Slab track optimisation considering dynamic train–track interaction
Doktorsavhandling, 2021

Slab track is a type of railway track that is frequently used e.g. in high-speed applications as an alternative to ballasted track. Slab track is also well suited on bridges and in tunnels since no ballast is required and the cross-section of tunnels can be reduced. Slab tracks generally have lower maintenance demands than ballasted track. However, if maintenance is required it may be expensive and intrusive. On the other hand, overdimensioning of slab track will lead to high environmental impact and monetary cost. This thesis aims to increase the knowledge and improve the understanding of the dynamic interaction between vehicle and track in order to allow for the optimisation of slab track.

To this end, both two-dimensional (2D) and three-dimensional (3D) slab track models, and a transition zone model between slab track and ballasted track, have been developed. These models are used to simulate the vertical dynamic vehicle–track interaction in the time-domain. The computational cost of the simulation is reduced by using a complex-valued modal superposition technique for the finite element model of the track. In the 3D model, both rails are represented by beam elements, while the concrete parts are described using shell or solid elements. The simulations employ a mix of in-house and commercial codes. The influence of different irregularities, e.g. variations in track support conditions and irregularities in longitudinal level, on significant track responses such as wheel–rail contact forces, stresses in the concrete parts and pressure on the foundation is assessed. From Single-Input-Multiple-Output (SIMO) measurements carried out in a full-scale test rig, the 3D model has been calibrated and validated.

The developed models have been used to improve the designs of slab track and transition zones. Based on a multi-objective optimisation problem that is solved using a genetic algorithm, the transition zone design has been optimised to minimise the dynamic loads generated due to the stiffness gradient between the two track forms. The slab track design has been optimised to minimise the environmental footprint considering the constraint that the design must pass the static design criteria described in EN 16432-2. This design is then employed in the dynamic model where it is shown that there is a further potential for design improvements and related CO2 savings. In particular, there may be possibilities to reduce the thickness of the concrete layers and the amount of concrete between the rails. Finally, a model of reinforced concrete has been implemented and combined with the dynamic model to assess consequences of cracking in the concrete panel and to evaluate stresses in the reinforcement bars.

Measurement

Dynamic vehicle–track interaction

Optimisation

Transition zones

Genetic algorithm

Ballastless track

Modelling

Slab track

Opponent: Professor Ernesto García Vadillo, Department of Mechanical Engineering, University of the Basque Country, Bilbao, Spain

Författare

Emil Aggestam

Chalmers, Mekanik och maritima vetenskaper, Dynamik

Simulation of vertical dynamic vehicle–track interaction using a two-dimensional slab track model

Vehicle System Dynamics,; Vol. 56(2018)p. 1633-1657

Artikel i vetenskaplig tidskrift

Multi-objective optimisation of transition zones between slab track and ballasted track using a genetic algorithm

Journal of Sound and Vibration,; Vol. 446(2019)p. 91-112

Artikel i vetenskaplig tidskrift

Simulation of vertical dynamic vehicle–track interaction using a three-dimensional slab track model

Engineering Structures,; Vol. 222(2020)

Artikel i vetenskaplig tidskrift

E. Aggestam, J. C. O. Nielsen, K. Lundgren, K. Zandi and A. Ekberg. Optimisation of slab track design considering dynamic train–track interaction and environmental impact. To be submitted for international publication. (2021).

To reduce global warming, greenhouse gas emissions need to be reduced. When comparing the environmental impact from different modes of transportation, railway transportation has great potential. However, to make railway transportation competitive, traffic at higher speeds and/or higher axle loads is essential. On the other hand, this will also increase the loading of trains and track and increase costs for maintenance. New innovative track structures can be used, where the so-called slab track is one of the most promising designs. In a slab track, a robust structure is obtained by typically replacing the sleepers and ballast in a conventional track with concrete plates. A major disadvantage of slab track compared to ballasted track is that the environmental footprint of the construction is larger due to the significant required amounts of steel and concrete.

Slab tracks generally have low maintenance demands. However, if maintenance is required it may be expensive and intrusive. On the other hand, overdimensioning of slab track will lead to high environmental impact and monetary cost. In this thesis, computer models of slab tracks have been developed to fit test results. These models are used to increase the understanding of the impact of different operational conditions and track designs. Finally, the models are used in optimisations to strike the delicate balance between having a high-quality track and the environmental costs of having an overdesigned solution.

Designkriterier för ballastfria spår (CHARMEC TS19)

Chalmers järnvägsmekanik (CHARMEC), 2019-01-01 -- 2021-06-30.

Trafikverket, 2016-07-01 -- 2018-12-31.

In2Track-2 (CHARMEC EU19)

Trafikverket, 2018-11-01 -- 2021-10-31.

Europeiska kommissionen (EU), 2018-11-01 -- 2021-10-31.

Ämneskategorier

Maskinteknik

Styrkeområden

Transport

Infrastruktur

C3SE (Chalmers Centre for Computational Science and Engineering)

ISBN

978-91-7905-454-0

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4921

Utgivare

Chalmers tekniska högskola

Online

Opponent: Professor Ernesto García Vadillo, Department of Mechanical Engineering, University of the Basque Country, Bilbao, Spain

Mer information

Senast uppdaterat

2021-05-12