Abstract

Engineering blasting is considered the most economical means of rock fragmentation. The explosive energy utilization is limited to 7% to 22% for fracturing and fragmentation though. The rest of energy components manifests itself into deleterious effects of engineering blasting, namely - noise, air overpressure, ground vibrations, etc. It has been established that proper application of air-decking and stemming plugs may enhance explosive energy utilization to a good extent. This paper substantiates this fact wherein distinct explosive energy utilization enhancement has been achieved with the combination of air-decking and stemming plug. The stemming plug used has acronym as, SPARSH (Stemming Plug Augmenting Resistance to Stemming in Holes) and it is perhaps the only available device which can effectively be used with air-decking. Further, SPARSH doesn't restrict the type of stemming material and stemming length. This is a significant advancement in the engineering blasting.

1. Introduction

Engineering blasting has many notable advancements since Alfred Nobel had invented detonator and dynamite in 1865 and 1867, respectively. Since then this engineering application has grown with newer forms of blasting agents (they are not explosive by themselves) and electronic detonators. The notable technological advancement also covers application of air-decking as propounded by Mel'Nikov [1], de-coupling as illustrated by Worsey et al. [2] and various form of stemming plugs proposed by several researchers [3]. The explosive energy utilization for fracturing and fragmentation, however, accounts for only 7% to 22% despite of all these advancements [4]. Also, there is no change in different rules of thumbs or specifications those were recorded by John Burgoyane in 1849 [5]. The notable rule of thumb still in vogue dictates that blast hole shall be charged up to 2/3rd of its length and the remaining 1/3rd top column shall have stemming material. The specifications for stemming materials are also unchanged those enforces that inert light weight angularly shaped materials of about 1/6th diameter with respect to blast hole diameter must be used for engineering blasting as stemming. These rules of thumbs and specifications creates practical problems for large diameter long hole blasting and yet the explosive energy ejects early from the borehole collar.

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