近层间距、多煤柱条件下采空区底板巷道联合支护技术研究

Study on combined support technology of goaf floor roadway under the conditions of close coal seam spacing and several coal pillars

以忻州窑煤矿14-2号煤层集中巷为工程背景,开展近层间距、多煤柱条件下采空区底板巷道围岩控制技术研究。分析得出,近层间距、多煤柱条件下采空区底板应力环境大致分为两类,即采空区煤柱下方的采动应力集中区和采空区下方的采动应力降低区,且二者交替分布,不同部位的不同地应力环境导致巷道矿压显现特征存在差异明显。在采空区煤柱下方的采动应力集中区,水平应力明显低于垂直应力,但总体应力环境相对较高,导致巷道围岩受力破坏程度严重,在采空区下方的采动应力降低区,水平应力高于垂直应力,但总体地应力环境相对较低,巷道围岩受力破坏程度较轻。由于巷道布置距离上覆采空区底板较近,上覆采空区的底板采动破坏与近距离的巷道顶板围岩破坏存在裂隙贯通,因此被动支护相对主动支护的作用更为有效;提出西二盘区14-2号煤层集中巷"锚杆+锚索+金属网+木垛壁后充填+U型钢支架"的主被动联合支护技术方案。工业实践支护效果反馈表明,主被动联合支护技术的围岩稳定性控制较好,达到预期使用要求。

The No.14-2 coal seam centralized roadway in the Xinzhouyao Mine was taken as the engineering background.Surrounding rock control technology of goaf floor roadway under the conditions of close coal seam spacing and several coal pillars was studied.The analysis showed that the stress environment of goaf floor under the conditions of close coal seam spacing and several coal pillars can be roughly divided into two types,the mining stress concentration area under the goaf pillar and the mining stress reduction area under the goaf,and the two were alternately distributed.As a result,under different stress environments at different goaf floor locations,the characteristics of roadway pressure appearance were obviously different;in the mining stress concentration area under the goaf floor of coal pillar,the horizontal stress was obviously lower than the vertical stress,but the goaf floor stress environment was relatively high,which led to the relatively serious stress damage degree of roadway surrounding rock;in the mining stress reduction area under the goaf floor,the horizontal stress was higher than the vertical stress,but the goaf floor stress environment was relatively low,which led to the relatively light stress damage degree of roadway surrounding rock;in addition,because the roadway layout was close to the overlying goaf floor,the mining failure of overlying goaf floor was connected with the near distance roadway roof failure,so the passive support was more effective than the active support;there was fracture connection between the mining failure of the overlying goaf floor and the surrounding rock failure of the roadway roof,so the passive support was more effective than the active support.The active and passive combined support technology scheme of anchor bolt+anchor cable+metal mesh+wood pile wall back filling+U-shaped steel support in No.14-2 coal seam centralized roadway was given in west No.2 panel.The feedback of support effect in industrial practice showed that the stability of surrounding rock was well controlled by active and passive combined support technology,which met the expected application requirements.