爆破荷载作用下隧道中隔岩稳定性研究

为研究爆破动力荷载作用下隧道中隔岩稳定性评价标准，以福州地铁2号线为工程背景，结合强度折减动力分析法和数值模拟，同时考虑中隔岩塑性区贯通、位移超过规范值、计算不收敛3种判据，综合对隧道中隔岩进行动力安全系数分析，研究隧道不同净距、不同开挖进尺后行洞隧道爆破开挖对隧道整体安全系数的影响。研究结果表明:中隔岩塑性区贯通时特征点位移和规范中位移限值较为接近，可共同作为评价中隔岩稳定性的最终评价标准；隧道净距越大、进尺越小，隧道整体安全系数越高；对围岩质量较差且净距小于1.6 m的双线隧道进行爆破开挖时，建议将爆破进尺控制在2 m以内。研究结果可为类似工程提供理论参考依据。

Study on stability of intermediate diaphragm rock in tunnel under blasting load

In order to study the evaluation criteria for the stability of intermediate diaphragm rock in the tunnel under the effect of blasting dynamic load,taking metro line 2 in Fuzhou as the engineering background,combining with the strength reduction dynamic analysis method and numerical simulation,and considering three criteria of plastic zone penetration,displacement exceeding specification value and non convergence of calculation for the intermediate diaphragm rock,the dynamic safety coefficient analysis on the intermediate diaphragm rock of tunnel was carried out comprehensively,and the influence of blasting excavation of following hole tunnel on the overall safety coefficient of tunnel under different net distances and different excavation footages was studied.The results showed that the displacement of characteristic points was close to the limit value of displacement in the specification when the plastic zone of intermediate diaphragm rock penetrated,which could be used as the ultimate criteria for evaluating the stability of intermediate diaphragm rock together.The greater the net distance of tunnel and the smaller the footage,the higher the overall safety coefficient of the tunnel.For the conditions that the quality of surrounding rock was poor and the net distance of tunnel was less than 1.6 m,it was suggested to control the blasting footage within 2 m.The results can provide theoretical reference for the similar projects.