Study On The Law And Mechanism Of Surface Subsidence Of Coal Mining In Mountainous Area Based On GNSS Technology

Coal mining activities will destroy the original stress balance state of overlying strata,cause surface subsidence and geological disasters,so the monitoring and research of mining subsidence has been widely concerned by the society.This paper takes the 8120 working face of Dayangquan Coal Mine as the engineering background.The working face belongs to the deep and thick coal seam mining in the mountainous area,and the geological and mining conditions differ greatly from the local shallow coal seam,which seriously restricts the effective evaluation of mining damage in the mining area.For the complex observation conditions in mountainous areas,it is pointed out that GNSS static measurement is still the preferred method of current monitoring.However,traditional GNSS monitoring belongs to point monitoring,which only takes into account the reality of the surface and wastes a lot of material and financial resources,so it is difficult to monitor multiple physical quantities in coordination.In order to clearly understand the law and mechanism of surface mining subsidence at 8120 working face,SBAS-InSAR technology was used to monitor the early surface micro-deformation,predict the mining subsidence range,determine the layout range of field observation points,and study the movement law of surface subsidence combined with UDEC.The main contents are as follows:(1)SBAS-InSAR technology was used to process 14 sentinel-1A image data from November 2018 to April 2019 in Dayangquan mining area,quantitatively analyze the subsidence rate and time series subsidence of subsidence funnel in the mining area,and obtain the potential surface mining subsidence area of the mining area.(2)Based on the surface mining subsidence characteristics of the mining area,the layout principle of GNSS mobile deformation monitoring network is proposed.According to the specific situation of the mining area,a detailed monitoring scheme is formulated.This paper summarizes the monitoring data from three aspects of time,space and influencing factors,and reveals the law of continuous deformation and non-continuous deformation of the surface during the mining process of deep and thick coal seams in mountainous areas.(3)Using UDEC,the numerical simulation study of deep and thick coal seam mining in mountainous area is carried out to obtain the change of failure field,displacement field and stress field in overburden under the geological conditions.By comparing with GNSS observation results,the reliability of the mathematical model was verified,and the surface deformation parameters were further calculated.Surfer software is used to visualize the simulation results and predict the volume of surface subsidence basin,which provides a scientific basis for the subsequent backfilling of subsidence basin.