Research on dynamic subsidence characteristics of coal mine industrial square based on D-InSAR technology

In recent years, the subsidence has occurred continuously to the industrial squares of mining areas in the thick water-bearing loose layer in eastern China, resulting in various extent of damage to the surface buildings (structures), which has seriously affected the safe production and normal operation of coal mines. In order to study the subsidence of industrial square in a long series, the dynamic deformation information of the surface was obtained based on 17 scenes of Sentinel-1A image data of a coal mine in Eastern China. On this basis, the surface subsidence monitoring accuracy of D-InSAR technology was analyzed in combination with the precise leveling. Besides, the spatial-temporal dynamic subsidence characteristics of industrial square were studied, and the deformation law of industrial square of mining area in the thick water-bearing loose layer was revealed. The results show that: (1) The error between D-InSAR monitoring and the subsidence value of 26 level monitoring points is 5.95 mm at maximum and 2.18 mm on average, which meets the subsidence monitoring requirements of industrial square. (2) With the continuous advancement of the working face, the subsidence of the industrial square during the 6-month monitoring period is 16 mm on average, and 36 mm at the point with maximum subsidence, which is located on the side of the working face in the southwest corner of the industrial square. The maximum tilt value is 0.31 mm/m, and the maximum curvature value is 0.016 mm/m². Generally, the damage of the surface buildings (structures) of the industrial square during the monitoring period is much less than the Class-I value. (3) The GIS spatial analysis shows that the area with subsidence between 0‒20 mm accounts for 93.10%, the dynamic subsidence of the point with maximum subsidence shows a clear linear negative correlation relationship with its distance from the center of the goaf, and the subsidence gradually increases as the goaf center gradually advances towards the industrial square. (4) The subsidence of industrial square is composed of 2 parts: the overall subsidence of rock cover caused by mining and the consolidation subsidence resulted from water loss in the aquifer. According to the dynamic subsidence of the point with maximum subsidence, the subsidence of industrial square is divided into two stages, with dewater subsidence unclear in stage I and consolidation subsidence resulted from water loss dominated in stage II. (5) The mining of the working surface has little impact on the subsidence of the industrial square. It should be that the water loss and consolidation at the bottom aquifer leads to the expansion of the surface subsidence, which in turn affects the industrial square. The above results provide a theoretical basis and technical reference for the future research on the subsidence of industrial plaza under the similar conditions.