The influence of initiation mode of explosives on ground vibration

The measurement and analysis of blast induced vibration is presently more state-of-the-art than ever before. A modern understanding of the basic concepts behind vibration effects can help a beleaguered end user more confident about what their measurement really mean. It is reported that blast conducted with non-electric initiation system enhance the efficiencies of HEMM machineries and reduced the reported nuisance of blasting. The developed countries are adopting the third generation of Electronic detonators but in India the use of detonating fuse for blast initiation is still in practice. There are number of reasons stated by mine officials for this practices being still followed by mining industry. The one of the important reasons is the price ratio of Nonel tubes and detonating cords/fuse, which is comparatively very high in India in comparison to the other countries. A study was planned to investigate the influence of direction of initiation on blast vibration. The four coal mines were selected for the study purpose. The two blasts at same bench were blasted while keeping all the blast design parameter such as, burden, spacing, hole depth, hole diameter, charge per hole, charge per delay total charge in blast round etc. were kept identical. The explosive make for a set of two blasts were of same manufacture and both the blasts were conducted on same day to avoid the variation in explosive formulation. Blast induced vibrations were monitored at 6-11 locations. The experimental set of blasts includes single hole blasts, production blasts, as well as dragline blasts, performed by only changing mode of initiation i.e. initiation of booster with detonating fuse and with non-electric initiation it the bottom of the hole at floor level while maintaining all other parameters identical. The result indicated that former generated lower vibration compared to previous mode of initiation. The reductions in vibrations were observed upto 36.2% by for blastholes of depth more than 20 m. the minimum reduction of vibration was 8.2% for shorter blastholes depth of 7.5 m