Ground-borne Vibration Research Articles

Study on the effect of mitigation strategies for rail corrugation in metro lines

Rail corrugation appears as a periodic irregularity on the rail running surface that causes severe dynamic loads at the wheel-rail interface. These dynamic forces may generate ground-borne vibrations that propagate from the line to the surrounding buildings causing discomfort to residents. Rail grinding is the most used countermeasure for the mitigation of corrugation. However, this maintenance operation determines high operative costs if frequently performed and must be carefully scheduled. To this end, it is important to assess the effectiveness of other mitigation solutions that may prevent or slow down its growth. The main objective of this study is to investigate the formation of rail corrugation on a sharp curve of the Cityringen underground line in Copenhagen. A wheel-rail interaction model is developed in the frequency domain to identify the root causes of the problem on the specific curve and predict the corrugation wavelength. Once the accuracy of the model is tested against experimental observations on the reference curve, it is used to explore the effectiveness of different mitigation actions, such as the use of friction modifiers, the variation of the speed, track design and track gauge. The results indicate that friction modifiers and speed variation are the most effective measures.

A Novel Application of Computational Contact Tools on Nonlinear Finite Element Analysis to Predict Ground-Borne Vibrations Generated by Trains in Ballasted Tracks

Predictive numerical models in the study of ground-borne vibrations generated by railway systems have traditionally relied on the subsystem partition approach (segmented). In such a method, loads are individually applied, and the cumulative effect of the rolling stock is obtained through superposition. While this method serves to mitigate computational costs, it may not fully capture the complex interactions involved in ground-borne vibrations—especially in the frequency domain. Recent advancements in computation and software have enabled the development of more sophisticated vibrational contamination prediction models that encompass the entire dynamics of the system, from the rolling stock to the terrain, allowing continuous simulations with a defined time step. Furthermore, the incorporation of computational contact mechanics tools between various elements not only ensures accuracy in the time domain but also extends the analysis into the frequency domain. In this novel approach, the segmented models are shifted to continuous simulations where the nonlinear problem of a rigid–flexible multibody system is fully considered. The model can predict the impact of a high-speed rail (HSR) vehicle passing, capturing the key intricacies of ground-borne vibrations and their impact on the surrounding environment due to a deeper comprehension of the occurrences in the frequency domain.

Experimental assessment of isolation performance of a building above metro lines: a case study with dual isolation levels

This paper presents an assessment of the acoustic performance of a five-story residential building constructed directly above a metro line in Prague. The building has been isolated at two levels: first, on top of the distribution beams above the metro tunnel and secondly, at the ground floor. The assessment of the building's performance has been conducted by a direct measurement of ground borne noise radiated inside the rooms and evaluating the vibration transmission loss through the isolation system. The transmission loss assessment was carried out using two different test setups. Firstly, during train pass-byes, ground borne vibrations were simultaneously measured at various locations above and below the vibration cut. Secondly, at the same measurement points, the vibration levels were measured using hammer impacts. Finally, the transmissibility obtained from both test setups was compared and discussed. Additionally, ground borne noise levels were measured inside rooms on different floors above the vibration cut. To identify noise events exclusively associated with train pass-byes, data obtained from synchronized vibration measurements at the center of a room inside an apartment were used. Finally, the measured noise levels were compared with the limit values of noise exposure recommended by the Czech standards.

On the reduction of FEM models dealing with vibrations propagation from ground to buildings

The problem of ground-borne vibrations in contact with a building's basement is crucial to the comfort of people living in buildings located very close to roads or railway tracks. The numerical finite elements models used to describe this situation are heavy to compute: it must combine the complexity of the building with the large dimensions of the soil. We propose a method to reduce the model computation cost while keeping accurate results. The goal of our study is to remove the ground from the model by applying efforts and boundary conditions to the building foundation to reproduce the soil/structure interactions. The full model of a simple building with a basement on a single-layer soil is studied to extract the coupling stresses. Corresponding efforts are applied to the building alone, with several boundary conditions tested. The results show similar vibration levels on the building floors, for a far lower time of computation.

Coupling model between building post structure and floors with the spectral element method

With the densification of urban area and public transport, the structure-borne noise disturbance due to railway traffic is a major issue. In order to mitigate it, ground-borne vibration propagation in building has to be investigated. The case of post-beam constructions necessitates 3D modeling with choices between complex, precise and computationally time-consuming approaches (3D finite element method for example), and fast but less accurate approaches like the statistical energy analysis (SEA) which need a strong modal density. For such post-beam constructions, the spectral element method (SEM) appears to be a good compromise. This method allows reducing the number of elements to represent the truss structure compared to the finite element method. However, the building walls and floor are difficult to consider with the SEM. In this paper, the challenge of coupling post-beam structures and floors is examined, a method is proposed and results are discussed. The aim is to develop a method applicable to different buildings while keeping advantage of SEM low discretization.

Guiding near-source elastic waves in a semi-infinite medium.

In this work, we propose elastic metamaterials with phase discontinuities to steer the propagation of near-source bulk waves in a semi-infinite elastic medium. Our design exploits an array of embedded subwavelength resonators with tailored masses to attain a complete phase shift spanning [Formula: see text]. This phase control allows for diverse wave functionalities, such as directional refraction and energy focusing. Through the use of dispersion diagrams and the generalized Snell's law, along with a multiple scattering formulation, we analytically demonstrate the effectiveness of our design in achieving the desired wavefront manipulation. The proposed design has the potential to advance the field of guiding elastic waves using metamaterials and find practical applications in areas such as isolating ground-borne vibrations in densely urbanized regions and energy harvesting. This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 1)'.

Numerical prediction of ground-borne vibrations due to continuous vibratory driving of circular closed-ended piles

Various types of pile driving work may induce high-intensity ground-borne vibrations. Predicting vibration intensity before adopting mitigation measures is vital for minimizing the impact of vibration on nearby structures and occupants. Vibratory pile driving is a commonly applied foundation construction method. However, numerical simulation models for ground vibrations during a complete process of vibratory driving have rarely been studied. This study introduces an axisymmetric finite element model that utilizes the arbitrary Lagrangian-Eulerian technique to simulate the continuous vibratory driving of a circular closed-ended pile penetrating from the ground surface to a target depth. The model validity was confirmed by assessing the calculated ground vibrations against the findings documented in earlier research. The results showed that the critical penetration depth of piles, at which the maximum peak particle velocity (PPV) occurs, varied with the radial distance and depth of points of interest, contradicting a common preconception. Moreover, the maximum PPV did not always occur on the ground surface across all radial distances. Parametric analysis revealed that an increase in the soil cohesion strength, pile diameter, or soil-pile friction, or a decrease in the driving frequency or soil damping ratio would increase ground vibrations due to vibratory pile driving.

Using tire derived aggregates (TDA) as infill material for wave barriers

Ground-borne vibrations caused by construction activities and highway and railway traffic may disturb adjacent structures and sensitive machines. Thus, studies on isolating this type of vibrations have accelerated in recent years. Few experimental work investigated the use of rubber-soil mixtures as infill material for vibration mitigation. However, despite its high damping capacity, almost no experimental work has been conducted to evaluate the use of Tire Derived Aggregates (TDA) as infill material for trench barriers. This paper aims to investigate the use of TDA trenches as a wave barrier. Also, the performance of buried TDA trenches was considered in this work. A series of vibration tests were conducted in a steel tank with dimensions of 2.75 m long, 2.25 m wide, and 1.80 m deep. The trench depth and frequency varied from 0.2 to 0.6 m and 100–200 Hz, respectively. The results showed that TDA trenches had a superior performance compared to open trenches. TDA trenches could reduce the vertical vibration amplitude by up to 30 % more than open trenches. Also, open and TDA trenches performed better in mitigating the vertical vibrations compared to the other directions. Furthermore, for optimum design of open and TDA trenches, the normalized trench depth should be between 1 and 1.3 D. Covering TDA trenches with soil was found to decrease their vibration isolation significantly at normalized burial depth larger than 0.15.

Impact of Train-Induced Vibrations on Residents’ Comfort and Structural Damages in Buildings

AbstractThe rapid growth of urbanization and the progress of industrialization have resulted in the construction of over or near-track buildings. Train-induced ground-borne vibrations have attracted attention because they can damage buildings and cause residents discomfort. This study conducted a series of finite element analyses on three 5-story concrete framed buildings, which were subjected to the passage of trains at various speeds. One of the buildings was modeled as an over-track building, whereas the other two buildings were located in close proximity to the track but at different distances. The present study investigated the impact of train speed and track-to-building distance on the acceleration and velocity responses of buildings. The comparison of residents’ comfort levels and the structural safety of buildings against potential damages was conducted using international standards as the controlling criteria. Furthermore, an efficient mitigation technique was implemented, involving the utilization of open trenches with different depths between buildings and the railway track. This approach was employed with the aim of minimizing the detrimental impacts caused by trains-induced vibrations. The findings indicated that the over-track building was impacted by the train-induced vibrations more than near-track buildings. Furthermore, it was shown that although the passage of high-speed trains can disturb the comfort of building residents and potentially cause some structural damage to buildings, it did not lead to any significant story drifts in the structures. Finally, the minimum required depth of open trenches to mitigate train-induced vibrations was computed for every type of buildings and train speeds.

Comparison of train noise and vibration measurements with U.S. Department of Transportation model predictions

Wayside noise and ground-borne vibration measurements of freight and light rail train operations were carried out in Denver, CO in support of the Burnham Yard Transportation Planning Study being pursued by the Colorado Department of Transportation (CDOT). This study was intended to evaluate various track layout alternatives for the Consolidated Main Line (CML) freight railroad alignment and enhancement of Regional Transportation District (RTD) light rail operations while maintaining options for Front Range Passenger Rail (FRPR) within Burnham Yard and the surrounding areas. The objective of the measurements was to compare measured train noise and vibration levels with predictions using models sanctioned by the U.S. Department of Transportation (USDOT) in order to validate the use of these models to assess the noise and vibration impacts of the project alternatives. The models included the Federal Railroad Administration (FRA) Chicago Rail Efficiency And Transportation Efficiency (CREATE) freight noise model, the FRA Horn Noise Model, and the models included in the Federal Transit Administration (FTA) Transit Noise and Vibration Impact Assessment Manual. Based on a comparison of measured and modeled results, it was concluded that the USDOT models could be used to assess noise and vibration from train operations in the Burnham Yard Study Area.

Investigating the effects of in-track countermeasures to reduce ground-borne vibration from underground railways

Investigating the effects of in-track countermeasures to reduce ground-borne vibration from underground railways

Criticality and chaos in auditory and vestibular sensing

The auditory and vestibular systems exhibit remarkable sensitivity of detection, responding to deflections on the order of angstroms, even in the presence of biological noise. The auditory system exhibits high temporal acuity and frequency selectivity, allowing us to make sense of the acoustic world around us. As the acoustic signals of interest span many orders of magnitude in both amplitude and frequency, this system relies heavily on nonlinearities and power-law scaling. The vestibular system, which detects ground-borne vibrations and creates the sense of balance, exhibits highly sensitive, broadband detection. It likewise requires high temporal acuity so as to allow us to maintain balance while in motion. The behavior of these sensory systems has been extensively studied in the context of dynamical systems theory, with many empirical phenomena described by critical dynamics. Other phenomena have been explained by systems in the chaotic regime, where weak perturbations drastically impact the future state of the system. Using a Hopf oscillator as a simple numerical model for a sensory element in these systems, we explore the intersection of the two types of dynamical phenomena. We identify the relative tradeoffs between different detection metrics, and propose that, for both types of sensory systems, the instabilities giving rise to chaotic dynamics improve signal detection.

An efficient pile-group foundation model to deal with ground-borne vibration problems

An efficient pile-group foundation model to deal with ground-borne vibration problems

Minimal Conditioned Stiffness Matrices with Frequency-Dependent Path Following for Arbitrary Elastic Layers over Half-Spaces

This paper introduces an efficient computational procedure for analyzing the propagation of harmonic waves in layered elastic media. This offers several advantages, including the ability to handle arbitrary frequencies, depths, and the number of layers above an elastic half-space, and efforts to follow dispersion curves and flag up possible singularities are investigated. While there are inherent limitations in terms of computational accuracy and capacity, this methodology is straightforward to implement for studying free or forced vibrations and obtaining relevant response data. We present computations of wavenumber dispersion diagrams, phase velocity plots, and response data in both the frequency and time domains. These computational results are provided for two example cases: plane strain and axisymmetry. Our methodology is grounded in a well-conditioned dynamic stiffness approach specifically tailored for deep-layered strata analysis. We introduce an innovative method for efficiently computing wavenumber dispersion curves. By tracking the slope of these curves, users can effectively manage continuation parameters. We illustrate this technique through numerical evidence of a layer resonance in a real-life case study characterized by a fold in the dispersion curves. Furthermore, this framework is particularly advantageous for engineers addressing problems related to ground-borne vibrations. It enables the analysis of phenomena such as zero group velocity (ZGV), where a singularity occurs, both in the frequency and time domains, shedding light on the unique characteristics of such cases. Given the reduced dimension of the problem, this formulation can considerably aid geophysicists and engineers in areas such as MASW or SASW techniques.

Analysis and intelligent prediction of subway train-induced vibration in the building with pile foundation

The rapid development of subway construction inevitably leads to the subway lines traversing through or adjoining the buildings. However, current research primarily focuses on the train-induced ground-borne or building with shallow foundation vibrations, with a relatively limited investigation into the vibration pertaining to the building with pile foundation. A vibration analysis model of a building with pile foundation adjacent to a subway is established in this study using the finite element method, and the effects of various factors on the vibration of the building are analyzed, then the prediction of building vibration characteristics is also carried out by combining artificial intelligence methods. The results show that the building floor has an amplifying effect on the vibration acceleration level and Z-vibration level in the high frequency range, and the vibration energy attenuation at high frequencies is faster in the building with pile foundation compared to the building with shallow foundation. In the meantime, it shows that the GA-BP model is capable of effectively capturing the vibration characteristics of the building with pile foundation within the dominant frequency range. and the vibration of the building with pile foundation can be predicted not only by parameters such as train speed, soil and structure parameters but also by train-induced ground-borne vibration, which provides the possibility of simplifying the process of vibration prediction process and enhancing the practical application.

Experimental Study on Reutilization of Waste Rubber Chips with Sheetpiles as a Coupled-Wave Barrier to Reduce Ground-Borne Vibrations

Abstract Purpose Environmental and man-made vibrations due to various sources have become an environmental issue in recent years. Wave barriers such as open and in-filled trenches have been commonly used in the mitigation of these vibrations. Even though the open trench has exhibited better performance than the others, it may not be applicable or feasible in many cases. Therefore, soft and stiff barriers have been used for the same purpose. The present study aims to reveal the vibration isolation performance of not only single barriers such as rubber chips in-filled trenches and sheetpiles but also a novel barrier, rubber chips-sheetpile coupled barriers. Methods Rubber chips and sheetpiles were employed as soft and stiff wave barriers, respectively. The screening effectiveness of rubber chips, sheetpiles and their coupled form was examined through comprehensive field tests. Vibrations having frequencies in the range of 10–80 Hz were generated by a state-of-the-art mobile seismic shaker and measured by highly sensitive acceleration and velocity pickups in the absence and presence of these wave barriers. The effectiveness of the wave barriers was quantitatively determined. Results and conclusion While the sheetpile was more effective than rubber chips at low frequencies, the case was vice versa at higher frequencies. However, the coupled wave barrier outperformed other barriers in each case. If one barrier could not provide the required amount of isolation or is only effective within a limited range of frequency, using a coupled barrier with the installation of the other may significantly provide better vibration isolation.

Mitigating train-induced building vibrations with rubber bearings designed for horizontal earthquake isolation

As rail transportation, including high-speed railways and urban metros, rapidly expands, its proximity to residential areas decreases, raising concerns about ground-borne vibrations. This study investigates the main characteristics of ground-borne vibrations induced by high-speed railways and metros through substructure method based on 2.5D FEM-MFS (finite element method-the method of fundamental solutions). Besides, the study also delves into the vertical vibration behaviors of buildings caused by train operations, evaluating the effect of laminated rubber bearings designed for horizontal seismic isolation on the train-induced building vibration mitigation. Our findings highlight that the broadband vibrations from train operations might coincide with the natural vibration frequencies of buildings, potentially leading to resonance. Implementing isolators allows the natural frequencies of the vibration modes with larger effective masses to be significantly lower than the dominant frequencies of train-induced ground-borne vibration, reducing the high-frequency responses. Additionally, the vibration mitigation enhances with the increase in the thickness of rubber layer. This research not only aims to reduce vibration levels in buildings adjacent to railways, enhancing the living conditions and health of residents but also underscores the engineering innovations necessary for sustainable urban development.

EVALUATION OF GROUND BORNE VIBRATION WITH RESPECT TO PILE DRIVING

Construction activities contribute to ground-borne vibrations, leading to structural damage and adverse environmental effects like noise pollution and human discomfort. Piling, particularly dynamic piling using a hammer drop, is a common construction practice in Malaysia for erecting high-rise buildings. However, this activity, if conducted near urban or residential areas, can result in various issues such as soil settlement and structural damage. Pile-induced vibrations result from the energy transfer initiated by the hammer drop, transmitting through the pile and subsequently propagating into the surrounding soil.he damping effects of these waves decrease with increasing distance from the pile, while the energy transferred to the ground rises with the depth of pile penetration. The relationship between the distance of the pile from the vibration source and Peak Particle Velocity (PPV) is inversely proportional, indicating that as the distance increases, the PPV decreases. Conversely, the relationship between pile depth and PPV is directly proportional, implying that as the pile depth increases, the PPV also increases. The analysis reveals that Peak Particle Velocity (PPV), distance, and pile depth exhibit similar positively skewed distributions with negative kurtosis. Negative linear correlation exists between PPV and distance, while a positive correlation is observed with pile depth. The multiple linear regression equation, PPV = 1.803 – 0.0810 Distance + 0.1176 Pile Depth, highlights PPV's dependence on both variables, with significant P-values. The model's explanatory power, indicated by an 82.80% R-squared value, is notable. Validation shows minor discrepancies within 0.3 mm/s between on-site PPV measurements and regression predictions. Although the highest recorded PPV suggests potential damage, most data remain below 3 mm/s, emphasizing the importance of considering distance and pile depth in managing ground vibrations. The regression model proves reliable. The primary objectives of this study are to establish and analyze the relationships between PPV, pile depth, and distance from the vibration source. Additionally, the study aims to develop a ground-borne vibration model using multiple linear regression.

Vibration mitigation using dual-open and infilled trenches in layered soil media: Field tests and numerical simulations

Ground-borne vibrations are increasing at a rapid rate due to the rise in urban expansion and industrial activities. The current solution to mitigate the unwanted vibrations is limited to the use of single trenches that require unrealistic depths. This paper presents the possibilities of using dual open and infilled trenches to mitigate the vibrations generated due to continuous harmonic motions. Full-scale field tests and comprehensive numerical studies were performed to systematically design dual trenches. The field vibration tests were performed under a wide range of frequencies using the Lazan-type mechanical oscillator. Similarly, numerical studies have been performed using finite element analysis software, PLAXIS 2D. Expanded polystyrene (EPS) geofoams of different densities, bentonite, ceramsite, concrete, and sand-rubber mixture were used as the infill materials. The normalized depths of 0.40 and 0.50 were observed as the optimal values to reach an average amplitude reduction ratio (average ARR) of 0.25 for the dual open and EPS15-infilled trenches, respectively. The isolation efficiency of EPS15-infilled trenches was observed to be 178 % higher compared to the EPS48-infilled trenches. The performance difference between EPS15 and ceramsite-filled dual trenches was observed to be only 4 % in terms of average ARR, the former being superior.

Tri-axial ground-borne vibration measurements during rail pass-bys

Ground-borne vibrations from rail pass-bys, transmitted from train wheels rolling on the rails, have the potential to cause various adverse effects at nearby receptors, such as annoyance and re-radiated noise. To assess the impact of rail pass-bys, surface-level vibration can be characterized in three components: one vertical and two horizontal directions. Prior experience, best-practice guidelines from the Federal Transit Administration Transit Noise and Vibration Impact Assessment Manual, and theory of propagation of Rayleigh surface waves indicate that the vertical component dominates the horizontal components, such that vibrations from rail pass-bys can be adequately characterized by the vertical component only. This purpose of this study is to assess the sufficiency of characterizing the impact of ground-borne vibrations caused by rail pass-bys based solely in the vertical direction. Tri-axial vibration measurements were conducted for freight and passenger trains in Ontario, Canada, using a multi-channel signal analyzer for simultaneous measurement of multiple-axis vibration levels. The measured levels were then examined across the three components.