Leps 2.0: updated strength envelopes for rockfill based on 900 large-scale triaxial tests

Authors: Cylwik, SD; Arrieta, M; Cunning, JC; Hawley, PM

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DOI https://doi.org/10.36487/ACG_repo/2535_0.02

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Cylwik, SD, Arrieta, M, Cunning, JC & Hawley, PM 2025, 'Leps 2.0: updated strength envelopes for rockfill based on 900 large-scale triaxial tests', in JJ Potter & J Wesseloo (eds), SSIM 2025: Fourth International Slope Stability in Mining Conference, Australian Centre for Geomechanics, Perth, https://doi.org/10.36487/ACG_repo/2535_0.02

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Abstract:
This paper presents a new shear strength criterion and empirical model for rockfill and coarse mine waste rock. The model is supported by a database of over 900 large-scale triaxial tests and is intended to update and improve upon the Leps strength envelopes commonly used for rockfill materials. The nonlinear shear strength criterion uses a single physically based input parameter, can reproduce the Leps strength envelopes, transitions smoothly between strength categories, and is compatible with both shear/normal and principal stress data. An empirical model is also presented to rapidly estimate rockfill strength from void ratio and rock type, providing a practical tool for field application when laboratory testing is unavailable. The model simplifies into five strength categories and maintains predictive accuracy with minimal complexity. Statistical analysis suggests that the models are applicable for materials with a median particle size greater than 2 mm and a fines content less than 25%. Two cases are presented that demonstrate practical application of the model for a rockfill dam and a mine waste stockpile.

Keywords: rockfill, shear strength, large-scale triaxial tests, waste dumps, heap leach pads

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