Monitoring And Analysis Of Surface Deformation Based On Time Series InSAR

Surface deformation monitoring is an important means of early identification of geological hazards.It can quickly and effectively identify hidden danger points of geological hazards.The Sichuan-Tibet Railway is a major national "13th Five-Year Plan" project.The terrain of the Zhe Duo Shan area where the route passes is characterized by large terrain fluctuations,large seasonal temperature differences,and complex geological environment.Most mountain peaks in the area have an altitude of more than 4,000 meters,the annual rainfall is heavy,and the mountains are frozen and thawed.The Xianshuihe fault zone in the area has obvious recent activity,the granite body is relatively broken,and there are more NW trending joints.In order to ensure the safety of the preliminary survey and the later construction and operation of the Sichuan-Tibet Railway in this area,it is of great significance to carry out surface deformation monitoring and identify hidden danger points of geological hazards.Interferometry Synthetic Aperture Radar(InSAR)is a new technology for surface deformation monitoring in recent years.Compared with traditional surface deformation monitoring methods,it has the advantages of all-weather,all-weather,high precision,and wide monitoring range.Time series InSAR technology is carried out in this paper.The surface deformation of the Sichuan-Tibet railway Zuoduoshan area is monitored by using the Sentinel-1A(2017.1-2019.7)orbit-raising data,and three suspected slip regions with obvious deformation are delineated.The spatial-temporal variation characteristics of the settlement in the slip zone analyzed the causes of surface deformation.The main research results of this article are as follows:(1)In complex and difficult areas,comparison of surface deformation monitoring methods with different time series InSAR technology.Based on the SARscape software platform,two conventional time series InSAR technologies,PS-InSAR technology and SBAS-InSAR technology,were used to monitor the time-series surface deformation of 76 scenes of Sentinel-1A data.Obtained the distribution map of the average annual surface subsidence rate in the Zhe Duo Shan area of Sichuan-Tibet Railway in this period of time,and compared and analyzed the differences of the subsidence rate,time-sequence subsidence change,subsidence position and surface deformation point density obtained by the two time series InSAR.(2)Research on screening of permanent scatterers for SBAS-InSAR technology.First,extract the stable permanent scatterers by setting three thresholds of deformation rate,coherence and amplitude dispersion index.Then,according to the optical image,remove those points that are not located in the flat area after filtering according to the three threshold method.Finally,it was introduced as a ground control point into the orbit refining step of SBAS-InSAR technology.The results show that the annual average surface subsidence rate,time-series subsidence change,subsidence location,and surface deformation point density obtained by this method are basically consistent with the traditional SBAS-InSAR technology,but the distribution rate histogram,subsidence rate accuracy and elevation In terms of precision and other precisions,the improved method has higher precision.(3)Monitoring and analysis of surface deformation in Zhe Duo Shan area of Sichuan-Tibet Railway.From the distribution map of the average annual surface subsidence rate,three suspected slip regions with obvious deformation are delineated.By analyzing the variation law of the historical cumulative subsidence in these suspected slip areas,combined with the local geographical environmental conditions and meteorological data,it is found that the temperature,precipitation,and slope of the area are important triggers for these suspected slip areas.