Please use this identifier to cite or link to this item: http://repositorio.lnec.pt:8080/jspui/handle/123456789/1012694
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dc.contributor.authorMiranda, L.pt_BR
dc.date.accessioned2020-06-03T17:02:39Zpt_BR
dc.date.accessioned2020-06-22T09:42:48Z-
dc.date.available2020-06-03T17:02:39Zpt_BR
dc.date.available2020-06-22T09:42:48Z-
dc.date.issued2019-05-09pt_BR
dc.identifier.urihttps://repositorio.lnec.pt/jspui/handle/123456789/1012694-
dc.description.abstractA state-of-the-art revision of immersed tunnels is done. The selected case-study for this thesis, an immersed tunnel for crossing Tagus River between Algés and Trafaria, is presented. Next, cases of earthquake-induced liquefaction and its associated mechanism are discussed. The most relevant constitutive models for the numerical simulation of the response of soils under cyclic loading are described, including the Manzari-Dafalias model. Subsequently, Tagus River sand is physically characterized and six monotonic drained triaxial tests are analysed, with the goal of characterizing the stress-strain behaviour of the sand and obtain its parameters. Five cyclic undrained torsional tests are also analysed with the goal of characterizing cyclic behaviour of the sand. Then, the calibration framework for the Manzari-Dafalias model is presented, combining results of laboratory tests with numerical sensitivity studies. A parameter sensitivity analysis is carried out to understand the relevance of some chosen model parameters, by using an OpenSees constitutive driver, both through numerical simulation of monotonic drained triaxial tests and of cyclic undrained torsional tests. Some model parameters are calibrated directly from triaxial testing. The remaining parameters are calibrated through numerical simulation and curve fitting of the model to the laboratory results. A new constitutive driver is implemented in MATLAB to clarify some of the Manzari-Dafalias model issues, namely in the liquefaction phase. Finally, multiple liquefaction mitigation measures, and their application in immersed tunnels, are described. Laboratory testing of a mitigation measure, specifically injection of a duromeric expansive polyurethane resin, commercially available, is accomplished. The physical characteristics of both the resin and of the sand-resin mixture are presented. A series of tests, namely high frequency ultrasonic pulse tests, uniaxial compression and tensile tests, and triaxial compression tests, are performed. The modulus of elasticity, the Poisson’s ratio, the uniaxial compressive and tensile strengths, the triaxial compressive strength and the shear strength parameters, are determined. Two additional injection tests are executed to check densification of the sand between injection columns and its relative density is determined. Finally, the main conclusions are summarized and guidelines for future developments are established.pt_BR
dc.language.isoengpt_BR
dc.relationSFRH/BD/99581/2014pt_BR
dc.rightsopenAccesspt_BR
dc.subjectimmersed tunnelspt_BR
dc.subjectliquefactionpt_BR
dc.subjectadvanced laboratory testingpt_BR
dc.subjectnumerical modellingpt_BR
dc.subjectTagus River sand - expansive polyurethane resin mixturept_BR
dc.titleLiquefaction mitigation measures: prospective application to immersed tunnel foundationspt_BR
dc.typedoctoralThesispt_BR
dc.identifier.localedicaoLisboapt_BR
dc.description.sectorDG/NGUTpt_BR
dc.contributor.arquivoSIMpt_BR
Appears in Collections:DG/NGUT - Programas de Investigação, Teses e Trabalhos de Síntese

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