New Detecting Method on the Connecting Fractured Zone Above the Coal Face and a Case Study

Underground coal mining activities cause redistribution of the stress and deformation fields in surrounding rocks, resulting in different degrees of failure to the overlying strata above the coal face (Liu et al. 2018; Wu et al. 2018; Wang et al. 2017a, b). Studies have shown that the failure of overlying strata has obvious zoning features, which can be divided into caved zone, fractured zone and sagging zone (Zhang et al. 2011, 2020; Wang et al. 2018; Fan et al. 2019b). The caved and fractured zones are good in water permeability (Liu et al. 2016; Huang et al. 2018). When there is a water-rich aquifer above a coal seam, whether the overlying fractured zone links up the aquifer or not determines the safety level of coal mining (Guo et al. 2012; Fan et al. 2020; Qu et al. 2020). Therefore, mastering the connecting condition of fractured zone above coal face can provide foundation for the prediction and prevention of water-related hazards in coal mines. …