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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Geocronologia (40Ar/39Ar e U-Pb), petrografia e litogeoquímica da intrusão alcalina do Marapicu RJ / Geochronology (40Ar/39Ar e U-Pb), petrography and lithogeochemistry from the Marapicu Alkaline Intrusion - Rio de Janeiro

Daniel Adelino da Silva 23 February 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A intrusão alcalina do Marapicu é uma intrusão localizada no maciço Marapicu-Gericinó-Mendanha situado na região metropolitana do Rio de Janeiro. Este maciço é formado por dois corpos alcalinos: Marapicu e Mendanha que fazem parte do lineamento magmático Poços de Caldas-Cabo Frio. Este lineamento inclui dezenas de corpos ígneos alcalinos de idade Cretácea com uma direção preferencial WNW-ESE. Os litotipos mais abundantes do Maciço Marapicu são representados por nefelina sienitos e sienitos de caráter plutônico, além de, fonolitos caracterizados por intrusões rasas geralmente em forma de diques. Além desses litotipos foram amostradas duas rochas com características químicas de magma parental (lamprófiro e fonolito tefrítico), porém, essas duas amostras não apresentam relação genética com as demais. Também foi amostrado um nefelina sienito que possui sodalita azul como feldspatóide, sendo assim, chamado de nefelina sodalita sienito. Entre os fonolitos coletados para esse trabalho, uma amostra apresenta granada melanita em sua assembleia mineralógica, e esta foi então denominada melanita fonolito. Quimicamente as rochas do Marapicu formam uma série alcalina predominantemente insaturada em sílica, miaskítica e metaluminosa. Dentro desta série se observam duas suítes sendo uma potássica (predominante) e outra sódica. A evolução química do corpo se deu por processo de cristalização fracionada com ou sem assimilação de crosta continental provavelmente dentro de uma fonte mantélica enriquecida. Duas idades de cristalização foram obtidas para o Maciço do Marapicu sendo uma idade 40Ar/39Ar de 80,46 0,58 Ma em hornblenda, e uma idade U-Pb em zircão bastante concordante de 78,0 2,1 Ma. Os dados apresentados aqui em conjunto com dados da literatura apontam para dois modelos geodinâmicos de geração dos corpos alcalinos do sudeste brasileiro, um considera a existência de uma pluma mantélica gerada na astenosfera, o outro tem por base a hipótese de flexura crustal e considera que a carga de sedimentos depositados na plataforma continental exerceria esforços que provocariam fraturas profundas permitindo a ascenção desses magmas. O presente trabalho vem para contribuir no entendimento do alojamento dos corpos alcalinos do sudeste brasileiro através do estudo especifico do Maciço Marapicu em conjunto com dados da literatura / The Marapicu Alkaline intrusion is an intrusion into the Marapicu-Gericinó-Mendanha massif. This massif is formed by two alkaline bodies: Marapicu and Mendanha both making part of the Cretaceous Poços de Caldas-Cabo Frio magmatic lineament located in the Southeastern region of Brazil. This lineament includes tens of Cretaceous alkaline bodies and has a WNW-ESE trend. The most abundant rocks in the massif are plutonic nepheline syenites and syenites and also phonolitic rocks characterized for shallow intrusions as a dike. Besides these rocks were sampling two rocks with chemistry characteristcs of parental magma (basanite tefrite and phonolitic tefrite), nevertheless, this samples have not relationship with the others. There is also a nepheline syenite having blue sodalite as a feldspatoid called nepheline sodalite syenite. Between sampled fonolites to this work there is only sample including melanita garnet in his mineralogy assemblage and them called melanita fonolite. Chemically the Marapicu massif rocks forming an alkaline series SiO2-undersatured predominantly miaskitic and metaluminous. This series presents both potassic and sodic suites being the first one in greater content. Geochemistry data shows that evolution process involved fractional crystallization with or without continental crust assimilation and also indicates that this alkaline magma was generating into the enriched mantle source. Two crystallization age were obtained for Marapicu: 40Ar/39Ar age in hornblende of 80.46 0.58 Ma and U-Pb age in zircon of 78.0 2.1 Ma. The presented data together with literature data pointing for two geodynamic models responsible by the generation of Brazilian alkaline bodies. The first one consider there is a mantellic plume from asthenosphere, the second is based on the hypotheses of crustal flexure and consider that sedimentary charge on the continental platform would make deep fails which the magma ascending. The present work came to contribute on understanding of Brazilian alkaline bodies emplacement through the specific study of Marapicu in conjunct with literature data
222

Televisionamento óptico de sondagens - proposta metodológica para execução e suas aplicações em obras subterrâneas / Optical televiewer in boreholes - methodological proposal for implementation and application in underground work

Daniela Garroux Gonçalves de Oliveira 06 April 2015 (has links)
A caracterização de um maciço rochoso constitui um passo essencial na geologia de engenharia, proporcionando a possibilidade de previsão do comportamento deste maciço frente às inúmeras solicitações de qualquer obra a ser realizada. No caso de obras subterrâneas urbanas, como linhas metroviárias, por exemplo, a caracterização geológico-geotécnica de maciços rochosos é fundamental para a identificação de condicionantes geológicos associados à sua estabilidade, sendo eficaz na determinação de parâmetros geotécnicos que influenciarão no projeto de escavação desse maciço, seja este através do método convencional (NATM) ou mecanizado, com o uso de tuneladoras (TBM). Feições estruturais como planos de foliação, dobras, falhas e sistemas de fraturas merecem atenção especial por estarem associadas a zonas de fraqueza, além de todas as características geomecânicas do maciço. Em zonas urbanizadas como a Região Metropolitana de São Paulo (RMSP) as condições geológicas, geomorfológicas e de ocupação dificultam a exposição e a identificação destas feições em superfície. Neste contexto foram desenvolvidas novas técnicas para facilitar o acesso às feições supracitadas. Dentre estas se encontra o televisionamento óptico (OPTV, OTV, Optical Televiewer), que consiste na obtenção de imagens 360º das paredes dos furos de sondagem, fornecendo o que pode ser considerado um testemunho virtual de sondagem. O televisionamento óptico é uma tecnologia introduzida no Brasil desde 2001, entretanto apenas recentemente tendo sido introduzido no manual de sondagens da ABGE (2013), contudo não havendo especificações sobre metodologia de aquisição, de interpretação e possibilidades de aplicação. Este trabalho apresenta sugestões para a aquisição destas imagens, sua interpretação e sugestões de aplicações em obras de engenharia, tendo como exemplo a aplicação em projetos de obras subterrâneas do Metrô de São Paulo. No caso específico de escavações subterrâneas urbanas, o conhecimento do subsolo é essencial, já que sua construção é uma atividade a ser desenvolvida dentro do contexto urbano, podendo provocar interferências significativas com a comunidade, implicando em um alto risco à população lindeira. Somado a isto há o fato de que um maciço pouco conhecido poderá implicar em contenções superdimensionadas, aumentando o custo da obra ou subdimensionadas, aumentando o seu risco. Conforme citado em ISRM (1978), à medida que as descrições de maciços rochosos e suas descontinuidades se tornem mais completas e unificadas, será viável projetar estruturas de engenharia em rocha reduzindo os gastos e aumentando a confiabilidade da interpretação e extrapolação dos resultados. / The rock mass characterization is an essential step in engineering geology, providing the possibility of performance prediction of this massive due to numerous requests of any work to be done. In the case of urban underground works, such as subway lines, for example, geological and geotechnical characterization of rock masses is critical for identifying geological conditions linked to its stability, being effective in determining the geotechnical parameters that influence the design of massive excavation, whether by the conventional method (NATM), or mechanized, using tunneling boring machines (TBM). Structural features such as foliation planes, folds, faults and fracture systems deserve special attention as they are associated with weakness zones in addition to all the geomechanical characteristics of the massif. In urbanized areas, such as São Paulo Metropolitan Region (RMSP), geological, geomorphological and occupation hinders exposure and identification of these features on the surface. In this context, new techniques have been developed to facilitate access to the above features. Among these new techniques is the optical televiewer (OPTV, OTV), which is to obtain 360° images of the borehole walls, providing what might be considered a virtual core of a borehole. The optical televiewer has been a technology introduced in Brazil since 2001, but only recently has been published in ABGE 1 Borehole Manual (2013), however, there are no specifications on the acquisition methodology, interpretation and application possibilities. This paper presents suggestions for the acquisition of these images, their interpretation and suggestions of applications in engineering works, taking as an example the design in projects of underground works of the São Paulo Metro. In the specific case of urban underground excavations ground knowledge is essential, since its construction is an activity to be developed within the urban context, which could cause significant interference with the community, resulting in a high risk to neighboring population. Added to this is the fact that a little-known mass can result in oversized contention, increasing the cost of the work or undersized, increasing its risk. As mentioned in ISRM (1978), as the descriptions of rock masses and discontinuities become more complete and unified, it will be feasible to design engineering structures in rock reducing the costs and increasing the reliability of the interpretation and extrapolation of the results.
223

Étiologies moléculaires des insuffisances surrénales primaires congénitales : développements statistiques pour la validation du séquençage parallèle massif / Genetics of congenital primary adrenal insufficiency and statistical developments for massive parallel sequencing validation

Boulez, Florence 30 March 2018 (has links)
L'insuffisance surrénale primaire (ISP) se caractérise par un déficit en hormones stéroïdiennes lié à un trouble du cortex surrénal qui expose au risque d'insuffisance aiguë et de menace vitale. Actuellement, 80% des formes pédiatriques d'ISP sont d'origine génétique et 5% restent sans étiologie génétique identifiée. Les récentes découvertes de mutations de gènes du stress oxydant ouvrent le champ des recherches d'anomalies génétiques non spécifiques de la glande surrénale. Le séquençage parallèle massif (MPS) autorise aujourd'hui la réalisation de millions de séquences et l'étude simultanée de plusieurs gènes de plusieurs patients ce qui permet d'accélérer le diagnostic. C'est aussi la technique de choix pour la recherche de nouveaux gènes. Cependant, parmi les défis de cette nouvelle technologie, il est possible de citer la gestion de la très grande quantité de données qu'elle génère et le besoin d'une validation rigoureuse préalable à son utilisation à des fins diagnostiques.Le premier objectif du présent travail était d'établir un diagnostic génétique dans une cohorte de patients atteints d'ISP et de rechercher de nouveaux gènes. L'étude des génotypes et des phénotypes permet de comprendre les mécanismes physiopathologiques pour les engager dans le traitement et le conseil génétique.Le second objectif était le développement de méthodes bio-informatiques et d'inférence statistique pour faciliter le transfert du séquençage classique (Sanger) vers la technique MPS. Ce développement comprend l'analyse graphique de la qualité du séquençage, l'ajustement de modèles log-linéaires pour comparer les propriétés de différents « pipelines », et l'ajustement de modèles additifs généralisés pour estimer les contributions des sources d'erreurs de séquençage. Les analyses statistiques ont considéré chaque paire de bases comme unité statistique et chaque patient comme étude indépendante, ce qui confère à l'analyse simultanée de tous les patients le caractère d'une méta-analyse / Primary adrenal insufficiency (PAI) is characterized by an impaired production of steroid hormones due to an adrenal cortex defect. This condition exposes to the risk of acute insufficiency which may be life-threatening. Today, 80% of pediatric forms of PAI have a genetic origin but 5% have no clear genetic support. Recently discovered mutations in genes relative to the oxidative stress have opened the way to research works on genes unrelated to the adrenal gland. Massive Parallel Sequencing (MPS) is now able to perform millions of sequences and study simultaneously several genes in several patients, which accelerates the diagnosis. Above all, MPS is the preferred technique for new gene discoveries. However, among the challenges of this new technology one may cite the management of the huge amount of data MPS generates and the need for a strict validation process before the use of MPS for diagnosis purposes.The first objective of the present work was to establish a genetic diagnosis in a cohort of patients with PAI and search for new genes. Study the genotypes and phenotypes allows a better understanding of the physiopathological mechanisms of PAI and offering appropriate care for the patients and counseling for families. The second objective was the development of bioinformatic and statistical inference methods to help shifting from the classical Sanger sequencing to MPS. This shift involves a graphical analysis of the quality of sequencing, an adjustment of log-linear models to allow comparing the properties of different pipelines, an adjustment of the generalized additive models to allow estimating the contributions of various sources of sequencing errors. The statistical methods have considered each DNA base-pair as a statistical unit and each patient as a separate study which confers the simultaneous study of all patients the status of a meta-analysis
224

Stanovení stáří sekundárních minerálů uranu metodou 230Th/234U na vybraných lokalitách Českého masívu / Determination of the age of secondary uranium minerals using 230Th/234U in selected localities of the Bohemian massif

Roll, Michal January 2017 (has links)
This thesis is focused on prominent uranium deposits in Czech Republic and their secondary uranium mineralization. Main goal of this thesis is to analyze collected minerals and to determine their ages. Next step is to prove or disprove hypothesis that this secondary uranium minerals are products of Quaternary glacier weathering. As a suitable analytical method, an alpha spectrometry was used and the age was calculated by 230 Th/234 U ratio. Firstly, chosen methodology was verified with admixture of reference material PU1 (Přibram uraninite) in secular equilibrium and internal standard, both with known activity. Analyzed spectra confirmed that some of the samples lay on the very edge of datability, especially in case of PL1 and GF1, both samples are very young, so they easily could be products of anthropogenic activity (changed environment due to mining works). On the other hand, in case of sample GF3, the age was successfully determined, although it is also quite young phase. In case of samples ME3, ME4 and ME6 was used threshold dating method, because they were considered to be too old for age calculation. The rest of the samples chosen for age determination was analyzed without further complications. Based on the age and geological setting, samples GF3 (3 725 ± 845 years), JE1 (10 655 ± 1 795...
225

De la richesse pour les dieux ... et pour la reproduction sociale : les dépôts non funéraires de l'âge du Bronze en Europe / Offerings for the deities... and for the social reproduction : Bronze Age hoards in Europe

Blitte, Hélène 22 July 2015 (has links)
Le travail mené dans le cadre de cette thèse porte sur la pratique des dépôts non funéraires de l’âge du Bronze (2200-800 av. J.-C.) en Europe. Ces ensembles d’objets métalliques présentent une très grande variabilité temporelle et spatiale, en termes de contenu et de fréquence, ce qui soulève de nombreuses questions. L’objectif principal de cette recherche est de montrer que ces dépôts sont des offrandes déposées pour solliciter les divinités, notamment pour stabiliser une reproduction sociale menacée. Pour cela, la réflexion se développe autour de deux axes majeurs, l’un portant sur la composition de ces ensembles (approche statistique) et l’autre sur leur implantation dans le paysage (approche spatiale). La mise en place d’un système d’information (base de données relationnelles couplée à un SIG) forme le noyau de ce travail. Les divers résultats obtenus pour chacune des cinq zones-échantillons choisies sont confrontés puis replacés dans leur contexte régional, afin d’aborder la signification sociale de ces dépôts. Une hiérarchie au sein de ces ensembles a ainsi pu être mise en évidence, de même qu’une diffusion de la pratique d’Est en Ouest. Pour conclure l’étude, une ouverture sur la question des réseaux d’échanges est proposée. / This PhD thesis is mainly concerned with the European Bronze Age hoards (2200-800 BC). These hoards of metal objects have a high variability in space and time, as far as their content and frequency are concerned, which leads to several questions. The primary aim of this study is to show that these hoards are offerings for the deities and made to strengthen an unstable social reproduction. My argument is developed following two research axes, the first one focusing on the content of the hoards (statistical analysis) and the second one on their repartition in the landscape (spatial analysis). The use of an information system (a RDBMS related to a GIS) is at the core of this thesis. The main results of the five chosen regions are compared and then repositioned within their regional context, in order to tackle the social meanings of the hoards. A hierarchy of the hoards is highlighted and a diffusion of the practice from east to west is shown. To conclude the study, a window is open on the exchange networks.
226

Origine des minéralisations stratiformes de fluorine de la bordure sud-est du bassin de Paris / Origin of stratabound fluorite deposits in the southeastern part of the Paris Basin

Gigoux, Morgane 02 July 2015 (has links)
En France, des minéralisations stratiformes de fluorine spatialement liées à une discordance socle/couverture sont localisées à la base de la série sédimentaire mésozoïque du bassin de Paris autour du Morvan cristallin, avec des réserves estimées à environ 5.5 Mt de fluorine. Ce travail concerne principalement quatre gisements de fluorine développés au sein de grès/conglomérats à Antully, de calcaires à Courcelles-Frémoy et de dolomies à Pierre-Perthuis et Marigny-sur-Yonne. L’objectif est d’apporter des contraintes sur l’âge et l’origine de ces minéralisations à l’aide d’une approche pluri-disciplinaire combinant géochronologie, pétrographie, géochimie élémentaire et isotopique afin d’élaborer un modèle métallogénique. Une première étude géochronologique permet de déterminer l’âge de mise en place des minéralisations de la génération géodique de fluorine de Pierre-Perthuis à 130 ± 15 Ma. L’élaboration d’une paragenèse générale détaillée révèle deux séquences minérales de type « fluorine-barytine-quartz », précédées par un événement de dissolution/karstification affectant les phases carbonatées des roches encaissantes. Au cours de ces phases de dissolution, le fluide s’enrichit en calcium et joue un rôle majeur pour la minéralisation en fluorine. Une étude microthermométrique des inclusions fluides piégées dans les cristaux géodiques de fluorine montre la présence de fluides particulièrement riches en CaCl₂ avec des températures entre 80-100°C, et des températures ponctuellement plus élevées. L’ensemble de ces données a été confronté à l’histoire thermique du sud-est du bassin de Paris et permet d’évoquer une remontée de fluides hydrothermaux au Crétacé inférieur jusqu’à la discontinuité entre le socle et la base du bassin sédimentaire. L’origine météorique de l’eau a été identifiée par les isotopes stables de l’oxygène sur les générations de quartz. L’implication d’une source granitique a été démontrée par les rapports isotopiques ²⁰⁶Pb/²⁰⁴Pb très radiogéniques dans la galène et l’étude des minéraux constituants du socle granitique, avec l’implication de la biotite en tant que source potentielle du fluor. Au cours du Crétacé inférieur, le soulèvement des bordures du bassin de Paris génère un gradient hydraulique susceptible de provoquer la mise en charge de fluides météoriques dans les massifs cristallins, percolant à travers le socle en profondeur (2 à 5 km). La dissolution des carbonates par les fluides ascendants hydrothermaux contenant du fluor va permettre la formation de la fluorine au cours de l’enrichissement du fluide en calcium dans le bassin au niveau de la discontinuité socle/couverture. / In France, unconformity-related stratabound fluorite deposits occurred at the base of Mesozoic sedimentary units from the Paris Basin around the Morvan Massif, and reserves are estimated to about 5.5 Mt. This work mainly concerns four fluorite deposits in sandstones at Antully, in limestones at Courcelles-Frémoy and in dolomite at Pierre-Perthuis and Marigny-sur-Yonne. The aim of this study is to constrain the age and origin of mineralizations inferred from a multi-disciplinary approach including geochronoly, petrography, elementary and isotopic geochemistry in order to produce a metallogenic model. Firstly, the geochronological study allows to determine the age of the geodic fluorite stage at Pierre-Perthuis at 130 ± 15 Ma. The detailed paragenetic sequence displays two major mineral successions of “fluorite-barite-quartz”, occurring after two dissolution or karstification events that affect the carbonate phases in host-rocks. During the dissolution event, the fluid is enriched in calcium and plays a key role for the fluorite mineralization. The microthermometric study of fluid inclusions in geodic fluorite crystals shows CaCl₂-rich fluids with temperature around 80-100°C, with sporadic higher temperatures. All these data has been confronted to the thermal history of southeastern part of Paris Basin and allows to evoke deep ascendant hydrothermal brine circulation during the Early Cretaceous at the basement/basin unconformity. The meteoritic origin of fluid is determined by the oxygen isotopic compositions in the quartz stages. The implication of basement source has been demonstrated by the radiogenic lead isotopic compositions added to the study of major minerals in basement with the involvement of biotite as a potential source of fluor. During the Early Cretaceous, it is proposed that flows of meteoric waters percolated downwards to depths of 2-5 km, driven by a hydraulic gradient due to the flexural deformation of the Paris Basin. The carbonate dissolution by the fluor-bearing ascendant hydrothermal fluids will allows the deposition of fluorite mineralization during the Ca enrichment of fluids in the basin at the basement/cover unconformity.
227

Kinematický vývoj rozhraní tepelsko-barrandienské jednotky a moldanubika během svrchního devonu a spodního karbonu / The Late Devonian to early Carboniferous kinematic evolution of the Teplá-Barrandian/Moldanubian boundary

Tomek, Filip January 2011 (has links)
ENGLISH ABSTRACT The Late Devonian to Early Carboniferous kinematic evolution of the Teplá-Barrandian/Moldanubian boundary The Staré Sedlo complex (SSC) is a relic of meta-igneous arc-related pluton in the southern part of the Sedlčany-Krásná Hora roof pendant, intruded by granitoids of the Central Bohemian Plutonic Complex along the boundary of Teplá-Barrandian (TBU) and Moldanubian units (MU), Bohemian Massif. The SSC mainly comprises deformed orthogneisses of calc-alkaline granodiorite to tonalite protoliths of Late Devonian age (380−365 Ma; Košler et al., 1993) that were commonly mingled with minor basic magmas. Locally preserved subhorizontal intrusive contacts of the orthogneisses against their meta-sedimentary host rock indicate that these magmas intruded as a sill complex. The SSC preserves a rather unusual flat-lying subsolidus foliation (dip <40ř) associated with subhorizontal ~NE-SW-trending mineral lineation. Mesoscopic structures, anisotropy of magnetic susceptibility (AMS), and deformational microstructures indicate prolate shape of the strain ellipsoid with dominant coaxial pure shear regime. The solid state microstructures record cooling of the orthogneiss protolith down to the ambient greenschist facies conditions followed by its static recrystallization due to the intrusion of the younger...
228

Paleogeografický vývoj kenozoických říčních systémů ve středních a severních Čechách a jejich vztah ke klimatickým změnám a neotektonice / Paleogeographic development of the Cenozoic river systems in the central and northern Bohemia and its link to climatic changes and neotectonics

Štor, Tomáš January 2018 (has links)
The main aim of this thesis is to provide greater details on the timing of the fluvial river systems formation in the middle and the northern Bohemia. We focused on the Ploučnice River and Vltava River evolution. The river systems are very complex therefore we have used multiple approaches of the research with the disciplines range from geology, sedimentology, geomorphology, geochemistry, over different dating methods such as 10Be and 26Al isochron burial dating, optically stimulated luminescence dating and radiocarbon dating methods. Our results suggests that the terraces are significantly older than previously proposed. The fluvial style of the Ploučnice River system changes from high-energy braided to long-bend meandered river in the upper terrace levels (36 to 29 m above the modern river) and from high- to medium-energy braided river in the middle terrace levels (22-14 m). In the lower terrace levels (13 to 5 m) high-energy braided to long-bend meandered river environments were identified. Terraces were dating at 34 m, 29 m and 14 m above the modern floodplain with cosmogenic radionuclides while the 19 m, 12 m and 6 m above the modern floodplain terraces were dating with OSL. The time span represented by the river terraces remains unclear and varies from Eburonian to Eemian (1.68 to 0.056 Ma)....
229

Méthodes d’essais de vieillissement accéléré des bétons à l’échelle des ouvrages / Accelerated aging test methods of concrete at a structural scale

Jabbour, Jacques 28 September 2018 (has links)
Cette thèse fait partie des programmes de recherche sur le vieillissement des ouvrages de génie civil nucléaire lancés par l’IRSN (Institut de Radioprotection et de Sûreté nucléaire) dans le cadre du projet de prolongement de la durée d’exploitation des centrales nucléaires françaises. Le but étant de contribuer à la connaissance des mécanismes de vieillissement des matériaux constitutifs des ouvrages non-remplaçables d’une centrale nucléaire, tels que les enceintes de confinement. En effet, leur comportement représente un point important pour l’évaluation de la sûreté des installations nucléaires, car elles représentent la troisième et la dernière barrière de confinement contre le relâchement éventuel des produits radioactifs dans l'environnement.Parmi les phénomènes intervenants lors du vieillissement des ouvrages, le développement éventuel des pathologies, notamment les réactions de gonflements internes (RGI) qui sont susceptibles de dégrader le béton et conduire à l’apparition des fissurations dans les structures touchées. Ces réactions de gonflement internes (RGI) englobent la réaction sulfatique interne (RSI), la réaction alcali-granulat (RAG) et la concomitance de ces deux. Il s’agit de réactions endogènes, se produisant suite à l’interaction des composants initiaux du matériau. Ces interactions peuvent avoir lieu suite à l’utilisation de granulats réactifs en cas de RAG et/ou suite à un échauffement important au jeune âge en cas de RSI. Dans les ouvrages nucléaires, l’éventualité de ces phénomènes ne peut pas être écartée. En effet, ils comportent des éléments structuraux massifs en béton armé pour lesquels un échauffement important a pu se produire lors de la prise du béton et des granulats réactifs ont pu être utilisés pendant la confection. Ce risque doit donc être étudié d’autant plus que le prolongement de la durée d’exploitation des installations est envisagé.Cependant, la cinétique d’apparition des désordres suite au développement de ces réactions dans les ouvrages est en général lente allant jusqu’à quelques dizaines d’années, d’où le recourt à des essais accélérés. Cependant les solutions pratiquées dans les laboratoires de recherche, consiste à utiliser des protocoles d’essais accélérés mis au point sur des éprouvettes de faibles dimensions.Le travail de recherche réalisé dans le cadre de cette thèse comporte trois grandes axes : la mise au point d’un protocole expérimental visant à accélérer les réactions de gonflement interne du béton à l’échelle de structures massives, l’analyse multi-échelle des phénomènes et la mise au point d’une instrumentation innovante adaptée à cette problèmatique. Trois maquettes (de dimensions 2,4 x 1,4 x 1 m3) représentatives d’un ouvrage massif ont été réalisées dans des conditions maitrisées et optimisées afin de favoriser respectivement le développement de la réaction sulfatique interne (RSI), de la réaction alcali-granulat (RAG) et de la concomitance des deux pathologies, RAG et RSI. Ceci a permis d’étudier ces pathologies et de les caractériser à une telle échelle.L’effet d’échelle sur la cinétique de gonflement est mis en évidence grâce à une étude expérimentale multi-échelle permettant de comparer l’évolution des réactions dans les maquettes avec leur évolution dans des éprouvettes en béton reconstitué et des carottages.Une méthode d’instrumentation innovante par fibres optiques a été spécifiquement développée pour ces maquettes, permettant de suivre l’évolution des pathologies dans la masse et d’en déduire les champs de déformation dans plusieurs plans d’intérêt. Les mesures sont utilisées pour décrire finement les mécanismes évolutifs du gonflement et la dégradation des structures. Ces mesures sont aussi utilisées comme référence pour des simulations numériques ultérieures. / This thesis is part of a research program on the aging of nuclear infrastructures launched by the IRSN (Institute for Radiological Protection and Nuclear Safety) within the project aiming to extend the lifespan of the French nuclear power plants. The goal is to contribute to the knowledge of aging mechanisms touching the constituents of non-replaceable structures of a nuclear power plant, such as the containment building. Matter of fact, the behavior of such structures is an important point for the safety assessment of nuclear installations because they represent the third and last barrier against the dispersion of radioactive particles in the environment. Among the phenomena involved in aging mechanisms, internal swellings reactions (ISR) are pathologies that can degrade concrete by causing swelling, cracking and major disorders in the affected structures. Internal swelling reactions (ISW) include the delayed ettringite formation (DEF), the alkali-aggregate reaction (AAR) and the concomitance of the two. These pathologies are endogenous reactions, occurring as a result of the interaction between the initial components of the material. These interactions take place following the use of reactive aggregates in case of AAR and/or following a significant warm-up at the concrete’s early age in case of DEF. In nuclear facilities, the possibility of these phenomena cannot be ruled out. Matter of fact, they include massive reinforced concrete elements for which a significant heating could have occurred at the early age. Moreover, reactive aggregates may have been used during the construction phase. Therefore those risks ought to be studied especially if the extension of the lifespan of these installations is envisaged.However, the kinetics of these reactions are generally slow and it can take for up to a few decades for disorders to appear in the structure. Among the solutions used in research laboratories, one is to use accelerated test methods developed on small specimens.The research work carried out in this context includes three major axis: the development of an experimental protocol to accelerate internal swelling reactions of concrete on a massive structure scale, multi-scale analysis of the phenomena involved and the development of innovative instrumentation adapted to this problem. The purpose is to allow better observation and understanding of swelling reactions at such scale. Hence, three representative massive concrete mock-ups whose dimensions are 2,4 x 1,4 x 1 m3 were realized under controlled and optimized conditions for the development of delayed ettringite formation (DEF), alkali silica reaction (ASR) and the concomitant ASR-DEF case respectively.The scale effect on swelling kinetics is demonstrated by an experimental study comparing the evolution of swelling reaction in the massive samples with the evolution in reconstituted concrete laboratory specimens as well as coring specimens.An innovative instrumentation method using optical fibers is also developed thus allowing the monitoring of the pathologies in the massive structures and the tracking of the respective deformation fields in several two-dimensional plans of interest. The measurements are to finely describe and help in understanding the evolutionary mechanisms of structural degradation and can be used subsequently as a reference for numerical simulations.
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Tunnels profonds dans les milieux viscoplastiques : approches expérimentale et numérique

Bernaud, Denise 09 July 1991 (has links) (PDF)
Les problèmes étudiés dans cette thèse relèvent du cadre général de la modélisation des tunnels profonds. Ce travail traite essentiellement de l'interaction complexe entre massif et soutènement. Initialement, on réalise une approche expérimentale portant sur l'optimisation du dimensionnement des soutènements des galeries dans des roches viscoplastiques. Une modélisation numérique fine de ce problème d'interaction massif viscoplastique-soutènement plastique est mise en oeuvre et permet de bien interpréter le comportement de la galerie expérimentale de Mol (Belgique). Ensuite, on s'intéresse à l'aspect 3D du creusement des tunnels a l'aide de la méthode numérique d'activation/désactivation des éléments en axisymétrie. On montre, par la réalisation d'abaques, que l'équilibre des tunnels dans les milieux viscoplastiques dépend largement de la rigidité et de la distance de pose du revêtement ainsi que de la vitesse de creusement de l'ouvrage. Dans la dernière partie, on compare les résultats donnés par notre méthode numérique d'une part, et par la méthode cv-cf d'autre part: on met en évidence les imprécisions de la méthode approchée cv-cf sous sa forme actuelle. Finalement, on propose une nouvelle méthode approchée en élasticité, qui conserve le formalisme de la méthode cv-cf, mais permet de mieux prendre en compte l'effet de la rigidité du soutènement sur la valeur de la convergence avant pose. Cette nouvelle méthode approchée conduit à des résultats tout a fait acceptables.

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