Estimation of the hydraulic parameters of unsaturated samples by electrical resistivity tomography / R. M. Cosentini in Géotechnique, Vol. 62 N° 7 (Juillet 2012)  

Public ISBD [article]  inGéotechnique > Vol. 62 N° 7 (Juillet 2012) . - pp. 583 –594 Titre : Estimation of the hydraulic parameters of unsaturated samples by electrical resistivity tomography Type de document : texte imprimé Auteurs : R. M. Cosentini, Auteur ; G. Della Vecchia, Auteur ; S. Foti, Auteur Année de publication : 2012 Article en page(s) : pp. 583 –594 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Geophysics Partial saturation Laboratory tests Seepage Suction Résumé : In situ and laboratory experiments have shown that electrical resistivity tomography (ERT) is an effective tool to image transient phenomena in soils. However, its application in quantifying soil hydraulic parameters has been limited. In this study, experiments of water inflow in unsaturated soil samples were conducted in an oedometer equipped to perform three-dimensional electrical measurements. Reconstructions of the electrical conductivity at different times confirmed the usefulness of ERT for monitoring the evolution of water content. The tomographic reconstructions were subsequently used in conjunction with a finite-element simulation to infer the water retention curve and the unsaturated hydraulic conductivity. The parameters estimated with ERT agree satisfactorily with those determined using established techniques, hence the proposed approach shows good potential for relatively fast characterisations. Similar experiments could be carried out on site to study the hydraulic behaviour of the entire soil deposit. ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.10.P.066 [article] Estimation of the hydraulic parameters of unsaturated samples by electrical resistivity tomography [texte imprimé] / R. M. Cosentini, Auteur ; G. Della Vecchia, Auteur ; S. Foti, Auteur . - 2012 . - pp. 583 –594. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 62 N° 7 (Juillet 2012) . - pp. 583 –594 Mots-clés : Geophysics Partial saturation Laboratory tests Seepage Suction Résumé : In situ and laboratory experiments have shown that electrical resistivity tomography (ERT) is an effective tool to image transient phenomena in soils. However, its application in quantifying soil hydraulic parameters has been limited. In this study, experiments of water inflow in unsaturated soil samples were conducted in an oedometer equipped to perform three-dimensional electrical measurements. Reconstructions of the electrical conductivity at different times confirmed the usefulness of ERT for monitoring the evolution of water content. The tomographic reconstructions were subsequently used in conjunction with a finite-element simulation to infer the water retention curve and the unsaturated hydraulic conductivity. The parameters estimated with ERT agree satisfactorily with those determined using established techniques, hence the proposed approach shows good potential for relatively fast characterisations. Similar experiments could be carried out on site to study the hydraulic behaviour of the entire soil deposit. ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.10.P.066

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Reliability of VS,30 evaluation from surface-wave tests / C. Comina in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 6 (Juin 2011)  

Public ISBD [article]  inJournal of geotechnical and geoenvironmental engineering > Vol. 137 N° 6 (Juin 2011) . - pp. 579-586 Titre : Reliability of VS,30 evaluation from surface-wave tests Type de document : texte imprimé Auteurs : C. Comina, Auteur ; S. Foti, Auteur ; D. Boiero, Auteur Année de publication : 2011 Article en page(s) : pp. 579-586 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Site characterization Seismic response Earthquake engineering Surface waves Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The reliability of surface-wave tests for the evaluation of VS,30 in seismic site characterization is assessed with respect to both uncertainty and accuracy. The discussion of uncertainty is mainly focused on the implications of solution nonuniqueness in inverse problems; only the inversion uncertainty is considered within this work, omitting other possible issues such as nontrivial geological settings (e.g., lateral variations) or the influence of different processing procedures. A Monte Carlo approach has been used to select, through a statistical test, a set of shear-wave velocity models that can be considered equivalent with respect to fitting the experimental dispersion curve according to the information content (dispersion velocities and frequency range) and the experimental uncertainties. This set of equivalent solutions is then used to evaluate the uncertainty in the determination of VS,30. Moreover, comparisons between the results obtained by surface-wave tests and invasive seismic methods are reported to assess the accuracy of VS,30 evaluation by using surface-wave methods. It is shown that, given an adequate investigation depth, the solution nonuniqueness is not a major concern and that the results are comparable in most situations with the results of invasive tests providing an accurate estimate of VS,30, even with simplified approaches. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i6/p579_s1?isAuthorized=no [article] Reliability of VS,30 evaluation from surface-wave tests [texte imprimé] / C. Comina, Auteur ; S. Foti, Auteur ; D. Boiero, Auteur . - 2011 . - pp. 579-586. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 6 (Juin 2011) . - pp. 579-586 Mots-clés : Site characterization Seismic response Earthquake engineering Surface waves Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The reliability of surface-wave tests for the evaluation of VS,30 in seismic site characterization is assessed with respect to both uncertainty and accuracy. The discussion of uncertainty is mainly focused on the implications of solution nonuniqueness in inverse problems; only the inversion uncertainty is considered within this work, omitting other possible issues such as nontrivial geological settings (e.g., lateral variations) or the influence of different processing procedures. A Monte Carlo approach has been used to select, through a statistical test, a set of shear-wave velocity models that can be considered equivalent with respect to fitting the experimental dispersion curve according to the information content (dispersion velocities and frequency range) and the experimental uncertainties. This set of equivalent solutions is then used to evaluate the uncertainty in the determination of VS,30. Moreover, comparisons between the results obtained by surface-wave tests and invasive seismic methods are reported to assess the accuracy of VS,30 evaluation by using surface-wave methods. It is shown that, given an adequate investigation depth, the solution nonuniqueness is not a major concern and that the results are comparable in most situations with the results of invasive tests providing an accurate estimate of VS,30, even with simplified approaches. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i6/p579_s1?isAuthorized=no

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