Mechanism of the in-hole detonation wave interactions in dual initiation with electronic detonators in bench blasting operation

Abstract With the development of electronic detonators, the precise initiation timing has been controlled at the microsecond level, which are accurate enough to guarantee waveform collision at precise locations in hole. The accumulated energy effect by collision of two oppositely traveling in-hole detonation waves was proved theoretically based on impact dynamics theory. And the fragment size distributions and blasting vibration under different initiation modes with electronic detonators were also investigated by comparing the field test and numerical simulations results of bench blasting. The results show that the detonation products density near the collision point is increased, the particle velocity is reduced, and the kinetic energy is converted into pressure energy, the pressure near the collision point is greater than the sum of the strength of the two detonation waves, demonstrating the potential for an increase in fragmentation and throw. At the same time, the angle of the shock wave formed in the rock mass is deflected, changing from tilt to horizontal direction, direct the pressure toward to the bench face. The field test also indicated that the in-hole dual initiation method could cause both higher peak particle velocity and higher vibration frequency.