Analysis of lateral vibrations of railroad due to the passage of the underground train (original) (raw)
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Vibrations due to the passage of a railway vehicle on straight and curved tracks
The paper presents the results of vibration measurements on line of railway during passages of a train at a constant speed. The measurements have been performed on a railway track at straight and curve sections as well as and inside the train on the floor. The experimental results exhibited higher amplitudes of vibrations on the curve of the track than on its straight segments. The lateral slip in rail/wheel contact zone is considered as a possible reason of such a phenomenon.
RAILWAY TRAFFIC VIBRATIONS: GENERATION AND PROPAGATION - THEORETICAL ASPECTS
The interest in vibrations due to railway traffic is increasing in all developed countries, and it requires to develop both experimental and theoretical studies. In fact, innovative track can reduce the transmission of vibrations toward buildings and people, but also a better knowledge of the physical phenomenon can be useful to apply other methodologies, like a better control of contact surface characteristics. Theoretical mechanical models, based on the analysis of dynamic interaction between wheel and rail, and between track and formation soil, are the key tool to understand the phenomenon and evaluate interventions. In the paper, after a review of principles of vibration theory, two different calculation models are presented: the first one is a mathematical model for the analysis of dynamic loads caused by rail and wheel irregularities, the second one is useful to study the transmission of vibrations in the railway track and soil. The models, which can be used in sequence, are valid for various applications, in particular concerning the analysis of the role of different system components (wheels, rail, track) and their importance in the generation and propagation problems of railway vibrations.
On the theory of railway-induced ground vibrations
Journal de Physique IV, 1994
In the present paper, the theory of generation of ground vibrations by moving train is considered. The theory takes into account contribution of each sleeper of the track subjected to the action of all wheel axles. Mechanical properties of the track and parameters of train and soil (including static contact nonlinearity of track-soil system) are taken into account. It is shown that generated ground-vibration spectra depend strongly on the periodicity of track (distance between adjacent sleepers), parameters of the train (train speed, distances between wheel axles and carriages), and on the axle loads of the carriages. A special attention is paid to the ground vibrations generated by superfast trains. It is shown that tremendous increase of vibration level may occur if the train speed exceeds the velocity of Rayleigh surface wave in the ground. Such a situation is not a fantastic one and may really happen, e.g., in the case of TGV trains for which the speeds of 500 km/h have been recently achieved on the experimental track in France. Simple methods of suppression of ground vibrations "on the track" are suggested.
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 2012
This article presents a mathematical model aimed at predicting wheel–rail contact vibration force arising from wheel profile irregularities. Prediction of vibrations caused by a passing train is a basic factor in environmental impact studies related to planning new railway lines. The prediction model is useful during the development of a project as it facilitates selection of the most suitable track for reducing vibration levels. This article presents the model, analyses the influence of the track base on the vibration-generating mechanisms, and compares the dynamic behaviour of the most widely used urban railway tracks.
Numerical Analysis of Railway Track Vibrations
The numerical prediction models are used both for evaluation of the track-soil interaction forces as well as for prediction of the ground-borne vibrations. The dynamic track-soil interaction forces are calculated using a detailed train model and the dynamic behaviour of the layered spring-damper system and the through-soil coupling of the sleepers for the soil model [1,2,3,6,7]. The calculation of the groundborne vibration level at the distance is based on the viscous-elastics soil model, too. In the frequency domain free-field response numerical results are presented using the response spectra and the frequency response function (FRF) of the viscoelastic soil medium at the distance, [6,8,9,10,11]. In the next step these functions can be applied to the structure (e.g. engineering and building) dynamic response calculation arising railway traffic using the relevant computational building structure model.
Effect of Rail Corrugation on the Amount of Train-Induced Vibrations Near a Historical Building
Advances in Railway Engineering, An International Journal, 2014
The evaluation and control of the trains induced vibrations needs even more attention in the case of underground tracks which passes near to monuments and historical sites. The rail corrugations which occur due to the wheels’ impulse loads during the operation period of underground railway tracks, usually amplify the ground borne noise and vibration. In the current study, the mentioned phenomenon is simulated in Isfahan metro line 1 which includes twin tunnels and passes nearby of ChaharBagh School monument. In this matter, a three dimensional vehicle track interaction software (Adams/Rail) was used in conjunction with a geotechnical FEM software (Plaxis 2D). For this purpose, the vehicle-track interaction problem was solved considering rail corrugation in Adams/Rail part of MSC Adams® software and the amplified wheel load was imposed in a 2D plain strain model in Plaxis and consequently, the ground borne vibrations were extracted as vertical vibration velocity at a bench mark point...
The experimental validation of a numerical model for the prediction of railway induced vibrations
Journal of Sound and Vibration, 2006
This paper presents the experimental validation of a numerical model for the prediction of train induced vibrations. The model fully accounts for the dynamic interaction between the train, the track and the soil. The track geometry is assumed to be invariant with respect to the longitudinal direction, which allows for an efficient solution of the dynamic track-soil interaction problem in the frequency-wavenumber domain. The model is validated by means of several experiments that have been performed at the occasion of the homologation tests of the new HST track on the line L2 between Brussels and Ko¨ln. A first set of experiments is used to determine the dynamic soil and track characteristics. In a second set of experiments, the soil transfer functions, the track-soil transfer functions and the track and free field vibrations during the passage of a Thalys high speed train have been measured. These results are used for a step-wise validation of the numerical model that is based on the identified model parameters and allows to study the propagation of errors in the prediction model.
Vibration response of a railway track obtained using numerical models based on FEM
MATEC Web of Conferences, 2012
In the last forty years, researchers have developed models of wheel-rail contact force in order to study vibrations and rolling noise caused by railway traffic. These models range from analytical models, who consider a single rail of a railway track in contact with a rigid wheel attached to the bogie by means of the primary suspension, to numerical models based on finite element methods, boundary element, and mixed methods. Unlike analytical models, numerical models allow us to characterize more precisely the different components of railway track structure and consider the interaction between the entire track and a complete vehicle wheel-set. The study of the elements constituting the set of the railway track, the wheel-set and the primary suspension, as well as the knowledge of their influence in vibration generation and transmission due to train passage is of great interest when evaluating the possible vibration effects in the railway surrounding areas. This paper presents a numerical model of the track structure based on the finite element method. It is devoted to the study of the vibration response caused by vertical forces applied at any location on the rails. The numerical results are compared with analytical results previously presented in the bibliography.
Prediction of Railway-Induced Ground Vibrations in Tunnels
Journal of Vibration and Acoustics, 2005
The authors of this paper present the results of a study concerned with the assessment of the vibrational impact induced by the passage of commuter trains running in a tunnel placed underground the city of Rome. Since the railway line is not yet operational, it was not possible to make a direct measurement of the ground vibrations induced by the railway traffic and the only way to make predictions was by means of numerical simulations. The numerical model developed for the analyses was calibrated using the results of a vibration measurement campaign purposely performed at the site using as a vibration source a sinusoidal vibration exciter operating in a frequency-controlled mode. The problem of modeling the vibrational impact induced by the passage of a train moving in a tunnel is rather complex because it requires the solution of a boundary value problem of three-dimensional elastodynamics in a generally heterogeneous, nonsimply connected continuum with a moving source. The subject is further complicated by the difficulties of modeling the source mechanism, which constitutes itself a challenge even in the case of railway lines running at the surface. At last, the assessment of the vibrational impact at a receiver placed inside a building (e.g., a human individual or a sensitive instrument) requires an evaluation of the role played by the structure in modifying the computed free-field ground motion. So far, few attempts have been made to model the whole vibration chain (from the source to the receiver) of railway-induced ground vibrations, with results that have been only moderately successful. The numerical simulations performed in this study were made by using a simplified numerical model aimed to capture the essence of the physical phenomena involved in the above vibration chain including the influence of the structural response as well as the dependence of the predicted vibration spectra on the train speed.
On Vertical Analysis of Railway Track Vibrations
The paper herein presents a vertical vibration analysis of the ballasted track using a new model of the periodic support of the rail that improves the prediction of the rail response for both low and high frequencies. The model of the periodic support consists of two three-directional Kelvin-Voigt systems for the rail pad and the ballast, and a mixed Kelvin-Voigt/Maxwell system for the subgrade. Also, the inertia of the sleeper and the ballast block are introduced. The rail response due to a stationary and moving harmonic load is analyzed by applying the Green's functions method. The influence of the rail pad stiffness and of the Doppler effect on railkway track vibrations are presented.