Impact of Bituminous Subballast on Railroad Track Deformation Considering Atmospheric Actions
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 137, Issue 3
Abstract
High-speed ballasted track design standards usually require the use of sand and gravel layers as subballast to fulfill an accurate protection of the formation layers, not only against traffic loads, but also against the effects of weather. Seasonal changes in soil water content, or suction changes, are responsible for cyclic volumetric strains on railroad trackbed layers, thus on the infrastructure. Being almost completely water-resistant when compared with granular-only layers, bituminous subballast offers a higher protection of the subgrade, consequently improving its behavior along the infrastructure life cycle. This question is investigated through the comparison of the performance of the track formation against atmospheric actions, taking into consideration the unsaturated state of the geomaterials. The method adopted consists of modeling the vertical displacements of both bituminous and granular subballast designs through a finite-element coupled thermo-hydro-mechanical (THM) analysis. The comparison of the two design solutions confirms that the adoption of a bituminous subballast layer might allow important reductions in seasonal vertical displacements.
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Acknowledgments
This research is being supported by the Portuguese National Science Foundation (FCT) since 2008 (Project Reference UNSPECIFIEDPTDC/ECM/70571/2006). The writers would like to thank the support and collaboration of Dr. S. Olivella with CODE_BRIGHT.
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Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 137 • Issue 3 • March 2011
Pages: 288 - 292
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Nov 25, 2009
Accepted: Aug 24, 2010
Published online: Sep 2, 2010
Published in print: Mar 1, 2011
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