Surface Deformation Monitoring And Two-dimensional Deformation Calculation By InSAR Technology Of Ascending And Descending Orbit

In recent years,synthetic aperture radar interferometry(In SAR)technology has been widely used in surface deformation monitoring.It has technical advantages such as large-scale and high-precision in surface deformation monitoring.However,the surface deformation obtained by the single-orbit In SAR technology is one-dimensional deformation along the radar line-of-sight(LOS)direction.The description of surface deformation is relatively simple.It can not meet diverse engineering needs.In response to the above problems,this paper combines the ascending orbit SAR data with descending orbit SAR data.The two-dimensional deformation of the surface deformation in the horizontal and vertical directions has been carried out.The research objects are Muli mining area in Qinghai province and Chengdu city in Sichuan province.By establishing a model algorithm,the two-dimensional deformation variables of the POI in the study area are extracted and analyzed.Firstly,this paper establishes a formula model for extracting the surface deformation in the horizontal and vertical directions by combining the orbit-ascending and orbit-descending In SAR.(1)The deformation of the surface is obtained in the LOS direction of the ascending and descending orbits,using time-series In SAR technology,respectively.(2)This paper establishes a two-dimensional deformation variable solution equation system,according to the spatial relationship between the flight direction of satellite,the LOS direction of the spaceborne radar and the ground points.(3)This paper uses the interpolation method to interpolate the surface deformation in the LOS direction of the ascending and descending orbits satellite.And the interpolation results are registered based on the time dimension.(4)We substitute the interpolation results into the two-dimensional deformation variable calculation formula,and solve the equation system,after registering the LOS direction deformation of the ascending and descending orbits.Then,we obtain the amount of surface deformation along the horizontal and vertical directions.In order to study the reliability and applicable area of ??the model algorithm,this paper firstly takes the Muli mining area as the research object.The surface deformation velocity results are shown below: The range of the deformation speed of the ascending orbit LOS direction is [-133 ～ 31]mm/a.The range of the deformation speed of the descending orbit LOS direction is [-95～21]mm/a.Then this paper takes the urban area of??Chengdu as the research object.The surface deformation velocity results are shown below: The range of the deformation speed of the ascending orbit LOS direction is [-12～6]mm/a.The range of the deformation speed of the descending orbit LOS direction is[-12～6]mm/a.The results show that in the mining area with complex topography,there is a big difference in the spatiotemporal distribution of the LOS direction deformation velocity of the ascending and descending orbits.In urban areas with relatively flat terrain,the spatial and temporal distributions of the LOS direction deformation velocities of the ascending and descending orbits are relatively small.Through comparative analysis the results of the two study areas,and the ascending and descending LOS direction deformation velocity field distribution of same research area,it is concluded that the method in this paper is more suitable for areas with higher building coverage.The time series deformation analysis is carried out for the Muli mining area and the urban area of ??Chengdu,combined ascending and descending orbit LOS deformation.Three POIs were selected in each study area.The two-dimensional deformation variables of each POI at 3 neighboring time are solved.And their deformation trends in the horizontal and vertical directions are analyzed.The following conclusions are obtained:The ground points show the opposite trend of deformation in the LOS direction of the ascending and descending orbits,that is because the deformation of the ground point in the horizontal direction is much greater than that in the vertical direction.In the LOS direction of the ascending and descending orbits,a ground point,both show a subsidence trend,or both show an uplift trend.Its deformation in the vertical direction is much larger than its deformation in the horizontal direction.In the ascending and descending LOS directions,there is no obvious deformation of the ground point.In practice,it is a relatively stable point.