Authors: Orrego, C; Lowther, R; Newcombe, G

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This paper is hosted with the kind permission of the Universidad de Chile, Eighth International Conference & Exhibition on Mass Mining, 2020.


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Orrego, C, Lowther, R & Newcombe, G 2020, 'Undercutting method selection at Cadia East PC2-3 extension', in R Castro, F Báez & K Suzuki (eds), MassMin 2020: Proceedings of the Eighth International Conference & Exhibition on Mass Mining, University of Chile, Santiago, pp. 370-384,

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The PC2-3 extension is set to be the first expansion of a previously established panel cave at Cadia East, which presents a unique boundary condition for the cave establishment and initiation. The choice of the undercutting method and the subsequent assessment of personnel exposure relating to seismic hazard was investigated through a comparative numerical modelling assessment of both the advanced and post undercut methods for the Cadia East PC2-3 extension using FLAC3D. This paper details the numerical modelling approach and interpretation of the results between the two methods spanning initial development, and undercutting. The results show a comparison of the stress abutment formation within the operating levels during cave establishment for each method coupled with a quantitative personnel exposure analysis to determine which method had the least amount of exposure of personnel working within the stress abutments. The results demonstrated that while each method had varying levels of exposure within specific areas, the overall personnel exposure is less for the post undercutting method. This finding, complemented with positive business outcomes and the implementation of safety controls including dynamic ground support, pre-conditioning, and caving rules, inclined the decision towards this method.

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