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Surface mining operations are increasingly transitioning to underground mass mining operations like block caving to extend the life of the mine. The presence of the open pit above the developing block cave will lead to complex stress–strain interactions, pit slope movements and ground deformations that may extend beyond the periphery of the pit, potentially having an adverse effect on mine infrastructure and operations within the zone of disturbance. These can be further complicated by major fault zones that crosscut the mine property. Experiences at the Palabora Copper Mine in South Africa provide one such example of a transition to block cave mining where the interactions that developed between the underground workings and overlying steep rock slopes evolved into a massive 800 m high pit slope failure. To properly assess the rock mass response to these interactions for the management of pit slope stability, surface subsidence and setback distances for mine infrastructure outside the pit rim, as well as for planning future underground development, understanding the controlling influence of geological structures on the ground response is crucial. Results are presented here from a series of 3D continuum and discontinuum numerical models that investigate the interactions between the open pit, block cave mine and large scale geological features present at Palabora. These results are compared to a detailed review of pit slope monitoring data to help provide understanding of the complex slope displacement patterns recorded and apparent pit slope kinematics.
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