Effect of initiation location on distribution and utilization of explosion energy during rock blasting

In mining, the explosive filled in each borehole is usually initiated by the detonator. However, the effect of the location of the detonator (i.e. initiation location), which determines the propagation direction of the detonation wave, cannot be ignored. In this study, the influence mechanism of initiation location was analyzed with the help of numerical simulation. Two blasting experiments were also conducted to study the effect of initiation location. The results indicate that the initiation location plays an important role in the distribution of the explosion energy transmitted to the surrounding rock mass. For the vertical borehole blasting, the peak particle velocity below the borehole can be reduced by 21.0–59.0% under bottom initiation, when compared to top initiation. The blast-induced damage of the remaining rock mass below the borehole is also weaker by 5.0–8.9% under bottom initiation. However, the problem of under break might become serious if the detonator is moved downwards in foundation excavation. The explosion energy is preferentially transmitted to the same orientation of the detonation wave during rock blasting. The bottom initiation, recommended by most previous researchers, is not always the best choice. The location of the detonator should be changed according to the onsite situations.