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Marchetti, Silvano L.
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Marchetti, Silvano L.
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- PublicationOpen AccessThe first Italian blast-induced liquefaction test (Mirabello, Emilia-Romagna, Italy): description of the experiment and preliminary results(2017)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ;; ; ;; ; ;; ; ; ; ;; ; ; ; ; ; ; ; ; ; ; ;; ;; ; ; ; ;; ;; Soil liquefaction can result in significant settlement and reduction of load-bearing capacity. Moreover, the generation of pore pressure during an earthquake and its post-seismic dissipation can generate permanent deformations and settlements. The quantitative evaluation of post-liquefaction settlements is of extreme importance for engineering purposes, i.e. for earthquake-resistant design of new buildings and safety evaluation of existing ones. Quantifying the extent of these phenomena is, however, rather difficult. Uncertainties arise from the stochastic nature of the earthquake loading, from the simplifications of soil models, and from the difficulty in establishing correlations between the pre-earthquake soil state and the post-seismic deformations. Field scale liquefaction tests, under controlled conditions, are therefore important for a correct quantification of these phenomena. Recent experiences (e.g. New Zealand, United States) show that liquefaction can be induced and monitored with field scale blast tests to study the related effects on soil geotechnical properties. Within this framework this paper introduces the preliminary results obtained from a research project on blast-induced liquefaction at field scale. Tests were performed at a trial site located in Mirabello (Ferrara, Italy), a village strongly affected by liquefaction phenomena during the 2012 Emilia Romagna earthquake. Invasive tests, such as piezocone, seismic dilatometer and down-hole tests, and non-invasive tests were carried out before and after the execution of two blast test sequences to study the variation in physical properties of the soils. Pore pressure transducers, settlement profilometers and accelerometers were installed with the objective of measuring, during and after the detonations, the generation and subsequent dissipation of the pore pressure, the vertical deformations, and the blast-induced ground motions respectively. Variations in load distribution on deep foundations due to soil liquefaction were also evaluated on a test micropile instrumented with a strain gauge array. Topographical surveys were carried out to measure ground surface settlements. Laboratory tests and trenches also provided increased understanding of the site characteristics.1685 138 - PublicationRestrictedOverconsolidation and Stiffness of Venice Lagoon Sands and Silts from SDMT and CPTU(2014)
; ; ; ; ; ; ; ; ; ; ; ; ;This study is part of an extensive research program carried out at the Treporti test site (Venice, Italy), where a cylindrical trial embankment was constructed and monitored from the beginning of its construction until complete removal, 4 years later. This paper concentrates mainly on the evaluation of overconsolidation and stiffness of the Venice lagoon sands and silts. The possibility of estimating the overconsolidation ratio (OCR) in sand by the combined use of seismic dilatometer (SDMT) tests and piezocone (CPTU) tests is investigated. A tentative correlation for estimating the OCR in sand from the ratioMDMT=qt is constructed. Field compression curves have been back-figured from 1-m field oedometer curves reconstructed from local vertical strains measured by a sliding deformeter under the embankment center. TheSDMTand CPTU soundings performed before embankment application and postremoval have permitted analyzing how the OCR caused by the embankment was reflected by the before/after SDMT and CPTU results. The paper also illustrates the possible use of the SDMT to assess the in situ decay of stiffness with the strain level, by comparison with the stiffness decay curves of the elements on the centerline back-figured from the observed embankment behavior under increasing loading.79 2