Research On Monitoring Mining Subsidence Based On InSAR And Probability Integral Method

As an important basic energy in China,underground mineral resource has brought a rich material foundation to the country and the people,but at the same time,its over-exploitation has caused a series of destruction,which endangered normal production and life.Therefore,it is necessary to monitor ground subsidence in mining areas.With the continuous development of space and earth technology,the theory of interferometric synthetic aperture radar(InSAR)has been also constantly improved,which provided a new way for mining subsidence monitoring.But due to the influence of its own characteristics,various noises and atmospheric delays,as well as the fast subsidence rate and large quantity value generated by mining,the progress of InSAR in mining application is not ideal.The actual accuracy of this technology in monitoring mining subsidence is yet to be explored.Therefore,in this paper,accuracy of InSAR in monitoring mining subsidence is studied in combination with the actual mining areas,so as to explore the problems existing in InSAR mining subsidence monitoring.On this basis,it further solves the problem of low accuracy of InSAR technology in monitoring large gradient mining subsidence,improves its actual monitoring capabilities and broadens its application in practical engineering.The main research contents of the paper are as follows:(1)Focusing on the problem of accurate verification of InSAR-monitored results,a new comparative analysis and verification method is proposed.This method unifies InSAR and leveling in time based on time domain interpolation.Further verification using leveling data shows that the method can accurately predict the actual subsidence information of each leveling point under the SAR imaging date and solve the problem of time inconsistency between the two methods.(2)Aiming at the accuracy of D-InSAR in monitoring mining subsidence,a qualitative and quantitative analysis method is used to comprehensively analyze and verify the D-InSAR-monitored results.The method first obtains the D-InSAR results of each study period according to the time series,and then calculates the simultaneous leveling data and D-InSAR absolute error.On this basis,the qualitative and quantitative comparative analysis of the D-InSAR results is carried out based on the spatial characteristics and magnitude of the subsidence in the mining area,so as to realize the comprehensive evaluation and verification of D-InSAR in monitoring mining subsidence.The research results indicate that the location,spatial distribution,scope,and variations of mining subsidence monitored by Sentinel-1A repeat track D-InSAR are consistent with the mining progress of the working faces,and the absolute difference from the leveling-monitored values is small at the subsidence edge but large at the subsidence center.(3)By analyzing the influence of coherence on the accuracy of D-InSAR in monitoring mining subsidence,it is found that the accuracy of D-InSAR results is directly related to the coherence of the subsidence zones:the higher the coherence is,the smaller the difference from the actual situation.Considering that too long time baseline will lead to time incoherence and reduce the accuracy of conventional D-InSAR,the temporal SBAS-InSAR technology is introduced to obtain the mining subsidence with a long time series.Through the actual data experiment,the analysis shows that the SBAS-InSAR technology can more effectively overcome the difficulties caused by the long-term monitoring,and can accurately detect the location and macro changes of mining subsidence that are consistent with the D-InSAR cumulative and actual results.In addition,the SBAS-InSAR feature points' subsidence curves are also consistent with the D-InSAR cumulative and leveling results in their shapes and overall change trends:the differences between the results of the three technologies are small at the edge and large at the center.(4)In order to solve the problem of low accuracy of InSAR technology in monitoring large gradient mining subsidence at the center,the study about large gradient subsidence monitoring based on combined InSAR and Probability Integration Method is given,and the corresponding technical processing is designed and realized.First,the time-series cumulative subsidence is obtained by InSAR.Then,the high coherence points of the InSAR results and a few leveling data are selected as the feature points.Based on these points,the Probability Integration Method and surface fitting method are used to receive the model parameters and the Probability Integration subsidence basin of the mining area.Finally,the continuous ground subsidence results are obtained by kriging interpolation.We make use of this method to obtain the subsidence information of Northern-Heze coal mine.The research results show that this method can obtain the same subsidence information with the actual situation,and its monitoring capability of large gradient deformation is obviously better than that of conventional InSAR method.