开切眼全生命周期顶板稳定性与精准控制技术研究

Research on roof stability and precise control technology throughout entire life cycle of open-off cut

  • 摘要: 针对开切眼从巷道掘进到基本顶初次垮落的全生命周期顶板稳定性及其控制缺乏系统深入研究的问题,提出开切眼全生命周期的概念,将开切眼全生命周期划分为一次巷道掘进、二次扩巷、采煤设备安装、采空区直接顶垮落和采空区基本顶初次垮落5个阶段。通过理论分析得出地质条件是决定开切眼顶板稳定性的基础因素,巷道布置、巷道跨度和掘进扰动是影响顶板岩层稳定性的重要开采技术因素,支护技术是控制顶板稳定的关键措施。通过建立基本顶岩梁力学模型,对5个阶段的开切眼覆岩结构特征进行研究,揭示了开切眼顶板从弯曲下沉至冒落的时空演化和动态变化过程。针对不同阶段的顶板结构特征,提出相应的控制技术,巷道掘进阶段应采用锚网索主动支护,初采前应在液压支架后方进行切顶卸压。工业性试验结果表明,在支架后方实施爆破预裂切顶,可以预先破坏开切眼顶板的完整性,缩小采空区顶板的初次垮落步距,减弱基本顶初次来压强度,避免采空区大面积悬顶安全隐患。

     

    Abstract: To address the lack of systematic and in-depth research on roof stability and its control throughout the entire life cycle of the open-off cut from roadway excavation to the first caving of the main roof, the concept of the entire life cycle of the open-off cut was proposed. The entire life cycle of the open-off cut was divided into five stages: primary roadway excavation, secondary roadway expansion, coal mining equipment installation, immediate roof caving in the goaf, and first caving of the main roof in the goaf. Through theoretical analysis, it was concluded that geological conditions were the fundamental factor determining roof stability in the open-off cut. Roadway layout, roadway span, and excavation disturbance were important mining technical factors affecting the stability of the roof strata. Support technology was the key measure for controlling roof stability. By establishing a mechanical model of the main roof rock beam, the overlying strata structure characteristics of the open-off cut in the five stages were studied, and the spatiotemporal evolution and dynamic change process of the open-off cut roof from bending subsidence to collapse were revealed. Corresponding control technologies were proposed according to the roof structure characteristics at different stages. During the roadway excavation stage, active support with bolt-mesh-cable should be adopted. Before initial mining, roof cutting and pressure relief should be conducted behind the hydraulic supports. Industrial trial results showed that implementing blasting pre-splitting for roof cutting behind the supports could pre-damage the integrity of the open-off cut roof, reduce the first caving interval of the goaf roof, weaken the first weighting intensity of the main roof, and avoid the safety hazard of large-area roof hanging in the goaf.

     

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