Ground-borne Vibration Research Articles

Relationships and statistics between various vibration metrics, derived from a large set of measured train pass-bys

The impacts of groundborne vibration (GBV) and sound (GBS) induced by railway infrastructure are assessed across the world through different metrics. Many national and international standards can be found for assessing GBV, based either on acceleration (UK, Spain, etc.) or velocity metrics (Germany, USA, etc.). Various frequency and/or time-weightings can be used, and different quantities (running RMS or highest levels) are also considered. Direct comparison between the various assessment criteria and measured metrics is, therefore, difficult. Although no international standard defines GBS criteria, many guidelines suggest such a criterion through a relationship between GBS levels and vibration velocity levels on room surfaces. Different quantities are often used, even for neighboring projects: London’s Crossrail (now Elizabeth Line) and Northern Line extension impact assessments both used maximum vibration velocity levels but with different time weighting (slow and fast, respectively). Arup has amassed a large dataset of vibration measurements through its involvement in many railway schemes over the years. For each of the thousands of train pass-bys, measured at different distances, infrastructure types, operation, and ground conditions, the most common European and North American GBS and GBV metrics are derived and compared to each other to develop statistical relationships and associated uncertainties.

Evaluating the impact of construction-induced vibration on nearby structures when building road embankment in Hanoi

Vietnam is currently undertaking numerous transportation and infrastructure projects in urban areas, particularly in densely populated cities such as Hanoi and Ho Chi Minh City. These cities have high traffic density and frequent traffic congestion, which necessitates the use of construction equipment such as vibratory rollers and pile drivers. However, these machines can cause vibrations that affect the surrounding structures. This study investigates the impact of roller compaction-induced vibration on the building structure of Ring road No.2 in Hanoi, Vietnam. The finite element method (Plaxis 2D) was applied to evaluate the impact of vibration on surrounding structures. The maximum measured velocity is similar to the values derived from numerical analysis. The Finite element method (FEM) results exhibited a high degree of correlation with the actual velocity measurement and frequency dominant structure responses caused by ground-borne vibration induced by roller compaction within the frequency range of 5 Hz to 10 Hz.

Train Mitigation Measures in the Transmission Path: Seismic Metamaterial and Granular Barriers

The development of new mitigation measures is an effective solution to the annoyance generated by the induced vibration coming from the railway traffic to the residents of urban areas. This paper aims to give a brief comparison of two novel concepts of mitigation measures applied within the transmission path presented recently in the literature. In particular, the use of seismic metamaterial will be compared to the use of heterogeneous barriers, to evaluate to which extent these two mitigation measures can help to tackle the problem of ground-borne vibration and noise. These two cases will be related by considering the same railway environment based on a two-step approach, already validated in the past; in this study, the soil simulated in the second step is reproduced using the finite element method and spectral element method for the seismic metamaterial and heterogeneous barriers respectively. Finally, a parametric investigation is conducted to understand how the material and geometrical proprieties affect the attenuation levels of the two measures.

Broadband surface wave attenuation in porous soil by elastic metasurfaces

To mitigate surface waves in ambient vibration, a novel broadband elastic metasurface is proposed by periodically burying the layered in-filled pipes below the ground surface. The present metasurface is a simple structure and can be easily implemented. In contrast to the existing studies of metasurfaces in single-phase elastic soil, the coupling of elastic metasurfaces with saturated porous soil is investigated within the framework of Biot's theory. Note that Biot's poroelasticity can capture the complexity of soils in the presence of fluids. Both dispersion and transmission analysis are comprehensively conducted. The present investigation shows that the elastic metasurfaces are suitable for a wide range of fluid-saturated porous soil, and a significant surface wave attenuation is observed within the attenuation zone of elastic metasurfaces. In addition, the burying depth is the key point of the design of elastic metasurfaces. Specifically, the surface wave attenuation zone (SWAZ) will vanish when the depth is larger than three times the periodic constant. Besides, the SWAZ will be widened by stacking the layers of elastic metasurfaces. Three layers is enough for the metasurface to attenuate more than 80 % surface wave energy. Due to the similar dynamic characteristics of elastic metasurface in the fluid-saturated porous half-space compared to dry half-space, single-phased soil can be used to simplify the analysis of saturated soil with ideal fluids. To widen the scope of application in elastic metasurfaces, the feasibility of ambient vibration mitigation by elastic metasurfaces is experimentally and numerically verified. The experimental results confirm an obvious wave attenuation within the SWAZ, and the average insertion loss (IL︸) is 9.8 dB. Last but not least, the performance of elastic metasurfaces to mitigate ground-borne vibration induced by trains is numerically studied in time domain. Elastic metasurfaces outperform traditional trenches within the main frequency range, and IL︸ is increased by 3.9–7 dB. Thanks to the excellent wave attenuation performance and subwavelength thickness, these novel elastic metasurfaces are expected to open new avenues in ambient vibration mitigation in the costal area of saturated soil.

Simplified Analysis Approach for Predicting Ground-Borne Vibrations Induced by Impact Driving of Concrete Piles

Simplified Analysis Approach for Predicting Ground-Borne Vibrations Induced by Impact Driving of Concrete Piles

Prediction of ground-borne vibration induced by impact pile driving: numerical approach and experimental validation

Prediction of ground-borne vibration induced by impact pile driving: numerical approach and experimental validation

A pile–soil interaction model for ground-borne vibration problems based on the singular boundary method

An efficient three-dimensional approach for solving pile–soil interaction problems is proposed. In the approach, the soil is modelled as an elastic half-space, and its response in the presence of the pile’s corresponding cavity is computed by employing the singular boundary method. The pile is modelled analytically using the classic rod and Euler–Bernoulli beam theories. For the coupling with the soil, the pile is divided in a set of rigid segments that interact along their circumference with the soil. The methodology allows the rotational motions and reaction torques at these segments to be accounted for and their contribution in the accuracy of the scheme is assessed. A criterion to define the minimum number of collocation points that offers an acceptable trade-off between accuracy and numerical performance is also proposed. The method is validated against well-established methodologies and using the reciprocity principle that relates the wave radiation from the pile to the ground field with the incident wave problem due to a load on the ground surface. Results are shown for different soil stiffnesses and different pile length to diameter ratios. The employment of the singular boundary method is shown to provide strong computational advantages to detailed modelling approaches such as the three-dimensional finite element-boundary element method, as well as overcoming the fundamental limitations of plane-strain and axisymmetric methods.

Field Measurement and Energy Analysis of Ground-Borne Vibration around High-Speed Railway Viaduct

In order to investigate the vibration characteristics and propagation mechanism of ground vibrations induced by high-speed train passing through the viaduct, a field experiment is carried out, and the measured data is deeply analyzed. Besides the independent time domain and frequency domain analysis, the continuous wavelet transform (CWT) is performed on the vibration signal to analyze the energy distribution characteristics of ground vibrations from the view of time-frequency synchronous analysis. The experimental results show that the ground vibrations have obvious nonstationary characteristics; the first dominant frequency of ground vibration is concentrated between 40–55 Hz, which is affected by the excitation frequency of the train wheel axle and the peak frequency of wheel-rail interaction force. The ground vibrations attenuate gradually as the distance from the railway track increases, in which the high-frequency components above 50 Hz attenuate faster, low-frequency components below 8 Hz continuously decay in the near field, and medium-frequency components within 8−50 Hz decay slower with a longer transmission distance. Compared with traditional methods, time-frequency synchronous analysis of ground vibration signals is more accurate and intuitive, and the CWT can be used as a promising method in the analysis of ground-borne vibration from high-speed railway.

Investigating the effect of using softer rail-pads on ground-borne vibration from underground railways

ABSTRACT In this study, a series of vibration measurements were performed on a section of one of the lines of the Doha Metro to explore the effect of changing rail-pads from conventional higher stiffness under-rail pads to lower stiffness web-supporting pads on the vibration levels at the free surface. Vibration levels were measured for the two cases of lower and higher stiffness’ pads at the free surface directly above the railway track. Additionally, vibration levels were measured in the railway tunnel to investigate the effect of changing rail-pad’s stiffness on the vibration levels at different locations inside the tunnel. Vibration measurements due to moving trains from the two cases were processed and analysed to calculate the Insertion Gain (IG) of vibration at the free surface and at the other locations. It was found that the use of softer rail-pads has resulted in reduction in the vibration levels at the free surface by about 10 dB for most frequencies in the range 40–200 Hz. Further numerical investigation was conducted to simulate the railway section under consideration. To simulate the track fastening system accurately, the dynamic stiffness of the rail-pads for the two cases was estimated using the measurement of vibration of rails due to impact hammer excitation and measurement of axle-box accelerations of a moving trains. The parameters of problem at-hand were used as inputs to the numerical Pipe-in-Pipe (PiP) model to calculate the insertion gain numerically at the free surface and this showed good match with the results from the measurements.

Allowable Limit of Human Annoyance Towards Ground-Borne Vibration Velocity Induced by Rail Traffic: A Review

Many industrialized nations have created their own standards for determining and grading the dangers posed by ground-borne vibration, notably in terms of human irritation. Excessive vibrations created by trains have an impact not only on individuals, but also on sensitive machinery and buildings. The authority as well as practitioners have critical responsibilities in managing and accessing vibrations. This study discusses the differences between the standard and the limit of vibrations caused by trains that can irritate people. The local standard guideline was compared to the standards used by the US, Norway, Sweden, California, Germany, and the Netherlands. This study was mainly interested in the limitations of vibration velocity in residential settings.

Analytical solution of ground-borne vibration due to a spatially periodic harmonic moving load in a tunnel embedded in layered soil

Analytical solution of ground-borne vibration due to a spatially periodic harmonic moving load in a tunnel embedded in layered soil

A multiple scattering formulation to design meta-trenches for mitigating low-frequency ground-borne vibrations induced by surface railways and subways

We propose a multiple scattering formulation to investigate the performance of meta-trenches. The meta-trench is a novel device, composed of an array of resonant units buried in the ground in a proper arrangement, aimed at reducing the railway and/or subway induced ground motion by exploiting its scattering and resonant properties. Compared to classical open trenches, the resonators contribute to improving the wave mitigation performance of the trench in the low-frequency regime.The proposed formulation allows to consider the wave source anywhere in the half-space and a generic distribution of resonators in terms of number and position. The incident wave field generated by the source, such as a train or subway, along with the scattered wave fields produced by the resonant units that constitute the meta-trench, are modeled via Green’s functions. The multiple scattering formulation enables the solution of coupled wave problems by determining the amplitudes of scattered wave fields at various frequencies. Through comparison with finite element simulations, we demonstrate that in both buried source (i.e., subway) and surface-located source (i.e., ground railway) scenarios, our analytical formulation is able to properly model the dynamics of the coupled problems with a noticeable computational cost saving. Opening to fast and reliable parametric simulations, our formulation allows for a deeper knowledge of the wave interaction processes, resulting thus in a reliable tool for predicting the coupled wave field under both bulk and Rayleigh waves.

Diagonal compression testing of masonry under fatigue loading and high static loads

Underground railway operations pose a significant impact on overlying, highly sensitive historic masonry structures. Here, the process of structural assessment involves fatigue actions, through induced ground-borne vibrations, from operating underground railways. Considering long-term exposure periods, fatigue can introduce local cracking and losses, which endanger the integrity of both structural and non-structural elements. The lack of experimental fatigue data on tensile actions in masonry and the apparent computational restraints from constitutive cementitious material models that do not account for damage due to repeated loading, increase the complexity of structural assessment, under combined fatigue actions and other hazards. The current paper aims at providing new experimental data on fatigue in historic brick and lime mortar masonry wallets, replicating realistic combinations of static and fatigue loading under diagonal compression. Material deterioration and stiffness degradation are monitored throughout the process. Hence, under moderate amplitudes of fatigue loading and high static loads, cracking occurred, at a relatively low number of cycles, demonstrating the need for more strict vibration thresholds to ensure the integrity of historic masonry buildings.

Active vibration screening characteristics of bamboo in-filled wave barriers

This paper presents the efficacy of bamboo in-filled wave barriers (IB) and open trench (OT) in mitigating ground-borne vibrations. The influence of excitation frequency, barrier location, barrier configuration, barrier dimensions, and foundation geometry on the active screening characteristics is evaluated using experimental and numerical investigations. The results obtained from the investigation demonstrate that the performance of IB as a vibration screening technique is quite satisfactory. It can be noticed that the effectiveness of wave barriers increases with an increase in frequency. It can also be observed that at lower frequencies, the barrier spacing notably impacts the performance of OT, while it does not influence the performance of IB significantly. Further, IB and OT are seen to screen vertical vibrations more efficiently than horizontal vibrations. Wave barriers are seen to be more effective in screening the induced vibration along the centreline of the vibration source compared to other radial lines.

An analytical formulation to model geometric and resonant scattering of buried metabarriers for traffic-induced vibrations mitigation

We propose a metabarrier composed of an array of pipes equipped with resonators and develop an analytical formulation to investigate its mitigation performance on tunnel-induced ground-borne vibrations. The formulation calculates the displacement fields of the half-space by modelling the interaction between the tunnel-radiated waves and metabarrier-scattered waves. Both geometric and resonance scattering effects of the metabarrier are taken into account in the metabarrier-scattered waves. With the aid of the wave function method, multiple geometric scatterings of the pipes are considered by imposing the boundary conditions at the soil-tunnel/pipe interfaces, and multiple resonance scatterings of the resonators are computed by accounting for the interplays between the resonators. We demonstrate that the proposed approach can model the tunnel-radiated waves interacting with single-unit and multiple-unit metabarriers. Our analytical formulation can correctly capture multiple bandgaps provided by a periodically arranged metabarrier, namely the bandgaps induced by Bragg-type scattering due to the spatial periodicity of the pipes and the ones induced by resonance-type scattering due to the barrier resonators. As a result, the proposed barriers can be used to shield the broadband incident waves generated by the trains in a tunnel.

Prediction of ground-borne vibration from random traffic flow and road roughness: Theoretical model and experimental validation

With the densification and closer distance to buildings of road traffic network in urban areas, the assessment and control of environmental vibrations becomes the focus of attention, in which the prediction of traffic flow-induced ground vibration is very critical. However, few studies have been reported on the theoretical prediction method of traffic flow-induced ground vibration from the perspective of stochastic theory. The present work contributes to the perfection and innovation of the current methodologies for the prediction of traffic flow-induced ground vibration. In this paper, a semi-analytical and semi-numerical method for predicting traffic flow induced ground vibrations is developed, in which the random effect generated from traffic flow and road roughness is considered by establishing the vehicle-road-soil coupling model. Aiming to predict the long-term vibration and transient vibration induced by road traffic flow, the average and the adverse velocity levels are used as the evaluation indicators. The effectiveness of the proposed method is validated by an on-site experiment, and the characteristics of ground vibrations are investigated in time and frequency domains, respectively. The results demonstrate that the proposed method can effectively predict the road traffic flow-induced ground vibrations, and the randomness of both traffic flow and road roughness cannot be neglected. For the experimental site, the main frequency band of ground vibrations concentrates on 7–25 Hz, and the predominant center frequency is 12.5 Hz, resulting from the resonance between the overlapping dominant frequency bands of the dynamic vehicle loads and the natural frequency of the soil.

A numerical assessment of variable saturation of the upper layers on the ground borne vibrations from underground trains: A case history

Ground borne vibrations generated by the passage of underground trains may change over time due to objective causes, such as increasing weight and speed of trains or ageing of the infrastructure components, as well as a variation in the dynamic response of the soil surrounding the tunnel. Among the possible causes of changes in the soil dynamic response, its hydrologic state has been seldom investigated. In this contribution, the role played by the conditions of the soil above the water table is addressed, starting from a case history in the city of Milano. Two-dimensional plane strain numerical models have been developed for the infrastructure. The models were calibrated on the results of two geophysical investigations performed at the same site in the city centre, but at two different times, which allowed distinguishing different dynamic responses. The system was excited by a synthetic load time history, matching a reference dynamic load spectrum included in Italian recommendations. Limitations of using this input on a 2D plane strain model were assessed by comparing the computed vibrations with experimental acceleration records collected on the tunnel. The results of the two numerical models are compared with those of a simulation performed assuming fully dry conditions above the water table. Overall, the set of analyses shows that even small changes in the dynamic response of the soil, interpretated as a consequence of variable saturation, may result in a change of a few decibels in the acceleration levels. Much larger accelerations are predicted on average with the simpler dry model, clearly showing the advantages of a more accurate modelling strategy.

Efficient mitigation of railway induced vibrations using seismic metamaterials

The fast growth of railway transport pushed by its sustainability requires all railway stakeholders to work together to minimise any possible drawbacks that might slow down this positive trend. Among these, the induced vibrations generated at the wheel–rail interaction during train passage are the most significant, especially in urban areas where in the form of ground-borne vibrations and/or noise negatively affects the daily life of the residents. In this direction, the innovative concept of seismic metamaterial can enhance the vibration attenuation levels of existing mitigation measures and, at the same time, ensure a straightforward application in the railway environment. This paper uses a combined vehicle/track/soil prediction dynamic model of the T2000 LRV (Light Rail Vehicle) tram operating in Brussels, based on a two-step approach already validated in the past, to analyse the effects that the inclusion of seismic metamaterials within the transmission path has in terms of vibration attenuation. In particular, a four-by-four group of piles is examined with different material proprieties for the inclusions, considering a range of velocities and distances from the track in order to quantify the achievable Insertion Loss (IL) for each configuration depending on the distances and the tram speed, attaining ILs up to 10 [dB]. The study is then extended to other possible arrangements of the group of piles, providing a direct relationship between the repetitiveness of each row of the primitive unit cell of the metamaterial and the gained levels of attenuation, in order to give a base for the costs of this type of mitigation measure. Furthermore, the influence on the attenuation levels of the soil characteristics, is evaluated by considering an ideal uniform underground, extending the IL to 18 [dB] in the case of steel inclusion. Finally, the paper gives insights into the use of metamaterials as mitigation measures for railway-induced vibration in order to understand and evaluate the potential of this novel concept and its benefits.

A Methodology for Continuous Monitoring of Rail Corrugation on Subway Lines Based on Axlebox Acceleration Measurements

Rail corrugation is a degradation phenomenon that manifests as a quasi-periodic irregularity on the running surface of the rail. It is a critical problem for urban railway lines because it induces ground-borne vibrations transmitted to the buildings near the infrastructure, causing complaints from the inhabitants. A typical treatment to mitigate the rail corrugation problem is the periodic grinding of the rails, performed by dedicated vehicles. The scheduling of rail maintenance is particularly critical because it can be performed only when the service is interrupted. A procedure for the continuous monitoring of rail corrugation is proposed, based on axlebox acceleration measurements. The rail irregularity is estimated from the measured acceleration by means of a frequency domain model of vertical dynamics of the wheel–rail interaction. The results obtained by using two different methods (a state-of-the-art method and a new one) are compared. Finally, the study of the evolution of the power content of the rail irregularity enables the identification of the track sections where corrugation is developing and rail grinding is necessary.

Identification of line-source transfer mobility and force density by ground acceleration measurements.

Ground-borne vibration caused by railway traffic has been a research concern due to its possible side effects on nearby residences. The force density and line-source mobility can effectively characterize the generation and transmission of train-induced vibrations, respectively. This research proposed a frequency-domain method for identifying the line-source transfer mobility and force density using measured vibrations at the ground surface, which was on the basis of the least-square method. The proposed method was applied to a case study at Shenzhen Metro in China, where a total of seven fixed-point hammer impacts with 3.3m equal intervals were used to represent the train vibration excitations. Line-source transfer mobility of the site and force density levels of the metro train were identified, respectively. Causes for different dominant frequencies can be traced by separating the dynamic characteristics of vibration excitation and transmission. It was found in the case study that at a location 3m away from the track, the peak at 50Hz was caused by excitations, while that at 63Hz was attributed to transmission efficiency related to the soil properties. Subsequently, numerical validations of the fixed-point loads' assumption and identified force density levels were carried out. Good comparisons between numerically predicted and experimentally identified force density levels indicated the feasibility of the proposed method. At last, the identified line-source transfer mobility and force density levels were applied to the forward problem, i.e., making predictions of train-induced vibrations. The predicted ground and structural vibrations at different locations were compared to corresponding measurements, with good agreement, which experimentally validated the identification method. The identification results of the case study can be employed by similar railway systems as a good reference.