极近距离下位煤层回采巷道合理布置及围岩控制技术研究

Surrounding rock control and reasonable layout of roadway in lower seam of extremely close coal seam

针对极近距离煤层回采巷道维护困难的问题,结合山西登茂通矿具体地质条件,采用理论计算和UDEC数值模拟相结合的方法,研究了3106工作面回采巷道合理布置及围岩控制,2^(#)煤残留煤柱下方11m范围内底板应力呈不均匀分布特征,受剧烈的非均布荷载影响下位煤层巷道顶板和巷帮易发生局部过度承载而破坏;距残留煤柱边缘15m范围内的巷道变形破坏具有显著差异性,距残留煤柱中心越近,巷道围岩破坏越严重,稳定性越差,极近距离下位煤层回采巷道布置应避开应力增高区和高水平应力的应力降低区;合适的锚杆(索)支护结构可有效抑制围岩损伤裂隙的增加并使围岩趋于稳定。3106工作面回采巷道实践表明:回采巷道布置在距残留煤柱边缘15m处并采用高强度锚杆(索)关键部位协同支护方案,可减小残留煤柱底板应力影响,有利于保持巷道围岩整体稳定性。

Aiming at the supporting difficulties in extremely close coal seams,based on the geological conditions of a mine in Shanxi province,theoretical analysis method and UDEC-Trigon numerical simulation were used to study the reasonable layout and surrounding rock control of the roadway in No.3106 working face.The floor stress within 11 m below 2^(#) coal residual coal pillar is unevenly distributed,and the roof and side of the roadway in the lower coal seam are prone to damage due to local over-loading under the influence of severe non-uniform load.The deformation and failure of the roadway within 15 m from the edge of the residual coal pillar is significantly different.The closer to the center of the residual coal pillar,the more serious the roadway surrounding rock damage and the worse the stability is.The layout of the roadway in the lower coal seam should avoid stress increasing area and high-level stress reduction area.Appropriate supporting structure can effectively restrain the increase of cracks and stabilize mining roadway.The practical results of the mining roadway at No.3106 working face show that the mining roadway is arranged 15 m away from the center of the residual coal pillar,which can reduce the influence of the floor stress.At the same time,the application of a high-strength anchor(cable)coordinated support scheme for key parts is conducive to enhancing the overall stability of the surrounding rock of the roadway.