Research On Deformation Monitoring Of Mining Area Based On SAR Technology And Offset-Tracking Technology

Mining subsidence is different from other surface deformation,which is characterized by large subsidence and severe deformation.Because coal mining will form a series of geological disasters such as ground fissures,collapse pits and landslides on the surface of the mining area,which will cause serious damage to the local structures,buildings and ecological environment,and the frequent secondary geological disasters will also pose a serious threat to the life and property safety of the residents in the mining area.Under the urgent need of national disaster reduction and prevention,it is very important to grasp the deformation of the mining area surface in real time and accurately,and form a scientific monitoring system of surface subsidence for the protection of the normal life of the mining area residents and the further optimization of the local ecological environment.Traditional measurement methods have many disadvantages,such as heavy workload,sparse points,small monitoring range,observation process easily affected by the weather,ground survey difficult to reach and so on.Synthetic aperture radar interferometry(InSAR)technology can real-time,accurate,large-scale,high-precision ground deformation monitoring,has been widely used in the actual ground engineering monitoring.According to the principle of D-InSAR,without considering the influence of external factors,it can achieve the monitoring accuracy of centimeter level or even millimeter level,but it can not monitor the large scale and large gradient deformation in the mining area.In order to solve the above problems,taking Yangquan mining area in Shanxi Province as an example,this paper systematically studies how to use D-InSAR technology to monitor the surface micro deformation and how to use SBAS InSAR and offset tracking technology to effectively extract large scale and large gradient surface deformation information.(1)This paper summarizes the research status of traditional time-series InSAR technology and pixel offset tracking technology at home and abroad,expounds in detail the basic principle,working method,system imaging characteristics of InSAR technology and the error sources in the process of InSAR technology processing,and puts forward corresponding solutions for these established errors.This paper briefly introduces the operation process of D-InSAR,SBAS InSAR and offset tracking technology,and analyzes their advantages and disadvantages in deformation monitoring.(2)In view of the common problems of traditional monitoring methods in mining area surface deformation monitoring and the advantages of D-InSAR in surface micro deformation monitoring,this paper uses 10 sentinel-1a data and D-InSAR technology to extract the surface deformation information of the study area.By using different filtering modes and phase unwrapping threshold for many experiments,the most suitable filtering mode and unwrapping threshold are selected.Combined with the existing measured data and deformation sequence diagram,the simulated strike monitoring line and tendency monitoring line of working face are set up,the subsidence information is extracted,the surface subsidence curve,the maximum subsidence point movement rate curve and the maximum subsidence point subsidence rate curve are drawn,and the dynamic subsidence law of the surface is analyzed systematically on this basis.(3)The traditional time series InSAR technology has strong advantages in the surface micro deformation monitoring,but the accuracy is not high in the surface large gradient deformation monitoring.Aiming at its shortcomings in the surface deformation monitoring,this paper proposes to integrate SBAS InSAR and offset tracking technology to monitor the whole subsidence basin in the study area,so as to obtain a complete deformation field.In the process of fusion,the traditional method of using coherence coefficient as fusion boundary is abandoned,and the manual mask is used to fuse the monitoring results of the two,and the accuracy of the fusion results is analyzed and verified.The results show that the maximum absolute error in the vertical direction is 320 mm,the average absolute error is 87 mm,the absolute error in the maximum subsidence is 105 mm,and the relative error is 4.0%.This method can provide a new theoretical idea for the large gradient deformation monitoring in the future.