Study On Mining Subsidence Law Of Whole Basin In Shilawusu Mine Based On InSAR Technology

There are a lot of coal resources in Western China,so the development potential is infinite.However,the law of surface subsidence is quite special because that the geological and mining conditions are different from those in the eastern region.In order to realize the large-scale rational mining of coal resources in western region of our country,taking Shilawusu coal mine in Dongsheng coalfield as an example.Based on the time series InSAR technology,the high-precision surface deformation monitoring of the whole basin in the study area is realized.Besides,combined with the measured data and numerical simulation methods,summarized the mining subsidence law of the whole basin in the study area.The main research results are as follows:(1)By analyzing the measured data of four mining faces in 221 mining area,obtained the surface subsidence,tilt and curvature dynamic deformation curves.The surface deformation in the study area shows the phenomenon of smaller subsidence value and subsidence speed in the stage of insufficient mining.The subsidence rate of17 mining panel is 0.04;after the mining of panel 01,subsidence rate increased to 0.33.The surface did not reach the full mining level in the whole process.(2)Realized the high-precision surface deformation monitoring of the whole basin in the study area based on time-series DS-InSAR technology.(1)After analyzing the relevant principle of InSAR technology and the specific method and mathematical principle of DS pixel processing,the phase optimization process is improved.The original phase of interferogram is optimized by combining eigenvalue decomposition and coherent weighting method.Then selected DS pixel and PS pixel to solve the surface deformation,which effectively improves the quality of surface deformation monitoring in mining area.(2)Used the sentinel-1A images from September 2016 to November 2019 to monitor the surface deformation in two stages,obtained the whole basin subsidence,which plays a good complementary role to the monitoring results of the measured linear observation station.(3)The accuracy evaluation with the measured results shows that the average absolute error of the InSAR monitoring results is 16 mm,and the root mean square error is 15 mm,which indicates that the time series DS-InSAR monitoring method has strong feasibility in this area during the period,and can realize the high-precision monitoring of surface subsidence in the whole basin.(3)Determined probability integral parameters in study area and got the law between the subsidence coefficient and mining degree.(1)In view of the fact that the FOA algorithm is easy to converge too fast,improved the search step size and constructed an adaptive step size FOA method for determining the probability integral parameters by InSAR monitoring results of the whole basin.(2)Determined the probability integral parameters of 17 and 06 A mining panel based on the results of whole basin subsidence.(3)In view of the limitation of the conventional subsidence coefficient correction method,supplemented the historical subsidence value of the dip line of 01 mining panel by InSAR results,and then obtained the subsidence coefficients of the two mining panels,fitted the relationship between the subsidence coefficient and the mining degree.With the increase of the mining degree,the subsidence coefficient tends to be normal,and it is expected that the fully mining subsidence coefficient will reach 0.6?0.8.(4)In order to obtain a complete mining subsidence law,built the numerical model to further explore the movement and deformation law of the surface and strata with the increase of mining degree.(1)The length and width of the goaf should be greater than2.2H when the surface reaches the full mining condition.With the continuous subsidence of mining,the coefficient finally reaches 0.69 after the full mining,which is consistent with the fitting prediction of 0.6 ? 0.8.(2)The development height of water flowing fracture zone is about 26 times of mining thickness,which shows the related characteristics of hard rock mining.(3)Under the topsoil,there are multi-layer thick medium grained sandstone,coarse-grained sandstone and fine-grained sandstone in study area.These hard strata become the key layers to control the movement and deformation of other weak strata and surface,resulting in the small amount of movement and deformation at the initial stage of mining.There are 87 figures,17 tables and 99 references.