A new approach to reduce blasting-induced vibration in tunnel blasting by utilizing the initiation time scatter of detonator

The charge weight per delay is one of the major variables in empirical models for predicting the peak particle velocity in tunnel blasting. In many instances, the corresponding initiation times of the detonators often overlaps. The overlaps occur because of the initiation time scatter of each of the detonators. The overlap, in turn, causes an increased charge weight per delay, which consequently causes an increase in the blast-induced vibration. In this study, a novel technique is introduced for development of a blasting pattern exploiting the initiation time scatter of the detonators. The initiation time of 423 detonators was measured using a vibration monitoring instrument and a high-speed camera. From the data obtained, a standard deviation of the initiation times of the detonators was determined. The probability of overlap of the initiation times of the detonators was calculated using a Monte Carlo simulation. After simulating both a new blasting pattern utilizing the initiation time scatter of the detonator and the conventional blasting pattern 10,000 times each, it was determined that, in the new blasting pattern, the number of sets in which four or more blastholes initiated simultaneously decreased from 17,595 to 1604. Moreover, the probability that four or more blastholes initiated simultaneously in a blasting round decreased from approximately 70% to 12%.