Abstract:

In order to realize vibration reduction of tunnel blasting in complex environmental conditions, a delaytime calculation method of millisecond blasting using electronic detonators is proposed based on timedelay calculation theory of millisecond blasting and considering physicomechanical parameters of surrounding rock and tunnel blasting parameters. And then the effects of primary charge on vibration velocity and main frequency of blasting seismic wave are studied, and site test is carried out in blasting project of Xinhongyan Tunnel on ChengduChongqing Passengerdedicated Line. The study results show that: (1) A rational timedelay of tunnel millisecond blasting should consider the time of rock failure and that of fissure extended to tunnel face. (2) By using the delaytime calculation method of millisecond blasting, the delay time of electronic detonators can be set rationally, the single hole separation millisecond blasting can be realized, the peak velocity can be reduced and the main vibration frequency can be improved effectively. (3) Compared to millisecond nonelectric detonator, the vibration velocity of electronic detonator applied to blasting project of Xinhongyan Tunnel is reduced by 60%, which indicates the rationality and accuracy of the delaytime calculation method of millisecond blasting using electronic detonators. 

Key words: tunnel blasting, millisecond blasting, timedelay calculation, electronic detonator