Blasting techniques are widely used in mining and quarry to fragment rock mass into smaller pieces. Fragment size distribution of rock after blasting is an important index to estimate the productivity of blasting activity. The main purpose of this study is to investigate numerically the effect of stemming length to burden ratio on rock fragmentation induced by blasting. Numerical investigation was carried out by utilizing the Discrete Element Method (DEM) and Particle Blast Method (PBM) approaches in LS-DYNA software, on the response of rock fragmentation. In bench blasting simulation, the rock media was modelled using DEM and the blast loading was modelled using PBM. The mean particle size (d50) and 80% passing size (d80) were determined using computer software. Relationship between stemming to burden ratio and mean particle size has been established. It was observed that the mean particle increases with the increases in stemming to burden ratio. The numerical model has successfully shown the crack propagation of rock which can form the rock fragments and helps to predict the fragment size distribution of rock.

1. Introduction

Rock fragmentation is a significant concern of any blasting operation and used to estimate the efficiency of bench blasting in the quarry and mining industry. The outcomes of blasting activity are determined by controllable and uncontrollable parameters. A good outcome of blasting operation leads to the productiveness of the loading, hauling and crushing process (Oraee and Asi, 2006). It is also essential to make sure there are no unwanted phenomena in every blasting activity. The controllable parameters are basic blast design parameters which can adjust to minimize the unwanted phenomena from occurs and at the same time to obtain the required rock fragmentation. Besides that, uncontrollable parameters such as properties of rock mass, discontinuities and geomechanical characteristics of the intact rock need to be factored and include in the blast design.

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