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爆破扰动高应力巷道围岩力学响应特征研究

Study on the dynamic response characteristics of surrounding rock in high stress tunnel under blasting disturbance

  • 摘要: 为研究深井厚硬顶板采场巷道围岩在高静载和强动载耦合作用下的力学响应,基于相似模拟试验分析原岩应力、采动应力及爆破扰动三阶段的巷道围岩应力场与位移场,结合光纤环向应变场研究巷道围岩破坏特征,探索爆破扰动应力波在不同煤岩体中的传播规律及巷道动力响应机制。研究结果表明:巷道开挖后顶底板卸压明显,两帮产生应力集中区,采动应力阶段应力集中区范围增加50%,爆破后顶板围岩沿垮落角大范围卸压,应力沿巷道左肩窝逆时针逐渐增大;浅部巷道围岩呈现向自由面膨胀–变形,受巷道肩窝处剪切滑移错动影响,锚杆、锚索支护场产生相反的位移量,应力波扰动后,巷道左帮产生拉伸裂纹并与锚杆支护场连成宏观裂纹,裂纹发育高度大于锚杆支护场高度;巷道围岩顶底板呈现明显的张拉破坏特征,左右肩角呈现张拉及剪切复合破坏形式;应力波由小阻抗介质进入大阻抗介质的衰减速度最快,在同种介质中衰减速度次之,由大阻抗介质进入小阻抗介质中应力波峰值反而增大,应力波峰值强度衰减后仍大于巷道顶板极限抗拉强度,导致巷道围岩大变形失稳并产生一定程度的动力响应。基于应力波连续穿过层状岩体理论模型,结合动静载叠加理论,可优化爆破参数从而实现减冲抗冲主被动联合支护。

     

    Abstract: This research delves into the mechanical response of surrounding rock in deep coal mine roadways under high static and dynamic loads, utilizing similarity simulation experiments. The focus is on the stress and displacement fields during distinct phases: original rock stress mining-induced stress, and blasting disturbance. Integrating fiber-optic technology for circumferential strain field examination, the study characterizes rock failure and investigates the rules governing stress wave propagation post-blasting in different coal rock masses, and the consequent dynamic roadway responses. The research results highlighted substantial stress reduction in roadway roofs and floors post-excavation, accompanied by a 50% expansion in stress concentration during mining. Post-blasting observations revealed extensive roof rock stress relief and increased stress along the roadway's left shoulder. Shallow surrounding rock showed expansion-deformation, with displacements in support structures due to shear slip faulting at the roadway shoulder. Stress wave disturbances induced tensile cracks on the roadway's left, leading to macroscopic fractures exceeding support field heights. The study observed pronounced tensile failures in rock roofs and floors, and combined tensile-shear failures at the shoulders. Stress wave attenuation is fastest from low to high impedance mediums, slower within identical mediums, and peak values escalate when transitioning from high to low impedance mediums, surpassing the roof's tensile strength and causing significant rock deformation and instability. Conclusively, blending the theoretical model of stress wave continuously passing through layered rock mass with static-dynamic load superposition principles, the research suggests blasting parameter optimization for enhanced impact reduction and robust joint support in roadway constructions.

     

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