A novel model for air velocities in airblast events in block caving mining

Abstract

An airblast is a sudden collapse of a large volume of rock that causes air to rapidly flow through an underground opening as a result of air being compressed in a small space. Through the solution of the Ergun equation for turbulent flows in porous media, we have modeled air gusts in this paper. To resolve the issue, we use the finite element method (FEM). At a drawbell’s associated drawpoints, air flows and velocities are calculated. A series of numerical simulations are run while taking into account different arrangements of the average size of the rocks in the fractured zone and the air gap length, Lag, which is implicitly represented as the boundary condition for incoming air velocity at the muckpile. We propose a novel mathematical function that, using scaling arguments, expresses the maximum air gust velocity at the drawpoints as a function of the air gap height and average particle diameter. Designing geomechanical risk mitigation strategies for airblast events during block caving mining can take advantage of the findings in this paper.