裸顶巷道强帮护顶强角控跨围岩控制技术研究

    Research on surrounding rock control technology for bare roof roadway with strong wall protecting roof and strong corner controlling span

    • 摘要: 为了研究在坚硬致密的K2灰岩下掘进时裸顶巷道围岩的稳定性,基于弹性理论构建软化地基和弹性地基共同支撑下坚硬裸顶岩梁力学模型,推导出顶板岩梁挠度的解析表达式,研究覆岩载荷作用下坚硬顶板的力学行为;基于巷帮的刚度效应和顶板的跨度效应提出“强帮护顶,强角控跨”围岩控制原理,通过数值模拟和现场监测,系统评估支护设计方案的可靠性。研究结果表明:顶板岩梁随两帮基础的压缩变形而呈现整体弯曲下沉,顶板岩梁下沉量与巷帮基础刚度呈负相关关系,与巷道跨度呈正相关关系;支护构件在围岩内部形成了连续的预应力叠加耦合支护应力场,有效提高了巷帮的基础刚度,实现了强帮护顶;通过锚杆的挤压效应改善了帮角区域煤岩的力学性质,控制了岩梁的等效跨度,实现了强角控跨;刚度效应和跨度效应能够有效控制顶板沉降,巷道表面变形在30 d后趋于稳定,支护构件未出现失效现象,巷道顶板、底板累计变形量分别为28 mm、33 mm,两帮最终移近量为45 mm,围岩未出现不可控变形,实现了坚硬顶板条件下裸顶巷道的安全有效使用;顶板局部出现独立微裂隙,未相互贯通形成裂隙带,顶板未出现离层现象,设计支护方案能与围岩形成良好的耦合状态,使顶帮底形成统一的承载结构,较好地保证了巷道围岩处于稳定状态。

       

      Abstract: To study the stability of bare roof roadway surrounding rock during excavation in the hard and dense K2 limestone, based on the theory of elasticity, a mechanical model of a hard bare roof rock beam supported by both softened foundation and elastic foundation is constructed, the analytical expression for the deflection of the roof rock beam is derived, and the mechanical behavior under overburden loads is investigated. The “strong wall protecting roof and strong corner controlling span” principle for surrounding rock control is proposed based on the stiffness effect of the wall and the span effect of the roof, through numerical simulation, on-site monitoring of surrounding rock deformation and detection of the internal structure of the roof, the reliability of the support design scheme is systematically evaluated. The results show that the roof rock beam undergoes overall bending and subsidence as the two side supports are compressed. The subsidence amount of the roof rock beam is negatively correlated with the stiffness of the side support and positively correlated with the span of the roadway; the supporting components formed a continuous prestressed superimposed coupling supporting stress field within the surrounding rock, which effectively enhanced the foundation stiffness of the roadway sides and achieved strong support for the roof; the squeezing effect of the anchor rods improved the mechanical properties of the coal and rock in the side angle area, controlled the equivalent span of the rock beam, and realized strong angle control of the span. The stiffness and span effects effectively control roof subsidence. The deformation of the roadway surface tends to stabilize after 30 d, the support components do not fail, the cumulative deformation of the roof and bottom plates of the roadway is 28 mm and 33 mm, respectively, the final displacement of the two sides is 45 mm, the surrounding rock does not have uncontrollable deformation, achieving safe and effective use of the bare roof roadway under the condition of hard roof condition. Independent microfissures which are not connected to form a fissure zone appear locally in the roof, the roof is not separated from the layer, and the support design achieves effective coupling with the surrounding rock, ensuring the stability of the surrounding rock in the roadway.

       

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