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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 110
Edited by: J. Pombo
Paper 1

Scoping Prediction of Railway Critical Velocity

D.P. Connolly1, S.B. Mezher1, P.K. Woodward1, Z. Yu1, O. Laghrouche1, J. Pombo1 and P. Alves Costa2

1Institute of Infrastructure and Environment, Heriot Watt University, Edinburgh, United Kingdom
2University of Porto, Portugal

Full Bibliographic Reference for this paper
D.P. Connolly, S.B. Mezher, P.K. Woodward, Z. Yu, O. Laghrouche, J. Pombo, P. Alves Costa, "Scoping Prediction of Railway Critical Velocity", in J. Pombo, (Editor), "Proceedings of the Third International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Stirlingshire, UK, Paper 1, 2016. doi:10.4203/ccp.110.1
Keywords: critical velocity, Rayleigh waves, high speed rail, railroad vibration, soil saturation.

When train speeds approach the wave propagation velocity of the supporting track-ground system, track displacement amplitudes can increase significantly. This is undesirable and can cause both elevated maintenance and safety concerns. Thus, it is important to determine the speed at which these effects will occur, however modelling the problem in detail (e.g. using numerical techniques) can result in long run times. Therefore, as an alternative, this paper uses an analytical approach to investigate the dispersion characteristics of the track-ground system, and thus calculate the critical velocity. Unlike alternative approximate critical velocity calculation approaches, the proposed method is fully automated thus not requiring any post-processing to extract the soil dispersion curve. It has low computational requirements meaning it can be used quickly for large sections of track. After the model is outlined, it is validated against a larger, more comprehensive model and found to have high accuracy. A Monte Carlo analysis is then undertaken using 1000 random soil profiles. It is found that ballasted tracks typically have a lower critical velocity than slab tracks and that track height and soil saturation play an important role on the critical speed.

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