Research On Application Of MT-InSAR Technology In Deformation Monitoring

The frequent occurrence of geological disasters poses a major threat to the safety of people's lives and properties,and seriously affects the sustainable development of the economy and society.Therefore,deformation monitoring in key areas should be carried out to identify hidden dangers of geological disasters as soon as possible,which is of great significance for the early warning and treatment of geological disasters.Traditional leveling and GNSS measurement technology are limited by its own observation complexity,observation cost and monitoring density,and it is difficult to implement it in large-area deformation monitoring,while the multi-temporal synthetic aperture radar interferometry technology(MT-InSAR)has the ability to perform large-scale,alltime,all-weather,and high-precision surface deformation monitoring,which is especially suitable for the identification of large-area hidden danger points.This thesis mainly uses SBAS-InSAR technology for deformation monitoring research.In the data processing process of this technology,phase unwrapping and atmospheric correction are two very important links.In view of the large errors in the traditional phase unwrapping results,a method is proposed to constrain the traditional unwrapping results by using the spatial domain continuity condition and the time domain phase triangle relationship respectively;for the atmospheric correction,the traditional spatio-temporal filtering method depends on the data itself whether it meets the constraints of low-pass in the space domain and high-pass in the time domain,so the ECMWF atmospheric correction model and linear empirical model based on external data are adopted for atmospheric correction.Finally,the improved method was applied to Dafang County,Guizhou Province to verify the effectiveness of the method.The main research contents and results of this paper are as follows:(1)The error correction processing of the traditional unwrapping results is carried out,and the average and standard deviation of the time series residual phases are used as evaluation indicators.Finally,it is found that the comprehensive error correction method fusing the constraints of time and space is the most robust and reliable.(2)The original differential interferogram is corrected by atmospheric correction.Starting from the phase continuity of the interferogram before and after the correction and the standard deviation of the interference phase,the atmospheric correction effects of the two models are analyzed quantitatively and qualitatively,and it is found that the overall correction effects of the two models are basically equivalent.In terms of local detail correction,the ECMWF atmospheric correction model performs better,while the calculation of the linear empirical model is easier.(3)Taking Dafang County in Guizhou Province as the research area,using 9 C-band RADARSAT-2 images covering the area,and adopting improved SBAS-InSAR technology for time series deformation analysis,it is found through the deformation rate map that the maximum subsidence rate in this area has reached 5.7cm/y,and there are 3 obvious deformation areas.Based on the time series deformation information,combined with local precipitation data and compared with optical remote sensing images,the deformation characteristics and trends of the three regions are analyzed,and it is found that there are large hidden dangers of geological disasters,which need to be paid attention to.Finally,based on the comparison of the deformation rate diagrams obtained before and after the method is improved,it is found that the improved deformation information is more pure and obvious,which once again verifies the effectiveness of the improved method.