Research On Surface Deformation Monitoring In Xuzhou City Based On Time Series InSAR

Land subsidence is a kind of vertical deformation of the surface formed by the combination of natural factors and human factors,which can develop into serious geological hazards.Land subsidence in cities will not only threaten the safety of human life,but also cause great losses to the local ecological environment and economic development.Many cities in our country have suffered different economic losses because of land subsidence.Xuzhou is located in the North China Plain,one of the three key areas of land subsidence in China.Therefore,it is of great significance to carry out land subsidence monitoring in Xuzhou,which cannot only grasp the dynamic of land subsidence in Xuzhou,but also provide reference for land subsidence disaster assessment and prevention and urban planning.InSAR technology developed in recent 20 years has been widely used in surface deformation monitoring.Compared with traditional measurement methods,it has the characteristics of all-weather,all-day,wide-range and high-precision monitoring,which makes up for the shortage of sampling points,long observation interval and high cost.This paper introduces the theory of InSAR technology in detail.Using Sentinel-1A SAR data combined with time series InSAR technology to study and analyze the surface deformation of surrounding villages and Xuzhou urban area.Analyzes the causes of surface deformation in Xuzhou city by combining the data of urban expansion,underground engineering activities and groundwater extraction.The main findings are as follows:(1)Using PS-InSAR technology monitor the surface deformation of Xuzhou urban area analyzed the results.The results show that there was a general phenomenon of land subsidence in the northwest and southeast regions of Xuzhou urban area,and there was ground lift in the area west of the central urban area(Hanwang Town and part of Dapeng Town).(2)According to the PS-InSAR results,the surface deformation of the mining area and its surrounding area in Xuzhou urban area is studied and analyzed.There is serious land subsidence around several mining areas located in the northwest region of Xuzhou City,there is ground uplift around several mining areas located in the central and western regions of the urban area;Study and analysis the surface deformation along the metro line and the metro line under construction in Xuzhou City.There is serious land subsidence in the vicinity of Gongnonglu Station,Renmingguangchang Station and The affiliated hospital of Xuzhou Medical University Station along the opened Metro Line 1,and there is no serious surface deformation along the under construction line 2 and line 3.(3)Using SBAS-InSAR technology monitor the land subsidence of Shixi Village near Pangzhuang Mine and Shitun Mine in the northwest of Xuzhou City and analysis the results.The results of 3D unwrapping method and 2D unwrapping method are compared in data processing and the results show that 3D unwrapping is better than 2D unwrapping.According to the InSAR results,the relationship between settlement value and time(days)in the study area is explored,and it is found that the settlement value and time are basically linear.Finally,the InSAR monitoring data are compared and verified by the measured data.(4)Combined with urban expansion data,underground engineering construction data,underground mineral mining data and groundwater extraction data,the causes of surface deformation in Xuzhou urban area are analyzed.Underground engineering construction,underground mineral mining and groundwater overexploitation are the main causes of land subsidence in Xuzhou urban area,and the increase of groundwater quantity may be the cause of surface uplift in local areas.