The Quasi-3D Surface Deformation Monitoring Method Research Based On Two-track In Sar Technology

InSAR(Interferometric synthetic aperture radar)is a new technology of earth observation,which has been developed and improved continuously.InSAR has been widely used in land subsidence,landslides,earthquake deformation and other fields for its ability to acquire the surface micro deformation efficiently and accurately.The surface subsidence caused by mining endangers the safety of production and restricts the development of economy.However,the accurate measurement of the surface deformation of mining area has always been a difficult problem in mining survey.InSAR can overcome the limitations of traditional measurement methods and obtain large-scale surface deformation in mining area efficiently.However,the line of sight(LOS)deformation obtained by InSAR can not effectively reveal the real surface deformation in mining area,because the deformation direction and intensity continuously change with the situation of mining,which is different from and more complex than ordinary land subsidence.In order to solve this problem,this paper proposes to build a model according to the spatial relationship between radar imaging geometry and the real deformation of the surface,which can extract the quasi three-dimensional deformation field of the surface using ascending and descending InSAR results.The extracted quasi three-dimensional deformation field could be used to study the characteristics of the surface deformation and monitor the dynamic change of the mining area.A quasi three-dimensional surface deformation model was established and applied in Yaojie mine area based on the ascending and descending deformation results obtained by SBAS-InSAR.It is found that the extracted quasi three-dimensional deformation results can clearly reflect the distribution of surface deformation in the mining area and the changes in different periods.The model was also used in Shanggong square landslide to extract the quasi three-dimensional deformation field and characteristics of surface deformation,which were then used to study the development process of the landslide.This method carried on the advantages of InSAR technology in accurately and quickly obtaining large-scale results,and improved the accuracy in complex surface deformation situations,because it makes full use of the ascending and descending data of the same radar platform and reduces the introduction of external observation data.The mainresearch results and conclusions are as follows:(1)A quasi three-dimensional surface deformation model is established based on the ascending and descending deformation results obtained by InSAR technology.Based on the systematic analysis of the spatial geometric relationship between the LOS deformation of InSAR and the real deformation of the earth's surface,combined with the geometric parameters of the ascending and descending satellite sensor,a spatial relationship model is constructed to extract the deformation of different dimensions of the earth's surface.The extracted quasi-3D surface deformation mainly includes the vertical deformation component and the specific horizontal deformation component.The accuracy of vertical deformation component is the same as that of a single orbit InSAR result,but the accuracy of horizontal deformation component changes with the angle between the direction of the horizontal deformation vector and the radar range direction,and the smaller the angle,the higher the accuracy.(2)The subsidence monitoring of Yaojie mining area is carried out based on quasi three-dimensional surface deformation model.Based on the ascending and descending sentinel 1 data and SBAS-InSAR,the quasi three-dimensional surface deformation extraction model is proposed to extract the vertical deformation field and the East-West deformation field of the surface in Yaojie mining area in three periods from January 2016 to August 2019.The results show that there are three subsidences in the mining area,and the boundary of subsidences can be clearly identified by vertical deformation results.Through the comparison with the measured data,it is determined that the vertical deformation rate-15mm/a isoline is the reference value for the subsidence area boundary;the East-West deformation field is greatly affected by the change of underground goaf location,and the East-West deformation results can be used to identify the subsidence centre.By analysing the surface deformation process of three subsidence areas based on the mining face data,it is found that,compared with the single track LOS deformation result,the vertical and east-west deformation results extracted by this method can better reveal the relationship between the surface deformation and the underground mining,and can be used as the basic data to study the mining subsidence mechanism.(3)The Shanggongye square landslide is carried out based on the quasi three-dimensional surface deformation model.The quasi three-dimensional surface deformation of the Shanggongye square landslide was was extracted based on the ascending and descending results,containing the vertical deformation field and sliding deformation field of the surface in the landslide area in four periods.Based on the comprehensive analysis of vertical and sliding deformation rate and time series deformation process,it is found that the distribution range of surface deformation and deformation rate change obviously in different periods are obvious.During the monitoring period from January 2016 to August 2019,it can be clearly identified that the deformation accelerated in September 2017,the landslide occurred in April 2018 and thedeformation slowed down in January 2019 until stable.Thus,the whole development process of landslide can be basically reduced from creep deformation stage to acceleration deformation stage,then to collapse stage and finally to stability stage.The results show that the quasi three-dimensional surface deformation model based on ascending and descending InSAR results can reflect the characteristics of landslide surface deformation better,and can identify the abnormal changes of landslide surface deformation better in the application of landslide monitoring.