SAR and SBAS-In SAR for extended time ground deformation measured.(2)The paper taking the analysis of the time-series of Hefei city through 27 Sentinel-1A images from September 2017 to December 2019 used PS and SBAS technique.The result illustrates that the study area was steady from September 2017 to December 2019 and without large-scale settlement funnel.The average subsidence rates between-4mm/a and3mm/a and some departmental area appear land subsidence,the surface deformation rate is in the range of-12mm/a?-4mm/a.The distribution features of large dispersion and small concentration are presented.And there is no large area of settlement funnel.(3)Based on PS-In SAR technology,the surface deformation along the three subway lines in Hefei was studied from September 2017 to December 2019.The results show that:During the monitoring period,the average annual deformation rate in the study area is mainly between-4mm/a?5mm/a,and the land subsidence occurs in some areas,with the subsidence rate between-4mm/a?-11mm/a.The subsidence area is mainly located in the Shu Mountain Area,Baohe Area and some areas of Feixi County in Feidong County,among which the subsidence range is the largest in Baohe Area.According to the research results,a detailed analysis of Metro Line 1,2 and 3 was made,as well as some suggestions on disaster prevention and control in subsidence area(4)SBAS-In SAR method based on PS points was used to study the surface deformation along the subway in Nanjing,and the monitoring results showed that: During the study period,the average annual deformation rate of the study area is concentrated in the range of-34.2mm/a?23.9mm/a,and some areas in the study area have a certain range of surface subsidence,the subsidence rate is concentrated in the range of-5.0mm/a?-0.1mm/a,and the subsidence area is mainly distributed in Jiangning area,the Yangtze River and the Hexi area.SBAS-In SAR method based on PS points is very close to the results of PS monitoring,and has high stability.In addition,combined with the geological conditions,hydrological information and spatial development and utilization of the area,subsidence results of this area are analyzed and discussed.