Using Time Series InSAR Technology To Monitor Bridge Deformation And Surrounding Surface Subsidence

Time series In SAR technology can use archived data to monitor the bridge's longterm deformation and evaluate the health of the bridge structure.It is an effective supplement to the existing bridge health monitoring.The paper uses SBAS and TCP technologies to process 92 Sentinel-1A images in Nanjing from 2017.03 to 2020.05.Obtain the deformation of bridge in the area and the surrounding ground settlement information,and use the bridge deflection sensor data to analyze and verify the time series In SAR monitoring results.The main contents of the paper are as follows:(1)The monitoring results of the two time-series In SAR technologies are basically consistent with the deflection sensor results.The results show that the accuracy of the time-series In SAR technology is lower than that of the sensor for deflection monitoring,and the accuracy of the SBAS is lower than that of the TCP.(2)Bridge A deflection sensor No.1002 needs to be maintained in time;9# 10#pier-column beam deflection changes are caused by the slope structure on the south bank and the erosion pit caused by the south of the main channel,and need to be monitored;B bridge pylons despite fluctuations but the overall stability;structural health risks exist C bridge,the maximum deformation rate of up to 27 mm / year,during the study period a total settlement of up to 97 mm.(3)Cyclical changes in the deflection of three bridges in the study area,mainly related to temperature.The emergence of the bridge settlement trend coincides with the operation of Nanjing Metro S3.Further research found that the deflection changes of Bridge A and Bridge C are related to the failure of Nanjing Metro Line S3 to reach the steady state period of operation.The study area is located in the geological environment of floodplain and silty clay in the upper part of the Quaternary,and subway operation activities are likely to cause uneven settlement.Bridge A 9# and 10# piers and bridge C are both need to be monitored.(4)Surface deformation monitoring results show that: SBAS technology and TCP technology monitoring results are basically the same,four surface subsidence areas are monitored in the study area.The obtained surface subsidence data can be used as the reference data of "technical requirements for risk assessment of geological hazards in Jiangsu Province"([2010] No.353),and provide support for hazard classification evaluation.(5)According to statistical principles,the outlier detection and time series analysis of the deflection data obtained by the time series In SAR technology and deflection sensors are carried out.The results show that the bridge deflection has no abnormal data,and the time series analysis model has millimeter-level accuracy,which proves that the time series analysis model can realize the short-term prediction of bridge health monitoring data.