English：

Blasting construction is prone to inducing vibration of adjacent building structures. Based onthe expansion project of the Lianhuashan Tunnel, aiming at the problem of vibration response of theadjacent existing tunnel induced by blasting construction of a newly built tunnel, a three⁃dimensionalnumerical model is established by FLAC3D to study the vibration response and settlement characteristicsof the existing tunnel vault and arch foot under blasting load. The results indicate that the distribution ofblasting vibration velocity has experienced the evolution law of “ local concentration, external diffusion,and uniform attenuation,” reaching the peak at about 0. 041 7s and basically stable at 1. 0s. The peakvibration velocity of the vault is generally higher than that of the arch foot, showing the spatial distributioncharacteristics of increasing first and then decreasing. And there are some differences due to thedifference in the mechanical excavation length of the left and right lines. The numerical simulation resultsindicate that the maximum vibration velocities of the vault and the arch foot of the existing tunnel are12. 23, 9. 15, 7. 30, and 6. 79cm / s, respectively, which are lower than the safety limit of the traffictunnel of 15cm / s. The maximum settlement values of vault and arch foot are -22. 47, -22. 30, -22. 85,and -22. 65mm, respectively, which are less than the warning value of 30mm. The research indicatesthat the blasting construction scheme and parameter setting are reasonable, which has little influence onthe safety of the existing tunnel structure and has good feasibility and safety.