Arora S.,NIT Kamataka |
Dey K.,Indian Institute of Technology Kharagpur
Journal of the Institution of Engineers (India): Mining Engineering Division | Year: 2011
Peak particle velocity (PPV) generated in blasting is accepted as a measure of rock and structural damage PPV is measured using a seismograph at a distance from the blast face to keep the instrument safe As the distance between the blast point and seismograph (point of interest) is significantly larger than the length of explosive charge column, the explosive column placed in the blast hole is considered as a point charge. Blast-induced rock damage occurs very close to the blast hole and therefore the charge length cannot be ignored. Thus, estimating the damaged zone by extrapolating far-field observations yields inaccurate results. In this paper, a mathematical model is developed for estimation of near-field PPV considering the effect of charge length in the hole. In the proposed model, effect of an elemental charge in the charge column is calculated and then summed up for the whole charge column of two adjacent holes. Apart from this it also takes into account the direction of blast waves originating from the blast holes. The proposed model is also tested for a field trial.