Experimental investigations of the effect of millisecond-delay time on the blast vibration reduction with electronic detonators

The error of precise initiation time controlled at the microsecond level in the electronic detonator blasting is accurate enough to realize blasting vibration reduction; however, the realization of precise control of blasting vibration using the electronic detonators remains rudimentary, researches on the precise zoning protection of buildings and field experiments are lacked. Therefore, multi-delay time of double-hole and multi-hole blasting experiments were carried out to explore the influence of different delay time on blast-induced PPV (Peak Particle Velocity). Based on the measured blasting vibration waveforms with blasting center distance of 16-200 m the reasonable delay time reducing PPV was investigated when the protective buildings at different blasting center distances and the reasonable delay time suitable for zoning protection was put forward to verify the applicability of the electronic detonators. The results show that as the initiation delay time increases, the PPV of blasting vibration first decreases then increases and finally attenuates to the single-hole PPV, with the increase of the blasting center distance, the reasonable delay time for reducing PPV gradually increases. However, a greater vibration enhancement effect will be produced when the delay time reaches at a certain value in the near area, the generated maximum PPV is about 1.8 times the single-hole PPV and there will be multiple short delay time producing enhancement effect in multi-hole blasting, the short delay time cannot be blindly adopted to reduce vibration. Therefore, the delay time of electronic detonators should be reasonably set to achieve the effect of blasting vibration reduction based on the distance between the protected buildings and the blasting zone.