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, Australian Centre for Geomechanics, Perth, pp. 273-290, https://doi.org/10.36487/ACG_rep/1511_15_Potgieter
The X41 shaft at Mount Isa Mines is one of the two vertical shafts and one of the three main accesses used to transport men and material to the underground copper mine. The X41 shaft is located on the eastern edge of the orebody. The X41 shaft is intersected by a number of geological features, most notable of these are the W41 fault, the W42 fault and the basement contact zone. The extraction of the orebody has allowed the block formed by these structures to rotate. The rotation has resulted in deformation to the shaft barrel, which in turn has resulted in damage to the shaft lining and deformation to the shaft steelwork. This deformation was first identified in the early 1980s. Due to the deformation and associated damage, a shaft pillar was put in place to protect the shaft. As the mine approaches its end of life, the relative value of the ore contained within the shaft pillar has increased considerably. An investigation was undertaken to determine the probable impacts to shaft operations if ore within this shaft pillar were to be extracted.
This paper discusses the assessments that were undertaken to determine the extent and rates of deformation that are expected to occur due to the mining operations. It describes the instrumentation that is being used to verify these predictions. Finally, it discusses the operational controls required to safely extract portions of the shaft pillar while allowing it to maintain operations supplying workers and material to the underground mine.
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