LAUSR

Abstract Rock related fatalities and injuries are still reported at an alarming rate in South Africa’s deep to ultra-deep level (1500 m to 4500 m from earth surface) hard rock mining/tunneling. Most of these events are associated with seismic hazards (rockburst) or intersecting hazardous features (old tunnels, seismic active geological features, etc). As a result, researchers have been called upon to provide solutions to the problem, given that, most solutions were in the form of numerical approximation of the rock behavior, requesting critical skills given to young rock engineers and seismologists. Nonetheless, the solutions provided appears to be inadequate in reducing the re-occurrence of rock-related fatalities and injuries within the mines. In this study, a modified Ground Penetrating Radar was used to distinguish between seismic and non-seismic hazards that were not identified using conventional and numerical approaches in hard rock mining/tunneling. The instrument was used in several case studies; firstly, to validate the effectiveness of preconditioning practice, secondly, to monitor the performance of the in-stope pillar, thirdly, to identify unknown seismic and non-seismic active geological features ahead of the tunnel faces and lastly to identifying old tunnels excavations ahead, above or below the excavation and monitor the quality backfill support installation. The GPR signal model, its shortcomings and suggestions are also described. Nevertheless, the instrument was found to provide reasonable results. The study proposed that the GPR scanner should have specific forward numerical software that incorporates inputs parameters of different material and it is also proposed that the GPR scan should always be calibrated by the borehole periscope. The study maintained that the instrument has the potential of reducing rock-related injuries, fatalities and also improve the mining/ tunnel designs; by predicting the hazardous features and the fracture frequency ahead of the mining/ tunnel faces as well within the rock pillar.