The mechanism and effects of subgrade fluidisation under ballasted railway tracks

Indraratna, B; Singh, M; Nguyen, TT

The mechanism and effects of subgrade fluidisation under ballasted railway tracks

Indraratna, B

Singh, M Nguyen, TT

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Publisher:: Springer Science and Business Media LLC
Publication Type:: Journal Article
Citation:: Railway Engineering Science, 2020, 28, (2), pp. 113-128
Issue Date:: 2020-06-01

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Field	Value	Language
dc.contributor.author	Indraratna, B https://orcid.org/0000-0002-9057-1514
dc.contributor.author	Singh, M
dc.contributor.author	Nguyen, TT
dc.date.accessioned	2021-01-14T03:57:36Z
dc.date.available	2021-01-14T03:57:36Z
dc.date.issued	2020-06-01
dc.identifier.citation	Railway Engineering Science, 2020, 28, (2), pp. 113-128
dc.identifier.issn	2662-4753
dc.identifier.issn	2662-4745
dc.identifier.uri	http://hdl.handle.net/10453/145422
dc.description.abstract	© 2020, The Author(s). The rapid growth in railway infrastructure and the construction of high-speed heavy-haul rail network, especially on ground that is basically unsuitable, poses challenges for geotechnical engineers because a large part of the money invested in the development of railway lines is often spent on track maintenance. In fact around the world, the mud pumping of subgrade fines is one of the common reasons why track performance deteriorates and track stability is hindered. This article presents a series of laboratory tests to examine following aspects of mud pumping: (1) the mechanisms of subgrade fluidisation under undrained condition, (2) the effects of mud pumping on the engineering characteristics of ballast, and (3) the use of vertical drains to stabilize subgrade under cyclic loads. The undrained cyclic triaxial testing on vulnerable soft subgrade was performed by varying the cyclic stress ratio (CSR) from 0.2 to 1.0 and the loading frequency f from 1.0 to 5.0 Hz. It is seen from the test results that for a specimen compacted at an initial dry density of 1790 kg/m3, the top portion of the specimen fluidises at CSR = 0.5, irrespective of the applied loading frequency. Under cyclic railway loading, the internal redistribution of water at the top of the subgrade layer softens the soil and also reduces its stiffness. In response to these problems, this paper explains how the inclusion of vertical drains in soft subgrade will help to prevent mud pumping by alleviating the build-up of excess pore pressures under moving train loads.
dc.language	en
dc.publisher	Springer Science and Business Media LLC
dc.relation	http://purl.org/au-research/grants/arc/LP160101254
dc.relation.ispartof	Railway Engineering Science
dc.relation.isbasedon	10.1007/s40534-020-00210-1
dc.rights	info:eu-repo/semantics/restrictedAccess
dc.title	The mechanism and effects of subgrade fluidisation under ballasted railway tracks
dc.type	Journal Article
utslib.citation.volume	28
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
pubs.organisational-group	/University of Technology Sydney
utslib.copyright.status	closed_access	*
dc.date.updated	2021-01-14T03:56:55Z
pubs.issue	2
pubs.publication-status	Published
pubs.volume	28
utslib.citation.issue	2

Abstract:

© 2020, The Author(s). The rapid growth in railway infrastructure and the construction of high-speed heavy-haul rail network, especially on ground that is basically unsuitable, poses challenges for geotechnical engineers because a large part of the money invested in the development of railway lines is often spent on track maintenance. In fact around the world, the mud pumping of subgrade fines is one of the common reasons why track performance deteriorates and track stability is hindered. This article presents a series of laboratory tests to examine following aspects of mud pumping: (1) the mechanisms of subgrade fluidisation under undrained condition, (2) the effects of mud pumping on the engineering characteristics of ballast, and (3) the use of vertical drains to stabilize subgrade under cyclic loads. The undrained cyclic triaxial testing on vulnerable soft subgrade was performed by varying the cyclic stress ratio (CSR) from 0.2 to 1.0 and the loading frequency f from 1.0 to 5.0 Hz. It is seen from the test results that for a specimen compacted at an initial dry density of 1790 kg/m3, the top portion of the specimen fluidises at CSR = 0.5, irrespective of the applied loading frequency. Under cyclic railway loading, the internal redistribution of water at the top of the subgrade layer softens the soil and also reduces its stiffness. In response to these problems, this paper explains how the inclusion of vertical drains in soft subgrade will help to prevent mud pumping by alleviating the build-up of excess pore pressures under moving train loads.

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http://hdl.handle.net/10453/145422