Ground Vibration Acceleration Research Articles

Ground vibrations induced by high-speed trains moving on layered near-saturated ground using 2.5D FEM

An improved 2.5-dimensional finite element model is developed to investigate ground vibrations induced by high-speed trains moving on layered near-saturated soil. The accuracy of the model is validated using a theoretical solution. The effects of the train speed, soil type, and saturation on the vibration acceleration, displacement, and excess pore pressure are evaluated by comparing soft- and hard-layered near-saturated and saturated soil models. The findings suggest that the effect of saturation on the ground vibration acceleration and displacement is minimal when the train speed is below the critical speed of the soil. The vibration acceleration, displacement, and excess pore pressure in the soft-layered soil are higher than those in harder soil. Compared to harder layered soil, saturation has a more prominent influence on vibration acceleration and displacement in softer soil, whereas its influence on excess pore pressure is low. The rebound of the excess pore pressure at the saturated soil interface is more pronounced than that at the near-saturated interface. The effect of saturation on excess pore pressure is independent of the train speed.

Predicting ground vibrations from railway tunnels using an improved 2.5D FEM-PML model with soil spatial variability

PurposeThis study establishes a method for predicting ground vibrations caused by railway tunnels in unsaturated soils with spatial variability.Design/methodology/approachFirst, an improved 2.5D finite-element-method-perfect-matching-layer (FEM-PML) model is proposed. The Galerkin method is used to derive the finite element expression in the ub-pl-pg format for unsaturated soil. Unlike the ub-v-w format, which has nine degrees of freedom per node, the ub-pl-pg format has only five degrees of freedom per node; this significantly enhances the calculation efficiency. The stretching function of the PML is adopted to handle the unlimited boundary domain. Additionally, the 2.5D FEM-PML model couples the tunnel, vehicle and track structures. Next, the spatial variability of the soil parameters is simulated by random fields using the Monte Carlo method. By incorporating random fields of soil parameters into the 2.5D FEM-PML model, the effect of soil spatial variability on ground vibrations is demonstrated using a case study.FindingsThe spatial variability of the soil parameters primarily affected the vibration acceleration amplitude but had a minor effect on its spatial distribution and attenuation over time. In addition, ground vibration acceleration was more affected by the spatial variability of the soil bulk modulus of compressibility than by that of saturation.Originality/valueUsing the 2.5D FEM-PML model in the ub-pl-pg format of unsaturated soil enhances the computational efficiency. On this basis, with the random fields established by Monte Carlo simulation, the model can calculate the reliability of soil dynamics, which was rarely considered by previous models.

Predicting the Distribution of Ground Vibration Acceleration Induced by Mining Activities Taking into Account the Directionality of Vibration Attenuation

Entrepreneurs carrying out mining works under seismic hazard conditions are obliged to conduct studies in the field of engineering geophysics, including measuring, interpreting and evaluating the effects of rock mass tremors on ground vibration parameters, and thus the occurrence of harmful impacts on surface objects. However, for technical reasons, this is a difficult task to implement at all points subject to the influence of mining activities. Therefore, it becomes expedient to look for solutions that would provide greater accuracy in forecasting the distribution of ground vibration parameters. This paper proposes a method for forecasting the distribution of peak ground accelerations (PGAs) induced by mining activities, taking into account the directionality of vibration attenuation. In many cases, the explanation of the variation in the magnitude of recorded ground surface vibrations after a rock mass tremor cannot always be explained by only the variation of epicentral distances and the value of the vibration amplification factor by quaternary formations. Therefore, it is reasonable to take into account the directionality of vibration attenuation. The authors analyzed and evaluated the accuracy of predicting the distribution of ground vibration accelerations induced by mining activities, taking into account the directionality of vibration attenuation, using three models: the first, a classical model assuming isotropic vibration attenuation; the second, a model taking into account the anisotropy of vibration attenuation with elliptical isolines; the third, a model without assuming the shape of the isolines of vibration intensity parameters. For both models that took into account anisotropy of vibration attenuation, better results (more accurate descriptions of observed ground vibration accelerations) were obtained than for the model assuming isotropy. The most accurate estimates of vibration magnitude were obtained using the latter model.

Pemetaan Tingkat Bahaya Gempabumi Berbasis Percepatan Getaran Tanah Maksimum Dan Intensitas Gempabumi Di Provinsi Bali

The Research has been carried out on the level of earthquake hazard in the Bali region based on maximum ground vibration acceleration (PGA) and earthquake intensity. The data that used in this research were obtained from the BMKG and USGS catalogs. The value of the earthquake hazard level is calculated using the appropriate PGA empirical equation through a correlation test of several empirical equations, namely the Katayama, Mc. Guire, Faccioli, Singh et al, Ambraseys, and Wang Tao with BMKG observation data.. Based on the correlation test, the Katayama equation (1974) was obtained with the smallest error value of 0.52. The calculation results show that the maximum PGA value ranges from 154-1944 gal and the earthquake intensity ranges from VII to X on the MMI scale with the highest hazard level in the Karangasem, Buleleng, and parts of Jembrana districts.

Numerical modelling of traffic-induced dynamic loading on a two-story residential building

BackgroundThis paper presents a numerical modelling procedure of dynamic loading due to traffic on a two-story residential building. In developing countries cities and towns, poor quality narrow road sections with high traffic density are common. In such cases, ground vibration due to traffic could be higher and lightweight buildings located closer are exposed to traffic-induced dynamic loading. Design codes require a proper assessment of such vibrations. However, a clear and definite procedure of assessment is not usually provided. This research presents an assessment procedure of dynamic loading due to traffic on a soil foundation system of light weight buildings based on numerical modeling. Traffic induced ground vibration acceleration amplitudes, frequencies and durations were measured, and the dynamic loads were calculated from measured vibration accelerations and vibrating mass of the vehicle. A two-story residential building with flexible square shallow footings was modelled together with the foundation soil using PLAXIS-2D. The dynamic load was modelled as harmonic loading considering the highest amplitude of vibration measured.ResultsOn the calculation stage, static loading analysis, dynamic loading analysis and free vibration dynamic analysis were carried out. A maximum increase in extreme total displacement of the soil to 22.03 mm was observed after the dynamic loading from 18.96 mm extreme total displacement due to static loading. Extreme effective mean stress in the soil increased to 112.81 kPa from 110.5 kPa, due to the dynamic loading. In addition, a differential settlement of 3.14 mm between two adjacent footings was observed after the traffic induced ground vibration. Furthermore, the Mohr–Coulomb plastic points were observed to be concentrated to the side of the soil-foundation system which the dynamic load was acting on.ConclusionThe regular exposure to traffic-induced vibrations may cause frequent change in stress and deformation response of the foundation-soil system. In areas where lightweight buildings are exposed to regular traffic induced vibrations, proper assessment of the effect should be carried out and measures should be taken to mitigate the problem. Improving road surfaces and limiting vehicle speed are possible remedial measures to reduce ground vibrations due to traffic.

Analysis of the ammunition explosion seismic wave propagation law

The seismic wave generated in the ammunition explosion process is one of the important technical indicators to evaluate the ammunition damage power. It is of great significance to evaluate the ammunition damage power and study the targets damage characteristics. In this study, experimental studies were carried out with TNT explosive mass of 1.25 kg, 5.25 kg, 10.5 kg and 30.75 kg, and the ground vibration velocity time-history curves at different measuring points were obtained. The functional relationship between ground particle vibration acceleration and TNT explosive mass was established by dimensional analysis method, and the functional relationship calculation accuracy was verified by the measured test data. The results show that the particle vibration acceleration peak value is positively correlated with the TNT explosive mass, and negatively correlated with the measuring point distance; The particle vibration acceleration calculation function established by the dimensional analysis method has high fitting accuracy for the existing test data, and can be used to calculate the ammunition explosion ground vibration acceleration peak value. The research results provide a high-precision calculation method for the peak value of explosion seismic wave ground vibration acceleration.

Analisis Percepatan Getaran Tanah Maksimum Untuk Memetakan Kerawanan Bencana Gempa Bumi dengan Metode Fukushima-Tanaka, Esteva dan Euclidean Distance di Pulau Lombok

Lombok island is a small area located on the border between the large Asian plate and the Autralian plate so that the islan of Lombok is verry vulnerable to the earthquake disasters. The level of damage caused by an earthquake depends on the strength and quality of the building, geological, and geotechtonic conditions and the maximum ground vibration acceleration of the area. This study aims to analyze the acceleration of ground vibrations to map earthquake vulnerability using the Fukushima Tanaka, Esteva, and Euclidean Distance methods on the island of Lombok. The data used is secondary data for earthquakes on the island of Lombok in Juli-September 2018. The calculation result show that the maximum ground vibration acceleration value is the highest of 100.810 gal located in the districts of EastbLombok and North Lombok. While the smallestmaximum ground vibrations acceleration value occurs in the Mataram and surrounding areas with a value of 0,3603 gal. From the three formulations, it can be seen that the value of ground vibration acceleration calculated in the area of the island of Lombok using the Fukushima Tanaka method is the most appropriate formula for calculating the value of ground accelaration on the Lombok island. That is because the value of the ground vibration acceleration from Fukushima Tanaka is almost the same as the ground vibration acceleration value from the accelerograph

Analisis Bahaya Gempa Bumi Menggunakan Metode Probabilistic Seismic Hazard Analysis Di Wilayah Likupang, Minahasa Utara

The Probabilistic Seismic Hazard Analysis (PSHA) method is a method used in seismic hazard analysis based on the definition of a probability distribution function that takes into account and combines the uncertainties of the earthquake event scale, location, and frequency of occurrence, to obtain a comprehensive picture of the hazard level or a location that reviewed. The Likupang area, North Minahasa is a location that is prone to earthquake disasters, for this reason, early mitigation is needed, one of which is mapping the potential for disaster hazards. Maximum ground vibration acceleration (PGA) is the greatest value of ground acceleration at a place caused by earthquake vibrations in a certain period of time. In this study, the results of the PSHA calculation in the North Minahasa Likupang area were obtained, the largest PGA value was 1.4g–1.8g, tilapia SA T= 0.2 seconds was 1.7g-2.1 and SA T=1 value, 0 seconds is 0.5g – 0.6g. Based on these results, the danger of light to severe damage can be caused.

Experimental validation of a simplified numerical model to predict train-induced ground vibrations

This study evaluates the effect of high-speed train (HST)-induced environmental vibrations using simplified computational models and validates the test results in full-scale field conditions. Experimental investigations and in-situ measurements were performed at the Istanbul-Ankara high-speed railway section to examine the effect of ground vibrations from HSTs on the surrounding residential lands. In this study, ground-borne free-field surface motion at different distances from the railway track was realized using accelerometers. The experimental results of vertical and horizontal ground vibration accelerations induced by HSTs with a velocity of 250 km/h were analyzed. In the first part of the study, a two-dimensional (2D) numerical model based on finite element method (FEM) was used to investigate ground vibrations and validate the experimental results. To minimize artificial reflections and dissipate vibrational energy at the boundaries, the lateral extension of an infinite domain was modeled with viscous absorbing boundaries. A dynamic analysis of the proposed railway-soil coupled model was performed in the time domain under plain-strain conditions using Plaxis 2D, a commercial FEM software. For the verification, the experimental results were compared with those obtained from the numerical analysis. The simplified computational model validated by the test results may help researchers determine further investigation strategies to develop cost-effective mitigation measures for structures with sensitive devices near the railway track and significantly contribute to understanding complex wave propagation problems. In the second part of the study, train-induced environmental ground vibrations were analyzed for different types of soil conditions using a 2D FE model. Computational analyses were performed with four types of soil: soft, medium, dense, and rock, based on the Turkish Earthquake Code. The HST was used as a dynamic source to observe the differences in vibration generation and wave transmission in different types of soil. The HST load on the slab track was simulated to study the effect of operational loads on ground-borne vibrations. Based on the dynamic analysis results, the response of the free-field motion was investigated to obtain the relative acceleration time histories for different points of soil. According to the results, the peak acceleration values of train-induced vibrations at soft, medium, and dense soil sites increased dramatically when compared to the rock site. Vibration measurement data collected from parametric experiments with a simple numerical model for various soil characteristics can be particularly useful when planning residential and industrial facilities at new locations near railroads, to avoid the adverse effects of environmental vibrations caused by HSTs.

The Influence of the Rate of Increase of Ground Vibration Accelerations During Earthquakes on the Value of the Observed Macroseismic Effect

Aims:It is known that along with the traditionally considered amplitudes and durations of ground vibrations, the rate of increase in the intensity of ground vibrations in time can also affect the level of macroseismic effects caused by earthquakes. According to the previously obtained correlations, the differences between the observed macroseismic effects during earthquakes with slow and fast increases in the amplitude level of oscillations can reach one point of the macroseismic scale. The purpose of these study is to obtain, on the basis of a significantly (almost 9 times) larger than before, the volume of initial data (in combination with a more effective method of analysis) new and more accurate quantitative estimates of the studied dependences, as well as their possible interpretation.Background:The work continues the research began in 1985-1989. A representative statistical material was used, including 1250 accelerograms of earthquakes that occurred in different regions of the world, with magnitudesM= 2.5-7.7, distances of 5-230 km and independent estimates of macroseismic intensitiesI= 3-10 points by theMSKorMMI.Objective:Correlations between the absolute and relative rates of increase of ground vibration accelerations during earthquakes with different magnitudes and distances, on the one hand, and macroseismic effects caused by these vibrations, on the other, are considered.Methods:The study was carried out in the form of a direct statistical comparison of the parameters describing the form of ground vibrations during earthquakes with the characteristics of variations in macroseismic effects caused by these vibrations. A sample was formed and analyzed, including 1250 accelerograms of sensible and strong earthquakes recorded in various regions of the world and having independent estimates of the macroseismic intensity of shaking at instrumental registration sites.Results:It is shown that the macroseismic intensity of shaking can depend on the relative rate of increase of acceleration amplitudes in the general wavetrain of ground vibrations. An increase in the macroseismic intensity of shaking was observed with an increase in the relative rate of increase of the amplitudes and, conversely, it decreases with a slowdown in the rate of increase of the acceleration intensity. Similar constructions, made according to the data of the Time-Frequency Signal Analysis (TFSA) of 50 accelerograms of earthquakes withM= 3.3-6.2, a distance of 7-139 km and a macroseismic intensity of 4-7MMIpoints, showed the same dependence, but clearer and with large coefficients of regression and correlation. The difference between earthquakes with “fast” and “slow” accelerations in the intensityIcan reach oneMSKpoint.Conclusion:The results of this study indicate that the rate of increase in the acceleration of ground vibrations during earthquakes can in a certain way affect the macroseismic effects. Earthquakes with slowly increasing amplitudes of ground vibration accelerations form average less macroseismic effects than those with rapidly growing accelerations.Variations in the shaking intensity, at the same time, are quite significant and can be compared with variations associated with differences in soil-geomorphological conditions, focal mechanisms, general seismotectonic conditions and other factors that are traditionally taken into account in detailed assessments of seismic hazard. Therefore, this factor should also be taken into account when conducting such studies.

Attenuation and Prediction of the Ground Vibrations Induced by High-Speed Trains Running Over Bridge

This paper aims to study the transfer laws of vibration signals in the free field near a high-speed train line by conducting a field test. The characteristics of ground vibration acceleration were analyzed in the time and frequency domains, and a prediction method in the frequency domain was proposed. The results show: (1) there is a vibration amplification area away from the bottom of the pier under the influence of high-speed trains running over the bridge due to the fluctuation attenuation of the vibration waves; (2) the dominant peak frequency points in the frequency spectrum of the acceleration can be regarded as the resonance frequency induced by periodic loading; and (3) the soil vibration can be effectively predicted by the proposed method with a strong capability to defend the interference of environmental vibrations according to the comparison between the predicted value and the experimental data.

ANALYSIS OF ON-SITE VIBRATION MONITORING OF STEEL SHEET PILE DRIVING CONSTRUCTION

In this paper, the self-designed system for ground vibration acceleration monitoring was used to monitor the ground vibration caused by steel sheet pile driving in three sites with different soil properties. The peak acceleration and frequency characteristics of ground vibration were analyzed. The vibration attenuation law and the influence on surrounding buildings were discussed. The results show that soil strength has significant influence on the vibration caused by steel sheet pile construction. The penetration rate of steel sheet pile in soil with low resistance is high, causing slight ground vibration response. While in soil with high resistance, the penetration rate is low and the ground vibration is relatively much more obvious. The ground longitudinal and tangential accelerations caused by steel sheet pile construction are close to each other at the same depth, and have a trend to increase with the depth. There is little influence of vibration source distance and soil property on the dominant frequency of ground vibration caused by steel sheet pile construction. A good positive linear correlation shows between the dominant frequency of ground vibration and the vibration frequency of pile construction. The construction vibration of steel sheet pile attenuates rapidly in the range of 4m from the vibration source. The minimum safety distance of steel sheet piles for surrounding buildings due to construction is far smaller than that of soil compaction pile.

Experimental investigation on train-induced vibration of the ground railway embankment and under-crossing subway tunnels

This paper presents a field measurement of the train-induced vibration in the northwest Shanghai, where Shanghai Metro Line 11 crosses under Beijing-Shanghai Railway. Ground and tunnel accelerations are measured for the separate and simultaneous passages of the ground and subway trains. Vibration characteristics are subsequently analyzed in the time domain and in the frequency domain. Measurement results show that the ground vibration acceleration level (VAL) induced by the simultaneous operation of the ground and subway trains is 6 ~ 13 dB greater than that induced by the separate operation for the frequency range 20 ~ 160 Hz. Significant frequency components of the vibration induced by the simultaneous operation are shown to be redistributed to cover those induced by the separate operation. Measured data in this experimental test can also be used to validate future numerical models for predicting train induced vibration of similar embankment-tunnel systems.

Dynamic characteristics and damage recognition of blast-induced ground vibration for natural gas transmission pipeline and its integrated systems

Abstract Natural gas pipeline network is a highly integrated network that moves natural gas throughout the continental and global services. Pipelines play a major role for the onshore and offshore gas transport, maintaining the record levels built up in recent years. However, once a rupture appears on a pipeline, the consequences of blast-induced incidents can pose a deadly threat in the vicinity of the failure location. Blast-induced ground vibration is the most significant impact that can seriously affect the surrounding parallel pipelines. In the present study, an experiment combined with a numerical investigation on the effect of blast-induced ground vibration of gas pipeline was undertaken. Dynamic characteristics such as peak vibration velocity, ground vibration acceleration, frequency response of blast-induced ground vibration were analyzed. Further, the modified prediction equations for blast-induced ground vibrational characteristics with distance were proposed. Ultimately, blast-induced displacement with the parallel pipeline was simulated, with a focus on risk vulnerability of gas pipeline. The main purpose of this paper is to facilitate a better understanding of the mechanical systems and dynamic characteristics governing the blast-induced ground vibration when the gas pipeline bursts, which is expected to be reliable for the safety spacing of buried integrated pipeline systems.

Experimental study on ground vibration response in gun firing environment

In order to know the ground vibration response law of gun firing environment, a large caliber gun was taken as the research object, and the ground vibration response law of gun firing environment was tested. Several acceleration sensors are arranged on the ground around the gun, and the ground vibration acceleration response laws of the gun position in the firing environment are obtained. The firing of gun will cause the ground vibration of gun position. In the bore period, as long as the projectile is fired, there will be acceleration response on the ground of the gun position. The maximum acceleration response of ground vibration in the bore period of projectile is less than 0.03 g. The maximum acceleration response of ground vibration is less than 0.1 g after projectile exits the muzzle and before the muzzle shock wave reaches the ground. If the sensor bracket is placed on the ground around the gun, when the muzzle shock wave does not reach the sensor position, the influence of ground vibration on the sensor can be neglected. Once the muzzle shock wave reaches the sensor position, its influence should be paid attention to.

Effects of the canyon topography on railway environment vibrations

The train-induced vibrations that permeate railway environments are becoming more prominent with the rapid development of China’s high-speed railway network. Because canyons are quite common in nature, it is inevitable that newly constructed railways will pass through these areas. Therefore, it is necessary to study the influences of canyons on the propagation of vibration waves. In this paper, a two-dimensional finite-element calculation model of the subgrade-canyon topography under the action of trains is established and the influences of the canyon width and shape in addition to the properties of the foundation soil within the canyon are studied. The results show that vibrations are amplified near the foot of the canyon. The canyon significantly reduces the ground vibration accelerations in both the vertical and the horizontal directions. Moreover, a wider canyon corresponds to a greater decrease in the acceleration at the centre of the canyon and a reduction in all vertical and horizontal vibration displacements. Furthermore, as the foundation soil hardens, the decreases in the accelerations in both the vertical and the horizontal directions are significantly reduced.

Nonlinear Behavior of Soils Under Exposure to Seismic Activity

A behavior of various soils under exposure to seismic effects is analyzed. To optimize the seismic stability calculations for buildings and structures, a relationship developed based on processing the instrumentation records of the previously occurred earthquakes is proposed, which can be used to estimate ground vibration accelerations considering the specifics of the rock formations.

High-frequency random vibration analysis of a high-speed vehicle–track system with the frequency-dependent dynamic properties of rail pads using a hybrid SEM–SM method

ABSTRACTA hybrid Spectral Element Method (SEM)–Symplectic Method(SM) method for high-efficiency computation of the high-frequency random vibrations of a high-speed vehicle–track system with the frequency-dependent dynamic properties of rail pads is presented. First, the Williams-Landel-Ferry (WLF) formula and Fractional Derivative Zener (FDZ) model were, respectively, applied for prediction and representation of the frequency-dependent dynamic properties of Vossloh 300 rail pads frequently used in China's high-speed railway. Then, the proposed hybrid SEM–SM method was used to investigate the influence of the frequency-dependent dynamic performance of Vossloh 300 rail pads on the high-frequency random vibrations of high-speed vehicle–track systems at various train speeds or different levels of rail surface roughness. The experimental results indicate that the storage stiffness and loss factors of Vossloh 300 rail pad increase with the decrease in dynamic loads or the increase in preloads within 0.1–10,000 Hz at 20°C, and basically linearly increase with frequency in a logarithmic coordinate system. The results computed by the hybrid SEM–SM method demonstrate that the frequency-dependent viscous damping of Vossloh 300 rail pads, compared with its constant viscous damping and frequency-dependent stiffness, has a much more conspicuous influence on the medium-frequency (i.e. 20–63 Hz) random vibrations of car bodies and rail fasteners, and on the mid- (i.e. 20–63 Hz) and high-frequency (i.e. 630–1250 Hz) random vibrations of bogies, wheels and rails, especially with the increase in train speeds or the deterioration of rail surface roughness. The two sensitive frequency bands can also be validated by frequency response function (FRF) analysis of the proposed infinite rail–fastener model. The mid and high frequencies influenced by the frequency-dependent viscous damping of rail pads are exactly the dominant frequencies of ground vibration acceleration and wheel rolling noise caused by high-speed railways, respectively. Even though the existing time-domain (or frequency-domain) finite track models associated with the time-domain (or frequency-domain) fractional derivative viscoelastic (FDV) models of rail pads can also be used to reach the same conclusions, the hybrid SEM–SM method in which only one element is required to compute the high-order vibration modes of infinite rail is more appropriate for high-efficiency analysis of the high-frequency random vibrations of high-speed vehicle–track systems.

Effect of temperature- and frequency-dependent dynamic properties of rail pads on high-speed vehicle–track coupled vibrations

ABSTRACTThe soft under baseplate pad of WJ-8 rail fastener frequently used in China’s high-speed railways was taken as the study subject, and a laboratory test was performed to measure its temperature and frequency-dependent dynamic performance at 0.3 Hz and at −60°C to 20°C with intervals of 2.5°C. Its higher frequency-dependent results at different temperatures were then further predicted based on the time–temperature superposition (TTS) and Williams–Landel–Ferry (WLF) formula. The fractional derivative Kelvin–Voigt (FDKV) model was used to represent the temperature- and frequency-dependent dynamic properties of the tested rail pad. By means of the FDKV model for rail pads and vehicle–track coupled dynamic theory, high-speed vehicle–track coupled vibrations due to temperature- and frequency-dependent dynamic properties of rail pads was investigated. Finally, further combining with the measured frequency-dependent dynamic performance of vehicle’s rubber primary suspension, the high-speed vehicle–track coupled vibration responses were discussed. It is found that the storage stiffness and loss factor of the tested rail pad are sensitive to low temperatures or high frequencies. The proposed FDKV model for the frequency-dependent storage stiffness and loss factors of the tested rail pad can basically meet the fitting precision, especially at ordinary temperatures. The numerical simulation results indicate that the vertical vibration levels of high-speed vehicle–track coupled systems calculated with the FDKV model for rail pads in time domain are higher than those calculated with the ordinary Kelvin–Voigt (KV) model for rail pads. Additionally, the temperature- and frequency-dependent dynamic properties of the tested rail pads would alter the vertical vibration acceleration levels (VALs) of the car body and bogie in 1/3 octave frequencies above 31.5 Hz, especially enlarge the vertical VALs of the wheel set and rail in 1/3 octave frequencies of 31.5–100 Hz and above 315 Hz, which are the dominant frequencies of ground vibration acceleration and rolling noise (or bridge noise) caused by high-speed railways respectively. Since the fractional derivative value of the adopted rubber primary suspension, unlike the tested rail pad, is very close to 1, its frequency-dependent dynamic performance has little effect on high-speed vehicle–track coupled vibration responses.

Experimental investigation of the vibration-attenuating effect of rail suspension fasteners on environment vibration induced by subway

A field test of environment vibration due to subway was carried out so as to investigate the vibration-alleviating effect of rail suspension fasteners in both time and frequency domains. The experimental results show that the time-domain vertical ground vibration accelerations would transform from several concentrated vibrations to the decentralized and uniform ones after replacement of common rail fasteners with rail suspension fasteners. Moreover, rail suspension fasteners have more significant vibration-mitigation effect on the time-domain peak particle accelerations (PPAs) at the nearer positions than at the farther ones, and the minimum PPA induced by common rail fasteners is still higher than the maximal PPA caused by rail suspension fasteners at all measuring positions. In frequency domain, the vibration-reduction effect of rail suspension fasteners is more remarkable in the dominant 1/3 octave center frequencies of 50-125 Hz than in the non-dominant ones from 1 to 40 Hz. Compared with common rail fasteners, the highest vibration acceleration levels (VALmax) in the dominant 1/3 octave center frequencies between 50 and 125 Hz at all measuring positions decrease by 8.7-21 dB after adoption of rail suspension fasteners. Additionally, the integrated VLzs in 1/3 octave center frequencies of 1-125 Hz at all measuring positions are ranged from 77.1 dB to 66.5 dB, evidently higher than the China’ standard threshold of 65 dB, before replacement of common rail fasteners, while the integrated VLzs are framed between 68.3 and 57.3 dB, mostly less than the threshold, after application of rail suspension fasteners.