Monitoring of mining-induced fractures and associated water-rich anomalies in coal seam roofs using microseismic and electrical methods

Microseismic monitoring and the mine audio-frequency electric perspective method are key techniques for monitoring roof disasters in coal mines, but neither can simultaneously capture the mechanical evolution of fractures and their water-bearing condition. To address this problem, a method integrating microseismic monitoring and the mine audio-frequency electric perspective method was proposed to monitor mining-induced fractures and associated water-rich anomalies in coal seam roofs. By unifying the spatial coordinate systems of the two monitoring systems, spatial coupling between microseismic source locations and three-dimensional apparent-resistivity images was achieved, and multi-parameter joint interpretation was used to determine the mechanical causes of water-rich anomalies and the water-bearing characteristics of fractured zones. Joint monitoring was conducted at working face 4106 of Wenjiapo Coal Mine. The results showed that the proportion of microseismic energy increased as events occurred closer to the roof in the vertical direction. During mining, the water-conducting fracture zone did not extend to the floor of the Yijun-Luohe Formation aquifer, and overburden failure exhibited a pronounced periodic pattern. When the mining advance approached twice the dip length of the working face, this stage represented a high-risk period for roof-overburden rupture and upward fracture propagation. Under mining-induced stress, a distinct low-resistivity, water-rich anomalous zone developed in the roof-overburden fracture zone and extended toward the goaf and the side adjacent to the section coal pillar. Microseismic energy concentration zones were markedly spatially coupled with low-resistivity electrical anomaly zones, and the mechanical process of fracture development further increased the water richness of fractures in the region. The method establishes a 'dynamic monitoring–static imaging–joint interpretation' framework and provides technical support for early warning of roof water hazards and development of transparent working faces.