Research On Surface Deformation Laws Caused By Deep Anhydrite Mining With SBAS-InSAR

China is rich in mineral resources.Underground mining produces varying degrees of surface deformation.Surface deformation monitoring is an important means to guarantee the safe operation of mining areas and protect people’s lives and property.Hengtai gypsum mine is located in Taochang Town,Hanshan County,Anhui Province,and the mining area is located more than 400 meters underground.After more than 10 years of exploitation,a huge underground space has been formed.The area where it is located has good structural stability.Because the anhydrite surrounding rock has a good stability,it can be converted into a underground petroleum storage hole reservoir after the gypsum mineral production is completed in the future.Therefore,the study of surface deformation monitoring in the mining area and the understanding of the effects of deep anhydrite mining on surface deformation can provide security for the life and property of buildings and residents in Taochang Town.At the same time,it will increase the effective basis for the planning and management of the mining area and provide support for the feasibility of petroleum storage in the caved tunnel.SBAS-InSAR is an advanced surface deformation monitoring method developed on the basis of InSAR technology in recent years.Compared with traditional level monitoring,GPS monitoring and other means,SBAS-InSAR technology has the advantages of full-time,all-weather,no-contact,large-area surface monitoring,and has extensive application prospects in the field of deformation monitoring.In this paper,SBAS-InSAR method was used to extract the time-series deformation laws of Hengtai gypsum mine since the mine was opened.Simultaneously,FLAC^3D software was used to simulate the gypsum mine excavation.Combining the results of the two methods,the impact of deep gypsum mine excavation on surface deformation was analyzed.The main research work and achievements of the paper are as follows:（1）The principle of InSAR technology is explained systematically,and its error source is analyzed.Based on this,the principle and advantage of SBAS-InSAR technology are explained.The geological survey,mining design and surface deformation monitoring of the Hengtai gypsum mine in Anhui Province were collected.After investigation,it was found that the geological conditions of the area are good.（2）Collected 16 scenes of PLASAR data from February 3,2007 to December30,2010 and 30 scenes of Sentinel-1A data from April 25,2015 to November 16,2017,using SBAS-InSAR technology to extract the time period Time series deformation of the surface.Select some of the high-coherence points and artificial level monitoring data comparison,the two results are in good agreement.The InSAR monitoring results show that most of the mining area has a small deformation,and the deformation rates are concentrated at-1.9 to+4.3 mm/a and-1.5 to+0.2 mm/a during the two time periods.（3）A three-dimensional model of Hengtai gypsum deposit was established and FLAC3D software was used to conduct numerical simulation of deep anhydrite mining.The simulation results show that the influence of mining of anhydrite on rock and soil is mainly concentrated near the excavation cavern and has little effect on the surface.The maximum surface settlement caused by mining is 2.6mm.Comparing the numerical simulation results with InSAR monitoring results,it is found that the actual deformation of the ground surface is affected little by deep anhydrite mining.