Keywords: high-speed train vibrations, vehicle-track-soil-structure interaction, dynamic loads, BEM-FEM coupling.

This paper is intended to develop a general numerical model for the analysis of vibrations due to high-speed trains (HST) and their effects on nearby structures. The numerical model is based on the three dimensional finite element and boundary element formulations in the time domain. As compared to two-and-a-half domain solutions, the present formulation can take into account local soil discontinuities, underground constructions such as underpasses, and coupling with nearby structures that brake the uniformity of the geometry along the track line. Track and other structures are modelled using the finite element method and their non-linear behaviour can be considered because a time domain formulation is employed. The soil is represented using the boundary element method, where a full-space fundamental solution is used in combination with quadratic boundary elements. The train vehicle is modelled as a multi-body and, therefore, the quasi-static and the dynamic excitation mechanisms can be considered, taking into account the dynamics effects due to sleeper discrete support and the wheel and rail irregularities.

The influence of the vehicle model in the quasi-static and dynamic responses has been studied. The inertia should be considered to predict accurately the quasi-static response. For the dynamic response, the suspended mass should be taken into account in order to predict the track and soil response at low frequencies.

The numerical model has been experimentally validated by comparison with existing experimental records taken in two HST lines: Córdoba-Málaga HST line [1] and Brussels-Paris HST line [2]. In the first case, the train speed was lower than the Rayleigh wave velocity in the soil. Thus, quasi-static and dynamic contributions, are important to reproduce the actual problem, and six samples of unevenness are generated to make the experimental validation of the numerical model because different samples of track unevenness yield different predictions of the track and free field response [3]. In the second case, the train speed is higher than the Rayleigh wave velocity in the soil and, therefore, the quasi-static contribution dominates the track and free field response. In both cases, the correlation between experimental and computed results is quite good.

The dynamic behaviour of a transition zone between a ballast track and a slab track has also been studied using the present three dimensional model. The computed results have been compared with those obtained from models which consider an invariant geometry with respect to the track direction and it has been concluded that three dimensional models should be used to obtain the response for these problems.

1

P. Galvín, J. Domínguez, "Experimental and Numerical Analysis of Vibrations Induced by High-Speed Trains on the Córdoba-Málaga Line", Soil Dynamics and Earthquake Engineering, 29, 641-657, 2009. doi:10.1016/j.soildyn.2008.07.001

2

G. Degrande, L. Schillemans, "Free field vibrations during the passage of a Thalys HST at variable speed", Journal of Sound and Vibration, 247, 131-144, 2001. doi:10.1006/jsvi.2001.3718

3

G. Lombaert, G. Degrande, "Ground-borne vibration due to static and dynamic axle loads of InterCity and high-speed trains", Journal of Sound and Vibration, 319, 1036-1066, 2009. doi:10.1016/j.jsv.2008.07.003

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