Multi-Method Synergistic Determination of the Development Height of the Water-Conducting Fractured Zone in the 82209 Working Face

Aiming at the problem of accurately determining the development height of the water-conducting fractured zone formed by roof overburden fracture after coal seam mining, taking the 82209 near-horizontal fully mechanized caving working face of No. 22 coal seam in Lijiayao Coal Mine as the research object, a multi-method synergistic system combining empirical formula calculation of codes, key strata theory prediction, multi-means field measurement of surface boreholes, and numerical simulation was adopted to systematically study the development height of the water-conducting fractured zone. The results show that the height of the water-conducting fractured zone calculated by different standard empirical formulas ranges from 56.09 m to 135 m, with significant differences in results, which can only be used as a reference for preliminary prediction. Based on the key strata theory, the hard rock strata in the overburden were identified layer by layer and the breaking span was calculated, and the predicted development height of the water-conducting fractured zone of the working face is 66.9 m. The field measurement of surface boreholes determined that the development height of the water-conducting fractured zone is 64.52 m for Borehole 1 and 113.58 m for Borehole 2. Numerical simulation reveals that the working face reaches full mining when advancing to 360 m, the maximum height of the water-conducting fractured zone is 120.12 m, and the final stable height range is 67.46 ~ 120.12 m. The relative error with the field measured results is only 1.36%~4.56%, which proves the reliability of the simulation results. The multi-method collaborative verification system formed in this study realizes the accurate determination of the height of the water-conducting fractured zone, and can provide an engineering reference for roof water disaster prevention and control of working faces under similar geological conditions.