Authors: Fenton, J; Maldonado, A

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Fenton, J & Maldonado, A 2023, 'Guidelines to improve geological confidence in geotechnical model definitions in Western Australian iron ore', in PM Dight (ed.), SSIM 2023: Third International Slope Stability in Mining Conference, Australian Centre for Geomechanics, Perth, pp. 115-124,

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Historically, the planning of drill programs to collect downhole data for resource modelling purposes has received limited review from a geotechnical perspective. As a result, geology models in the waste rock outside a defined resource were often produced at a low confidence level. The design acceptance criteria (DAC) for slope-design stability analysis have recently been updated to include an assessment of the geology model confidence. This has highlighted the scale of areas of low confidence in geology models for geotechnical purposes. The cost of the additional drilling required for increasing the geology model confidence can now be compared to the potential value when applying these DAC and the resultant optimised slope designs. The timing of an opportunity to increase this confidence is in the order of three to five years prior to detailed geotechnical design projects and such an opportunity had been missed prior to this improvement. This paper outlines the process of communicating the geotechnical requirements of the geology model confidence and the assessment of drill plans with regard to requirements for a highconfidence geotechnical model. An evaluation of the gaps highlighted in drill planning has been included to provide broad guidelines for assigning additional drill metres for various project types. A checklist has been compiled as a reference guide for assessing resource-planning data collection to ensure the resultant geology models will be fit for geotechnical design purposes.

Keywords: data collection, model confidence, geotechnical model

Macciotta, R, Creighton, A & Martin, CD 2020, ‘Design acceptance criteria for operating open-pit slopes: an update’, CIM Journal, vol. 11, no. 4, pp. 248–265.
Wesseloo, J & Read, J 2009, ‘Acceptance criteria’, in J Read & P Stacey (eds), Guidelines for Open Pit Slope Design, CSIRO Publishing, Melbourne.

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