特厚煤层巷道冲击破坏机理及全锚索支护技术

Shock failure mechanism of roadway in extra thick coal seam and full anchor cable support technology

  • 摘要: 针对特厚煤层巷道围岩冲击破坏严重等问题,基于弹性力学与冲击动力学,研究了特厚煤层巷道冲击破坏机理,揭示了顶煤破坏主控影响因素,分析了动载应力波传播过程及巷道围岩支护体系动力响应特征,确定了特厚煤层巷道围岩抗冲支护技术。研究发现:巷道顶煤岩梁冲击破坏程度与围岩静载集中应力、冲击震源强度和岩梁长度成正比,与应力波传播距离、岩梁厚度及强度成反比;冲击动载应力波传播过程分为应力起始振动期、应力波动期和应力调整期;应力起始振动期巷道围岩表面质点开始振动,锚杆索出现预卸压,应力波动期巷道围岩破坏加剧,锚杆索产生一定损伤,应力调整期巷道围岩趋向于稳定,锚杆索轴力也趋向于稳定值;随着冲击动载强度增大,巷道围岩质点振动速度、位移增量和加速度呈指数关系增长;巷道围岩临界冲击能量为105 J,大于临界冲击能量,巷道围岩动力破坏加剧,锚杆索损伤增大;采用全锚索梯次让压支护技术,巷道可形成浅表深锚高预应力层与深部梯次让压协同支护层,增强巷道顶煤岩梁强度及厚度,降低锚索冲击动载损伤值,提升巷道围岩抗冲性能。工程应用表明,采用全锚索梯次让压支护技术,巷道围岩裂隙发育深度降低50.47%~55.42%,变形量降低52.89%~68.78%,锚杆索损伤降低,巷道围岩稳定性显著提升。

     

    Abstract: In view of the serious shock failure of roadway in extra thick coal seam, based on elastic mechanics and shock dynamics, this paper studies the shock failure mechanism of roadway in extra-thick coal seam, reveals the main influencing factors of roof coal failure, analyzes the propagation process of dynamic load stress wave and the dynamic response characteristics of roadway surrounding rock and support system, and determines the effective anti-impact support technology of roadway surrounding rock in extra thick coal seam. It is found that the impact damage degree of the roadway roof is directly proportional to the static concentrated stress, the intensity of the shock source and the length of the roof coal rock beam, and inversely proportional to the propagation distance of the stress wave, the thickness and strength of the roof coal rock beam. The stress wave propagation process under shock dynamic load can be divided into stress initial vibration period, stress fluctuation period and stress adjustment period. During the stress initial vibration period, the particles on the surrounding rock surface of the roadway begin to vibrate, the pretension of the anchor cables is reduced. During the stress fluctuation period, the surrounding rock of the roadway becomes more damaged, the anchor cable appears to be damaged. During the stress adjustment period, the surrounding rock of the roadway tends to be stable, and the axial force of the anchor cable also tends to be stable. With the increase of shock dynamic load strength, the particle vibration velocity, displacement increment and acceleration of surrounding rock increase exponentially. The critical shock energy of roadway surrounding rock is 105 J, above which the damage to the roadway surrounding rock and anchor cable is aggravated. By adopting the full anchor cable multi-length yielding support technology, the roadway can form a shallow deep anchor high prestress layer and a deep multi-length yielding support layer, which can enhance the strength and thickness of the roof coal rock beam, reduce the dynamic load damage value of the anchor cable, and improve the impact resistance of the roadway surrounding rock. The engineering application shows that the development depth of cracks in the surrounding rock of the roadway is reduced by 50.47%−55.42%, the deformation is reduced by 52.89%−68.78%, the damage value of the anchor cable is reduced, and the stability of the surrounding rock of the roadway is significantly improved by using the full anchor cable multi-length yielding support technology.

     

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