基于离散元模拟的巨厚煤层分层开采覆岩裂隙演化分形特征

为了探究左权五里堠煤业有限公司上组煤5号煤层老空水是否对下组煤15号煤层首采面综放开采造成突水水害威胁，以下组煤首采面为背景，系统分析了研究区地质及水文地质条件，建立了两煤层开采后顶底板变形破坏空间分布特征模型，提出了老空水是否威胁下组煤综放开采的3个可能条件。在此基础上，采用具有针对性的经验公式和数值模拟相结合的方法，综合获得了下组煤15号煤层首采面最大导水裂隙带高度和上组煤5号煤层底板最大破坏深度量化参数，并与下组煤首采面附近施工的地面钻孔揭露这两层煤间距进行对比。认为下组煤15号煤层开采后，通过导水裂隙带将会波及到上组煤采动底板破坏带内部，在正常条件下可能与上组煤5号煤层老空水导通，建议开采前要进行提前探查和疏放。研究结果对下组煤首采工作面顶板老空水害防治具有很好的参考价值。

Discrete element simulation for crack fractal evolution laws associated with slicing mining in super thick coal stratum

This paper aims to explore whether the old goaf water of No. 5 coal seam threats on No. 15 coal seam in initial mining lower coal group water inrush in Zuoquan Wulihou Coal Industry Co., Ltd. It uses the lower coal group of initial mining coal working face as the background, and comprehensively analyzes the geological and hydrogeological conditions in the study area. It examines the spatial distribution characteristics of two coal seams for roof and floor. The deformation and destruction model is set up after mining. Three possible conditions are put forward for the old goaf water whether threat. On this basis, the quantitative parameters of the height of the water-conducting fracture zone at the first mining face of the No. 15 coal seam in the lower coal group and the failure depth of the floor of the No. 5 coal seam in the upper coal group are obtained using the empirical formula and numerical simulation method, and comparison with the spacing between the two coal seams revealed by the boreholes. It is considered that after the mining of No. 15 coal seam of the lower coal group, the water in the goaf of No. 5 coal seam of the upper coal group is likely to pass through the water conducting fractured zone under normal conditions. It is suggested that drainage should be carried out before mining. The research results have a good reference value for the prevention and control of water damage in the roof old goaf of the first working face in the lower coal group.