冲击载荷下围岩−支护体系动力响应影响因素研究

    Study on influencing factors of dynamic response of surrounding rock-support system under impact loading

    • 摘要: 为得到减小冲击地压动力危害、提升围岩−支护体系稳定性的有效方法,建立了冲击载荷下的围岩−支护体系动力学响应简化模型,使用Newmark−β平均加速度法,借助编程数值计算软件,研究动力学模型的支护端动力响应:分析在常规支护下,增加支护刚度、改变岩层结构对支护端动力响应的影响;对比在扰动载荷和岩层模型相同的情况下,使用常规支护、耗能支护和吸能支护时,支护端的动力响应和能量峰值。结果表明:在常规支护下,支护刚度增加为原来的5倍,扰动载荷作用前后的位移响应峰值分别下降80%和87%、加速度响应峰值分别下降74%和61%,进一步增加支护刚度,支护端动力响应的下降量不再明显;使用粉砂岩层不变、煤层质量块五等分的方法优化岩层结构后,扰动载荷作用前后的位移响应峰值分别下降60%和69%、加速度响应峰值分别下降66%和45%;相同条件下,与常规支护相比,使用耗能支护和吸能支护的支护端振动能量峰值分别下降18%和92%,动力响应持续时间分别为10.7、8.9 s。通过合理增加支护刚度、优化岩层结构可有效降低支护端的位移和加速度幅值,减小支护端的动力响应;在巷道支护中设置阻尼和吸能构件有利于耗散并吸收冲击能量,快速平息支护端岩块的振动,因此,可使用高强度、带阻尼的吸能支护防治冲击地压。

       

      Abstract: To obtain effective methods for reducing the dynamic hazard of rock burst and improving the stability of the surrounding rock-support system, a simplified dynamic response model of the surrounding rock-support system under impact loading was established. The dynamic response at the support end was investigated using the Newmark-β average acceleration method and numerical calculation software. The effects of increasing support stiffness and changing rock stratum structure on the dynamic response of the support end under conventional support were analyzed. Under the same disturbance load and rock stratum model, the dynamic response and energy peak at the support end were compared among conventional support, energy-dissipating support, and energy-absorbing support. The results show that when the support stiffness is increased to 5 times the original value under conventional support, the peak displacement responses before and after the disturbance load decrease by 80% and 87%, respectively, and the peak acceleration responses decrease by 74% and 61%, respectively. Further increasing the support stiffness no longer leads to an obvious reduction in the dynamic response at the support end. After optimizing the rock stratum structure by keeping the siltstone stratum unchanged and dividing the coal seam mass into five equal parts, the peak displacement responses before and after the disturbance load decrease by 60% and 69%, respectively, and the peak acceleration responses decrease by 66% and 45%, respectively. Under the same conditions, compared with conventional support, the peak vibration energy at the support end decreases by 18% and 92% for energy-dissipating support and energy-absorbing support, respectively, with the dynamic response durations of 10.7 s and 8.9 s. Reasonably increasing support stiffness and optimizing the rock stratum structure can effectively reduce the displacement and acceleration amplitudes and weaken the dynamic response at the support end. Installing damping and energy-absorbing components in roadway support is conducive to dissipating and absorbing impact energy and quickly suppressing the vibration of the rock blocks at the support end. Therefore, high-strength energy-absorbing support with damping can be used to prevent and control rock burst.

       

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