Blast propagation and hazard mapping outside coal mine tunnels and shafts

Although there is a wealth of information on the emission of gas and explosions due to methane-air and/or coal dust in mines underground, the underlying threats on the surface from the explosive energy transmitted through the mine entrances have been largely overlooked. These hazards have the potential to cause injuries and loss of life. Additionally, they can lead to severe damage to the surface infrastructure surrounding the mine entrance. This study aims to establish the relationship between characteristics of blast waves emanating from the mine entries for different magnitudes of explosions and radial distances. An Advanced Blast Simulator (shock tube) was used to experimentally study the propagation of blast waves from mine entrances and over an outside mine site terrain (for mine portals) or upwards towards the sky (for mine shafts). Computational Fluid Dynamics modelling was utilised to interpret the experimental data, verify the applicability and scalability of the smallscale experimental data for actual (large) scale problems, and provide more data points for the creation of blast overpressure contours with enhanced resolution. The paper concludes with several worked examples with detailed steps and commentary for characterising explosion risk around entrances of coal mines using the results derived from the present study.