Experimental Validation of a 2.5D FEM-BEM Model for the Assessment of Vibrations Induced by Traffic

Abstract eng:
This paper presents two main parts, encompassing the experimental assessment and the numerical modelling of vibrations induced by railway traffic. Firstly, a global description of an experimental trial field developed in the Portuguese railway network is presented. In that trial field several tests were performed in order to obtain a reasonable mechanical characterization of the main elements involved in the process of generation and propagation of waves induced by traffic. So as to reach the proposed goal, a geotechnical characterization campaign was performed, including crosshole tests and specific tests to estimate the ground damping properties. Concerning the track properties, receptance tests and a campaign of measurement of irregularities were conducted. After the global characterization of the site and of the track, vibrations induced by the railway traffic were then measured both in the railway track and in the free-field. The results of the tests are used in the validation of a 2.5D FEM/BEM model developed by the authors. The model fully accounts for the dynamic interaction between the train, the track and the layered ground. The railway track and embankment, assumed to be invariant in the longitudinal direction, are modelled with 2.5D finite elements [1]. On the other hand, the layered ground below the embankment is simulated by a 2.5D boundary elements formulation. This formulation allows an efficient solution of the track-ground dynamic interaction problem in the frequency-wavenumber domain, as recently explained by François et al. [2]. Regarding the modelling of the rolling stock, a multi-body model is adopted, where the main masses and suspensions of the train are incorporated. The study, involving experimental and numerical techniques, revealed to be very useful, allowing not only the experimental validation of the numerical model proposed by the authors, but also a deep understanding of the influence of several aspects who determine the problem’s solution.

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