[pt] Construção de barragens de terra é uma atividade milenar, empregada com o objetivo de atender às mais diversas necessidades humanas como o armazenamento de água, irrigação, regularização de cursos d água, geração de enregia elétrica, etc. Ao longo da história, o projeto destas obras de terra passou de conceito simples, baseados em técnicas empíricas e regras intuitivas, para as análises modernas que consideram o comportamento da barragem em suas diversas fases de vidas (construção, enchimento do reservatório, regime de plena operação), sob carregados estáticos e sísmicos, condições de contorno complexas e sofisticadas relações constitutivas dos materiais da estrutura e do maciço de fundação. Nesta trabalho a construção, primeiro enchimento do reservatório e a resposta sísmica da barragem de terra de Pomacocha, Peru, são analisados pelo método dos elementos finitos, utilizando o software ABAQUS (versus 6.3). Os campos de tensão e de deslocamentos para diversos estágios de aplicação dos carregamentos estático e sísmico são apresentados, incluindo-se histórias de deformação e de tensão para determinados pontos do corpo da barragem e do solo de fundação. / [en] Dam construction is a millenary activity, carried out with the objective of fulfilling human necessities as water supply, land irrigation, water flow regularization, electric power generation, etc. Along the history, the design of these earthworks evolved from simple concepts, based on empirical techniques and rules of thumb, to modern analyses that consider all phases of a dam s life (construction, first reservoir filling, full operation) understatic and seismic loads, as well as complex boundary conditions and sophisticated constitutive relationships for the structure itself and the foundation mass. In this work, the construction, first reservoir filling and the seismic response of the Pomacocha Dam, located in Peru, are analyzed by the finite element method using the software ABAQUS (version 6.2). At several loading stages the corresponding stress and displacement are presented as well as, for some specific points in the dam body and in the foundation soil, the characteristic stress and strain histories during the static and seismic loads.

[pt] O desenvolvimento de campos de petróleo afeta significativamente o meio geológico ao redor do reservatório. Os efeitos geomecânicos decorrentes da exploração podem ser nocivos à integridade de componentes presentes no sistema, notadamente os poços. O objetivo deste estudo foi analisar os efeitos do desenvolvimento do reservatório sobre a integridade de poços, empregando simulações de natureza fluido-mecânica e multi-escala. Para as análises globais, foi implementada e validada uma configuração de acoplamento fluido-mecânico parcial, utilizando o programa de simulação de reservatórios IMEX e o programa de análise de tensões ABAQUS, baseada na metodologia de acoplamento parcial desenvolvida pelo Grupo de Tecnologia e Engenharia de Petróleo da PUC-Rio. A conexão teórica entre modelos de poço e reservatório foi estabelecida através de um workflow multi-escala, desenvolvido para nortear a análise de integridade de poços em virtude dos efeitos de produção. Para a otimização da conexão numérica entre os modelos de diferentes escalas, foi desenvolvido um módulo gerenciador de análises locais, denominado Módulo APOLLO, capaz de incluir na simulação local as etapas de perfuração e completação do poço, bem como os efeitos geomecânicos provenientes da simulação global acoplada. Análises acopladas e multi-escala foram realizadas em dois poços hipotéticos, presentes em um modelo de reservatório com a geometria do Campo de Namorado. Através das ferramentas desenvolvidas nesta Tese, foi possível realizar uma previsão detalhada e precisa do mecanismo que levou os poços avaliados ao colapso. Constatou-se que o caráter dos estados limites observados foi essencialmente tridimensional, bem como dependente da abordagem de acoplamento empregada na simulação global. / [en] The development of petroleum fields affects substantially the geological environment around the reservoir. The geomechanical effects arising from hydrocarbon exploration may present harmful effects on the integrity of the system components, particularly the wells. The aim of this work was to analyze the reservoir development effects over the well integrity, employing fluid-mechanical and multi-scale simulations. For the global analyzes, it was implemented and validated a fluid-mechanic partial coupling configuration, using the reservoir simulation software IMEX and the stress analysis software ABAQUS, based on the coupling methodology developed by the Group of Technology and Petroleum Engineering of PUC-Rio. The theoretical connection between the models of reservoir and wells was established by a multi-scale workflow, which was developed to guide the well integrity analysis due to production effects. In order to optimize the numerical connection between distinct scale models, it was developed a local analysis manager, called APOLLO module, which can include the steps of drilling and completion, as well as the geomechanical effects from the global simulation, in the local simulations. Coupled multi-scale analyzes were performed in two hypothetical wells, present in a reservoir model based on the geometry of the Namorado Field. Through the tools developed in this Thesis, it was possible to perform a detailed and accurate prediction of the mechanism that leads the evaluated wells to the collapse. It was found that the character of the observed limit states was essentially three-dimensional, as well as dependent of the coupling approach employed on the global simulation.

La circulation hydrothermale océanique est un élément clé dans le transfert de chaleur et de matière des profondeurs de la Terre vers sa surface. Certains sites hydrothermaux produisent de grandes quantités d’hydrogène et de méthane. C’est le cas du site de Rainbow (36°N), situé sur la dorsale médio-atlantique, auquel on s’intéresse ici. Les fortes concentrations d’hydrogène ([H2]=16 mM kg-1) et de méthane ([CH4]=2,5 mM kg-1) des fluides chauds (~365°C) émis par ce site ont été interprétées comme étant issues de l’hydratation des péridotites du diapir mantellique qui constitue son socle géologique du site, mais l’altération d’assemblages gabbroïques pourrait également être à l’origine de sa production d’hydrogène. Ces processus géochimiques dépendent fortement des caractéristiques de l’écoulement des fluides au sein de la matrice poreuse et fracturée du site. Cette étude a donc consisté au développement et à l’application de modèle numériques, thermo-hydrogéologique et géochimique et de leur chaînage, dans le but de caractériser la circulation hydrothermale, la production d’hydrogène et son transport au sein du site de Rainbow. Plusieurs résultats découlent de ces modélisations : la circulation hydrothermale est tridimensionnelle, de faible extension horizontale (Ø~2-8km), doit très probablement être canalisée par un chemin préférentiel de forte perméabilité, et peut être stable sur plusieurs milliers d’années. Nous avons pu montrer que l’hydrogène est produit par serpentinisation en amont de la zone de décharge et estimer les coefficients cinétiques in situ, la quantité d’hydrogène produite et montrer la possibilité d’une production d’une durée supérieure à 25 000 ans. / Hydrothermal activity along the axis of mid-ocean ridges is a key driver for energy and matter transfer from the Earth’s interior to the ocean floor. Numerous hydrothermal sites have been discovered, and some of them emit high quantities of hydrogen and methane. In this manuscript, the presented studies focus on the Rainbow site (36°N), situated on the Mid-Atlantic Ridge crest. The high hydrogen and methane concentrations ([H2]=16 mM kg-1and [CH4]=2,5 mM kg-1) of the hot fluids at this site have been interpreted as indicators of ongoing serpentinization processes. However, such high hydrogen and methane concentrations might be also produced by gabbroic alteration processes which could lead to a mineral assemblage such as chlorite + talc + magnetite + tremolite. These alteration processes are strongly dependent on the hydrothermal circulation characteristics and behaviours. In this study, we developed and used thermo-hydrogeological and geochemical numerical models, and their coupling, for characterization of hydrothermal circulation, and hydrogen production and transport, of the Rainbow vent site. We showed that hydrothermal circulation is conditioned by its 3D spatial configuration. This circulation is of small dimension (Ø > 2km), and should probably be organized by a preferential pathway of high permeability values. It has remained stable for several thousand years. We also showed that hydrogen was a product of serpentinization process that occurs far from the discharge zone. We estimated in situ kinetic coefficients, and the hydrogen mass currently produced each year. We showed the possibility of a long lifetime hydrogen production (>25000 yrs).

Les simulations des écoulements diphasiques à l’échelle réelle de l’application nécessitent des modèles pour les termes non fermés des équations macroscopiques. Des simulations numériques directes à particule résolue utilisant la méthode de pénalisation visqueuse ont été réalisées afin de mesurer les interactions entre des particules de différentes formes (sphérique et ellipsoïdale) et le fluide porteur à différents régimes d'écoulement (de stokes à l'inertiel). Deux méthodes ont été développées durant cette thèse afin d'extraire les forces hydrodynamiques ainsi que le transfert de chaleur sur les frontières immergées représentant les particules. Plusieurs validations ont été conduites pour différentes configurations de particules : de la simulation d’une particule isolée à un réseau aléatoire de sphères en passant par réseau cubique face centrée de sphères. Une corrélation du nombre de Nusselt est proposée pour un sphéroïde allongé plongé dans un écoulement uniforme. / The simulations of multiphase flows at real application scale need models for unclosed terms in macroscopic equations. Particle-Resolved Direct Numerical Simulations using Viscous Penalty Method have been carried out to quantify the interactions between particles of different shapes (spheres, ellipsoids) and the carrier fluid at different regimes (from Stokes to inertial). Two methods have been developed to extract hydrodynamic forcesand heat transfers on immersed boundaries representing the particles. Validations have been conducted for various configuration of particles: from an isolated sphere and spheroid to Face-Centered Cubic to a random arrangement of spheres. A correlation of the Nusselt number for an isolated prolate spheroid past by a uniform flow is proposed.

Le littoral méditerranéen français est fréquemment affecté en automne par des épisodes de forte pluie. La région montagneuse des Cévennes – Vivarais (Massif Central) est une des régions affectées par ces épisodes de précipitations intenses (appelés Cévenols) qui peuvent provoquer des catastrophes naturelles entraînant des dommages économiques importants et des pertes de vies humaines. La prévision de tels épisodes par les modèles numériques de prévision du temps a été considérablement améliorée; cependant, des incertitudes en ce qui concerne leur intensité demeurent. L’amélioration des paramétrisations microphysiques dans ces modèles de prévision est un élément clé pour la réduction des erreurs. Le but de cette étude était de mieux comprendre les processus microphysiques qui régissent les épisodes de fortes précipitations et l’impact des particules d’aérosol atmosphériques sur ces précipitations en exploitant les observations du programme de recherche HYMEX et de la campagne de mesures associée qui s’est déroulée en 2012 dans le Sud de la France. L’étude s’est portée sur l’épisode de précipitation intense observé le 26 Sept. 2012 lors de la Période d’Observations Intenses (POI) 7a. Les observations disponibles ont été évaluées et comparées aux résultats de simulations effectuées avec le DEtailed SCAvenging Model (DESCAM, Flossmann and Wobrock; 2010) qui est un modèle tridimensionnelle utilisant un schéma bin pour représenter de manière détaillée la microphysique nuageuse ainsi que les interactions entre les particules d’aérosols et les nuages. Les observations utilisées ont été faites à partir d'instruments au sol et des mesures aéroportées in situ et permettent d'évaluer le modèle. Les observations au sol sont issues de radars en bande X, de Micro-Rain Radars (MRR), de disdromètres, mais également d’une réanalyse statistique des mesures de pluie par pluviomètres et radars opérationnels (Boudevillain et al. 2016). Les observations aéroportées in-situ ont été réalisées à l’aide de sondes microphysiques et du radar nuage RASTA embarqués à bord de l'avion de recherche français, le Falcon-20. Le rôle de la pollution sur le développement et l'évolution de l’épisode de précipitation intense du POI7a a été étudié en modifiant la concentration des particules d’aérosol à l’aide de spectres en aérosols observés lors de la campagne de mesures. Les résultats ont montré que la concentration initiale des particules d’aérosol influence la distribution spatiale et la quantité des précipitations, ainsi que le contenu vertical en eau de pluie et en eau glacée du système nuageux précipitant. Pour le cas étudié, une augmentation de la concentration initiale en nombre de particules d’aérosol diminue la quantité totale de pluie au sol. Enfin, une étude de sensibilité supplémentaire sur le choix du domaine de simulation a permis de montrer le rôle essentiel de la dynamique et de l’humidité des basses couches atmosphériques de grande échelle sur la représentation du système précipitant. / The French coastline in the Mediterranean Sea is affected by heavy rainfall episodes especially in autumn. Cévennes – Vivarais, which is part of the Massif Central Mountains, is one of the affected regions. The associated heavy precipitation episodes (HPE), namely “Cévenols”, can cause natural disasters with important economic damages and life losses. The prediction of such episodes by Numerical Weather Prediction (NWP) models has been significantly improved; uncertainties remain though, regarding their occurrence and strength. The improvement of microphysical parameterizations in NWP models is one key-component for the reduction of forecast errors. The aim of this study was provide a better understanding of the microphysical processes that govern HPE and their interaction with atmospheric aerosol particles (APs) by exploiting observations from the HYMEX research program.The present study focused on the HPE from the HYMEX Intense Observation Period (IOP) 7a, whose observations were assessed and compared with modelling results from the bin-resolved microphysics scheme DEtailed SCAvenging Model (DESCAM, Flossmann and Wobrock; 2010) with 3D dynamics. This research model uses a detailed representation of the APs. Observations from ground-based instruments, as well as in-situ measurements were used for the evaluation of the model’s performance. The ground-based dataset consists of X-band Radars, Micro-Rain Radars (MRR), disdrometers, but also a rainfall reanalysis by rain gauges and operational radars (Boudevillain et al. 2016). Moreover, hydrometeor probes and the 95GHz cloud radar RASTA provided observations on-board of the French research aircraft Falcon-20.The role of pollution on the development and evolution of the HPE of IOP7a was investigated, as well. Considering that the highest AP concentrations were observed during IOP7a, the followed strategy was to perform model simulations by using less polluted observed AP spectra with lower total number concentrations. The results showed that the initial AP concentration influences the spatial distribution and quantity of rainfall, as well as the vertical properties of the rain water content and the ice water content of the precipitating cloud system. For the studied cases, with increasing the initial number concentration of APs, the total rain amount was decreased. Finally, the present study revealed a critical role of the model’s large-scale configuration necessary to correctly represent the dynamics.

Small-scale volcanoes represent diverse group of landforms which vary in morphology, morphometry, and mechanisms of their formation. They are the most common volcanic form on Earth, and their existence and basic characteristics were also predicted for Mars. Availability of high-resolution image data now allows to search, identify and interpret such small volcanic features on the martian surface. This thesis extends our knowledge about the small-scale volcanoes with the following objectives: (a) to document the existence of martian analogues to some of the terrestrial volcanoes, in particular scoria cones, tuff cones, tuff rings and lava domes; (b) to establish their morphological and morphometrical parameters; and (c) to examine the effect of environmental factors, which differ on Earth and Mars, on the mechanisms of formation of the scoria cones. Interpretation of remote sensing images and digital elevation models reveals that scoria cones, tuff rings and cones, and lava domes exist on different parts of the martian surface and, in some cases, far away from previously well-known volcanic provinces. Scoria cones have been identified in the volcanic field Ulysses Colles situated within the Tharsis volcanic province; tuff cones and tuff rings have been found in the Nephenthes/Amenthes region at the...

Les normes européennes d'émissions de CO2 étant de plus en plus contraignantes, les constructeurs automobiles cherchent, entre autres, à alléger leurs véhicules pour en diminuer la consommation. Ainsi, le remplacement des pièces métalliques par d'autres réalisées à partir de matériaux moins denses tels que les matériaux composites polymères chargés en fibres courtes est de plus en plus utilisé dans l'industrie automobile. Cependant, lors du processus de conception, les ingénieurs sont confrontés à des difficultés lors de la modélisation numérique de la réponse vibro-acoustique de ces pièces et/ou assemblages. En effet, ces matériaux sont très sensibles aux paramètres extérieurs tels que la température, la fréquence de sollicitation et l’humidité. De surcroît, leur comportement dépend également du procédé d’injection utilisé qui influe sur leur microstructure et plus particulièrement sur l’orientation et la dispersion des charges renforçantes. De fait, leur modélisation numérique est complexe et la confrontation aux mesures expérimentales non satisfaisante. Dans ce travail de recherche, l'influence des paramètres ambients sur le comportement dynamique d'un carter d'huile réalisé en polyamide 6 renforcé à 35\% en masse de fibres de verre a été étudiée. Les caractérisations mécaniques et microstructurales locales ont été effectuées afin d'investiguer les relations entre la microstructure et les propriétés de ces matériaux. Un modèle numérique a alors été développé sur la base de ces études expérimentales et a permis d’évaluer l'influence de la microstructure sur le comportement vibratoire d'un système modèle "plaque". Enfin, des corrélations calculs/essais ont été réalisées pour confronter la méthode de modélisation numérique aux mesures. Ces études ont permis de mettre en exergue la sensibilité de ces matériaux à leur environnement, d’établir une hiérarchisation de l'influence des différents paramètres sur leur comportement vibratoire et de proposer une méthodologie numérique basée sur la caractérisation expérimentale des éléments constitutifs pris séparément. / As European standards for CO2 emissions are becoming more stringent, car manufacturers are seeking, among other strategies, to lighten their vehicles to reduce their consumption. Thus, the replacement of metal parts by others made from lighter materials such as polymeric composite materials filled with short fibers is increasingly used in the automotive industry. However, during the design process, engineers face difficulties when trying to numerically model the vibro-acoustic response of these parts and / or assemblies. Indeed, these materials are very sensitive to external parameters such as temperature, loading frequency and humidity. In addition, their behavior also depends on the injection process which has an influence on their local microstructure and more particularly on the orientation and dispersion of the reinforcing fillers. In turn, their numerical modeling is complex and the comparison with the experimental measurements unsatisfactory. In this research work, the influence of the ambient parameters on the dynamic behavior of an oil pan made of polyamide 6 reinforced with 35\% by mass of glass fibers was studied. Local mechanical and microstructural characterizations were performed to investigate the relationship between the microstructure and the properties of these composite materials. A numerical model was then developed on the basis of these experimental studies and allowed to evaluate the influence of the microstructure on the vibratory behavior of a model plate system. Finally, computation / test correlations were performed to compare the numerical modeling method to the measurements. These studies have made it possible to highlight the sensitivity of these materials to their environment, to establish a hierarchy of the influence of the various parameters on their vibration behavior and to propose a "low cost" numerical methodology based on the experimental characterization of constituent elements taken separately.

L’installation et la maintenance des ancrages passifs scellés au rocher représentent un coût important dans le budget de fonctionnement des infrastructures de transport sujettes à l’aléa rocheux. Dans ce contexte, clarifier et optimiser les méthodes de dimensionnement actuellement employées représente un enjeu fort. Or le comportement d’un ancrage passif scellé au rocher est très complexe : il fait intervenir non seulement la rupture des matériaux constituants mais également la rupture des interfaces. Par ailleurs, la résistance de l’interface barre-scellement lors de l’arrachement d’un ancrage dépend du caractère dilatant de cette interface, liée à la géométrie de la barre (verrous) et à la plastification du matériau de scellement. Le travail de cette thèse porte sur une meilleure compréhension du comportement en traction d’un ancrage passif scellé au rocher, l’objectif étant d’améliorer la conception et le dimensionnement des ancrages sollicités axialement. Premièrement, le travail a consisté à définir le comportement de l’interface barre-scellement, Pour cela, un modèle numérique a été développé afin de reproduire des essais d’arrachement, sous différentes contraintes de confinement radial, de barres d’acier de haute adhérence (HA) scellées sur une longueur de 15 cm dans un cylindre de coulis de ciment (Moosavi et al. 2005). La géométrie réelle de l’interface acier–scellement a été considérée dans le modèle. Le comportement du coulis de scellement a été représenté par un modèle de type «concrete damage plasticity» (CDP), modèle de Lubliner (1986), implémenté dans Abaqus (2012). La représentation dans une approche continue de la plastification locale et de la fissuration, a nécessité un calage pour tenir compte des effets d’échelle. Le comportement de l’interface barre-scellement a ainsi été identifié comme cohésif dommageable avec frottement, dans une bande de cisaillement de largeur entre 2 et 3 fois la hauteur des verrous. Dans l’objectif de simuler un ancrage sur le terrain, des éléments d’interface représentant le contact acierscellement (sans les verrous) ont été développés.. La performance des éléments a été testée par la modélisation d’essais réalisés par Benmokrane et al. (1995) pour des barres de HA scellées en forage dans un bloc de béton, c’est-à-dire avec des conditions-limites radiales à rigidité constante. En parallèle, afin de tester l’influence de différents paramètres (géométrie, propriétés de matériau, accessoires de mise en oeuvre) sur le comportement de l’ancrage, une campagne insitu de 36 essais d’arrachement de barres d’acier HA scellées dans un massif calcaire résistant a été réalisée. Certaines barres équipées de fibre optique ont permis d’étudier finement la mobilisation de l’interface entre la barre d’acier et le matériau de scellement lors de la sollicitation axiale. Ces observations expérimentales, comparées aux résultats de la simulation numérique des essais, ont permis de valider le modèle numérique développé et en particulier les éléments d’interface. Par ailleurs, dans nos conditions d’essais, il n’est pas noté d’effet de la longueur de scellement ou de la résistance du coulis de scellement sur la résistance de l’ancrage : la résistance est limitée par la résistance en traction de la barre d’acier. Quant à la rigidité de l’ancrage, c’est le rapport diamètre de la barre/diamètre du forage ou un coulis plus résistant qui tend à rigidifier le comportement de l’ancrage. Pour un rocher résistant et homogène, la longueur de scellement efficace est au maximum de 65cm pour les diamètres usuels de barre. Elle tend à augmenter quand le système est plus déformable : coulis de scellement moins résistant ou, pour un diamètre de barre donné, diamètre de forage plus grand. La présence de la canule d’injection ne semble pas perturber le comportement de l’ancrage. Par contre, une attention particulière doit être portée à la mise en oeuvre de la chaussette géotextile. / Fully grouted rockbolts have been used for decades for transport infrastructure exposed to rockfall hazards. However their installation and maintenance are usually costly. Therefore, understanding and optimizing of the current design method for this type of anchorage is a major challenge. This study is not simple because of the complexity of fully grouted rockbolt behavior: its failure involves not only the failure of constituent materials (rockbolt, grout, rock), but also the failure of bolt-grout and grout-rock interfaces. Moreover, the strength of bolt-grout interface depends on the interface dilatancy, which is likely linked to the geometry of ribs and to the plastification of grout material. This thesis which includes two different parts, a numerical modeling and an experimental work, contributes hence to a better understanding of fully grouted rockbolt behavior under an axial tensile load, in order to improve the current design method. Firstly the bolt-grout interface behavior in particular the force transmission between the bolt and the grout, was studied. For this purpose, a numerical model was proposed to simulate the pull-out test of a short length of 15cm of bolt grouted in a cylinder of cement hardened paste, under constant confinement pressure (Moosavi et al., 2005). In this model, the bolt-grout interface was modeled with its real geometry, including ribs. To consider the different types of behavior and failure (tension, compression and shear) of the grout, this one was modeled by the concrete damage plasticity model (CDP model), which was developed by Lubliner et al. (1986) and implemented in Abaqus (2012). Moreover, the localization of plastic strain and the fracture of grout imply different size effects, which were also taken into consideration within the calibration of the parameters of the CDP model. The bolt-grout interface behavior was also identified to be a cohesive-damage friction interface within a 2 or 3 times the height of the ribs wide shear band. From these numerical modeling results, a constitutive model for the bolt-grout interface was developed to replace the real geometry of bolt-grout contact, in order to model in-situ anchors, whose length is much longer than that of anchors in laboratory tests. The interface model was then validated by performing the numerical simulation of the pullout tests of grouted bolt in borehole drilled in concrete block, carried out by Benmokranne et al. (1995), under constant rigidity of confinement instead of constant pressure of confinement. For the second part of this study, a series of 36 pull-out field tests of fully grouted rockbolt in a rigid limestone rock wall was conducted in order to study the influence of different parameters on the behavior of rock anchors (geometry, material characteristics, accessories). Certain of the bolts equipped with optical fiber allowed bolt strains to be measured along their length, and hence, the stress mobilization along the bolt-grout interface to be studied. The comparison between experimental and numerical results permitted us to validate the numerical simulation, in particular the proposed interface model. With our field test conditions, no influence of grouting length or grout resistance on the strength of anchor was noticed and the bolt strength was limited by the tensile strength of the steel rebar. It is the ratio of bolt diameter/borehole diameter or a stronger grout that tends to stiffen anchor. In a resistant and homogeneous rock and for usual rebar diameters, the efficient grouting length is lower than 65cm. This length increases when the system is more deformable, by using a less resistant grout or a higher grout thickness. The instalation of the cannula seem not to affect the anchor’s strength. However, a particular attention must be paid to the use of the geotextile sock.

[pt] A avaliação do potencial de contaminação de capatações de água, por causa das águas residuais provenientes dos sistemas de tanque séptico, é feita a partir da definição da distância de separação mínima que deve existir entre a captação e o local de infiltração do efluente. A determinação dessa distância define a zona de proteção da captação. Existem três metodologias para definir o tamanho dessa zona de proteção: metodologias baseadas em distâncias fixas e tempos de trânsito, metodologias baseadas na vulnerabilidade e metodologias baseadas no risco de infecção. No caso da Costa Rica, as avaliações são feitas através do uso da metodologia baseada no tempo de trânsito. O tempo de trânsito empregado corresponde ao tempo de sobrevivência dos vírus. Nesta análise determina-se a distância máxima percorrida pelos vírus durante esse tempo, e essa distância define a separação mínima. Esse método considera que o transporte ocorre por percolação vertical saturada através da zona não saturada, e por transporte ao longo da interface água-ar na zona saturada segundo o gradiente natural. Neste trabalho apresenta-se um novo procedimento, baseado no risco de infecção, para a determinação da distância de separação considerando os efeitos da saturação variável e o fraturamento. Este procedimento determina a distância máxima percorrida, a partir do cálculo das concentrações de vírus. A distância de separação mínima corresponde à distância entre a fonte de injeção e o ponto aonde a concentração atinge o valor máximo de concentração permitida. Para o desenvolvimento deste novo procedimento foi implementado um código de programação que inclui: fluxo saturado-não saturado e transporte explícito nos poros e nas fraturas, advecção, dispersão, decaimento, sorção na superfície dos sólidos, sorção nas interfaces água-ar e água-sólido, filtração mecânica e exclusão de poros. Foi realizada uma análise comparativa entre as metodologias acima descritas para três geometrias tipo representativas das condições estratigráficas de algumas áreas do Vale Central da Costa Rica. Os resultados obtidos indicaram que a metodologia normalmente empregada na Costa Rica pode ser inadequada para prever na maioria dos casos a possibilidade de contaminação. / [en] Setback distances of wellhead and catchments from septic tanks are establised by three aproaches: methods based on fixed setback distances or fixed travel times; methods based on vulnerability analysis and methods based on infection risk. In Costa Rica, the determination of setback distances is based on fixed travel times. This approach considers that during and specified travel time all microorganisms will be inactivated, and that the distance traveled during this time defines the minimum safe separation. In this approach a unitary hydraulic gradient and saturated hydraulic conductivity are considered for transport in the unsaturated zone and the natural hydraulic gradient and saturated conductivity for transport in the saturated zone. Only advection is considered as the responsible mechanism for virus transport. A new procedure is presented in this document to define the setback distance. This procedure is based on the infection risk approach. According to this approach the minimum required setback distance is defined as the distance between the injection point and the location where the contaminant reaches a maximum allowable concentration. This procedure was implemented in a computer code that considers variable saturated water flow, fractured-porous media, advection, dispersion, dynamic sorption, inactivation and mechanical filtration. A comparative analysis was performed for three hypothetical geometries using the two approaches described. The results indicate the approach normally used in Costa Rica may no reproduce adequately the possibility of catchments and wellhead contamination.

Cette thèse s'inscrit dans le cadre d'une collaboration étroite entre la société Innoveox (http://www.innoveox.com) et le groupe Fluides Supercritiques de l'Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB). La société Innoveox a mis en œuvre une technologie révolutionnaire non polluante qui détruit des déchets qu'ils soient dangereux ou non, urbains, industriels ou même militaires, avec une efficacité de 99.99%. Cette technologie s'appelle l'oxydation hydrothermale supercritique. Cette technologie est étudiée à l'ICMCB depuis le début des années 1990 au sein du groupe Fluides Supercritiques. Ce travail de recherche a pour objet l'étude des phénomènes de précipitation des sels en eau supercritique. La motivation de ce projet repose sur la compréhension des processus mis en jeu lors de la précipitation afin d'améliorer le fonctionnement du procédé industriel. Ce projet de thèse repose sur 3 principaux objectifs. Le premier concerne la détermination expérimentale de la solubilité des sels en conditions supercritiques, via la mise en place d'un système de mesure en continu. Le second objectif porte sur la détermination expérimentale des tailles de particule de sel, aussi bien au niveau de la formation de la cristallite que de l'agrégat. Pour ce faire, des analyses in situ sont notamment réalisées. Enfin, le dernier objectif est la réalisation d'une simulation numérique de la précipitation des sels en conditions supercritiques, utilisant les résultats expérimentaux des deux précédents objectifs. Les résultats de cette modélisation sont en accord avec les résultats expérimentaux et apportent également de nouveaux éléments de compréhension du mécanisme de précipitation. / This thesis is part of a close collaboration between the Innoveox Company (http ://www.innoveox.com) and the Supercritical Fluids group in the Institute of Chemistry and Condensed Matter of Bordeaux (ICMCB). The Innoveox Company has developed a revolutionary nonpolluting technology, degrading toxic and dangerous waste from industrial, urban or military use, with a 99.99% efficiency. This technology is called Supercritical Water Oxidation and is studied at the ICMCB since the beginning of the 90's in the Supercritical Fluids Group. The present research work objective is the study of the salt precipitation phenomenon in supercritical water, with the aim of understanding the processes and mechanisms involvedduring precipitation, to then improve the industrial process. The project is built on 3 main objectives. The first one is dedicated to the experimental determination of solubility data of salts, in supercritical conditions, with the development of a continuous experimental set-up. The second objective is related to the experimental determination of particle sizes, from crystallite to aggregates formation, using in situ analyses. Last objective concerns the numerical modeling of salt precipitation in supercritical water conditions, using previous experimental data obtained. The results of the modeling are in agreement with the experimental ones, and bring new understanding elements for the precipitation mechanism.technology is called Supercritical Water Oxidation and is studied at the ICMCB since the beginning of the 90's in the Supercritical Fluids Group.