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Particle shape factors and fractal dimension after large shear strains in carbonate sand

Zhang, X; Hu, W; Scaringi, G; Baudet, BA; Han, W; (2018) Particle shape factors and fractal dimension after large shear strains in carbonate sand. Géotechnique Letters , 8 (1) pp. 73-79. 10.1680/jgele.17.00150. Green open access

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Abstract

Changes of grain shape and breakage under compression and shearing can affect the mechanical properties of granular soils. In this work, a parametric study was performed through ring-shear tests on carbonate sand, under σn = 600 kPa and v = 6 mm/min, to evaluate the evolution of particle breakage, fractal dimension and particle shape with the shear strain. Breakage mostly occurred for γ ≤ 4000%, with a consequent increase in fractal dimension. Under larger strains, only negligible breakage occurred, while the particles became more rounded, and the fractal dimension increased only slightly. Interestingly, the shape factors also tend towards similar values for particles of any size larger than 0·063 mm after large shearing. This indicates that these particles tend towards a self-similar form – and hence scale invariance – when the grading reaches a fractal particle size distribution. Some tests were also performed on soils with different median size and coefficient of uniformity, which showed that larger particles and poorly graded soils are more prone to breakage, and are closer to a fractal distribution after shearing. Conversely, the final particle shape did not seem to be affected by grading and size significantly.

Type: Article
Title: Particle shape factors and fractal dimension after large shear strains in carbonate sand
Open access status: An open access version is available from UCL Discovery
DOI: 10.1680/jgele.17.00150
Publisher version: https://doi.org/10.1680/jgele.17.00150
Language: English
Additional information: This is the published version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: sands, particle crushing/crushability, fractals, particle-scale behaviour, laboratory tests
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10050413
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