既有隧道扩建爆破振动数值模拟研究

基于原有隧道改扩建拱顶塌腔段扩建开挖，系统研究了多临空面条件下岩体爆破振动规律。采用完全重启动数值方法和拉格朗日算法分析岩体爆破振动规律，模拟爆破振动对隧道塌腔加固区和既有隧道围岩的影响，并获得了特征点的振动速度和衰减规律。数值模拟的最大振速符合爆破振动安全允许标准的要求，从而验证了爆破设计的可行性，并指导了爆破施工。同时，对隧道塌腔段开挖进行爆破振动监测。通过对比分析现场振动监测数据，数值模拟与现场监测结果吻合。结果表明，采用拉格朗日算法和完全重启动数值模拟方法可以描述隧道多孔毫秒延期爆破破岩和质点振动传播规律。该研究结论对隧道多孔毫秒延时控制爆破工程具有参考和指导意义。

Numerical simulation of blasting vibration on existing tunnel extension

In this paper, the blasting vibration of rock is analyzed under the condition of multi-free surfaces, which is based on the excavation of a collapse cavity section in the extension of the existing tunnel. The effect of simulating blasting vibration on the reinforcement area of the collapse cavity and surrounding rock is investigated by a fully restarted numerical method and Lagrangian algorithm method. Furthermore, vibration velocities and the attenuation law of characteristic points are obtained. It is found that the maximum vibration velocities calculated by the numerical method are in accordance with the requirement of the safety of blasting vibration. It also verifies the feasibility of blasting design, and can be used a guide for the blasting construction. Meanwhile, the blasting vibration monitoring of collapse section excavation is also conducted. The obtained vibration velocities from field experiments with the numerical simulation are in a good agreement. The results indicate that numerical methods can be used to describe the rock fragmentation and blasting vibration well in the millisecond delay blasting. Therefore, the current study shows a good example for the similar engineering conditions.