| 1. |
- Costa, Pedro Alves, et al.
(author)
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Influence of soil non-linearity on the dynamic response of high-speed railway tracks
- 2010
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 30:4, s. 221-235
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Journal article (peer-reviewed)abstract
- The main objectives of this paper are the evaluation of the relevance of the non-linear behaviour of the soil on the track response and the validation of a methodology, which includes these effects through an equivalent linear analysis. The proposed numerical model is based on 2.5D finite/infinite elements method, coupled with an iterative procedure in order to obtain an agreement between the strain levels and the dynamicproperties of the materials. In order to validate the model, the case study of Ledsgard was simulated, and the experimental and numerical results of displacements of the trackwere compared, considering several circulation speeds for the X2000 train. From the results, it is possible to recognize that the stiffness degradation, function of the strain level, plays a relevant role for the case of high-speed railway lines on soft ground. Moreover, the simulations developed with the proposed methodology provided similar results to those observed, independently of the train speed, contrary to what was obtained when the elastic linear model was used.
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| 2. |
- Deckner, Fanny, et al.
(author)
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Sheet pile behavior during vibratory driving : numerical study based on a field test
- 2017
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In: Soil Dynamics and Earthquake Engineering. - 0267-7261 .- 1879-341X.
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Journal article (peer-reviewed)abstract
- Vibrations due to sheet pile driving are a problem in many urban areas today. Increased knowledgeof the vibration transfer process from source to nearby objects is important in order to enableminimization of induced vibrations. The transfer of vibrations from sheet pile to soil is dependent onthe sheet pile behaviour during driving. This paper presents a 3D finite element study of thebehaviour of a vibratory driven sheet pile, complementing results from a full-scale field test. Thefinite element model accounts for strain dependent soil stiffness using an equivalent linear soilmodel. The conclusion is that the sheet pile bends considerably during driving with eccentricclamping. Furthermore, it is shown that the bending mode is similar irrespective of sheet pilepenetration depth.
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| 3. |
- Hildebrand, Robert
(author)
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Effect of soil stabilization on audible band railway ground vibration
- 2004
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 24:5, s. 411-424
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Journal article (peer-reviewed)abstract
- Although railway-generated ground vibrations usually have greater energy levels at lower frequencies, vibrations in the audible range above 20 Hz can nevertheless be relevant for secondary noise problems in buildings. One countermeasure is soil stabilization under the track embankment. While effective at low frequencies, a potential side effect is amplification in some audible bands. Presented here are both experimental and theoretical assessments of the countermeasure in the audible bands. The main innovation is the treatment of an infinite periodic track-ground system, using a transfer matrix approach with a repeating element including the rail, pad, sleeper, and an underlying half-space (ballast and soil). Excitation in this band is attributed to rail and wheel roughness. The model makes successful predictions when the half-space properties are allowed to be frequency-dependent such that the dispersion of the surface wave matches that in the actual layered earth (including ballast and underlying soil layers). The field measurements are also unique in that both before and after evaluation of the countermeasure was possible.
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| 4. |
- Martakis, Panagiotis, et al.
(author)
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A centrifuge-based experimental verification of Soil-Structure Interaction effects
- 2017
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier. - 0267-7261 .- 1879-341X. ; 103, s. 1-14
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Journal article (peer-reviewed)abstract
- A series of prototype dynamic centrifuge experiments is carried out to investigate the influence of soil properties and structural parameters on the Soil Structure Interaction (SSI) effect. Established analytical models are herein experimentally verified, and are proven accurate in estimating the system's natural frequency characteristics. It is observed that period elongation is strongly correlated to the relative superstructure-foundation stiffness. Although the present study deals exclusively with the small-strain near-linear range, the experimental response indicates occurrence of nonlinearity. The identified damping results remarkably larger than its analytical estimate and proves highly strain-dependent, raising questions on the reliability of existing analytical methods in capturing the actual dissipation mechanisms. An extended experimental dataset is formed under realistic stress and strain soil conditions, and is implemented, for the first time, for verification of existing analytical models offering valuable insight into the theory and serving as a benchmark for engineering practice.
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| 5. |
- Mihaylov, Aleksandar, et al.
(author)
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Approximate analytical HVSR curve using multiple band-pass filters and potential applications
- 2019
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier. - 0267-7261 .- 1879-341X. ; 127
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Journal article (peer-reviewed)abstract
- The Nakamura method, which utilizes the Horizontal to Vertical Spectral Ratio (HVSR) analysis, is widely used for seismic microzonation studies. The HVSR is an easy tool for estimation of site response resonances based on recorded ambient noise; however, it gives amplifications at resonant frequencies that are poorly correlated to the actual amplifications during strong ground motion.Generally, the site response, including any resonant effects, depends on the amplitude, frequency and duration of ground motion. An approach was proposed previously by McGuire [1], in which the transfer function of the soil response was approximated as a Single Degree of Freedom (SDOF) oscillator with one resonant frequency, obtained from the maximum in HVSR. A new approach is developed here, in which the entire HVSR curve is approximated by a manageable set of parallel band-pass resonators. Each individual oscillator is defined by three parameters: center frequency, gain, and steepness (Q factor). This approximation allows for the development and use of an analytical model of the HVSR curve.The application of the new approach is demonstrated on data recorded by the stations of the Southern Ontario Seismic Network (SOSN/Polaris), which have well studied characteristics and site response [2,3]. Data collected at each site consists of noise recordings to obtain the HVSR, as well as earthquake records. The analytical HVSR curves for each station are used to remove the site effect component from the recorded seismograms.
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| 6. |
- Olafsdottir, Elin Asta, et al.
(author)
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Combination of dispersion curves from MASW measurements
- 2018
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier Ltd. - 0267-7261 .- 1879-341X. ; 113, s. 473-487
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Journal article (peer-reviewed)abstract
- Multichannel analysis of surface waves (MASW) is a seismic exploration method for determination of near-surface shear wave velocity profiles based on analysis of horizontally travelling Rayleigh waves. This paper aims to propose a methodology and recommendations for combining dispersion data from several multichannel records. The dispersion curves are added up within logarithmically spaced wavelength intervals and the uncertainty of the mean phase velocity estimates is evaluated by using classical statistics and the bootstrap. The results indicate that combining multiple dispersion curves, which have been gathered by receiver spreads of different lengths (but with the same midpoint), can increase the investigation depth of the survey, improve its resolution at shallow depth and overall improve the reliability of the results as compared to the use of a single record. Moreover, the uncertainty of the combined mean dispersion curve can be determined and further used to present the shear wave velocity profile with upper and lower boundaries.
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| 7. |
- Peplow, Andrew T., et al.
(author)
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Prediction and validation of traffic vibration reduction due to cement column stabilization
- 2007
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 27:8, s. 793-802
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Journal article (peer-reviewed)abstract
- The transmission and reduction of vibrations in the far-field of the surface of the ground due to a surface load is investigated theoretically and validated with given field measurement data. The performance of a given stabilization column, located directly underneath the load, at a number of receiver positions is studied and-measured in terms of insertion loss. A numerical model is presented, which enables the wave-field in the region of the column to be determined, based on an integral equation formulation of the problem which is solved using a boundary element approach. It is shown that the column has a beneficial effect at low frequencies especially in certain frequency bandwidths and is validated with field data. However, when the Rayleigh wavelength becomes short compared with the depth and width of the column adverse effects occur at some frequencies which are also observed in the far-field. Various depths of columns and material properties of the surrounding soil medium are studied and results presented so that some preliminary physical conclusions may be derived.
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| 8. |
- Theland, Freddie, et al.
(author)
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Assessment of small-strain characteristics for vibration predictions in a Swedish clay deposit
- 2021
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 150
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Journal article (peer-reviewed)abstract
- Environmental vibrations induced by human activities such as traffic, construction or industrial manufacturing can cause disturbance among residents or to vibration sensitive equipment in buildings. In Sweden, geological formations of soft clay overlying a stiff bedrock are soil conditions prone to ground vibrations that are encountered both in urban areas and along parts of the national railway network. This paper presents an extensive investigation of the small-strain soil properties for the prediction of environmental ground vibrations in a shallow clay where the bedrock is situated at 7.5 m depth. The small-strain properties are estimated using available empirical correlations, bender elements, seismic cone penetration tests, seismic refraction and inversion of surface wave dispersion and attenuation curves. The results are synthesised into a dynamic layered soil model which is validated by measurements at the soil's surface at source-receiver distances up to 90 m in the frequency range 1-80 Hz. Analyses of uncertainties in the estimated values of wave speeds and material damping are performed by model investigations, indicating that surface wave tests overestimate the damping compared to bender element tests. The properties of the topmost unsaturated part of the soil is found to have a significant influence on the response at large distances, caused by critically refracted P-waves resonating in the top layer.
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| 9. |
- With, Christoffer, et al.
(author)
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Evaluation of track stiffness with a vibrator for prediction of train-induced displacement on railway embankments
- 2009
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 29:8, s. 1187-1197
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Journal article (peer-reviewed)abstract
- A measuring car, the rolling stiffness measuring vehicle (RSMV), has been developed to investigate track conditions. The investigation described in this paper firstly attempts to understand whether the point flexibility of the track, i.e., the track-embankment-subsoil system, can be obtained by simultaneously measuring the force applied to an axle of the measuring car and the resulting acceleration response. Secondly, it attempts to determine the physical properties of the track by modelling it as a Bernoulli-Euler beam oil a Kelvin foundation. The final part of the paper investigates the possibility of predicting displacements on a railway embankment based oil the physical properties obtained after a train passage. Results from two sites in Sweden, Kumla and Kåhög, have been used. Investigations give encouraging results. However, as seen here, it can be difficult to analyse and obtain parameters if the resonance frequency of the system is low. The peak particle displacement of the ballast on the railway embankment was achieved with fair accuracy for both Kumla and Kåhög using the results from the accelerometer on the RSMV.
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| 10. |
- With, Christoffer, et al.
(author)
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Prediction of train-induced vibrations inside buildings using transfer functions
- 2007
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In: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 27:2, s. 93-98
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Journal article (peer-reviewed)abstract
- This article presents a study of the use of transfer functions to predict vibrations inside a building due to train-induced ground vibrations. It is proposed that knowing the transfer function of a building, the vibrations inside a similar building can be predicted given a known ground motion outside. A comparison has been conducted between predicted and measured vibrations inside a building in south-western Sweden due to freight and passenger trains. The transfer function was derived by using a stationary vibrating source. The average particle velocity (1 s-r.m.s.) inside the house was calculated with the transfer functions with an average error of -10%, -0.02mm/s. Prediction was achieved with a standard deviation of 23%, 0.06mm/s when no filtering of the data was used. Further work is needed to ascertain the accuracy of this method.
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