Ground-borne Vibration Research Articles

The effect of road unevenness on the dynamic vehicle response and ground-borne vibrations due to road traffic

In this paper, the relation between road unevenness, the dynamic vehicle response, and ground-borne vibrations is studied. In situ measurements of road unevenness and the dynamic vehicle response for six roads with different types of pavement are supplemented by numerical predictions of ground vibrations. The predictions are performed in two stages. In the first stage, the dynamic vehicle response is computed based on the measured road unevenness. The vehicle model is validated by comparing the predicted and measured vehicle response and subsequently used to predict the dynamic vehicle loads. In the second stage, the dynamic road–soil interaction problem is considered and the transfer functions between the road and the soil are computed. The effect of the pavement type (continuous, jointed, or composed of individual pavers) on the road–soil transfer functions is investigated and the free field vibrations are calculated using the dynamic vehicle loads computed in the first stage. The predicted free field vibrations are validated by measurements at one of the measurement sites before and after rehabilitation of a deteriorated concrete pavement. Finally, the results are used to investigate the relation between indicators of road unevenness such as the ISO 8608 road class, the International Roughness Index, and the coefficient of evenness on one hand, and the dynamic vehicle response and level of ground-borne vibration on the other hand.

Prediction of vibrations induced by trains on line 8 of Beijing metro

This paper mainly discusses the problem of ground-borne vibrations due to the planned line 8 of Beijing metro which passes under the National Measurement Laboratory. A lot of vibration sensitive equipments are placed in the laboratory. It is therefore necessary to study the impact of vibrations induced by metro trains on sensitive equipments and important to propound a feasible vibration mitigation measure. Based on the coupled periodic finite element-boundary element (FE-BE) method, a 3D dynamic track-tunnel-soil interaction model for metro line 8 has been used to predict vibrations in the free field induced by trains running at variable speeds between 30 km/h and 80 km/h. Four types of track structures commonly used on the Beijing metro network have been considered: (1) high resilience direct fixation fasteners, (2) Vanguard fasteners, (3) a floating slab track and (4) a floating ladder track. For each of these track types, the vibration isolation efficiency has been compared. The results of the numerical study can be used to predict vibrations in nearby buildings and to decide upon effective vibration countermeasures.

Vibrations induced by HST passage on ballast and non-ballast tracks

The use of ballastless slab track is significantly increasing in HST line technology. This development is due to some structural and operational advantages over ballasted track. In addition, floating slab tracks can be used to control ground-borne vibrations generated by surface and underground rail transportation systems. In this paper, a general and fully three dimensional multi-body-finite element-boundary element model is used to study vibrations due to train passage on ballast and non-ballast tracks. The vehicle is modelled as a multi-body system, the track, in both cases, using finite elements and the soil is represented using boundary elements. The three components of the load are considered; the quasi-static excitation (force generated by moving axle loads), the parametric excitation due to discrete supports of the rails and the excitation due to wheel and rail roughness and track unevenness. Track receptances are computed for both track systems and vibrations induced by high-speed train passage at the track and the free-field are evaluated for different train speeds. Soil behaviour changes significantly with the track system. Finally, a floating slab track is studied to show how this type of solution leads to a significant vibration reduction for surface tracks.

Concrete pier foundation and building design for electron microscope installations with vibration disturbances from train, truck, and bus traffic.

A university microscopy and imaging center housing nine instruments including scanning electron microscopes and transmission electron microscopes was proposed for a site near an active railroad and roadways. Low-frequency sound and vibration from trains, trucks, and buses can affect the performance and use of electron microscopes, by disturbing the stability and resolution of the specimen’s image. On-site observations and spectrum measurements were conducted to determine the ambient and transient ground borne vibration conditions. Measurements showed that disturbances from trains as well as bus and truck traffic on campus roads significantly exceeded allowable floor vibration tolerances for many of the instruments. Soils exhibited response to disturbances at dominant frequencies around 5 and 10 Hz. This paper addresses the potential for concrete pier-supported floor vibration and structural resonance contributions to ground borne vibration levels and solutions proposed to mitigate the disturbances for sensitive instrument installations. Graphic diagrams of structural design concepts and results from on-site measurements prior to construction will be discussed. The designs and effectiveness of the microscope rooms, structural treatments, and actively damped, pneumatic vibration isolation systems are discussed, along with post-construction vibration measurement results and photographs.

Two healthcare buildings get the power, the noise, and the vibration from a gas turbine generator system.

A package gas turbine generator was installed at a small, 4.3-MW cogeneration power plant of a mixed use development with office, retail, hospital, residential, and other occupancies. Shortly after commissioning, noise complaints were received from nearby medical offices about undesirable tonal noise intrusions. At another nearby hospital building, a neurosurgery suite addition would include a new intra-operative magnetic resonance imaging (iMRI) unit. Ambient vibration measurements at that site indicated prominent discrete frequencies of disturbance that could affect iMRI image quality. Investigations found loud broadband noise and dominant ground borne vibration in the vicinity of the turbine, with strong tonal peaks relating to turbine and generator rotational rates. The intrusive noise in nearby medical offices and the structure borne vibration at the hospital included matching strong tonal peaks. Various noise- and vibration-mitigating measures were proposed and some were implemented with successful results for the medical offices and new iMRI suite. Mitigating measures are discussed, along with measurement results and photographs.

Modeling ground response functions in rock: A comparison of multiple methods.

Rail transit operations often produce groundborne vibration with energy that extends into the audible frequency range. It is often necessary to predict potential ground/structure-borne vibration and noise transmission in the design of new buildings in close proximity to existing rail lines or for new rail facilities/alignments. In a detailed analysis, key factors include source vibration characteristics (spectral force input to soil and/or track structure), ground vibration propagation characteristics (spreading and material damping losses), building foundation type (soil/structure interaction and coupling losses), and structural design of upper floors (floor and wall resonances and attenuation through the building). This paper focuses on methods for obtaining vibration propagation characteristics in rock which is an efficient transmitter of vibration at audible frequencies. Three methods for obtaining one-third octave band response functions are compared: empirical methods, finite element analysis, and seismic modeling.

Numerical Calculation Method for Prediction of Ground-borne Vibration near Subway Tunnel

This paper describes the development of prediction method for ground-borne vibration from railway tunnels. Field measurement was carried out both in a subway shield tunnel, in the ground and on the ground surface. The generated vibration in the tunnel was calculated by means of the train/track/tunnel interaction model and was compared with the measurement results. On the other hand, wave propagation in the ground was calculated utilizing the empirical model, which was proposed based on the relationship between frequency and material damping coefficient α in order to predict the attenuation in the ground in consideration of frequency characteristics. Numerical calculation using 2-dimensinal FE analysis was also carried out in this research. The comparison between calculated and measured results shows that the prediction method including the model for train/track/tunnel interaction and that for wave propagation is applicable to the prediction of train-induced vibration propagated from railway tunnel.

Comparisons of the environmental footprint of heavy vehicles in the UK and Switzerland

The European Union project Eureka Logchain Footprint is an ongoing project to identify road and rail vehicles by means of their environmental footprint as characterised by dynamic load, noise, ground borne vibrations and gaseous emissions induced by the vehicle. Part of the project involves the installation of road and rail footprint monitoring stations throughout Europe. This paper presents results of the road stations in Switzerland and the UK. Individual vehicle data from weigh-in-motion and noise are compared. The results indicate that a significant number of vehicles surpass the limits set in both countries. It was shown that the UK sites are generating higher noise levels than their Swiss counterparts; in part due to the much coarser aggregate embedded in the running course of the pavement employed in the UK. Such data can be used to create an incentive for vehicle types with a low footprint and a penalty for vehicles with a large footprint.

Experimental investigation of railway train-induced vibrations of surrounding ground and a nearby multi-story building

In this paper, a field experiment was carried out to study train-induced environmental vibrations. During the field experiment, velocity responses were measured at different locations of a six-story masonry structure near the Beijing-Guangzhou Railway and along a small road adjacent to the building. The results show that the velocity response levels of the environmental ground and the building floors increase with train speed, and attenuate with the distance to the railway track. Heavier freight trains induce greater vibrations than lighter passenger trains. In the multi-story building, the lateral velocity levels increase monotonically with floor elevation, while the vertical ones increase with floor elevation in a fluctuating manner. The indoor floor vibrations are much lower than the outdoor ground vibrations. The lateral vibration of the building along the direction of weak structural stiffness is greater than along the direction with stronger stiffness. A larger room produces greater floor vibrations than the staircase at the same elevation, and the vibration at the center of a room is greater than at its corner. The vibrations of the building were compared with the Federal Transportation Railroad Administration (FTA) criteria for acceptable ground-borne vibrations expressed in terms of rms velocity levels in decibels. The results show that the train-induced building vibrations are serious, and some exceed the allowance given in relevant criterion.

Wave barrier of lime–cement columns against train-induced ground-borne vibrations

This paper presents a comparison between measured train-induced ground vibrations in the free-field before and after countermeasures had been taken at Kåhög near Gothenburg in Sweden. A wave barrier of lime–cement columns was constructed parallel to the railway in order to reduce the ground-borne vibrations inside nearby buildings. On top of the barrier an embankment was built to reduce air-borne vibrations. Due to the wave barrier design, part of the energy content of the waves was expected to be reflected by the screen and transmitted energy was expected to be partly scattered. Contribution from the noise-embankment was not thought likely but could not be ruled out due to its fairly large mass and its close proximity to the railway. The effect of the mitigating measures resulted in a 67% reduction of the maximum particle velocity at 30 m and 41% at 60 m from the railway. A simple two-dimensional finite element model has been used to study the relative importance of the wave barrier and the noise-embankment as contributors to the mitigation recorded of the ground vibrations in the field. It is concluded with respect to ground vibrations that both the barrier and the embankment had a mitigating effect but that the contribution from the barrier dominated. Furthermore, it is seen from the field results as well as the simulation that the effect of the mitigating action is reduced with increasing distance from the railway.

Vibration Characteristics and Effectiveness of Floating Slab Track System

Ground-borne vibration excited by metro traffic is becoming a more and more important problem for the rapidly developing transport system in urban areas and increasing public concern about environmental problems. In order to attenuate the vibration influence down to an acceptable level, floating slab track have been applied worldwide on metro line. An analytical dynamic model is employed in this paper to assess vibration characteristics and effectiveness of floating slab system. The dispersion equations of floating slab track system are solved by means of Fourier transformation method. The contour integration method is used to convert the vibration responses of the track system. The result demonstrates that the dispersive characteristics of the track system act as a continuous layered wave conductor with an infinite length slab. It will generate same-phase oscillation and infinite wavelengths in track system when excitation frequency is close to the cutoff frequencies. An increase of slab mass is most effective to expand the vibration isolation range, whereas it has no obvious effect to enhance the vibration isolation efficiency. A relatively high slab searing damping and low slab bearing stiffness generally decrease force transmission to improve the vibration isolation effectiveness and decrease resonant response of the track system.

Assessing the Open Trenches in Screening Railway Ground‐Borne Vibrations by Means of Artificial Neural Network

Reducing ground borne vibrations in urban areas is a very challenging task in railway transportation. Many mitigation measures can be considered and applied; among these open trenches are very effective. This paper deals with the study of the effect, in terms of reduction of vertical and horizontal displacements and velocities, of the open trenches. 2D FEM simulations have been performed and several open trench configurations have been analysed varying the main geometric features such as width and depth, distance from the rail, thickness of the soil layer over the rigid bedrock, type of the ground, ratio between the depth of the trench, and the thickness of the soil layer. For quantifying the influence of the above specified parameters in reducing ground‐borne vibrations an analysis using artificial neural networks (ANNs) has been carried out. Results show that among the geometric parameters the role of the depth of the trench is very significant; however the influence of the depth must be also evaluated in relation to the thickness of the soil layer.

Soil Vibrations Caused by Underground Moving Trains

The wave propagation problems caused by the underground moving trains are analyzed by the 2.5-dimensional finite/infinite-element approach. The near field of the half-space, including the tunnel and parts of the soil, is simulated by finite elements, and the far field extending to infinity by infinite elements. The train is simulated as a sequence of wheel loads moving at constant speeds. Using the present approach, a two-dimensional profile with three degrees per node is used to simulate the three-dimensional behavior of the half-space, which is valid for the case when the material and geometry of the system are invariant along the tunnel direction. The factors considered in the analysis of ground-borne vibrations include the damping ratio and stratum depth of the supporting soils, the depth and thickness of the tunnel, and the moving speed and excitation frequency of the trains. It was found that moving train loads with nonzero excitation frequencies can induce significantly higher vibrations than the static moving loads. The effect of stratum depth depends highly on the excitation frequency. For a tunnel constructed in a stiffer soil, the ground surface vibrations can be greatly reduced. Other conclusions useful to practical engineers are contained in the parametric study.

Ground-borne vibration due to static and dynamic axle loads of InterCity and high-speed trains

In predictions of railway-induced vibrations, a distinction is generally made between the quasi-static and dynamic excitation. The quasi-static excitation is related to the static component of the axle loads. The dynamic excitation is due to dynamic train–track interaction, which is generated by a large number of excitation mechanisms, such as the spatial variation of the support stiffness and the wheel and track unevenness. In the present paper, the quasi-static excitation and the dynamic excitation due to random track unevenness are evaluated by means of numerical predictions. A solution strategy is presented that allows for the evaluation of the second-order statistics of the response due to dynamic excitation based on the power spectral density function of the track unevenness. Due to the motion of the train, the second-order statistics of the response at a fixed point in the free field are non-stationary and an appropriate solution procedure is required. The quasi-static and dynamic contribution to the track and free-field response are analysed for the case of InterCity and high-speed trains running at a subcritical train speed. It is shown how the train speed affects the quasi-static and dynamic contribution. Finally, results of numerical predictions for different train speeds are compared with field measurements that have been performed at a site along the high-speed line L2 Brussels–Köln within the frame of homologation tests.

Foraging Cues Used by Insular Florida Cottonmouths, Agkistrodon piscivorus conanti

Abstract Previous studies have shown that snakes can use groundborne vibrations for localizing prey, and some have proposed that such vibrations provide important cues for cottonmouth snakes while foraging on fish that fall from island bird rookeries. The latter hypothesis was tested by using fish and fish models to study the behavioral response of insular Agkistrodon piscivorus conanti to groundborne vibrations and olfactory cues. Diving and wading birds that nest on Seahorse Key, a small island adjacent to the northern Florida peninsula in the Gulf of Mexico, regularly drop fish in the vicinity of resident A. piscivorus during the colonial nesting period. Here we report that presentation of an equivalent groundborne vibration, without associated chemosensory or visual stimuli, failed to induce overt foraging behavior in these snakes. However, presentation of a fish-based olfactory stimulus, without associated groundborne vibration or motion, triggered a foraging response in A. piscivorus. Snakes from tw...

Building Isolation from Ground Borne Vibration

Building Isolation from Ground Borne Vibration

Nanotechnology research facility‐ A vibration and noise control design case study

Vibration and noise control would be critical to the success of a proposed nanotechnology and molecular research facility. Roadway traffic, a nearby power generation plant and buildings in the vicinity were potential sources of ground borne vibration disturbances. Mechanical equipment, occupant installed support apparata and occupant activities were potential sources of internally generated vibration disturbances. On‐site ground borne vibration was measured for comparison with generic floor vibration criteria for sensitive installations. Results were analyzed relative to criteria for potential disturbance of sensitive equipment, perception by occupants, audible radiated structure borne noise in acoustically sensitive spaces and resolution‐degrading motion for scanning and for transmission electron microscopes and other nanotechnology clean room equipment. Design guidelines and structural vibration control concepts were recommended to the structural engineers, including de‐tuning, damping and isolation methods. Recommendations were provided for mechanical noise control and vibration isolation. Architectural noise control, sound isolation and room acoustics guidelines were provided for research, office and meeting spaces. This case study will discuss the desired vibration and noise control objectives and the design solutions that were implemented. Building photographs will be presented. Post‐construction measurement results will be graphically compared with pre‐construction conditions to demonstrate apparent degree of success in mitigating vibration.

A parametric study on the isolation of ground-borne noise and vibrations in a building using a coupled numerical model

Underground traffic induced vibrations and noise in buildings are a major environmental concern in urban areas. To quantify these vibrations a numerical prediction model has been developed and validated. A coupled FE-BE model is used to compute the incident ground vibrations due to the passage of a train in the tunnel. A dynamic soil-structure interaction model is used to determine the vibration levels of the building. The soil-structure interaction problem is solved by means of a 3D boundary element method for the soil coupled to a 3D finite element method for the structural part. An acoustic 3D spectral finite element method is used to predict the acoustic response. The coupled numerical model is used to quantify the efficiency of vibration and noise mitigation measures at different stages of the vibration propagation chain. Vibration isolation with a floating slab track is modeled on the source side, base isolation is incorporated in the structure model, and a box-within-box arrangement is considered for the isolation of re-radiated noise in the building's rooms. The insertion gain of the three methods is compared using the model of a multi-story portal frame office building subjected to ground-borne vibrations from an underground railway line.

In situ measurements of the environmental footprint of freight vehicles in Switzerland

Eureka Logchain Footprint is an ongoing European cooperative project aimed at developing methods to identify road and rail vehicles through their environmental “footprint” as characterised by their dynamic load, noise, ground borne vibrations, and gaseous emissions. Part of the project involves the installation of road and rail footprint monitoring stations throughout Europe. This paper reports the results of the first road station built on the A1 motorway in Switzerland on a flexible asphalt pavement. Individual vehicle data on weigh in motion, noise and vibration sensors were measured in situ. Methods for the incorporation of gaseous emissions from vehicles are discussed. The results indicate that the various footprint parameters need to be assessed separately to determine the environmental impact of heavy vehicles.

Book Review: Review of ‘Train-Induced Groundborne Vibration and Noise in Buildings’

Book Review: Review of ‘Train-Induced Groundborne Vibration and Noise in Buildings’