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Modelling and measurements of critical train speed effects and associated track movements

Modelling and measurements of critical train speed effects and associated track movements
Modelling and measurements of critical train speed effects and associated track movements
As train speeds are increased, there is a greater likelihood of encountering critical velocity effects at sites with soft soil. These can lead to increased rates of track geometry degradation, poor ride quality and increased maintenance costs. These phenomena occur when the train speed approaches that of the Rayleigh waves of the underlying ground. A study of critical velocity effects is presented, based on a semi-analytical model of the vibration of the vehicle/track/ground system. Results from this model are compared with measured track deflections obtained at a site on a classic UK mainline at which large track displacements were observed following an increase in line speed from 160 km/h to 200 km/h. Geotechnical investigations have shown that the site is underlain by a layer of peat of low stiffness. By refining the parameters used in the model, assuming that the peat was the primary cause of the large track movements at high speed, it was possible to obtain reasonably close agreement between site measurements and the results from the model in terms of maximum deflections and frequency spectra of rail displacements. As the water table has been observed to be quite high at the site, an additional investigation is presented into the effect of the water level on the critical speed effects. Three levels of saturation are considered for the peat layer, ranging from fully saturated to relatively dry. The results suggest that a reduction in the water levels at the site is unlikely to lead to a reduction in the critical velocity effects.
Duley, A.
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Le Pen, L.
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Thompson, D.
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Powrie, W.
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Watson, G.V.R.
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Peter, M.
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Andrew, C.
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Duley, A.
6d09ebcc-097b-4c20-b9c4-cf3940a5db0f
Le Pen, L.
4a38e256-d113-4bba-b0d4-32d41995928a
Thompson, D.
bca37fd3-d692-4779-b663-5916b01edae5
Powrie, W.
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
Watson, G.V.R.
a7b86a0a-9a2c-44d2-99ed-a6c02b2a356d
Peter, M.
240e9272-9a79-45bf-8984-5543cb47f2bb
Andrew, C.
316570e5-8c28-4c46-9963-9312e1c98ce2

Duley, A., Le Pen, L., Thompson, D., Powrie, W., Watson, G.V.R., Peter, M. and Andrew, C. (2014) Modelling and measurements of critical train speed effects and associated track movements. International Conference on High Speed Rail, Birmingham, United Kingdom. 08 - 11 Dec 2014.

Record type: Conference or Workshop Item (Paper)

Abstract

As train speeds are increased, there is a greater likelihood of encountering critical velocity effects at sites with soft soil. These can lead to increased rates of track geometry degradation, poor ride quality and increased maintenance costs. These phenomena occur when the train speed approaches that of the Rayleigh waves of the underlying ground. A study of critical velocity effects is presented, based on a semi-analytical model of the vibration of the vehicle/track/ground system. Results from this model are compared with measured track deflections obtained at a site on a classic UK mainline at which large track displacements were observed following an increase in line speed from 160 km/h to 200 km/h. Geotechnical investigations have shown that the site is underlain by a layer of peat of low stiffness. By refining the parameters used in the model, assuming that the peat was the primary cause of the large track movements at high speed, it was possible to obtain reasonably close agreement between site measurements and the results from the model in terms of maximum deflections and frequency spectra of rail displacements. As the water table has been observed to be quite high at the site, an additional investigation is presented into the effect of the water level on the critical speed effects. Three levels of saturation are considered for the peat layer, ranging from fully saturated to relatively dry. The results suggest that a reduction in the water levels at the site is unlikely to lead to a reduction in the critical velocity effects.

Text
Birmingham HSR 2014 Duley et al modeling and measuring crit vel effects.pdf - Accepted Manuscript
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More information

Published date: 8 December 2014
Venue - Dates: International Conference on High Speed Rail, Birmingham, United Kingdom, 2014-12-08 - 2014-12-11
Organisations: Infrastructure Group

Identifiers

Local EPrints ID: 381370
URI: http://eprints.soton.ac.uk/id/eprint/381370
PURE UUID: c1905a76-c615-4544-aec6-65d5dff0b1bf
ORCID for L. Le Pen: ORCID iD orcid.org/0000-0002-4362-3895
ORCID for D. Thompson: ORCID iD orcid.org/0000-0002-7964-5906
ORCID for W. Powrie: ORCID iD orcid.org/0000-0002-2271-0826
ORCID for G.V.R. Watson: ORCID iD orcid.org/0000-0003-3074-5196

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Date deposited: 30 Sep 2015 16:42
Last modified: 15 Mar 2024 03:24

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Contributors

Author: A. Duley
Author: L. Le Pen ORCID iD
Author: D. Thompson ORCID iD
Author: W. Powrie ORCID iD
Author: G.V.R. Watson ORCID iD
Author: M. Peter
Author: C. Andrew

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