煤矿冲击地压巷道三级支护理论与技术

Theory and technology of three levels support in bump-prone roadway

建立了冲击地压巷道“应力-围岩-支护”力学模型,得到了考虑巷道支护作用下冲击地压启动应力条件为远场应力大于临界应力,停止的能量条件为近场围岩吸收能量和支护吸收能量大于远场释放能量。基于巷道围岩与支护体动力响应分析发现,冲击地压发生过程中围岩阻尼特性、锚固岩体的抗冲击吸能特性及巷内支护体的阻尼及刚度对冲击载荷作用下巷道围岩的稳定性具有重要影响。提出巷道冲击地压防冲支护应从静-动力学两个角度,同时考虑“启动—破坏—停止”全过程。①在冲击启动前,依据冲击启动的应力条件降低煤体应力,减少弹性能积聚,提高支护阻力,增加启动难度;②依据冲击停止的能量条件,在冲击过程中,通过改变煤岩体结构与介质属性,吸收或消耗冲击能;③在冲击应力波传播的末端,通过提高巷内支护结构阻尼吸收剩余冲击能,减弱冲击应力波对巷道支护结构的破坏。提出冲击地压巷道支护结构应具有让压可缩与吸能特性,防冲支护应根据冲击地压能量特性进行分级设计。研发了吸能锚杆索、吸能O型棚、吸能液压支架等吸能支护装备,利用吸能构件的结合及功能互补特性建立了三级吸能支护体系,三级吸能支护系统具有径向让位、环向可缩以及轴向稳定特性,实现了冲击地压巷道三维立体吸能支护。

In this study,the“stress-surrounding rock-support”mechanical model of rockburst roadway was estab-lished,and it revealed that the starting stress condition of rockburst is that the far-field stress is greater than the critical stress,and the stopping energy condition is that the energy absorbed by the near-field surrounding rock and the energy absorbed by the support is greater than the energy released from the far-field.Based on the dynamic response analysis of the surrounding rock and support in the process of rockburst,it was found that the damping characteristics of the surrounding rock,the impact-resistant and energy absorption characteristics of the anchored rock and the damping and stiffness of the support in the roadway have an important influence on the stability of the surrounding rock subjected to an impact loading.Considering the whole“starting-breaking-stopping”process of the rockburst,the authors proposed some prevention and control methods on rockburst in the roadway in terms of static and dynamic mechanics.Firstly,before the rockburst starts,according to the stress condition of rockburst start,the methods of reducing the stress and the accumulation of elastic energy of coal and rock mass and improving the resistance of support to increase the difficulty of rockburst start-up are conducted.Secondly,during the process of rockburst,according to the energy condition of rockburst stopping,the methods of changing structure and properties of coal and rock mass on the propagation path of impact stress wave are conducted to absorb or dissipate the impact energy.Thirdly,at the end of the propagation of the impact stress wave,the method of increasing the strength and damping of the supporting structure in the roadway is conducted to absorb the residual impact energy,and weaken the damage of the supporting structure caused by the impact stress wave.It is proposed that the supporting structure of rock burst roadway should have the characteristics of yielding and energy absorption,and the impact-resistant support should be designed according to the energy characteristics of rock burst.Combined with the failure characteristics of support and surrounding rock under the impact load and the support structure requirements of the rockburst roadway,the energy absorption support equipment,including energy absorption anchor cable,energy absorption O-shaped shed and energy absorption hydraulic support,have been developed.The three-level energy absorption support system was established by the combination of energy absorption components and their complementary functions.The three-level energy absorption support system has the characteristics of radial yield,circumferential shrinkage and axial stability,and realizes the three-dimensional energy absorption function of the rockburst roadway.