| 1. |
- Erlingsson, Sigurdur, 1960-, et al.
(författare)
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Stiffness of sandy sites using the Multichannel Analysis of Surface Waves method
- 2017
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Ingår i: ICSMGE 2017. - : 19th ICSMGE Secretariat. ; , s. 593-597
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Konferensbidrag (refereegranskat)abstract
- Multichannel Analysis of Surface Waves (MASW) is seismic exploration method to evaluate shear wave velocity profiles of near-surface soil materials based on analysis of horizontally travelling Rayleigh waves. The MASW method has been applied at four loose sandy sites in South Iceland providing shear wave velocity (VS) profiles for the uppermost 25 m at each site. The VS-profile obtained for one of the test sites was compared to empirical profiles estimated on the bases of CPT measurements carried out at the site. The results indicate that the MASW profile corresponds adequately well to the empirical estimations, strengthening the results obtained by MASW. However, further comparison of MASW and CPT data is needed in order to evaluate the overall applicability of existing CPT-VS correlations at Icelandic sand sites.
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| 2. |
- Olafsdottir, Elin Asta, et al.
(författare)
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A Tool for Processing and Inversion of MASW Data and a Study of Inter-session Variability of MASW
- 2024
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Ingår i: ASTM geotechnical testing journal. - : ASTM International. - 0149-6115 .- 1945-7545. ; 47:5
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Tidskriftsartikel (refereegranskat)abstract
- Multichannel analysis of surface waves (MASW) is a noninvasive active-source technique for determination of near-surface shear wave velocity (VS) profiles. Here we introduce and describe MASWavesPy, an open-source Python package for processing and inverting MASW data, whose design follows an object-oriented paradigm. To assess the performance of the new tool, measurements were conducted at four benchmark sites in Norway, characterized as silt, soft clay, silty sand, and quick clay. The results show that the VS profiles obtained with MASWavesPy compare well with those obtained previously at the respective sites using invasive, noninvasive and laboratory techniques. Furthermore, the efficiency and usability of the new package is superior to previous versions developed by same authors. The software can be accessed through the Python Package Index (PyPI) at https://pypi.org/project/maswavespy/ along with sample data. This work further explores the inter-session variability of MASW measurements for civil engineering applications at soft soil sites. For this purpose, repeated measurements were conducted over a 7-year period at a silty sand site in South Iceland and the recorded time series analyzed using the newly developed tool. The inter-session variability of the analysis results is reported in terms of Rayleigh wave phase velocity, interval VS profiles, and time-averaged VS for reference depths commonly used in practice.
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| 3. |
- Ólafsdóttir, Elin Ásta, et al.
(författare)
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Application of MASW in the South Iceland seismic zone
- 2019
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Ingår i: Geotechnical, Geological and Earthquake Engineering. - Cham : Springer Netherlands. ; , s. 53-66
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Konferensbidrag (refereegranskat)abstract
- Multichannel Analysis of Surface Waves (MASW) is a seismic exploration method to evaluate shear wave velocity profiles of near-surface materials. MASW was applied at seven locations in or close to the South Iceland Seismic Zone, providing shear wave velocity profiles for the top-most 15–25 m. The profiles were utilized for seismic soil classification according to Eurocode 8. The results indicated that the sites that are characterized by sandy glaciofluvial, littoral or alluvial sediments fall into category C and the sites where the deposits are cemented to some degree belong to category B. Furthermore, the MASW measurements were used to evaluate the liquefaction potential at a site where liquefaction sand boils were observed during an Mw6.3 earthquake occurring in May 2008. The simplified procedure of assessing cyclic stress ratio to normalized shear wave velocity revealed that liquefaction had occurred down to 3–4 m depth, which is consistent with observations on site.
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| 4. |
- Olafsdottir, Elin Asta, et al.
(författare)
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Hybrid non-invasive characterization of soil strata at sites with and without embedded lava rock layers in the South Iceland Seismic Zone
- 2023
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Ingår i: Bulletin of Engineering Geology and the Environment. - : Springer. - 1435-9529 .- 1435-9537. ; 82:4
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Tidskriftsartikel (refereegranskat)abstract
- The geological setting of Iceland is unusual, with highly jointed rock mass, loose sediments created in glacial outburst floods and eruptions, and layers of lava rock embedded in or overlying soft sediments. This study aims to assess the feasibility of a composite analysis of dispersion and ellipticity curves for characterization of two of the primary classes of soil sites in the South Iceland Seismic Zone. Specifically, it seeks to develop a cost-effective workflow to identify and characterize sites where a layer of lava rock is embedded in the sedimentary stratum at shallow depth, along with deep soil site characterization. Microtremor HVSR (horizontal-to-vertical spectral ratio) is found to be efficient to distinguish between sedimentary sites with and without an embedded lava rock layer. The results further demonstrate the effectiveness of hybrid ellipticity and dispersion curve inversion to characterize soil sites with an embedded layer of lava rock, which results in a strong velocity reversal with depth. Consistent with previous studies, the hybrid dispersion-ellipticity inversion is also found efficient for characterization of sites with a simpler structure.
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| 5. |
- Olafsdottir, Elin Asta, et al.
(författare)
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Open-source MASW inversion tool aimed at shear wave velocity profiling for soil site explorations
- 2020
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Ingår i: Geosciences. - : MDPI AG. - 2076-3263. ; 10:8, s. 1-30
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Tidskriftsartikel (refereegranskat)abstract
- The shear wave velocity profile is of primary interest for geological characterization of soil sites and elucidation of near-surface structures. Multichannel Analysis of Surface Waves (MASW) is a seismic exploration method for determination of near-surface shear wave velocity profiles by analyzing Rayleigh wave propagation over a wide range of wavelengths. The inverse problem faced during the application of MASW involves finding one or more layered soil models whose theoretical dispersion curves match the observed dispersion characteristics. A set of open-source MATLAB-based tools for acquiring and analyzing MASW field data, MASWaves, has been under development in recent years. In this paper, a new tool, using an efficient Monte Carlo search technique, is introduced to conduct the inversion analysis in order to provide the shear wave velocity profile. The performance and applicability of the inversion scheme is demonstrated with synthetic datasets and field data acquired at a well-characterized geotechnical research site. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
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