Discrete element modelling of cyclic behaviour of granular materials

Sitharam, Thallak G (2003) Discrete element modelling of cyclic behaviour of granular materials. In: Geotechnical and Geological Engineering, 21 (4). pp. 297-329.

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Abstract

Discrete Element Modeling (DEM) of cyclic behavior of granular material has been attempted to understand liquefaction behavior of sands. A series of cyclic biaxial tests in both undrained and drained conditions with constant stress and strain amplitudes were performed on assemblage of loose and dense systems. Tests are conducted on monodisperse (uniform) and polydisperse (well graded) samples. From this study, it has been shown that DEM can simulate the cyclic behavior of sands very satisfactorily. Characteristic features, i.e., occurrence of large plastic strains and changing over from contractile to dilative behavior beyond the phase transformation angle, anisotropy of reduced strength on the extension side etc are very well reflected in numerical simulations. Liquefaction of loose assemblage seems to be mainly due to continued and cumulative loss of co-ordination number under each cycle as there is a reversal of loading direction and hence a continuous reorientation of fabric. There is no cumulative loss of co-ordination number in dense states because the stress ratios are mostly higher than the phase transformation level where the fabric has reached a limiting orientation. Micro mechanical explanations to the macroscopic behavior of the disc assemblage under cyclic loading are presented in terms of the force and fabric anisotropy coefficients.

Item Type:	Journal Article
Publication:	Geotechnical and Geological Engineering
Publisher:	Springer Netherlands
Additional Information:	Copyright of this article belongs to Springer Netherlands.
Keywords:	Liquefaction;Numerical modeling;Repeated loading;Sands
Department/Centre:	Division of Mechanical Sciences > Civil Engineering
Date Deposited:	05 Feb 2007
Last Modified:	19 Sep 2010 04:34
URI:	http://eprints.iisc.ac.in/id/eprint/9669

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