Application Of PSInSAR Technology In Monitoring Highway Subsidence

With the rapid development of China's transportation industry,the number of high-grade highway is increasing.However,due to human and natural factors,subsidence and deformation will occur on highways and surrounding areas.Severe subsidence will cause road cracks,collapses,etc.It will pose a threat to road safety.Therefore,in order to ensure the safe operation of highways,it is of great significance to monitor ground subsidence along highways and timely find severe subsidence areas.Traditional road deformation monitoring methods such as horizontal surveying which need to work in the field for a long time and consume a lot of manpower and funds.It can not adapt to the rapid development monitoring requirements of highways.Differential InSAR(DInSAR)technology has the characteristics of wide monitoring range and high spatial resolution.It gradually plays an important role in subsidence monitoring.However,it is vulnerable to the influence of time decorrelation,spatial decorrelation and atmospheric delay.In order to overcome the limitations of DIn SAR technology,this paper makes a research on monitoring subsidence of highways by using persistent scatterer interferometry technology(PSInSAR)and provides a reference for future monitoring in highways.The main research content includes:Taking the Beijing section of Beijing-Tianjin highway from Chemical Bridge to Yizhuang Station as the experimental area,PSInSAR technology is used to monitor subsidence in this area by using 1m resolution TerraSAR-X data,3m resolution TerraSAR-X data and 5m×20m resolution Sentinel-1A data and the application characteristics of different band and resolution radar image data in highway are analyzed.The experimental results show that in the spatial distribution of subsidence velocity field,the results of the three types of data are consistent,and the locations of the subsidence areas are the same,indicating that the monitoring results are relatively reliable.Meanwhile,in the processing procedure,the higher resolution radar image detected more high-coherence points,namely PS points.It can reflect the subsidence details of the road.The cumulative time series change of the area obtained by X-band data is similar with that by C-band data.But time series change from X-band data is smoother than C-band data and long-band data can easily cause phase noise during processing procedure.The subsidence results along the roads obtained by PSInSAR are overlay analyzed with the changes of groundwater level and rainfall of Beijing in 2015 and 2016.The results show that the exploitation of groundwater has a certain impact on the subsidence.The subsidence profile diagram of the road and its two sides show that the location of the road is at the troughof the subsidence rate profile diagram indicating that the subsidence rate near the road is greater than the two sides,and the dynamic load generated by the highway also has a certain impact on the subsidence of the ground.The analysis of the experimental results shows that PSInSAR technology can monitor the subsidence of wide range roads.At the same time,the processing results of the medium-resolution data can provide a qualitative reference for the subsidence,and high-resolution radar images can provide more refined results for the subsidence of roads.It is of great significance to provide valuable reference information for formulating relevant measures such as monitoring land subsidence and ensuring the normal operation of the highway.