Abstract: Exploring the spatiotemporal evolution characteristics of vibration during adjacent tunnel blasting excavation
under multiple factors and the safety vibration velocity threshold to ensure the stability of surrounding rock is of great significance
for more accurate prediction and control of blasting vibration,as well as improving the safety and efficiency of tunnel construction.
Based on the measured vibration data of the equipment chamber blasting excavation site at the entrance level of the
Badaling Great Wall Station,the vibration spatiotemporal evolution characteristics of different parts of adjacent tunnels were
studied through VMD-WT noise reduction,vibration velocity spectrum analysis,and numerical calculation methods. The safety
vibration velocity threshold was determined by establishing the relationship between peak vibration velocity and stress peak.
The results show that the vibration velocity on the back explosion side is generally lower than that on the front explosion side,
and the maximum vibration speed occurs at the arch waist on the front side;Under the same longitudinal distance (12. 5 m),
the peak vibration velocity at the arch waist on the blasting side (2. 29 cm/ s) is approximately twice that at the arch shoulder
on the blasting side (1. 12 cm/ s). Decomposition of blasting vibration signals containing noise in on-site measured data using
VMD-WT joint processing method,filtering and performing HHT transformation,it was found that the energy attenuation rate on
the approaching side was generally slower than that on the back side,and the energy dominant frequency band at the arch waist
of the approaching side was mainly distributed between 41~100 Hz. Finally,based on the maximum tension theory,the safe vibration
velocity threshold for ensuring the stability of surrounding rock is 16. 92 cm/ s,which means that the surrounding rock
will not be damaged when the maximum equivalent stress does not exceed 1. 1 MPa. This has certain guiding significance for
controlling blasting vibration effects and ensuring construction safety in similar projects.

Key words: adjacent tunnels,electronic detonators,blasting vibration,safety vibration velocity,VMD-WT