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为了研究南溪长江大桥锚碇隧道后续洞掘进爆破时隧道围岩的振动特征,采用动力有限元(LS-DYNA)数值计算的方法,对锚碇隧道后续洞掌子面开挖至隧道轴线27 m处的工况进行了数值计算,将计算结果与现场实测数据进行了对比分析,证明了数值计算的可行性。根据数值计算结果对隧道中隔岩墙的振动特征进行分析可以得到以下主要结论:先行锚碇隧道迎爆侧水平向的峰值振动速度最大。随着距离爆破掌子面轴向距离的不断增大,先行洞迎爆侧边墙上各监测点在三个方向上的振速峰值分量越趋近于一致。后续洞掘进爆破引起的在中隔岩墙上的最大振速峰值的位置位于掌子面掘进方向上约1 m左右。在后续洞进行爆破开挖时,振速峰值均随着距离掌子面轴向距离的增大而减小,并且沿隧道掘进方向的衰减速度比反方向的衰减速度慢。
In order to study the vibration characteristics of tunnel surrounding rock during the subsequent tunnel excavation of Nanxi Changjiang River Bridge, the finite element method (LS-DYNA) was used to excavate the tunnel face of subsequent tunnel to the tunnel axis 27 m at the conditions of the numerical calculation, the calculated results with the field measured data were analyzed and compared to prove the feasibility of numerical calculations. According to the results of numerical calculation, the following conclusions can be drawn from the analysis of the vibration characteristics of the rock wall in the tunnel: The peak vibration velocity at the blast side of the pre-anchored tunnel is the highest. As the axial distance from the blasting face increases, the peak components of the vibration velocity of the monitoring points in the first hole on the side wall tend to be close to the same. The location of the peak of maximum vibration velocity on the septal dyke caused by subsequent tunneling blasting is about 1 m in the tunneling direction of the face. In the subsequent hole blasting excavation, the peak value of vibration velocity decreases with the increase of the axial distance from the face, and the decay rate in the tunneling direction is slower than that in the reverse direction.