Abstract
A trial on de-stressing a dyke that was located 60 m ahead of mining faces was conducted through drilling face-perpendicular preconditioning holes that intersected and passed the dyke by two metres. A sticky explosive (Ug101s) with a density of 1.1 g/cc, charging amass of 30.4 kg, powder factor of 1.3 kg/tonne, with gassing gap and 5 m long tamping material were used. After detonating the holes, a small seismic magnitude was noted. As mining progressed towards the dyke and passing through the dyke, good ground conditions were observed. Numerical modelling was conducted to simulate rate of energy release (RER), major principal stress ahead of the mining faces and simulation of the ride. The results of the study showed a gradual decrease of sigma 1,RER and high possibility of large seismic events to occur when mining through the dyke and also increase in the ride at the vicinity of the dyke.
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