Research On Settlement Monitoring Of High Speed Railway Based On PS-InSAR Technology

China’s high-speed railway has the advantages of fast running speed, good safety and low energy consumption. However, due to the rapid running of the train, it will do an impact on the bridge and roadbed. Because of the influence of the human factors and natural factors, the speed railway not only along but also around it will produce slow subsidence. At the same time, the running of high-speed train will generate pressure on the roadbed and bridges, as the time went by, roadbed and bridges will produce deformation, especially in vertical direction. As a big country with many high-speed railways, China’s high-speed railways distribute in all parts of the motherland and the directions, so how to effectively monitor the slow subsidence of high-speed railway has become a new hot topic. At the same time, the running of high speed railway will pass through different geological environment, therefore we need a high monitoring efficiency, wide monitoring range and high precision monitoring method to monitor subsidence.Differential interferometric synthetic aperture radar(DInSAR) as an expansion and extension of interferometric synthetic aperture radar(In SAR) technique, it can monitor the surface deformation information. Because its advantages of no matter what weather, large area, rapid monitoring, it has gradually become an important technology to study surface deformation subsidence. In the high-speed railway settlement monitoring, the traditional geodetic methods(leveling, GPS measurement)as contact measurements have a relatively long monitoring cycle, also it is very effected by the influence of natural environment. But interferometric synthetic aperture radar(In SAR) technique can effectively compensate for these deficiencies.However, due to the traditional interferometric synthetic aperture radar(InSAR)technique is easily affected by the time correlation, spatial decorrelation and atmospheric effects influence, so in the monitoring of the surface of the timing of tiny deformation, traditional DInSAR technique is restricted. And based on the traditional DIn SAR technique, Permanent scatterers interferometric synthetic aperture radar(PS-In SAR) can effectively overcome the time, spatial decorrelation and atmosphericdelay effects, the monitoring precision is higher and the result of monitoring is more reliable.PS-InSAR technology is developed on the basis of traditional DIn SAR technology(a radar data processing technology), this technology can accept the low accuracy of the DEM data as a reference DEM, so it is very suitable for monitoring the slow surface deformation. The datas used by this article are 30 King X-band high resolution SAR image data taken by the German TerraSAR-X satellite from March 27,2009 to December 14, 2010 and 90 m SRTM DEM data. Through data preprocessing of SAR image data processing, selecting the master image, selecting PS point,interference and differential interferometric phase function model establishment and solution after get Tianjin Jinghai area of ground subsidence maps and settlement timing diagrams. Finally we choose the typical PS points in Jinghai high-speed railway to analysis their time series settlement. The feasibility and reliability of PS-InSAR technology in the settlement monitoring of high speed railway are verified by the experiment.