Performance of Ballast Influenced by Deformation and Degradation: Laboratory Testing and Numerical Modeling

Indraratna, B; Ngo, T; Rujikiatkamjorn, C

Performance of Ballast Influenced by Deformation and Degradation: Laboratory Testing and Numerical Modeling

Indraratna, B

Ngo, T Rujikiatkamjorn, C

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Publisher:: ASCE-AMER SOC CIVIL ENGINEERS
Publication Type:: Journal Article
Citation:: International Journal of Geomechanics, 2020, 20, (1)
Issue Date:: 2020-01-01

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Field	Value	Language
dc.contributor.author	Indraratna, B https://orcid.org/0000-0002-9057-1514
dc.contributor.author	Ngo, T
dc.contributor.author	Rujikiatkamjorn, C https://orcid.org/0000-0001-8625-2839
dc.date.accessioned	2021-03-26T02:04:18Z
dc.date.available	2021-03-26T02:04:18Z
dc.date.issued	2020-01-01
dc.identifier.citation	International Journal of Geomechanics, 2020, 20, (1)
dc.identifier.issn	1532-3641
dc.identifier.issn	1943-5622
dc.identifier.uri	http://hdl.handle.net/10453/147542
dc.description.abstract	© 2019 American Society of Civil Engineers. This paper presents a study on the deformation and degradation responses of railway ballast using large-scale laboratory testing and computational modeling approaches. A series of large-scale triaxial tests were carried out to investigate the ballast breakage responses under cyclic train loading subjected to varying frequencies, f=10-40 Hz. The role of recycled rubber energy-absorbing mats (REAMs) on reducing ballast breakage was also examined. Laboratory test results show that the ballast experiences significant degradation (breakage) and deformation, while the inclusion of REAMs can reduce the ballast breakage up to about 35%. Numerical modeling using the coupled discrete-continuum approach [coupled discrete-element method-finite-difference method (DEM-FDM)] is introduced to provide insightful understanding on the deformation and breaking of ballast under cyclic loading. Discrete ballast grains were simulated by bonding of many circular elements together at appropriate sizes and locations. Selected cylinders located at corners, surfaces, and sharp edges of the simulated particles were connected by parallel bonds; and when those bonds were broken, they were considered to represent ballast breakage. The subgrade and rubber mat were simulated as a continuum media using FDM. The predicted axial strain ϵa and volumetric strain ϵv obtained from the coupled DEM-FDM model are in good agreement with those measured in the laboratory. The model was then used to explore micromechanical aspects of ballast aggregates including the evolution of particle breakage, contact force distributions, and orientation of contacts during cyclic loading. These findings are imperative for a more insightful understanding of the breakage behavior of ballast from the perspective of microstructure characteristics of discrete particle assemblies.
dc.language	English
dc.publisher	ASCE-AMER SOC CIVIL ENGINEERS
dc.relation	http://purl.org/au-research/grants/arc/IC170100006
dc.relation.ispartof	International Journal of Geomechanics
dc.relation.isbasedon	10.1061/(ASCE)GM.1943-5622.0001515
dc.rights	info:eu-repo/semantics/closedAccess
dc.subject	0905 Civil Engineering, 0914 Resources Engineering and Extractive Metallurgy
dc.subject.classification	General Mathematics
dc.title	Performance of Ballast Influenced by Deformation and Degradation: Laboratory Testing and Numerical Modeling
dc.type	Journal Article
utslib.citation.volume	20
utslib.for	0905 Civil Engineering
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	closed_access	*
dc.date.updated	2021-03-26T02:04:15Z
pubs.issue	1
pubs.publication-status	Published
pubs.volume	20
utslib.citation.issue	1

Abstract:

© 2019 American Society of Civil Engineers. This paper presents a study on the deformation and degradation responses of railway ballast using large-scale laboratory testing and computational modeling approaches. A series of large-scale triaxial tests were carried out to investigate the ballast breakage responses under cyclic train loading subjected to varying frequencies, f=10-40 Hz. The role of recycled rubber energy-absorbing mats (REAMs) on reducing ballast breakage was also examined. Laboratory test results show that the ballast experiences significant degradation (breakage) and deformation, while the inclusion of REAMs can reduce the ballast breakage up to about 35%. Numerical modeling using the coupled discrete-continuum approach [coupled discrete-element method-finite-difference method (DEM-FDM)] is introduced to provide insightful understanding on the deformation and breaking of ballast under cyclic loading. Discrete ballast grains were simulated by bonding of many circular elements together at appropriate sizes and locations. Selected cylinders located at corners, surfaces, and sharp edges of the simulated particles were connected by parallel bonds; and when those bonds were broken, they were considered to represent ballast breakage. The subgrade and rubber mat were simulated as a continuum media using FDM. The predicted axial strain ϵa and volumetric strain ϵv obtained from the coupled DEM-FDM model are in good agreement with those measured in the laboratory. The model was then used to explore micromechanical aspects of ballast aggregates including the evolution of particle breakage, contact force distributions, and orientation of contacts during cyclic loading. These findings are imperative for a more insightful understanding of the breakage behavior of ballast from the perspective of microstructure characteristics of discrete particle assemblies.

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http://hdl.handle.net/10453/147542