Authors: Linero, S; Fityus, S; Simmons, JV; Azéma, E; Estrada, N; Dixon, J

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Linero, S, Fityus, S, Simmons, JV, Azéma, E, Estrada, N & Dixon, J 2020, 'Influence of particle size-shape correlation on the shear strength of scaled samples of coarse mine waste', in PM Dight (ed.), Proceedings of the 2020 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 667-676,

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Coarse materials like rockfill and coarse mine waste must be scalped or scaled for shear strength testing in the laboratory as the size of commercial equipment is not big enough to test the full-scale material. Samples of coarse material prepared for testing differ from their prototypes in the characteristic sizes of the particles and/or the form of the particle size distribution (PSD) curve. The representativeness of the shear strength parameter determined in the laboratory on scaled samples is questionable, nevertheless they are typically used for geotechnical design without additional consideration. The particle shapes in a natural mine waste of colluvium sediments derived from eroded ancient sedimentary rocks from the Pilbara region of Australia was analysed and a correlation between shape and size was identified. The fragments have a particle shape ranging from slabs to sub-equant blocks with a tendency of larger particles to be flatter and platy. Therefore, material scaling for shear strength determinations inevitably alters not only the size of particles and proportion of sizes, but also the characteristic shapes of the material particles as it implies substituting larger (slabs) particles by smaller (sub-equant) particles. The direct-shear shear strength of a prototype sample of the colluvium sediment was evaluated in the laboratory, as well as two different scaled representations (models) with reduced maximum particle size. The scaled specimens, composed of more equant fragments due to the nature of the size-shape correlation, showed lower shear strength compared with the prototype sample. Simulations with a discrete element method reveal that the changes in the shear strength observed when altering the PSD are not due to the change in particle sizes. Instead, these changes in shear strength result from the variation of the particle shapes induced by the alteration of the PSD. This suggests that particle shape is a higher order factor than particle sizes and PSD shape on the shear strength of granular materials. This finding highlights the importance of particle shape quantification in soil classification and its consideration in activities such as sampling, sub-sampling, and scaling of coarse materials for geotechnical testing.

Keywords: material scaling, shear strength of mine waste, particle morphology, large-scale testing

Azéma, E, Linero, S, Estrada, N & Lizcano, A 2017a, ‘Does modifying the particle size distribution of a granular material (i.e. material scalping) alter its shear strength?’, EPJ Web of Conferences, vol. 140.
Azéma, E, Linero, S, Estrada, N & Lizcano, A 2017b, ‘Shear strength and microstructure of polydisperse packings: The effect of size span and shape of particle size distribution’, Physical Review E, vol. 96, issue 2, pp. 022902-1–022902-10.
Azéma, E & Radjai, F 2010, ‘Stress-strain behavior and geometrical properties of packings of elongated particles’, Physical Review E, vol. 81, issue 5, pp. 051304-1–051304-17.
Blott, SJ & Pye, K 2008, ‘Particle shape: A review and new methods of characterization and classification’, Sedimentology, vol. 55, pp. 31–63.
Cantor, D, Azéma, E, Sornay, P & Radjai, F 2018, ‘Rheology and structure of polydisperse three-dimensional packings of spheres’, Physical Review E, vol. 98, issue 5, pp. 052910-1–052910-11.
Dubois, F, Acary, V & Jean, M 2018, ‘The contact dynamics method: A non-smooth story’, Comptes Rendus Mécanique, vol. 346, issue 3, pp. 247–262.
Estrada, N 2016, ‘Effects of the grain size distribution on the packing fraction and shear strength of frictionless disk packings’, Physical Review E, vol. 94, pp. 1–7.
Holtz, WG & Gibbs, HJ 1956, ‘Triaxial shear test on pervious gravelly soils’, Soil Mechanics and Foundation Division ASCE, vol. 82, pp. 1–22.
Hyslip, JP & Vallejo, LE 1997, ‘Fractal analysis of the roughness and size distribution of granular materials’, Engineering Geology, vol. 48, issue 3–4, pp. 231–244.
Krumbein, WC 1941, ‘Measurement and geological significance of shape and roundness of sedimentary particles’, Journal of Sedimentary Petrology, vol. 11, issue 2, pp. 64–72.
Lindholm, R 2012, A practical approach to sedimentology, Springer Science & Business Media, Berlin.
Linero, S, Fityus, S, Simmons, J & Lizcano, A 2019a, ‘Scaling of coarse granular material for shear strength determination’, manuscript submitted for publication.
Linero, S, Bradfield, L, Gibson, R, Fityus, S, Simmons, J & Lizcano, A 2019b, ‘Design of a 720 mm square direct shear box and investigation of the impact of boundary conditions on measured strength’, manuscript accepted for publication in Geotechnical Testing Journal.
Linero, S, Azéma, E, Estrada, N, Fityus, S, Simmons, J & Lizcano, A 2019c, ‘Impact of grading on steady-state strength’, Geotechnique Letters, vol. 9, issue 4, pp. 328–333, 10.1680/jgele.18.00216
Linero, S, Fityus, S, Simmons, J & Cassidy, J 2017, ‘Trends in the evolution of particle morphology with size in colluvial deposits overlying channel iron deposits’, EPJ Web of Conferences, vol. 140.
Linero, S, Palma, C & Apablaza, R 2007, ‘Geotechnical characterization of waste material in very high dumps with large scale triaxial testing’, in Y Potvin (ed.), Proceedings of the 2007 International Symposium on Rock Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp, 59–75.
Lindholm, R 2012, A practical approach to sedimentology, Springer Science & Business Media, Berlin.
Marachi, ND, Chan, CK & Seed, B 1972, ‘Evaluation of properties of rock fill materials’, Journal of Soil Mechanics and Foundation Division, vol. 98, issue SM1, pp. 95–115.
Marsal, RJ 1972, Resistencia y Compresibilidad de Enrocamientos y Gravas (Strength and compressibility of rock-fills), Instituto de Ingenierıa, UNAM, Mexico City.
Nguyen, DH, Azéma, E, Sornay, P & Radjai, F 2015, ‘Effects of shape and size polydispersity on strength properties of granular materials’, Physical Review E, vol. 91, pp. 1–9.
Ovalle, C 2013, Contribution a l’etude de la rupture des grains dans les materiaux granulaires (Contribution to the study of grain fracture in granular materials), PhD Thesis, École Centrale de Nantes, Nantes.
Palma, C, Linero, S & Apablaza, R 2009, ‘Caracterización geotécnica de materials de lastre en botaderos de gran altura mediante ensayos triaxiales y odométricos de gran tamaño’ (Geotechnical characterisation of waste material in very high dumps with large-scale triaxial and odometer testing), Proceedings of the III Conferencia Sudamericana de Ingenieros Geotécnicos, International Society for Soil Mechanics and Geotechnical Engineering, Córdoba.
Santamaria, C & Narsilio, G 2008, Clasificación de suelos: Fundamento físico, prácticas actuales y recommendations, Proceedings of the 50th Anniversary Conference, Sociedad Venezolana de Geotecnia, Venezuela.
Stimpson, B 1980, ‘A suggested technique for determining the basic friction angle of rocks surfaces using core’, International Journal of Rock Mechanics and Mining Sciences and Geomechanics, vol. 18, pp. 63–65.
Voivret, C, Radjai, F, Delenne, JY & El Youssoufi, MS 2007, ‘Space-filling properties of polydisperse granular media’, Physical Review E., vol. 76, pp. 021301-1–021301-12.
Voivret, C, Radjai, F, Delenne, JY & El Youssef, MS 2009, ‘Multiscale force networks in highly polydisperse granular media’, Physical Review Letters, vol. 102, pp. 1–4.
Wadell, H 1932, ‘Volume, shape, and roundness of rock particles’, The Journal of Geology, vol. 40, issue 5, pp. 443–451.

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