Prediction and control of railway-induced vibration

Prediction and control of the vibration or re-radiated noise in buildings and other facilities induced by railway infrastructures or construction activities.

Targeted problem

The existing transport infrastructures in a specific region are sources of noise and vibration, generating an annoyance on the people living near them. Great advances has been achieved in the past three decades on noise control of transport infrastructures. Nowadays it is a well-established and normalized engineering subject. In contrast, vibration control has traditionally remained in the background. However, its importance is growing increasingly once the noise problem has been solved by means of underground infraestructures, the inclusion of acoustic screens, acoustic pavement, etc... Specifically, in recent years, the prediction and control of ground-borne vibration and re-radiated (structural) noise induced railways (especially underground) has become a relevant public concern, leading to many countries all around the world to establish regulations for the maximum ground-borne noise and vibration levels that can be reached in buildings near a railway infrastructure. The rise of high-speed lines has just pushed the concern on this topic a bit more.

 

Field experience

LEAM has been working for over 15 years on the phenomenology associated with the ground-borne noise and vibration induced by railway infrastructures. In this context, LEAM has formed or currently forms part of research projects focused on the prediction of this vibration impact, such as the CATdBTren, RECYTRACK, ISIBUR, NVTRail and VIBWAY funded by different national and european agencies. Moreover, the group has been providing consultancy services to companies and administrations along these years, resulting on the development of a large amount of impact assessment studies. In order to deal with the increasing demand of consultancy and technology transfer services in this topic, AV Ingenieros spin-off company was created in 2008. The group has established collaboration with research centers in the field such as FEUP (University of Porto), the Dynamics Group of the ISVR (University of Southampton) and LADICIM (University of Cantabria).

 

Simulation and prediction of railway-induced ground-borne vibration

The experience accumulated during these 15 years has led LEAM to develop a software for the simulation of railway-induced vibrations, called VIBWAY. This software is especially designed to save computational and engineering costs in environmental assessment and detailed studies of traffic-induced ground-borne induced vibrations [1].

Figure 1. Environmental assessment studies in new railway lines.

The VIBWAY software is based on the research outcomes of the group during these years through the following topics:

  • Computational enhancements based on new analytical/numerical aspects for the calculation ground response, leading to large computational savings [2,3,4].
  • Improvement of the computational cost of the wave progapagation simulation on the ground due to the use of meshless methods and semi-analytical solutions [5,6].
  • Simplified modelling of the building structure and the building/soil interaction [7,8].

LEAM is also working in other topics associated to the control of railway-induced ground-borne noise and vibration:

  • Intensive research has been conducted to study the specific case of a tunnel with an inner floor partition. This is a tunnel layout solution used in some sections of the new metro line (L9) of Barcelona's underground metro network. A novel modelling approach is probably the most significant contribution of the group on this topic [9].

                                     

                                     

Figure 2. Tunnel with inner floor partition in L9 of Barcelona's underground metro network.

  • Another research topic in where LEAM has been working last years is the mitigation of railway-induced vibrations using dynamic vibration absorbers (DVAs). Theoretical developments [10] together with experimental studies (Fig. 3) has been carried out in order to investigate the problem and its implementation in detail.

                                                                                                                                             

                                             
Figure 3. Dynamic vibration absorbers (DVAs) implemented in L9 of Barcelona's underground metro network.


  • The group has also developed in-house 3D FEM-BEM and 3D FEM-SBM (Singular Boundary Method) solvers that are suitable to study soil-structure interaction problems until 250 Hz in detail.
  • Nowadays, the group is directing its efforts on the development of hybrid methods for the prediction railway-induced ground-borne noise and vibration that combine experimental measurements with theoretical models [11]. Developments to include the uncertainty associated to the imperfect knowledge of soil mechanical properties, to the soil-structure interaction, and to the building interior acoustic response due to ground-borne vibration are in progress.


Characterization of elastic components for railway applications.

One of the most important issues to ensure proper predictions is to have reliable input data. In this regard, elastic elements inserted in railway tracks are usually demonstrating highly uncertain mechanical properties. The group has been collaborating with TU Delft and University of Salford in this topic. LEAM is working through two main lines:

  • Laboratory characterisation of elastic elements for railway applications. The group is working in advanced methods for the determination of the dynamic stiffness of elastomeric or rubber track components, such us rail pads, under-ballast mats, etc. The group is focusing its effort on improve the procedure described in ISO 10846 in terms of accuracy along the frequency range and on the uncertainty of the stiffness estimation [12].

                                                                              

                           
Figure 4. Characterisation of elastomeric components for railway applications in the laboratory.


  • In situ characterisation of elastic elements for railway applications. LEAM developed an excitation device capable to excite railway tracks at low frequencies while the input forces are measured. The system can be observed in Fig. 5. The device can be loaded to apply preloads to the track, allowing to better represent the real condition of the track when the train is passing and also to perform studies of the non-linearity of the elastic components of the track due to the preload.

Figure 5. In situ characterisation of railway tracks, with focus on elastic elements.

 

Experimental assessment of traffic-induced noise and vibration

For the assessment of vibration impact, LEAM has proper instrumentation to do such studies, carrying out experimental measurement campaigns (mainly with LMS Pimento as multichannel equipment and seismic and piezoelectric accelerometers) as well as in-house computer programs specifically designed to perform the post-processing of the signals acquired according to current regulations and standards.

References

[1] ISO 14837-1. Mechanical vibration. Ground-borne noise and vibration arising from rail systems. Part 1: General Guidance.

[2] Noori, B., Arcos, R., Clot, A., Romeu, J. A method based on 3D stiffness matrices in Cartesian coordinates for computation of 2.5D elastodynamic Green's functions of layered half-spaces. Soil Dynamics and Earthquake Engineering, 114 (2018) 154-158.

[3] Arcos, R., Romeu, J., Clot, A., Genescà, M.. Some analytical aspects of viscoelastic Lamb's problem for improving its numerical evaluation. Wave Motion, 50(2) (2013) 226–232.

[4] Arcos R., Clot, A., Romeu, J., Martín, S.R. Fast computation of an infinite, longitudinally-varying and harmonic strip load acting on a viscoelastic half-space. European Journal of Mechanics - A/Solids, 43 (2014) 58-67.

[5] Liravi, H., Arcos, R., Ghangale, D., Noori, B., Romeu, J. A 2.5D coupled FEM-BEM-MFS methodology for longitudinally invariant soil-structure interaction problems. Computers and Geotechnics, 132 (2021) 104009.

[6] Ghangale, D., Arcos, R., Clot A., Noori, B., Romeu, J. A methodology based on 2.5D FEM-BEM for the evaluation of the vibration energy flow radiated by underground railway infrastructures. Tunnelling and Underground Space Technology, 101 (2020) 103392.

[7] Clot, A., Arcos, R., Romeu, J. Efficient three-dimensional building-soil model for the prediction of ground-borne vibrations in buildings. Journal of Structural Engineering, 143(9) (2017) 04017098

[8] Conto, K.F., Arcos, R., Parente, C., Costa, P.A., Romeu, J. A new semi-analytical approach for dynamic pile-soil interaction problems. Proceedings of the International Conference on Structural Dynamics, EURODYN 2020, 2, pp. 2807-2816.

[9] Clot, A., Arcos, R., Romeu, J., Pàmies, T. Dynamic response of a double-deck circular tunnel embedded in a fullspace. Tunnelling and Underground Space Technology, 59 (2016) 146-156.

[10] Noori, B., Arcos, R., Clot, A., Romeu, J. Control of ground-borne underground railway-induced vibration from double-deck tunnel infrastructures by means of dynamic vibration absorbers. Journal of Sound and Vibration, 461 (2019) 114914

[11] Arcos, R., Soares, P.J., Alves Costa, P., Godinho, L. An experimental/numerical hybrid methodology for the prediction of railway-induced ground-borne vibration on buildings to be constructed close to existing railway infrastructures: Numerical validation and parametric study. Soil Dynamics and Earthquake Engineering, 150 (2021) 106888.

[12] Reina, S., Arcos, R., Clot, A., Romeu, J. An efficient experimental methodology for the assessment of the dynamic behaviour of resilient elements. Materials, 13 (2020) 2889.