Constriction size distributions of granular filters: a numerical study

Shire, T. and O'Sullivan, C. (2016) Constriction size distributions of granular filters: a numerical study. Géotechnique, 66(10), pp. 826-839. (doi: 10.1680/jgeot.15.P.215)

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The retention capability of granular filters is controlled by the narrow constrictions connecting the voids within the filter. The theoretical justification for empirical filter rules used in practice includes consideration of an idealised soil fabric in which constrictions form between co-planar combinations of spherical filter particles. This idealised fabric has not been confirmed by experimental or numerical observations of real constrictions. This paper reports the results of direct, particle-scale measurement of the constriction size distribution (CSD) within virtual samples of granular filters created using the discrete-element method (DEM). A previously proposed analytical method that predicts the full CSD using inscribed circles to estimate constriction sizes is found to poorly predict the CSD for widely graded filters due to an over-idealisation of the soil fabric. The DEM data generated are used to explore quantitatively the influence of the coefficient of uniformity, particle size distribution and relative density of the filter on the CSD. For a given relative density CSDs form a narrow band of similarly shaped curves when normalised by characteristic filter diameters. This lends support to the practical use of characteristic diameters to assess filter retention capability.

Item Type:Articles
Additional Information:Computing resources from Research Councils UK’s HECToR HPC (by way of EPSRC grant EP/I006761/1), the European PRACE Program and the CX1 HPC at Imperial College are gratefully acknowledged. The first author was funded by an EPSRC Doctoral Training Account.
Glasgow Author(s) Enlighten ID:Shire, Dr Thomas
Authors: Shire, T., and O'Sullivan, C.
College/School:College of Science and Engineering > School of Engineering > Infrastructure and Environment
Journal Name:Géotechnique
Publisher:ICE Publishing
ISSN (Online):1751-7656
Published Online:14 September 2016

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