Assessment of objective based blast performance: Ranking system

Abstract

Rock fragmentation using chemical energy is commonly followed for fragmenting and displacing the rock mass in mining, civil and other excavation projects. In case of mines, the objective of rock fragmentation is to get a uniform sized material to suit the subsequent operations like loading, hauling and crushing. In case of civil engineering projects like canals, tunnels, it is to provide the space for some facilities and the material produced may not be having a specific use. In case of blasting near to the human habitats or important structures like dams, ground vibrations generated should be within permissible safe limits, along with proper fragmentation. Cost reduction is also a prime factor in all the cases. In general, assessment of blast performance refers to fragmentation assessment. However, based on the objective, the approach to blast design may be different. An attempt is made through this paper to discuss different blast performance assessment methods, through a case study and a ranking system is proposed. Field studies were carried out in a limestone mine in southern India, using eight controlled blasts by changing the initiation system, initiation pattern and maintaining same blast geometry parameters. Blast performance was assessed based on fragmentation using digital image processing technique, energy distribution, and productive yield and powder factors resulting from the blasts. Rankings were given to different blasts as per the performance.