再论负煤柱巷顶沿空掘巷合理位置及其围岩主动控制原理

Re-discussion on reasonable position and support technology of entry driven under the gob edge of previous split-level longwall panel

  • 摘要: 负煤柱工作面采空区弧形底板下方的巷顶沿空掘巷长期惯用架棚被动支护,劳动强度大、成本高、成巷慢,限制了该技术的推广和升级。为此,在大量前人相关研究基础上,以开滦集团唐山矿负煤柱开采实践为背景,采用现场实测、理论分析和数值模拟,重新分析论述了负煤柱巷顶沿空掘巷合理位置及其围岩主动控制原理。结果表明:(1)负煤柱工作面来压强度表现出中部最大、上部次之、下部最小的非对称分布的倾向分区特征,采空区矸石呈现出下部充实、中部充满、上部悬空的非对称堆积形态,下部充实区显著缓解了支承压力影响,为弧形底板创造了良好的应力环境优势。(2)揭示了负煤柱工作面弧形底板下巷顶沿空掘巷内错距离不同时围岩破坏区与弧形底板破坏区的联通规律,巷顶煤体较薄时,巷顶易产生裂隙并不断与其上采空区底板裂隙沟通导致巷道顶板失稳。(3)最佳布巷位置位于上区段弧形底板正下方,既可保留足够顶煤用于锚杆索支护,又可避开上区段采空区左侧应力集中区及应力变化剧烈区。(4)给出了基于自稳隐形拱理论的巷顶沿空掘巷主动支护设计原理,推导了巷顶沿空掘巷的自稳隐形拱表达式,揭示了该自稳隐形拱的非对称特征,最大拱高位于巷道中轴线偏左0.1 m处。研究可为负煤柱沿空掘巷围岩控制提供理论支持和科学依据。

     

    Abstract: Passive support of steel sets has long been used in the entries driven under arc-shaped gob edge(GDAGE)of previous negative pillar longwall panels(NPLP). It is of high labor intensity, high cost, and slow drivage, which limits its promotion and upgrade. Therefore, on the basis of a large number of previous studies, against the practice of the NPLP at the Tangshan Mine of the Kailuan Group, using field measurement, theoretical analysis, and numerical simulation, the reasonable position and support technology for the GDAGE are re-studied and re-discussed. The result shows that:(1) Periodic loading in the NPLP shows the asymmetric and zoning distribution characteristics such as the largest loading in the middle section, the second largest loading in the upper section and the smallest loading in the lower section. Caved rocks in gob is asymmetric with compaction in the lower section, full in the middle section and suspension in the upper section. The lower compaction mitigates the abutment pressure and provides a favorable stress environment for the GDAGE.(2) It is revealed that the connection law between the failure zone of surrounding rock and the failure zone of arc floor with the different offset distances of the working face with the negative pillar. When the roof coal of the gate road is thin, some cracks are easy to occur in the roof and the gradual connection of cracks with that in the arc floor leads to a roof instability.(3) The best position of the GDAGE is directly below the arc floor of the previous negative pillar longwall panel. It can not only retain sufficient thickness of top coal for bolt and cable support, but also avoid the left stress concentration and dramatic change area of upper section gob.(4) The principle of positive support based on the theory of self-stabilizing invisible arch is given. The arch of GDAGE is derived and it presents asymmetric characteristics. The maximum arch height is located 0.1 m to the left of the central axis of the roadway. The research can provide a theoretical support and scientific basis for the surrounding rock control of the GDAGE.

     

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