Development Height of the Water-Conducting Fractured Zone in Super-Wide Longwall Panel Mining of Medium-Depth Coal Seams

Abstract

The development height of the water-conducting fractured zone (HWCFZ) serves as an important basis for the prevention of mine water disasters and assessment of water resource impacts. In recent years, with the increasing adoption of super-wide coal mining longwall panels with a width exceeding 300 m, studies on their HWCFZ have been limited and relevant field measurement data remain sparse. This study aimed to determine the development HWCFZ in super-wide longwall panels during the mining of medium-depth coal seams. The research area comprised the adjacent 01 and 02 fully mechanised longwall panels in Xiaobaodang No. 2 Coal Mine, China, with widths of 300 m and 450 m, respectively. The development HWCFZ was determined via drilling exploration and numerical simulation. The results revealed that compared with the conventional longwall panel with a 300 m width, the HWCFZ in the central area and near the boundary roadway area increased in the super-wide longwall panel with a 450 m width. The HWCFZ increased by 6.4 m and 5.9 m, corresponding to growth rates of 11.3% and 8.4%, respectively. The HWCFZ in the boundary areas of both longwall panels was greater than that in the central areas, exhibiting a saddle-shaped distribution characterised by lower values in the middle and higher values on both sides along the inclination direction. According to the numerical simulation results, the width of the coal mining face exhibited a nonlinear positive correlation with the maximum HWCFZ. A width of 300 m represented the threshold at which the rate of increase of the HWCFZ began to decline, whereas a width of ~450 m represented the critical threshold beyond which the HWCFZ tended to stabilise. These findings offer valuable insights for the accurate prediction of the HWCFZ in super-wide longwall panels, the prevention of mine water disasters and assessment of water resource impacts.