Regulating effect of detonator location in blast-holes on transmission of explosion energy in rock blasting

Based on the numerical simulation of a cylindrical explosive charge, the acting mechanism of the detonator location is analyzed from the views of the transmission of explosion energy and the distribution of blasting stress field. Meanwhile, the on-site blasting experiment investigation is also conducted. Finally, the spatial distribution of the explosion energy as well as the blasting outcome under three different traditional detonator locations (including top, bottom and mid-point locations) is comprehensively evaluated. As a result, an improved scheme for the layout of in-hole detonators is proposed. The results indicate that the detonator location plays an important role in the transmission of explosion energy, and it determines the spatial distribution of the explosion energy along the blast-hole axis. The explosion energy is preferentially transmitted to the front direction of the detonation wave. In bench blasting, the explosion energy is preferentially transmitted to the hole-collar under bottom initiation, and it can form relatively better blasting crater. Moreover, the bottom initiation can reduce the damage and disturbance towards the rock mass below the hole-bottom, but it may induce serious toe rocks or under break. The problems of poor rock fragmentation and toe rocks at the hole-bottom can be relieved if moving the detonator upwards, as some explosion energy is transmitted to the hole-bottom in this case. The traditional recommendation of the bottom initiation is not always the best choice, whereas the detonator location should be regulated in time according to special engineering purposes and onsite situations so as to achieve the optimal utilization of the explosion energy.