隧道内脉冲激励下地层振动传递特性研究

目前，对于地铁运营引起的振动在地层中的传递特性一直未有系统深入的研究。利用自动落锤激励装置锤击轨道减振与控制实验室10m埋深隧道内轨道，研究了0~200Hz频段振动加速度在地层中的传播衰减特性。试验结果表明：(1)隧道结构-地面振动加速度峰值衰减率达到81.25%，地层对振动有很强的衰减作用。(2) 除了30Hz附近频段传递函数幅值大于1，隧道结构到地面振动响应传递函数幅值普遍小于0.4。(3) 隧道结构-地面1/3倍频程加速度级传递损失曲线呈V形分布，传递损失在30Hz附近最小，且为负值，此频段振动加速度能量从隧道传递到地面有放大现象。

Study on Stratum Vibration Transfer CharacteristicBased on the Pulse Experiment inside tunnel

At present, there is no systematic research on the transfer characteristic of stratum vibration induced by the metro operation. The stratum vibration transfer characteristic tests were carried out in the Lab. of Track Vibration Abatement﹠Control, by using of the automatic falling weight system to hammer the underground track. The propagation attenuation characteristic of vibration accelerations in the ground were studied in the frequency range of 0 ~ 200 Hz. The results indicate: (1) the attenuation rate of the acceleration peak value from the tunnel to the ground can reach 80% and the layers have the strong attenuation function; (2) the transfer function amplitude of the vibration responses from the tunnel to the ground is less than 0.4, except that the transfer function amplitude in the near 30Hz frequency band is greater than 1. (3) 1/3 octave acceleration level transmission loss curve from the tunnel to the ground show the V-shape distribution, the transmission loss is least in the near 30Hz and is a negative number. The vibration acceleration energy from the tunnel to the ground has the transmission amplifier phenomenon at this frequency.