Research On Ground Surface Subsidence Monitoring In Mining Area Based On SBAS-DInSAR Technology

The coal industry plays an important role in the development of our country at present,and the surface subsidence caused by coal mining will seriously affect the local ecological environment and the living safety of the surrounding urban residents.Monitoring the surface subsidence can obtain the law of surface movement and change,and play a guiding role in the further mining of coal seams.Therefore,monitoring the surface subsidence of mining areas has important practical significance.Traditional leveling methods have the disadvantages of high cost,low efficiency and vulnerability to weather.D-InSAR technology can effectively compensate for the shortcomings of traditional leveling methods,and can theoretically achieve centimeter-level accuracy.The theoretical accuracy of SBAS time series analysis method can reach millimeter-level.In the process of subsidence monitoring in mining area,because of the characteristics of fast subsidence rate and high intensity of surface subsidence in mining area,the incoherent movement of surface monitoring,time incoherence,accuracy of DEM and the meaning of monitoring deformation value of surface monitoring in mining area will be caused.In order to solve these problems,this paper takes a mine in Datong mining area as the research background and uses Sentinel-1A data of 16 scenery C bands to monitor and study the surface of the mining area from two perspectives of conventional D-InSAR and SBAS time series analysis methods.The main research contents are as follows:(1)Incoherent movement of measuring target is one of the main difficulties in mining area monitoring.The monitoring scheme of "time-adjacent four-pass method" is designed.The large deformation of mining area is decomposed based on time baseline,and the deformation gradient is reduced to enhance the image interference effect.The flat effect is removed by reconstructing the DEM model of mining area,and the surface deformation map of mining area is obtained.The feasibility of the scheme is verified by the measured data.(2)The inconsistency between the pixel values of the interferometric results and the representative meanings of the leveling data makes it impossible to directly compare them.According to the position relationship between the pixels and the measured points,a Gaussian convolution algorithm is proposed to link the two.The validity and necessity of introducing the Gaussian weight matrix are analyzed,and its accuracy is verified with the measured data.(3)Aiming at the problems of atmospheric effect and time incoherence that conventional D-InSAR can't solve,SBAS time series analysis method is introduced and its advantages for conventional D-InSAR technology are discussed.Based on the deformation characteristics of the mining area,image interference parameters are designed,and the cumulative deformation map and deformation rate map of the mining area are obtained,and the time series analysis is carried out.(4)The three-dimensional model of deformation results and subsidence rate results of mining area is constructed,and the deformation results of key points in the three-dimensional subsidence model are analyzed according to the actual mining situation of working face.The rationality of SBAS time series analysis method in monitoring deformation of mining area is verified,and the causes of local point interference errors are analyzed.