INVERSION OF UNDERGROUND GOAF IN ZHENFENG COAL MINE IN GUI ZHOU PROVINCE BASED ON INSAR THREE-DIMENSION DECOMPOSITION TECHNOLOGY

Coal mined-out area, formed in mine production, usually induces a certain degree of ground subsidence and collapse. In many areas, the background information of coal seam mining is unclear, which brings trouble to the ecological restoration of the mining area and the reuse of land resources. Therefore, the calculation of the underground mining range is particularly important and can play a monitoring role in the cross-border mining of coal mines. This paper uses Japan's PALSAR-2 satellite data with a data resolution of about 3 m, and a total of 16 scenes in two observation directions of ascending and descending. Using InSAR technology, the multi-phase surface deformation monitoring is carried out in the mine goaf of Zhenfeng County, Guizhou Province. Based on the geological conditions, underground mining conditions, and field investigations in the study area, this paper calculates the relationship between mining subsidence parameters and time lags in the study area. The calculation combines the surface deformation of the known coal mines and the underground mining information. Then using the above-mentioned parameters and surface deformation information, this paper inverts an abandoned coal mine near the area and calculates the underground goaf range and mining time. The results are as follows. The study area is dominated by slow-sloping sandstone and mudstone. The coal mining strike influence angle is 83°, the uphill influence angle is 75°and the downhill influence angle is 80°. Inversion calculation gives the mining range of 380 m×150 m underground and the mining time of each area. FLAC^3D numerical simulation calculation of the mined area of the abandoned coal mine is used to verify the accuracy of the range of the mined area. Compared with the calculation results of InSAR, the surface deformation trend of the mining area obtained by FLAC^3D is more consistent, and the root meant square error of the trend and tendency is about 6 cm.