| 1. |
- Theland, Freddie, et al.
(författare)
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Assessment of small-strain characteristics for vibration predictions in a Swedish clay deposit
- 2021
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 150
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Zangeneh, Abbas, 1980-, et al.
(författare)
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Modal analysis of coupled soil-structure systems
- 2021
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 144
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an efficient approach for the modal analysis of coupled soil-structure systems, for which the dynamic response is strongly influenced by the embedment in the soil. The methodology is based on a finite element-perfectly matched layer model that allows for the derivation of frequency-independent system matrices and the computation of the modal properties of the coupled system. This is achieved by solving a nonlinear eigenproblem using a Compact Rational Krylov (CoRK) eigensolver. A procedure is developed to sort the computed eigenpairs, filter out the spurious modes of the system which are related to the near-field and truncated far-field soil subdomains and select the physical structural modes of system. The proposed method can be used in the dynamic assessment and structural identification of strongly coupled soil-structure systems such as fully or partially buried structures and allows for the interpretation of experimentally identified modal properties of these systems, especially in the presence of highly damped or closely spaced coupled modes. The applicability and the scalability of the proposed approach for 2D and 3D problems is demonstrated in two case studies.
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| 3. |
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| 4. |
- Malmborg, J., et al.
(författare)
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Effects of modeling strategies for a slab track on predicted ground vibrations
- 2020
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261. ; 136
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Tidskriftsartikel (refereegranskat)abstract
- In the paper, the effect of modeling strategies regarding the dynamic behavior of a railway slab track on a layered half-space is studied. The track is modeled with various degrees of accuracy through the use of either beam theory, shell finite elements or solid finite elements. The underlying soil response is included through a dynamic stiffness, obtained via the Green's function for a horizontally layered visco-elastic half-space in the frequency–wavenumber domain. The effect of different assumptions regarding the track cross-section behavior and the track–soil interface conditions on the resulting free-field vibrations are studied for a harmonic load moving along the track. First, only the out-of-plane displacements of the slab–soil interface are coupled, i.e. only the vertical contact pressure is accounted for. Secondly, the effect of coupling the slab–soil in-plane displacements on the free-field vibrations is studied. It is found that the in-plane slab–soil coupling significantly affects the vertical vibration in the free-field. It is also found that a beam model of the track yields accurate response levels compared to a solid continuum model in the case of a thick slab, whereas considerable differences are obtained for a thin slab.
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| 5. |
- Zuada Coelho, Bruno, et al.
(författare)
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The impact of soil variability on uncertainty in predictions of induced vibrations
- 2023
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Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261. ; 169
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Tidskriftsartikel (refereegranskat)abstract
- Soil is by nature a variable, non-homogeneous material, which has implications for engineering problems involving wave propagation. This paper investigates the impact of the spatial heterogeneity of the stiffness of the soil on the three-dimensional wave propagation. A dynamic Random Finite Element Model is presented in which the soil variability is modelled by means of random fields, applied to the Young's modulus of the soil, following a Monte-Carlo approach. The results show the importance of accounting for soil variability when making predictions on the maximum vibration level. Deterministic analysis is demonstrated to be insufficient when quantifying the maximum vibration level, because no information on the expected variability of the maximum vibration level is obtained. Furthermore, the scale of fluctuation and anisotropy of the random field strongly impact the estimation of the maximum vibration level, and the time of occurrence.
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