极近距离煤层切顶留巷关键参数分析与留巷技术研究

    Research on key parameters of roof cutting and roadway retaining and roadway retaining technology in extremely close range coal seams

    • 摘要: 针对极近距离下煤层开采受上覆采空区影响导致围岩控制难度大、顶板补强支护易失效等问题,本文以山西某矿90104运输顺槽为研究对象,开展极近距离煤层切顶留巷关键参数分析与留巷技术研究,建立了极近距离煤层切顶留巷顶板悬臂梁结构模型,得到了极近距离煤层切顶留巷的围岩结构特征与切顶卸压技术原理。通过理论计算与分析,确定90104运输顺槽的最大切顶高度为5.7 m,切顶角度为15°,切顶孔间距为0.65 m;针对留巷顶板支护易失效、煤帮易发生片帮和破坏等问题,使用锚索对留巷煤帮进行补强支护设计,根据变形分区特征将留巷分为超前支护区、顶板变形剧烈区、顶板变形轻微区和成巷稳定区,并给出针对性的支护方案设计:超前支护区使用单体支柱与铰接梁配套进行超前支护;顶板变形剧烈区采用一梁四柱的方式进行加强支护;顶板变形轻微区和成巷稳定区逐步回撤单体支柱与π型顶梁,对留巷段进行巷旁挡矸设计和喷层设计,形成了极近距离煤层切顶留巷成套技术方案。现场工程实践与监测结果表明,90104运输顺槽顶板最大移近量为120.1 mm,帮部最大位移量为165.3 mm;顶、帮锚索受力最大值分别为204.3 kN和227.3 kN,较初始受力分别增大了34.9%和48.6%,巷道变形量与锚索受力增长幅度均在合理范围内,巷道整体较为稳定,未发生失稳现象,支护系统承载正常,切顶留巷围岩控制效果良好,为类似极近距离条件下的开采提供了参考。

       

      Abstract: Aiming at the problems of difficult control of surrounding rock and easy failure of roof reinforcement support caused by the influence of overlying goaf in the mining of extremely close range lower coal seam, this paper takes the 90104 transportation gateway of a mine in Shanxi as the research object, carries out the key parameter analysis and roadway retaining technology research of roof cutting and roadway retaining in extremely close range coal seam, establishes the roof cantilever beam structure model of roof cutting and roadway retaining in extremely close range coal seam, and obtains the surrounding rock structure characteristics and roof cutting and pressure relief technology principle of roof cutting and roadway retaining in extremely close distance coal seam. Through theoretical calculation and analysis, it is determined that the maximum roof cutting height of the 90104 transport gateway is 5.7 m, the roof cutting angle is 15°, and the roof cutting hole spacing is 0.65 m. In view of the problems that the roof support of the retained roadway is easy to fail, and the coal side is prone to spalling and damage, the anchor cable is used to reinforce the support design of the coal side of the retained roadway. According to the characteristics of deformation zoning, the retained roadway is divided into advanced support area, severe roof deformation area, slight roof deformation area and roadway stability area, and the targeted support scheme designs are given: the advance support area uses a single pillar and a hinged beam to support the advance support; the severe roof deformation area adopts the method of one beam and four columns to strengthen the support; the single prop and π-type roof beam are gradually withdrawn in the slight roof deformation area and the roadway stability area. The retaining gangue support design and spray layer design are carried out in the retaining section, and a complete set of technical scheme for roof cutting and roadway retaining in extremely close range coal seam is formed. The field engineering practice and monitoring results show that the maximum displacement of the roof of the 90104 transportation gateway is 120.1 mm, and the maximum displacement of the side is 165.3 mm. The maximum stress of the top and side anchor cables is 204.3 kN and 227.3 kN, which are 34.9% and 48.6% higher than the initial stress, respectively. The deformation of the roadway and the increase of the stress of the anchor cable are within a reasonable range. The whole roadway is relatively stable and no instability occurs. The bearing capacity of the support system is normal, and the control effect of the surrounding rock of the roof cutting and roadway retaining is good, which provides a reference for mining under similar extremely close conditions.

       

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