| 1. |
- Costa, Pedro Alves, et al.
(författare)
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Influence of soil non-linearity on the dynamic response of high-speed railway tracks
- 2010
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 30:4, s. 221-235
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Tidskriftsartikel (refereegranskat)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. |
- Obando, Edwin, et al.
(författare)
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Phase-scanning approach to correct time-shift inaccuracies in the surface-wave walk-away method
- 2010
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261. ; 30:12, s. 1528-1539
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Tidskriftsartikel (refereegranskat)abstract
- In order to maintain lateral resolution while maximizing investigation depth in a multichannel surface wave method, it is beneficial to implement the walk-away approach by using a relatively short receiver spread. Combined walk-away records, however, normally suffer from time-shift inaccuracies that adversely influence the subsequent dispersion imaging process. Time-shift inaccuracies produce phase discontinuities which can generate false apparent higher modes in the dispersion images misleading the correct interpretation of the dispersion curve. To minimize these adverse effects, we present a phase-scanning approach that searches for an optimum phase shift to correct the phase shift generated by the walk-away method. Results obtained from synthetic and real-world field data show that for the specific case of a single dominating mode the proposed approach reduces the distortions in the dispersion image caused by the walk-away approach. The proposed method is especially efficient in the presence of ambient random noise. (C) 2010 Elsevier Ltd. All rights reserved.
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| 3. |
- Persson, Peter, et al.
(författare)
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Reduction in ground vibrations by using shaped landscapes
- 2014
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261. ; 60:May, s. 31-43
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Tidskriftsartikel (refereegranskat)abstract
- Reduction in traffic-induced ground vibrations by the use of shaped landscapes is investigated here by shaping the landscape surrounding a high-tech facility, using the landscape thus produced as a wave obstacle. The effects of the geometric parameters of a shaped landscape were examined in parametric studies. An architectural landscape design was also investigated in terms of its effectiveness in reducing traffic-induced ground vibrations. Finite element models, analysed in the frequency domain, were employed. The models involve a layer of soil and the underlying bedrock. It was found that anywhere from an appreciable reduction to an appreciable amplification of the vibrations produced can occur,depending upon the geometric parameters of the shaped landscape involved. The most effective shape was found for a topography that acted as a waveguide that reduced the level of vibration by approximately 35%.
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