Griffith, M. D & Michelin, FCD 2024, 'Ventilation network modelling for acceleration from air blasts from caving events', in Daniel Johansson & Håkan Schunnesson (eds), MassMin 2024: Proceedings of the International Conference & Exhibition on Mass Mining, Luleå University of Technology, Luleå, pp. 604-613, https://doi.org/10.36487/ACG_repo/2435_D-12
(https://papers.acg.uwa.edu.au/p/2435_D-12/)
Abstract: With mining methods involving large underground voids, a significant risk to be managed is the air blast resulting from intentional or accidental caving events. There are difficult to determine factors influencing the extent of a caving air blast, such as, the amount of airflow pushed from the void drawpoints and through the porous falling rock, as well as the ability of seals on the void and throughout the mine to resist overpressure. Another factor is the airflow resistance of the entire mine, which will mitigate the blast to some extent; but this is a difficult factor to model in a mine ventilation network solver typically steady state in nature. The overpressure from a large air blast event will introduce a strong acceleration of the airflow, which will in turn increase the frictional pressure loss. This is problematic for a ventilation network solver that models airflows as if the overpressure from the air blast event is steady state, leading in general to an overestimation of the airflow velocities attained. This study presents a method for better simulating the airflow acceleration and deceleration, using the steady state solver to attain a temporary steady state airflow, towards which the actual airflows are relaxed over a certain timestep. This dynamic airflow is used to recalculate pressure losses through the mine, which are then accounted for in the diminishing overpressure in the caved void, leading to a better representation of airflow velocities during an air blast event, which can be used to inform risk management.