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Behavior of fresh and fouled railway ballast subjected to direct shear testing: discrete element simulation

Journal Article


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Abstract


  • This paper presents the three-dimensional discrete element method (DEM) that was used to study

    the shear behaviour of fresh and coal fouled ballast in direct shear testing. The volumetric

    changes and stress-strain behaviour of fresh and fouled ballast were simulated and compared

    with the experimental results. ‘Clump logic’ in Particle Flow Code (PFC3D) incorporated in a

    MATLAB Code was used to simulate irregular shaped particles in which groups of ten to twenty

    spherical balls were clumped together in appropriate sizes to simulate ballast particles. Fouled

    ballast with various Void Contaminant Index (VCI), ranging from 20%VCI to 70%VCI, were

    modelled by injecting a specified number of miniature spherical particles into the voids of fresh

    ballast. The DEM simulation captures the behaviour of fresh and fouled ballast as observed in

    the laboratory showing that the peak shear stress of the ballast assembly decreases and the

    dilation of fouled ballast increases with an increasing of VCI. Furthermore, the DEM also

    provides insight to the distribution of contact force chains and particle displacement vectors,

    which cannot be determined experimentally. These micromechanical observations clearly justify

    the formation of a shear band and the evolution of volumetric changes during shearing. The

    reduced maximum contact force associated with increased particle contact area due to fouling

    explains the decreased breakage of fouled ballast. An acceptable agreement was found between

    the DEM model predictions and laboratory data.

Publication Date


  • 2014

Citation


  • Indraratna, B., Ngo, N., Rujikiatkamjorn, C. & Vinod, J. S. (2014). Behavior of fresh and fouled railway ballast subjected to direct shear testing: discrete element simulation. International Journal of Geomechanics, 14 (1), 34-44.

Scopus Eid


  • 2-s2.0-84892834921

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2816&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/1807

Has Global Citation Frequency


Number Of Pages


  • 10

Start Page


  • 34

End Page


  • 44

Volume


  • 14

Issue


  • 1

Place Of Publication


  • United States

Abstract


  • This paper presents the three-dimensional discrete element method (DEM) that was used to study

    the shear behaviour of fresh and coal fouled ballast in direct shear testing. The volumetric

    changes and stress-strain behaviour of fresh and fouled ballast were simulated and compared

    with the experimental results. ‘Clump logic’ in Particle Flow Code (PFC3D) incorporated in a

    MATLAB Code was used to simulate irregular shaped particles in which groups of ten to twenty

    spherical balls were clumped together in appropriate sizes to simulate ballast particles. Fouled

    ballast with various Void Contaminant Index (VCI), ranging from 20%VCI to 70%VCI, were

    modelled by injecting a specified number of miniature spherical particles into the voids of fresh

    ballast. The DEM simulation captures the behaviour of fresh and fouled ballast as observed in

    the laboratory showing that the peak shear stress of the ballast assembly decreases and the

    dilation of fouled ballast increases with an increasing of VCI. Furthermore, the DEM also

    provides insight to the distribution of contact force chains and particle displacement vectors,

    which cannot be determined experimentally. These micromechanical observations clearly justify

    the formation of a shear band and the evolution of volumetric changes during shearing. The

    reduced maximum contact force associated with increased particle contact area due to fouling

    explains the decreased breakage of fouled ballast. An acceptable agreement was found between

    the DEM model predictions and laboratory data.

Publication Date


  • 2014

Citation


  • Indraratna, B., Ngo, N., Rujikiatkamjorn, C. & Vinod, J. S. (2014). Behavior of fresh and fouled railway ballast subjected to direct shear testing: discrete element simulation. International Journal of Geomechanics, 14 (1), 34-44.

Scopus Eid


  • 2-s2.0-84892834921

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2816&context=eispapers

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/1807

Has Global Citation Frequency


Number Of Pages


  • 10

Start Page


  • 34

End Page


  • 44

Volume


  • 14

Issue


  • 1

Place Of Publication


  • United States