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

Indraratna, B; Ngo, NT; Rujikiatkamjorn, C; Vinod, JS

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

Indraratna, B

Ngo, NT Rujikiatkamjorn, C

Vinod, JS

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Publisher:: ASCE-AMER SOC CIVIL ENGINEERS
Publication Type:: Journal Article
Citation:: International Journal of Geomechanics, 2014, 14, (1), pp. 34-44
Issue Date:: 2014-01-01

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Field	Value	Language
dc.contributor.author	Indraratna, B https://orcid.org/0000-0002-9057-1514
dc.contributor.author	Ngo, NT
dc.contributor.author	Rujikiatkamjorn, C https://orcid.org/0000-0001-8625-2839
dc.contributor.author	Vinod, JS
dc.date.accessioned	2022-07-28T00:19:14Z
dc.date.available	2022-07-28T00:19:14Z
dc.date.issued	2014-01-01
dc.identifier.citation	International Journal of Geomechanics, 2014, 14, (1), pp. 34-44
dc.identifier.issn	1532-3641
dc.identifier.issn	1943-5622
dc.identifier.uri	http://hdl.handle.net/10453/159235
dc.description.abstract	This paper presents the three-dimensional discrete element method (DEM) that was used to study the shear behavior of fresh and coal fouled ballast in direct shear testing. The volumetric changes and stress-strain behavior of fresh and fouled ballast were simulated and compared with the experimental results. Clump logic in particle flow code in three dimensions (PFC3D) incorporated in a subroutine was used to simulate irregular-shaped particles in which groups of 10-20 spherical balls were clumped together in appropriate sizes to simulate ballast particles. Fouled ballast with a various void contaminant index (VCI) ranging from 20 to 70% VCI was modeled by injecting a specified number of miniature spherical particles into the voids of fresh ballast. The DEM simulation captures the behavior 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 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. © 2014 American Society of Civil Engineers.
dc.language	English
dc.publisher	ASCE-AMER SOC CIVIL ENGINEERS
dc.relation.ispartof	International Journal of Geomechanics
dc.relation.isbasedon	10.1061/(ASCE)GM.1943-5622.0000264
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	0905 Civil Engineering, 0914 Resources Engineering and Extractive Metallurgy
dc.subject.classification	General Mathematics
dc.title	Behavior of fresh and fouled railway ballast subjected to direct shear testing: Discrete element simulation
dc.type	Journal Article
utslib.citation.volume	14
utslib.for	0905 Civil Engineering
utslib.for	0914 Resources Engineering and Extractive Metallurgy
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
utslib.copyright.status	open_access	*
dc.date.updated	2022-07-28T00:18:37Z
pubs.issue	1
pubs.publication-status	Published
pubs.volume	14
utslib.citation.issue	1

Abstract:

This paper presents the three-dimensional discrete element method (DEM) that was used to study the shear behavior of fresh and coal fouled ballast in direct shear testing. The volumetric changes and stress-strain behavior of fresh and fouled ballast were simulated and compared with the experimental results. Clump logic in particle flow code in three dimensions (PFC3D) incorporated in a subroutine was used to simulate irregular-shaped particles in which groups of 10-20 spherical balls were clumped together in appropriate sizes to simulate ballast particles. Fouled ballast with a various void contaminant index (VCI) ranging from 20 to 70% VCI was modeled by injecting a specified number of miniature spherical particles into the voids of fresh ballast. The DEM simulation captures the behavior 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 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. © 2014 American Society of Civil Engineers.

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http://hdl.handle.net/10453/159235