Transmission of train-induced vibrations to buildings located in the vicinity of the track is one of the main negative externalities of railway transport, since both human comfort and the adequate functioning of sensitive equipment may be compromised. In this paper, a 3D FEM model is presented and validated with data from a real track stretch near Barcelona, Spain. Furthermore, a case study is analyzed as an application of the model, in order to evaluate the propagation and transmission of vibrations induced by the passage of a suburban train to a nearby 3-storey building. As a main outcome, vertical vibrations in the foundation slab are found to be maximum in the corners, while horizontal vibrations keep constant along the edges. The propagation within the building structure is also studied, concluding that vibrations invariably increase in their propagation upwards the building. Moreover, the mitigation capacity of a wave barrier acting as a source isolation is assessed by comparing vibration levels registered in several points of the building structure with and without the barrier. In this regard, the wave barrier is found to effectively reduce vibration in both the soil and the structure.
Two types of track gauges are currently in use in the Spanish railway network: the traditional ‘iberian’ wide gauge of 1668 mm used in the conventional network and the international 1435 mm gauge used for the high-speed lines. The dual-gauge track, in which a third rail is added to the classical two-rail layout, has recently been proposed for the design of new lines. This solution implies a substantial modification of the classical ballasted track structure and thus requires an analysis of mechanical phenomena occurring on the rail-sleeper grid of the track. In particular, this study focused on lateral track buckling, produced by the axial compression stresses on the rails induced by increases in temperature. Whenever the axial compression force exceeds a critical threshold, the track could become unstable as significant lateral deflections may appear thus leading to unacceptable riding safety levels. In this case, the addition of the third rail increases the steel section and therefore the axial compression, which may lead to track instability. This study assessed this phenomenon in detail by means of a three-dimensional, nonlinear, numerical finite element model, based upon the latest reports of the European Railway Research Institute. Several conclusions have been derived from this study as regards the increasing risk of instability in a dual-gauge track.
A railway track stretch comprising three different track typologies (i.e., ballasted track, asphalt slab track and concrete slab track) has been modeled using a three-dimensional Finite Elements model, which has been calibrated and validated using real acceleration records. In this model, two different analyses have been run: a static analysis to assess the stiffness evolution and a dynamic analysis to calculate the accelerations induced by the train loads along the transition zones. These analyses have been used to assess the performance of three different techniques existing in the literature to improve the structural behavior of the track in the transition areas: the variation of the stiffness of the elastomers, the implementation of additional rails and the use of resilient mats. Results have demonstrated that these techniques perform generally better in the track vertical stiffness transition between the concrete and asphalt slab tracks while the dynamic response is not significantly altered in any scenario.
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