Authors: Huaman, A

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Huaman, A 2023, 'Geotechnical design considerations for ‘nose’ geometries in pit design', in PM Dight (ed.), SSIM 2023: Third International Slope Stability in Mining Conference, Australian Centre for Geomechanics, Perth, pp. 201-214,

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Convex geometries in open pits, also known as ‘nose’ or ‘bullnose’ slopes, are generally considered sectors with high potential to develop sliding instabilities. Despite this, within the current state of practice, design considerations for these sectors are scarce or limited to certain types of rock mass conditions. Practical experience has shown that the performance of this type of slope geometry heavily relies on the effects of stress redistribution given the slope convexity, the competency of the rock being excavated, the presence of major and minor geological structures as well as operational factors that may include blasting damage. In this light, this paper reviews the technical literature pertaining to geotechnical design considerations for convex and concave slope geometries and presents examples where the effect of deconfinement and the influence of lateral stresses are evaluated through three-dimensional numerical modelling. The effect of convexity (plan curvature) on slope stability is analysed by evaluating ‘nose’ geometries assuming idealised slope geometries and isotropic homogeneous rock masses with low to medium geotechnical quality.

Keywords: nose geometry, bullnose, convex slope, lateral stress, deconfinement

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