ASSESSMENT OF POWDER FACTOR IN SURFACE BENCH BLASTING USING SCHMIDT REBOUND NUMBER OF ROCK MASS

Bhanwar S. Choudhary, Kumar Sonu

Abstract: Rock mass characterisation helps in selection and optimum usage of explosive in bench blasting. There are various methods to characterize the rock mass but use of Schmidt hammer in rock characterization before blasting may be a good option. Schmidt hammer, since its simplicity and capability of instant data production, has so far been a powerful tool utilized by many researchers to predict compressive strength of rocks. In this light the present study was conducted in opencast coal mines to see the effect of Schmidt hammer rebound number or transformed compressive strength of rocks on powder factor. The correlation was found sufficiently reliable to enable the determination of optimum powder factor for surface bench blast in different rock types maintaining the required blasting results in terms of fragmentation.

Keywords: Powder factor, Schmidt hammer, Rebound number, Rock mass, Overburden bench

DOI: https://doi.org/10.15623/ijret.2013.0212023