Monitoring of surface subsidence disasters and evolution laws caused by multiple mining activities in coal mines based on SBAS-InSAR

In underground coal mining, surface subsidence disasters are likely to be induced. Especially, under the condition of multi-seam mining, the movement characteristics of the overlying strata are more complex. Once these characteristics are transmitted to the surface, it is easy to lead to intensified deformation and the appearance of ground fissures. This not only causes damage to surface buildings but also may have irreversible impacts on the aquifer. Taking 1208# working face of Hongyang No. 3 Coal Mine as a case in study, this paper uses the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technology to systematically monitor and analyze the surface subsidence characteristics of the multi-mining area (MMA) and the single-mining area (SMA) changing over time, with a focus on discussing the subsidence laws of the MMA. The comparative analysis results show that: (1) There is an obvious hysteresis in surface subsidence, the position of the subsidence center basically corresponds to that of the working face, but the influence range of subsidence exceeds the boundary of the working face, besides, significant surface subsidence occurred 36 days after mining the No. 1208 working face, and the change in the structure of the overlying strata was transmitted to the surface; (2) Compared with the single-mining area (SMA), the maximum subsidence rate (MSR) and the maximum subsidence value (MSV) in the multi-mining area (MMA) are higher, and both the subsidence center and its influence range are significantly expanded; and (3) After the mining of the working face stops, the subsidence rate slows down, but the subsidence increment in the MMA area is still higher than that in the SMA. The above findings deepen the understanding of the evolution mechanism of surface subsidence disasters caused by multiple mining activities, and provide an important basis for the monitoring, prevention and control of subsidence disasters in similar mining areas. • The main innovation of this paper lies in the application of the Small Baseline Subset Synthetic Aperture Radar Interferometry (SBAS-InSAR) technique to comparatively analyze the distinct performance characteristics of subsidence disasters caused by the single mining area (north side) and the repeated mining area (south side) of the 1208 working face, and to explore the occurrence process of subsidence disasters after coal mining. According to the mining time and the spatial location of coal seams, the study area is divided into three phases for analysis, deriving the subsidence processes, rates, and magnitudes under the two mining methods, and then comparing their surface subsidence characteristics. Additionally, governance strategies are proposed for the characteristics of subsidence disasters caused by multiple mining activities to ensure surface safety. • To improve the accuracy of subsidence monitoring, this paper uses Sentinel-1A C-band SAR images from the European Space Agency, and employs AUX_POEORB orbital data for orbital refinement and phase re-flattening. The Digital Elevation Model (DEM) selected is a 30-meter resolution DEM provided by NASA, which is used for terrain phase removal, geocoding, etc. Compared with traditional methods, the SBAS-InSAR technique can accurately and efficiently obtain the surface subsidence rates and cumulative subsidence amounts in the study area. Especially for large-scale subsidence disasters caused by multiple mining activities in coal mines, the application of the SBAS-InSAR technique can not only save substantial human resource costs but also quickly acquire information on subsidence disasters.