A study of deformation mode and formation mechanism of abedding landslide induced by mining of gently inclined coal seam based on InSAR technology

The coal seam of a coal mine in Zhenfeng county in Guizhou Province is dominated by the synclinal gently dipping Upper Triassic Torch Group (T3h), which is different from the anticlinal gently dipping coal seam of the most coal mines in Guizhou. The ground subsidence and landslide risks induced by mining activities also show different deformation and failure modes. In this paper, PALSAR -2 SAR with a total spatial resolution of 3 m and L -band in 15 periods of orbit ascending and descending observations is used as the data source to carry out D -InSAR measurements of surface deformation in multiple periods, and the location, range and lag time of deformation are determined. Through field investigation and verification, the InSAR calculation results are well consistent with the mining area and the surface damage situation, confirming the accuracy of InSAR in identifying temporal surface deformation in the coal mine area. Furthermore, the 3D surface deformation is decomposed and calculated, and the correlation analysis with the underground mining scope and process deepens the understanding of the bedding landslide deformation mode and formation mechanism induced by the underground mining of gently inclined coal seam in this area. The results show that (1) InSAR can identify and calculate the surface deformation range and settlement of the mining area, and the deformation of the mining area is shown in the interference image as a circular ring deformation fringe with the surface of the goaf as the center and spreading around. (2) The surface deformation area covered the region above the underground mined -out area and areas near the surface, and according to the scope of the surface deformation condition and underground mined -out area in the region the mountain border angle is calculated as about 70°, and the mountain border angle, about 58°. (3) There is a time lag of about 30 d between the underground mining and surface subsidence deformation. (4) The horizontal movement direction of the surface caused by underground mining in bedding strata is affected by the occurrence of strata and the direction of surface slope, and the horizontal direction is the resultant movement result of bedding slip along the bedding strata and convergence to the settlement center. (5) The overlying bedding slip along the plane and surface slope factors results in the tension fracture of the rock on the surface of the goaf on the uphill side, while the subsidence pit and fracture are not easy to occur on the downhill side.