Wave barriers for the reduction of railway induced vibrations. Analysis in tracks with geometric restrictions (original) (raw)
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761. Study of wave barriers design for the mitigati on of railway ground vibrations
Journal of Vibroengineering, 2012
Nowadays, the consolidation of the rail in highly p opulated areas has become a reality. Foundations, buildings, high accuracy devi ces and people are susceptible to suffer from vibrations induced by passing trains. Therefore, mo dels for predicting ground vibrations are required in order to determine new mitigation measu res. Rectangular open or in-filled trenches are a suitable solution to be used near constructed railway lines. Their installation is fast, easy and economic since no intrusion in the track is nee ded. In this work, the influence of the trench design on its effectiveness is analyzed considering a train moving with subsonic speed. A finite element model of the track has been developed and validated with real data registered along the tram network in Alicante (Spain). The analysis is c arried out in the time domain considering the quasi-static movement of the vehicles. The results demonstrate that, in ascending order, the most relevant parameters in a trench are its w...
Stiff Wave Barriers for the Mitigation of Railway Induced Vibrations
Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 2015
This paper studies the efficiency of stiff wave barriers for the mitigation of railway induced vibrations. Coupled finite element-boundary element models developed at KU Leuven and ISVR are employed; these models have been cross-validated within the EU FP7 project RIVAS [1]. A first mitigation measure consists of a block of stiffened soil included in a halfspace that acts as a wave impeding barrier. The existence of a critical frequency from which this mitigation measure starts to be effective, as well as a critical angle delimiting the area where the vibration levels are reduced, is demonstrated. Next, a sheet piling wall is considered, accounting for the orthotropic behaviour of this wall. Calculations show that the reduction of vibration levels is entirely due to the relatively high axial stiffness and vertical bending stiffness, while the longitudinal bending stiffness is too low to affect the transmission of vibrations. Field tests are being carried out in Spain and Sweden to confirm the conclusions of these numerical computations.
Experimental evaluation of the efficiency of trenches for the mitigation of train-induced vibrations
Transportation Research Part D: Transport and Environment, 2014
In this work, the efficiency of absorbing barriers for the mitigation of ground vibrations induced by railway traffic has been evaluated by means of two different experimental campaigns conducted in situ, along the newly-built, high-speed railway line that connects the Italian cities of Milan and Bologna. In the first stage of testing, a series of ideal barriers created from unsupported empty trenches were tested to assess the effects of barrier depth on their efficiency in reducing vertical ground accelerations. The second stage of testing was performed to investigate the efficiency of a full-scale prototype barrier, made of a 2meter-deep trench supported by two precast reinforced concrete plates connected by steel bars, during transit of an ETR 500 train at a speed of 120 km/h.
Railway induced vibrations are an important source of annoyance in the built environment, causing malfunctioning of sensitive equipment and nuisance to people. Within the frame of the EU FP7 project RIVAS, mitigation measures on the transmission path between source (railway track) and receiver (surrounding buildings) have been investigated. This paper reports on the numerical and experimental study of stiff wave barriers as efficient vibration reduction measures. Numerical simulations have demonstrated that the wave impeding effect of such barriers depends on the stiffness contrast between the surrounding soil and the barrier, as well as on the barrier's depth. Findings from the numerical studies are verified by means of two field tests. In El Realengo (Spain), a continuous barrier has been created close to an existing railway track using overlapping jet grout columns, while a sheet pile wall has been installed along a track in Furet (Sweden). At both sites, geophysical and geotechnical tests were carried out prior to the installation of the mitigation measures for the determination of the dynamic soil characteristics. Measurements of train passages before and after installation of the barriers are compared to numerical simulations in order to assess the vibration reduction efficiency. In El Realengo, additional measurements have been performed at a reference site adjacent to the test site in order to correct for variations of track, train, and soil characteristics in time. It is shown that both barriers are effective and result in vibration reduction from 8 Hz (El Realengo) and 4 Hz (Furet) on, respectively; the largest reduction is obtained immediately behind the barriers. This ability to solve low frequency vibration problems is a unique feature compared to most other vibration mitigation measures for existing railway lines.
Reducing Railway Induced Ground-Borne Vibration by Using Trenches and Buried Soft Barriers
Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 2015
To reduce railway induced low frequency vibration, two mitigation measuresopen trenches and buried soft wall barriers, have been studied in this paper by using coupled finite element-boundary element models. These models were developed at KU Leuven and ISVR, and have been cross-validated within the EU FP7 project RIVAS (Railway Induced Vibration Abatement Solutions). Variations in the width, depth, location of trench and properties of soft barrier material are considered under various soil conditions. Results show that in all ground conditions, the notional rectangular open trench performs better than the other constructions. The width of an open trench has little influence on its performance, whereas increasing the width of a filled trench reduces the stiffness of the material, improving the performance of the trench. Likewise, fill materials with lower Young's modulus give higher insertion losses.
Study of the barriers for the mitigation of railway vibrations
The reduction of environmental interference caused by the passage of railway convoys at high speed, in recent years, has become a key element for optimization and approval of the design alternatives. Therefore the need to develop models which analyze the effects of the vibrations induced on buildings close to rail lines appears primary, in order to define and classify possible improvement choices. In this paper we analyze the problem of the propagation of vibrations in the ground and focus the attention on the dampening effect of a barrier placed between source and receiver, in particular, we model the phenomenon through the finite element method considering the presence in the ground of one or several discontinuities. A parametric study to investigate the importance of the position, for example, of the discontinuity, introduced by the membrane is performed; then, different numerical simulations are analyzed by changing the position, the dimension and the materials of the barrier in order to optimize the FE model in terms of stress agents on the foundations and to study how the wave propagation and the soil-structure interaction are influenced by the membrane which can be seen as a damping barrier.
Shock and Vibration, 2017
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 compari...
Reduction of train-induced vibrations by using a trench in a layered half-space
Journal of Vibroengineering, 2016
A coupled model of a track-layered ground-in-filled trench system is developed to investigate the isolation effects of an in-filled trench on reducing vibrations generated by moving train loads. By using the substructure method, the whole model is decomposed into two parts: the layered ground containing the in-filled trench and the track. Firstly, the flexibility coefficient for moving uniformly distributed loads applied on the layered ground containing the trench is obtained by using the 2.5D indirect boundary element method. Then, the dynamic equilibrium equation of the track under the moving train loads and uniformly distributed loads are established. Finally, the layered ground and the track are coupled according to the equivalence between the deformation of the track and the vertical displacement of the layered ground. The validity of the method is confirmed by comparing its results with the published ones. Numerical calculations are performed by embedding an in-filled trench in a homogenous ground, in a single layered ground and also in the real site at Ledsgard as examples. The results show that the isolation effects are different for different ground conditions and for different geometric parameters such as the depth, width and location of the in-filled trench.
Mitigation of Railway Traffic Induced Vibrations: The Influence of Barriers in Elastic Half-Space
Advances in Acoustics and Vibration, 2009
In this paper, the problem of vibrations induced by trains and their propagation through the soil is studied. Particular attention is focused on the vibration induced by trains in motion and on the effects of such vibrations on the foundations of buildings in proximity of the tracks. The interaction between propagating waves induced by trains in motion and buildings foundations is a problem which does not admit a straightforward analytical solution; thus a solution is given by the use of a model based on the finite elements method. Firstly, we analyze the theoretical aspects of the problem by considering constant or harmonic loads moving along a straight railway track; then, we define a transfer function soil-railway and the response function of the entire system. The study aims to address the wave propagation in an elastic semi-space and the presence in the ground of a discontinuity element, such as a barrier of a given depth is considered. The efficiency variation of barriers is analyzed in function of the different materials used, and different numerical simulations are analyzed in order to study how the wave propagation and the track-soil interaction are influenced by the membrane, seen as damping barrier.