Analysis of spatial-temporal distribution characteristics of surface deformation during grouting filling in goaf based on SBAS-InSAR technology

InSAR technology has been widely used in monitoring of surface subsidence in mining areas, but it is poor to research on the spatial-temporal distribution characteristics of surface deformation in grouting areas. In order to obtain the spatial-temporal distribution characteristics of surface deformation during grouting filling in goaf, this paper proposes a data processing method based on SBAS-InSAR technology, which jointly uses various technologies such as D-InSAR technology, PS-InSAR technology, SBAS-InSAR technology, etc., and selects the image pairs with better spatial-temporal baselines to be combined by the SBAS image pair selection strategy. The D-InSAR technology is used to generate the interferogram images, select the stable scattering coherent target points by the PS method, solve the phase information of the coherent target points, and obtain the information of the surface subsidence rate and time series of the coherent target points. The comparison with some leveling data shows that the method is consistent with traditional leveling survey. Based on the 39-phase RadarSAT-2 data and 40-phase Sentinel data, the deformation characteristics of surface during grouting filling in goaf have been obtained: the max deformation rate before grouting filling （from July 2015 to December 2016） reaches −98 mm/a, and the max uplift rate reaches 134 mm/a; the max uplift rate during grouting filling （from August 2019 to September 2022） reaches 18.7 mm/a, and the max subsidence rate is −11.2 mm/a; after grouting filling （from January 2023 to December 2023）, the max uplift rate reaches 16.0 mm/a, and the max subsidence rate reaches −10.0 mm/a. The regional surface deformation rate shows a decreasing trend. Through the analysis of the average deformation rate, the series accumulated subsidence and typical coherent points, obtains the distribution characteristics of surface deformation in the research area from before grouting filling, during grouting filling to after grouting filling, the rule of the surface deformation in the study area is discovered that the surface of the study area subsidence before grouting filling, the surface slowly subsidence and then uplift during grouting filling, the surface gradually reaches a steady state after grouting filling.