Spatiotemporal evolution patterns of overlying rock damage based on microseismic monitoring under mining influence

To address the threat of the Luohe Formation sandstone aquifer to Jurassic coal seams in western China, this study employed theoretical analysis and microseismic monitoring to research the spatio-temporal evolution of water-conducting fracture zone (WCFZ) as they change with mining footage. Firstly, by solving the stress field of a hypothetical model, the movement patterns of a single rock beam in the advancing direction were explained, leading to the proposal of a "four-zone" classification structure for overburden failure in the vertical direction and defining the upper boundary of WCFZ development. Additionally, Using Shaozhai Coal Mine as an example, based on singular spectrum analysis, and energy-weighted maps, it identified key mining footage reflecting significant overburden failure. The "four-zone" structure and WCFZ upper limit were determined according to the sedimentary characteristics, the density of microseismic events, and a comprehensive stratigraphic column. A comparison between theoretical analysis and field measurements revealed that the upper boundary of WCFZ was determined in stratum No.21, No.14, No.4, and No.4 at 74 days, 197 days, 320 days, and 432 days, respectively. The WCFZ developed up to a maximum thickness of 37.46 m in mudstone, without disturbing the Yijun and Luohe formations' aquifers. This study uncovers WCFZ evolution laws and delineates the "four-zone" structure, providing a basis for water prevention measures.