Blasting operation is performed to fracture and break rock into pieces for construction and aggregate processing. Bench height to burden ratio, also known as stiffness ratio, is an important blast parameter influencing rock fragmentation. This study aims to investigate the effect of bench height to burden ratio on rock fragmentation numerically. Bench blast numerical simulation using hybrid finite-discrete element method (FEM-DEM) approach was conducted. Bonded particle model (BPM) combined with particle blast method (PBM) was used to model the bench blasting simulation. The rock media in the simulation was modelled using BPM, and the blast loading was modelled using PBM. Based on the bench blast model simulation, extraction of mean particle size (d50) was conducted. The bench height to burden ratio was plotted against the mean particle size to investigate the graph relationship. It can be seen that mean particle size exhibits reduction with an increase in bench height to burden ratio. By increasing the bench height to burden ratio, the bench becomes more flexible and resulting in better fragmentation of rock.
Blasting has been commonly used in mining and quarry for rock breakage into the desired size, and it can be varying in size, shape and weight. Blasting aims to fragment rock in a safe, cost-effective and environmental way. The poorly conducted blast will be resulting in poor fragmentation and other blast results such as ground vibration, flyrock, airblast and backbreak. One of the major concerns related to blasting operations in mining and civil engineering projects is rock fragmentation. The mean fragment size of rock should not be too high or too low. This is because it shows the oversize rock and very fines rock. Large-sized fragments of rock known as boulders can be fragmented with or without the use of explosives. The required fragmentation is important as it affects the downstream mining process of loading, hauling, crushing, and secondary blasting (Dershowitz, 1993; Faramarzi et al., 2013; Goodman & Shi, 1985). Rock fragmentation is the distribution of fragment size of blasted rock material. It is used as an index in the mining and quarry industry to estimate the efficiency of bench blasting.
