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Mechanically coupled distributed dynamic strain measurement for track systems and earthworks

Mechanically coupled distributed dynamic strain measurement for track systems and earthworks
Mechanically coupled distributed dynamic strain measurement for track systems and earthworks

Distributed optical fibre sensors are one of the few sensing technologies that could be embedded into our infrastructure to provide quantitative and mechanistic measurements of the condition of the infrastructure at network scales. This study considers the analysis of a sensing fibre deployed along 50 m of rail with a 7.5 m section buried beneath the line of the rail in the trackbed. The fibre was interrogated using a Distributed Acoustic Sensing (DAS) system based on Phase Optical Time Domain Reflectometry (ϕ-OTDR). This technique offers a short gauge length and high sample rate suited for measurement of moving loads. Data were captured as the site was trafficked by passing trains. Complementary simulation and measurements (using accelerometers and pressure sensors) were used to aid and improve the interpretation of the signal from the sensing fibre. In general, the measured signal agreed with the simulation indicating that the buried fibre provides a means of measuring horizontal strain in the ground under moving loads. Results from the different measurement systems led to a consistent interpretation of site behaviour, particularly where local variation of stiffness and load distribution were detectable at the same locations along the track. These analyses support the idea that DOFS have the potential for providing quantitative and high-resolution, and hence, high-utility sensing by interrogating an optical fibre embedded in infrastructure.

Fibre Optic Sensors, Railway Track, Strain Measurement
2214-3912
Milne, David
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Powrie, William
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
Watson, Geoff
a7b86a0a-9a2c-44d2-99ed-a6c02b2a356d
Masoudi, Ali
8073fb9b-2e6c-46c9-89cf-cb8670d76dc0
Brambilla, Gilberto
815d9712-62c7-47d1-8860-9451a363a6c8
Harkness, John
026f02e8-41d9-403f-83be-0d880058ecf1
Lee, Benjamin Robert
791c9c18-0abb-493a-8837-22d558d51b10
Le Pen, Louis
4a38e256-d113-4bba-b0d4-32d41995928a
Milne, David
6b321a45-c19a-4243-b562-517a69e5affc
Powrie, William
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c
Watson, Geoff
a7b86a0a-9a2c-44d2-99ed-a6c02b2a356d
Masoudi, Ali
8073fb9b-2e6c-46c9-89cf-cb8670d76dc0
Brambilla, Gilberto
815d9712-62c7-47d1-8860-9451a363a6c8
Harkness, John
026f02e8-41d9-403f-83be-0d880058ecf1
Lee, Benjamin Robert
791c9c18-0abb-493a-8837-22d558d51b10
Le Pen, Louis
4a38e256-d113-4bba-b0d4-32d41995928a

Milne, David, Powrie, William, Watson, Geoff, Masoudi, Ali, Brambilla, Gilberto, Harkness, John, Lee, Benjamin Robert and Le Pen, Louis (2025) Mechanically coupled distributed dynamic strain measurement for track systems and earthworks. Transportation Geotechnics, 53, [101605]. (doi:10.1016/j.trgeo.2025.101605).

Record type: Article

Abstract

Distributed optical fibre sensors are one of the few sensing technologies that could be embedded into our infrastructure to provide quantitative and mechanistic measurements of the condition of the infrastructure at network scales. This study considers the analysis of a sensing fibre deployed along 50 m of rail with a 7.5 m section buried beneath the line of the rail in the trackbed. The fibre was interrogated using a Distributed Acoustic Sensing (DAS) system based on Phase Optical Time Domain Reflectometry (ϕ-OTDR). This technique offers a short gauge length and high sample rate suited for measurement of moving loads. Data were captured as the site was trafficked by passing trains. Complementary simulation and measurements (using accelerometers and pressure sensors) were used to aid and improve the interpretation of the signal from the sensing fibre. In general, the measured signal agreed with the simulation indicating that the buried fibre provides a means of measuring horizontal strain in the ground under moving loads. Results from the different measurement systems led to a consistent interpretation of site behaviour, particularly where local variation of stiffness and load distribution were detectable at the same locations along the track. These analyses support the idea that DOFS have the potential for providing quantitative and high-resolution, and hence, high-utility sensing by interrogating an optical fibre embedded in infrastructure.

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Accepted/In Press date: 6 June 2025
e-pub ahead of print date: 8 June 2025
Published date: 12 June 2025
Keywords: Fibre Optic Sensors, Railway Track, Strain Measurement

Identifiers

Local EPrints ID: 503123
URI: http://eprints.soton.ac.uk/id/eprint/503123
ISSN: 2214-3912
PURE UUID: 3051b794-fe05-4788-8c4a-630e95944a7d
ORCID for David Milne: ORCID iD orcid.org/0000-0001-6702-3918
ORCID for William Powrie: ORCID iD orcid.org/0000-0002-2271-0826
ORCID for Geoff Watson: ORCID iD orcid.org/0000-0003-3074-5196
ORCID for Ali Masoudi: ORCID iD orcid.org/0000-0003-0001-6080
ORCID for Gilberto Brambilla: ORCID iD orcid.org/0000-0002-5730-0499
ORCID for John Harkness: ORCID iD orcid.org/0000-0003-0908-0791
ORCID for Louis Le Pen: ORCID iD orcid.org/0000-0002-4362-3895

Catalogue record

Date deposited: 22 Jul 2025 16:33
Last modified: 22 Aug 2025 02:21

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Contributors

Author: David Milne ORCID iD
Author: William Powrie ORCID iD
Author: Geoff Watson ORCID iD
Author: Ali Masoudi ORCID iD
Author: Gilberto Brambilla ORCID iD
Author: John Harkness ORCID iD
Author: Benjamin Robert Lee
Author: Louis Le Pen ORCID iD

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