爆破振动对邻近隧道衬砌安全的数值模拟分析

摘要

Here,a numerical model for impact of blasting construction on existing tunnel linings was built and the simulation method of peak load,loading time and the waveform of blasting load was presented.To realize energy radiation and reduce boundary effects,viscoelastic boundary was defined.Furthermore,the impacts of different footages in new tunnels' blasting excavation and different tunnel spacings on nearby tunnels were analyzed.Results showed that on the blast side of the existing tunnel,the arch and the sidewall are affected most significantly by blasting;in the construction of a new tunnel,the greater the footage,the higher the velocity of the existing lining;meanwhile,the larger the distance between the tunnels,the less the vibration velocity of the exiting lining;according to “Blasting Safety Regulations”,the vibration velocity of the existing linging obtained with numerical simulation can be compared with the standard safe vibration velocity to determine the safety of the lining;the results provide a reference and guidance for engineering design and construction.%建立了爆破施工对既有衬砌振动影响的数值模型，给出了数值计算中爆破荷载的波形、荷载峰值、加载时间的模拟方法；为了实现能量辐射，减小边界效应，定义了粘弹性边界；在此基础上研究了新建隧道爆破开挖进尺不同、间距不同、埋深不同，对既有邻近隧道的影响。结果表明：在既有隧道迎爆侧的拱脚和墙腰部位，衬砌受到爆破施工影响最显著；新建隧道爆破施工时，开挖的进尺越大，既有衬砌的振速就越高；既有衬砌受隧道间的距离影响显著，隧道间距越大，既有衬砌的振动速度受影响越小。结果还表明，参考《爆破安全规程》的规定，可以用数值模拟的衬砌振动速度与安全振动速度标准进行比对，从而判断既有衬砌的安全性，为工程设计和施工提供分析参考和指导。