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Track behaviour: the importance of the sleeper to ballast interface

Track behaviour: the importance of the sleeper to ballast interface
Track behaviour: the importance of the sleeper to ballast interface
The aim of this research is to develop a fuller understanding of the mechanical behaviour of the
sleeper/ballast interface, related in particular, to the forces applied by high speed tilting trains on
low radius curves. The research has used literature review, field measurements, and laboratory
experiments on a single sleeper bay of track. Theoretical calculations are also presented.

Field measurements are carried out using geophones to record time/deflection for sleepers
during passage of Pendolino trains on the West Coast Main Line. Calculations are presented to
quantify normal and extreme magnitudes of vertical, horizontal and moment (VHM) loads on
individual sleepers.

Results from laboratory experiments, on the pre-failure behaviour of the sleeper to ballast base
contact area, show that lateral load/deflection behaviour is load path dependent and relations are
determined for improved computer modelling of the sleeper/ballast interface. Further test results
are used to establish the failure envelopes for combined VHM loading of the sleeper/ballast base
contact area. Tests show that the sleeper/ballast base resistance at failure occurs at a load ratio
(H/V) of about 0.45 (24°) at 2 mm of displacement tending to 0.57 (30°) at greater
displacements. In addition, measurements from pressure plates within the testing apparatus are
used to describe the development of confining stress within the ballast during 100 cycles of
vertical load. The development of confining stress is assessed with reference to a finite element
model of the laboratory apparatus and it is shown that the earth pressure ratio moves towards the
active condition for peak load and the passive condition at minimum load per cycle.

The contribution to lateral resistance of the crib ballast and varying sizes of shoulder ballast is
also established and it is found that the shoulder and crib resistance can best be characterised by
taking the mean resistance over a range of deflection from 2 mm to 20 mm. Calculations are
presented, supported by the experimental data, to quantify the resistance from different sizes of
shoulder ballast and a chart is presented which can be used as the basis for shoulder
specification in practice.
Le Pen, Louis
4a38e256-d113-4bba-b0d4-32d41995928a
Le Pen, Louis
4a38e256-d113-4bba-b0d4-32d41995928a
Powrie, William
600c3f02-00f8-4486-ae4b-b4fc8ec77c3c

Le Pen, Louis (2008) Track behaviour: the importance of the sleeper to ballast interface. University of Southampton, School of Civil Engineering and the Environment, Doctoral Thesis, 292pp.

Record type: Thesis (Doctoral)

Abstract

The aim of this research is to develop a fuller understanding of the mechanical behaviour of the
sleeper/ballast interface, related in particular, to the forces applied by high speed tilting trains on
low radius curves. The research has used literature review, field measurements, and laboratory
experiments on a single sleeper bay of track. Theoretical calculations are also presented.

Field measurements are carried out using geophones to record time/deflection for sleepers
during passage of Pendolino trains on the West Coast Main Line. Calculations are presented to
quantify normal and extreme magnitudes of vertical, horizontal and moment (VHM) loads on
individual sleepers.

Results from laboratory experiments, on the pre-failure behaviour of the sleeper to ballast base
contact area, show that lateral load/deflection behaviour is load path dependent and relations are
determined for improved computer modelling of the sleeper/ballast interface. Further test results
are used to establish the failure envelopes for combined VHM loading of the sleeper/ballast base
contact area. Tests show that the sleeper/ballast base resistance at failure occurs at a load ratio
(H/V) of about 0.45 (24°) at 2 mm of displacement tending to 0.57 (30°) at greater
displacements. In addition, measurements from pressure plates within the testing apparatus are
used to describe the development of confining stress within the ballast during 100 cycles of
vertical load. The development of confining stress is assessed with reference to a finite element
model of the laboratory apparatus and it is shown that the earth pressure ratio moves towards the
active condition for peak load and the passive condition at minimum load per cycle.

The contribution to lateral resistance of the crib ballast and varying sizes of shoulder ballast is
also established and it is found that the shoulder and crib resistance can best be characterised by
taking the mean resistance over a range of deflection from 2 mm to 20 mm. Calculations are
presented, supported by the experimental data, to quantify the resistance from different sizes of
shoulder ballast and a chart is presented which can be used as the basis for shoulder
specification in practice.

Text
Phd_thesis_LLP_Nov_2008.pdf - Other
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More information

Published date: 2008
Organisations: University of Southampton

Identifiers

Local EPrints ID: 73284
URI: http://eprints.soton.ac.uk/id/eprint/73284
PURE UUID: 213c8b9d-ae33-479d-b97f-3459c42f675b
ORCID for Louis Le Pen: ORCID iD orcid.org/0000-0002-4362-3895
ORCID for William Powrie: ORCID iD orcid.org/0000-0002-2271-0826

Catalogue record

Date deposited: 03 Mar 2010
Last modified: 14 Mar 2024 02:50

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