Analysis on Influencing Factors of Blasting Vibration Caused by Shallow Tunnel Excavation

With the widespread construction of urban subway, more and more shallow tunnels will be constructed by blasting, and the problem of blasting vibration will become more prominent. Because of the randomness and variability of blasting source and topographic and geological factors, the propagation mechanism and influencing factors of blasting vibration wave are very complex. Based on blasting-vibration sample data obtained from the established numerical model of blasting excavation in shallow tunnel, the relational degree analysis was carried out for influencing factors of blasting vibration caused by shallow tunnel excavation with method of grey relational analysis. The results of the study are as follows: Among the four related factors, there is no optimal factor, and the maximum charge of one section is the quasi-optimal factor; The charge of the first section is the main factor affecting the peak particle velocity of blasting vibration; The maximum charge of one section is the main factor affecting the main frequency of blasting vibration; The delay interval is the main factor affecting the duration of blasting vibration. Furthermore, the measures to control blasting vibration caused by shallow tunnel excavation were put forward, such as reducing the charge of the first section, reducing the maximum charge of one section and rationally setting up the delay interval. The study has important guiding significance for safe blasting construction in shallow tunnel and scientific control of blasting vibration effect.