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Manuel, Maria Rosaria
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Manuel, Maria Rosaria
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Manuel, Maria
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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 - PublicationOpen AccessBlast-induced liquefaction in silty sands for full-scale testing of ground improvement methods: Insights from a multidisciplinary study(2020)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; In the engineering geology field increased attention has been posed in recent years to potential liquefaction mitigation interventions in susceptible sand formations. In silty sands this is a major challenge because, as the fines content increases, vibratory methods for densification become progressively less effective. An alternative mitigation technique can be the installation of Rammed Aggregate Pier® (RAP) columns that can increase the resistance of the soil, accounting for its lateral stress increase and for the stiffness increase from soil and RAP composite response. To investigate the influence of these factors on liquefaction resistance, full-scale blast tests were performed at a silty sand site in Bondeno (Ferrara, Italy) where liquefaction was observed after the 2012 Emilia-Romagna earthquake. A multidisciplinary team of forty researchers carried out devoted experimental activities aimed at better understanding the liquefaction process at the field scale and the effectiveness of the treatment using inter-related methods. Both natural and improved areas were investigated by in-situ tests and later subjected to controlled blasting. The blast tests were monitored with geotechnical and geophysical instrumentation, topographical surveying and geological analyses on the sand boils. Results showed the RAP effectiveness due to the improvement of soil properties within the liquefiable layer and a consequent reduction of the blast-induced liquefaction settlements, likely due to soil densification and increased lateral stress. The applied multidisciplinary approach adopted for the study allowed better understanding of the mechanism involved in the liquefaction mitigation intervention and provided a better overall evaluation of mitigation effectiveness2131 40 - PublicationOpen AccessMicrozonazione sismica speditiva del centro storico di Sulmona (AQ)(2009-03)
; ; ; ;Di Capua, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia ;Peppoloni, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Manuel, M.R.; Freelance; ; L’UO Geologica si è occupata del recupero delle informazioni geologiche relative al sottosuolo del centro storico campione di Sulmona per le elaborazioni del Livello 1 del task 5/7 del Progetto Reluis – Linea 10. Al termine dell’attività sono state reperite le stratigrafie di tre sondaggi geognostici (S1c, S2c e S3c – Figura 1) che sono stati terebrati nel periodo dicembre 2006 – febbraio 2007, nell’ambito del progetto “Microzonazione sismica di secondo livello; indagini e risultati ai fini della progettazione esecutiva della Microzonazione sismica del centro abitato di Sulmona” finanziato dalla Regione Abruzzo e condotto dai ricercatori della “Sapienza” Università di Roma in collaborazione con l’Università degli Studi di L’Aquila (Manuel, 2007). All’interno di due dei tre fori sono state realizzate anche prove down‐hole.551 1058 - PublicationRestrictedEvaluation of liquefaction potential in an intermountain Quaternary lacustrine basin (Fucino basin, central Italy)(2018)
; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ;; ; ; ;; In this study, we analyse the susceptibility to liquefaction of the Pozzone site, which is located on the northern side of the Fucino lacustrine basin in central Italy. In 1915, this region was struck by a M 7.0 earthquake, which produced widespread coseismic surface effects that were interpreted to be liquefaction-related. However, the interpretation of these phenomena at the Pozzone site is not straightforward. Furthermore, the site is characterized by an abundance of fine-grained sediments, which are not typically found in liquefiable soils. Therefore, in this study, we perform a number of detailed stratigraphic and geotechnical investigations (including continuous-coring borehole, CPTu, SDMT, SPT, and geotechnical laboratory tests) to better interpret these 1915 phenomena and to evaluate the liquefaction potential of a lacustrine environment dominated by fine-grained sedimentation. The upper 18.5 m of the stratigraphic succession comprises fine-grained sediments, including four strata of coarser sediments formed by interbedded layers of sand, silty sand and sandy silt. These strata, which are interpreted to represent the frontal lobes of an alluvial fan system within a lacustrine succession, are highly susceptible to liquefaction. We also find evidence of paleo-liquefaction, dated between 12.1–10.8 and 9.43–9.13 kyrs ago, occurring at depths of 2.1–2.3 m. These data, along with the aforementioned geotechnical analyses, indicate that this site would indeed be liquefiable in a 1915-like earthquake. Although we found a broad agreement among CPTu, DMT and shear wave velocity ‘‘simplified procedures’’ in detecting the liquefaction potential of the Pozzone soil, our results suggest that the use and comparison of different in situ techniques are highly recommended for reliable estimates of the cyclic liquefaction resistance in lacustrine sites characterized by high content of fine-grained soils. In geologic environments similar to the one analysed in this work, where it is difficult to detect liquefiable layers, one can identify sites that are susceptible to liquefaction only by using detailed stratigraphic reconstructions, in situ characterization, and laboratory analyses. This has implications for basic (Level 1) seismic microzonation mapping, which typically relies on the use of empirical evaluations based on geologic maps and pre-existing sub-surface data (i.e., age and type of deposits, prevailing grain size, with particular attention paid to clean sands, and depth of the water table).358 6