综放面“双硬”煤层临空煤柱宽度及承载强度校核

Width and bearing strength check of"two hard"coal pillar in fully mechanized caving face

具有“双硬”特征煤层的工作面其护巷煤柱的极限尺寸确定与常规工作面有所不同。以榆树岭煤矿505工作面沿空掘进巷道为背景,首先测试了煤岩样的力学性质和不同高径比煤样的抗压强度,得到了不同高径比煤样峰值强度曲线;其次分析了沿空掘巷覆岩结构模型,建立了沿空掘巷护巷煤柱顶板力学模型,得到了不同宽度煤柱所受的载荷应力;建立了不同高宽比煤柱的数值模型,得到了不同高宽比煤柱的极限强度校核公式;最后通过对比不同宽度煤柱所受的载荷应力和极限强度,得出4m宽度的煤柱即可满足支护要求,并在此基础上提出了沿空掘进巷道支护工艺。现场监测结果表明,煤柱宽度为4m时,巷道整体变形量较小,巷道稳定性得到有效维护。研究结果可为小煤柱护巷宽度的确定提供参考。

In coal seams characterized by"two hard"features,the determination of the limit size for protective coal pillars diverges from the standard approach for conventional working faces.This study,using the gob-side entry driving roadway of the 505 working face in Yushuling Coal Mine as a backdrop,first involved testing the mechanical properties of coal and rock samples and their compressive strength across various height-to-diameter ratios to establish peak strength curves.Subsequently,by analyzing the overlying rock structure model and constructing a mechanical model for the coal pillar roof in gob-side entry driving,the study identified the load stress experienced by coal pillars of varying widths.A numerical model for coal pillars with different aspect ratios was developed,yielding an ultimate strength verification formula for these pillars.Upon comparing the load stress and ultimate strength across different coal pillar widths,it was determined that a width of 4 meters for the coal pillar suffices to meet support requirements.Based on these findings,a support technology for gob-side entry driving is proposed.Field monitoring results indicate that with a coal pillar width of 4 meters,the overall deformation of the roadway is minimal,ensuring effective maintenance of roadway stability.The research provides a reference for determining the optimal width of small coal pillars in coal seams with"two hard"charac-teristics.