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深孔爆破在小煤柱巷道顶板控制中的应用

Application of deep hole blasting in roof control of small coal pillar roadway

  • 摘要: 为保证深埋坚硬顶板厚煤层开采条件下小煤柱巷道稳定性,采用深孔爆破的方法对巷道顶板进行预卸压。通过小煤柱巷道顶板弧形三角块结构分析,确定顶板预断裂位置,在此基础上,根据现场地质及施工条件,首先分析确定深孔爆破单孔施工参数及装药参数,然后通过理论计算和现场爆破试验的方法,综合确定爆破孔间距为10 m,进而指导现场爆破方案设计。工程实践表明:工作面微震事件大多集中在回风巷一侧,未采取深孔爆破预卸压措施时,能量大于104J的微震事件释放能量占总能量的69%,采取措施后,工作面回采区域尤其是回风巷一侧顶板能量以小能量微震事件的形式有效释放,大能量微震事件明显减少;微震层析成像分析表明,断顶爆破作用致使煤岩体中高应力区域向深部转移,避免了对巷道及煤柱的直接影响;支架工作阻力监测得出,回风巷侧顶板来压周期较短且较稳定,来压步距平均为19.1 m,约为爆破孔间距的2倍,说明断顶爆破对顶板来压活动起到了一定的控制作用;由现场巷道变形观测得出,采取断顶爆破预卸压措施后,巷道两帮变形量及顶板下沉量较未采取措施时减少了78%和80%,未出现严重帮鼓和支护失效现象,巷道变形控制效果明显。

     

    Abstract: In order to ensure the stability of the small coal pillar roadway under the mining conditions of deep buried hard roof and thick coal seam, the method of deep hole blasting was used to pre-release the pressure of the roadway roof. The pre-fracture position of the roof was determined through the structural analysis of the arc-shaped triangular block of the roof of the small pillar roadway. On this basis, according to the site geology and construction conditions, the single hole construction parameters and charging parameters of deep hole blasting were first analyzed and determined, then through theoretical calculation and field blasting experiment, the distance between blasting holes was comprehensively determined to be 10 m, and then the design of on-site blasting scheme was guided. Engineering practice shows that:most of the microseismic events in the working face were concentrated on the side of the return airway. When the pre-pressure relief measures for deep hole blasting are not taken, the energy released from microseismic events with energy greater than 104 J accounts for 69% of the total energy. In the mining area, especially the roof energy on the return air side was effectively released in the form of small energy microseismic events, and the large-energy microseismic events were significantly reduced. Microseismic tomographic analysis shows that, the high stress area in the coal rock mass was transferred to the deep part due to the roof blasting, which avoided the direct influence on the roadway and coal pillar. The working resistance monitoring shows that the period of roof weighting on the return air side was short and stable, and the average weighting step distance was 19.1 m, which was about 2 times of the spacing of blasting holes, indicating that the roof breaking blasting had a certain control effect on roof weighting; According to the field observation of roadway deformation, the deformation of the two sides of the roadway and the subsidence of the roof were reduced by 78% and 80% after adopting the measures of blasting and pre-relief measures. There was no serious failure of bulge and support, and the control effect of roadway deformation was more obvious.

     

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