Surface Subsidence Monitoring In Ningbo No.1 Rail Transit Based On Time Series InSAR Technology

With the increasing scale of China's rail transit construction,the construction of rail transit and its construction process will have a certain impact on the local geological conditions,which is easy to induce land subsidence,viaduct tilt,subgrade instability,road landslide and other disasters.Therefore,how to efficiently and quickly monitor urban rail transit is of great significance.Taking Ningbo as an example,this paper uses time series InSAR technology to monitor the surface settlement of Ningbo Rail Transit Line 1,analyzes the settlement situation,compares the settlement results obtained by time series InSAR technology with the original leveling data,and preliminarily studies the feasibility of time series InSAR Technology in monitoring the settlement of Urban Rail Transit,and explores the settlement rules and reasons.In this paper,the research work is mainly carried out in the following aspects.(1)Combined with the data of sentry-1 covering Ningbo Rail Transit Line 1,the small baseline technology is used to monitor Ningbo Rail Transit Line 1.The settlement data along the whole rail transit line from 2015 to 2020 are obtained,and the cumulative settlement and average settlement rate along the whole rail transit line are calculated.Through the interference processing of 60 SAR images and combined with the existing leveling data,it focuses on the analysis of 7 main settlement intervals of rail Transit Line 1.During 2015-2020,the settlement map of Rail Transit Line 1 will increase The average settlement of line No.1 is-4.49mm/a,and the area with the largest accumulated settlement is near the 25 th ring road of Dongtian entrance and exit section,with the maximum settlement of-135.5mm.(2)This paper studies the method and means of using PS-InSAR technology to monitor land subsidence in the same period of Ningbo Rail Transit Line 1,and uses 60 SAR images from February 2015 to December 2020 for PS-InSAR processing.The results show that the settlement monitoring results using PS-InSAR technology are basically consistent with those using SBAS technology,and the settlement law and development characteristics are verified.(3)Combined with the monitoring results of PS-InSAR technology and SBAS-InSAR technology,this paper focuses on the analysis of the settlement characteristics and causes along Ningbo Rail Transit Line 1.The research results show that the cumulative settlement in the east direction of Century Avenue of Ningbo Rail Transit Line 1 is significantly greater than that in the west direction of Century Avenue,and the local geological conditions and construction factors are the main causes of settlemen.