Controlling the effects of stress and seismicity in a sublevel caving operation

Abstract

The Ernest Henry mine (EHM) in Queensland, Australia is developed to a depth of just over 1 km, and current active production cave levels have reached a depth of 730 m. Caving started just below the pit floor at a depth of 535 m, and is progressing deeper. The impact of stress and seismicity with increasing depth requires ongoing review and re-assessment of established practices and standards, and the implementation of new measures where required. Adverse effects of stress and the associated seismicity can have a significant impact on the safety, production and morale at a mine site. At EHM, an inclined sublevel caving operation, the geometry of the orebody and increasing depth provides for some interesting stress and seismic impacts, which are actively monitored and assessed. This paper outlines some of the observed rock mass responses, the impacts these had, and ongoing measures implemented to provide stability in an increasingly challenging environment.