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Mitigation of railway-induced vibration by using subgrade stiffening

Mitigation of railway-induced vibration by using subgrade stiffening
Mitigation of railway-induced vibration by using subgrade stiffening
Railway-induced ground vibration is often associated with sites with soft ground. Stiffening of the subgrade beneath the railway track is one particular measure that has potential to reduce the vibration level at such sites. However, the mechanisms behind this reduction are not well understood. Here, the effects are examined in the context of two alternative approaches: (i) subgrade stiffening, where the soil directly under the track is stiffened, and (ii) stiff inclusions introduced at some depth beneath the track, sometimes known as ‘wave impeding blocks’. The efficacy of the measures is considered for different ground types in a parametric study carried out using a 2.5D coupled finite-element/boundary-element methodology. The soil is considered to consist of a soft upper layer over a stiffer substratum; corresponding homogeneous grounds are also considered. With a 6 m wide, 1 m thick, concrete block directly under the track, the vibration between 16 and 50 Hz was found to be reduced by between 4 and 10 dB for ground with a 3 m deep soft upper layer. For a deeper soft layer the reductions were greater whereas, for a stiffer ground without the soft upper layer, the reductions in vibration from this block were negligible. Slightly smaller reductions in a similar frequency region were observed when the block was positioned 1 m below the surface, suggesting that, as with stiffening directly under the track, the reduction in vibration was primarily due to the increase of the effective stiffness of the soil beneath the track rather than the effective creation of a new, thinner soil layer. Jet grouting is considered as an alternative to concrete and, although it is found to be less effective due to its comparatively low stiffness, it may still be considered as a practical measure for existing tracks on soft soil sites. The reduction in vibration from this form of soil improvement with a depth of 3 m is similar to that for a 1 m thick concrete block. Finally, results are presented for three example sites with different soil properties which show similar trends.
ground transmitted vibration, subgrade stiffening, wave impeding blocks, 2.5D modelling, finite element/boundary element methods
0267-7261
89-103
Thompson, D.J.
bca37fd3-d692-4779-b663-5916b01edae5
Jiang, J.
b034e623-ea89-4b17-88e3-4276c260db99
Toward, M.G.R.
1d10e993-e6ef-449d-bccb-1f8198169bee
Hussein, M.F.M.
97e17881-e5e7-45a4-8765-00065c2277ce
Dijckmans, A.
b37d2437-74fb-4ce7-a26d-56712b873ca7
Coulier, P.
93733f1d-0868-4f2f-87ed-96c003647ec4
Degrande, G.
c79408b0-fe8a-4b0c-a2e2-347ccd2e052a
Lombaert, G.
4e069245-6ec6-40fe-a767-46eabf4dcc2b
Thompson, D.J.
bca37fd3-d692-4779-b663-5916b01edae5
Jiang, J.
b034e623-ea89-4b17-88e3-4276c260db99
Toward, M.G.R.
1d10e993-e6ef-449d-bccb-1f8198169bee
Hussein, M.F.M.
97e17881-e5e7-45a4-8765-00065c2277ce
Dijckmans, A.
b37d2437-74fb-4ce7-a26d-56712b873ca7
Coulier, P.
93733f1d-0868-4f2f-87ed-96c003647ec4
Degrande, G.
c79408b0-fe8a-4b0c-a2e2-347ccd2e052a
Lombaert, G.
4e069245-6ec6-40fe-a767-46eabf4dcc2b

Thompson, D.J., Jiang, J., Toward, M.G.R., Hussein, M.F.M., Dijckmans, A., Coulier, P., Degrande, G. and Lombaert, G. (2015) Mitigation of railway-induced vibration by using subgrade stiffening. Soil Dynamics and Earthquake Engineering, 79, part A, 89-103. (doi:10.1016/j.soildyn.2015.09.005).

Record type: Article

Abstract

Railway-induced ground vibration is often associated with sites with soft ground. Stiffening of the subgrade beneath the railway track is one particular measure that has potential to reduce the vibration level at such sites. However, the mechanisms behind this reduction are not well understood. Here, the effects are examined in the context of two alternative approaches: (i) subgrade stiffening, where the soil directly under the track is stiffened, and (ii) stiff inclusions introduced at some depth beneath the track, sometimes known as ‘wave impeding blocks’. The efficacy of the measures is considered for different ground types in a parametric study carried out using a 2.5D coupled finite-element/boundary-element methodology. The soil is considered to consist of a soft upper layer over a stiffer substratum; corresponding homogeneous grounds are also considered. With a 6 m wide, 1 m thick, concrete block directly under the track, the vibration between 16 and 50 Hz was found to be reduced by between 4 and 10 dB for ground with a 3 m deep soft upper layer. For a deeper soft layer the reductions were greater whereas, for a stiffer ground without the soft upper layer, the reductions in vibration from this block were negligible. Slightly smaller reductions in a similar frequency region were observed when the block was positioned 1 m below the surface, suggesting that, as with stiffening directly under the track, the reduction in vibration was primarily due to the increase of the effective stiffness of the soil beneath the track rather than the effective creation of a new, thinner soil layer. Jet grouting is considered as an alternative to concrete and, although it is found to be less effective due to its comparatively low stiffness, it may still be considered as a practical measure for existing tracks on soft soil sites. The reduction in vibration from this form of soil improvement with a depth of 3 m is similar to that for a 1 m thick concrete block. Finally, results are presented for three example sites with different soil properties which show similar trends.

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Accepted/In Press date: 8 September 2015
e-pub ahead of print date: 29 September 2015
Published date: December 2015
Keywords: ground transmitted vibration, subgrade stiffening, wave impeding blocks, 2.5D modelling, finite element/boundary element methods
Organisations: Dynamics Group

Identifiers

Local EPrints ID: 382084
URI: http://eprints.soton.ac.uk/id/eprint/382084
ISSN: 0267-7261
PURE UUID: e8a8626d-4ce5-4786-9bf1-8469391a6785
ORCID for D.J. Thompson: ORCID iD orcid.org/0000-0002-7964-5906
ORCID for M.G.R. Toward: ORCID iD orcid.org/0000-0001-7334-4355

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Date deposited: 22 Oct 2015 11:05
Last modified: 15 Mar 2024 03:07

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Contributors

Author: D.J. Thompson ORCID iD
Author: J. Jiang
Author: M.G.R. Toward ORCID iD
Author: M.F.M. Hussein
Author: A. Dijckmans
Author: P. Coulier
Author: G. Degrande
Author: G. Lombaert

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