Nesta tese o autor estabelece um método sistemático de quantificação de risco em obras subterrâneas em maciço rochoso fraturado utilizando de maneira eficiente conceitos de confiabilidade estrutural. O método é aplicado a um caso de estudo real da caverna da Usina Hidrelétrica Paulo Afonso IV, UHE-PAIV. Adicionalmente, um estudo de otimização de projeto com base em risco quantitativo também é apresentado para mostrar as potencialidades do método. A estimativa do risco foi realizada de acordo com as recomendações da Organização de Auxílio contra Desastres das Nações Unidas, UNDRO, onde o risco pode ser estimado como a convolução entre as funções de perigo, vulnerabilidade e perdas. Para a quantificação da confiabilidade foram utilizados os métodos de aproximação FORM e SORM com uso de acoplamento direto e de superfícies de resposta polinomial quadráticas. A simulação de Monte Carlo também foi utilizada para a quantificação da confiabilidade no estudo de caso da UHE-PAIV devido à ocorrência de múltiplos modos de falha simultâneos. Foram avaliadas as ameaças de convergência excessiva das paredes, colapso da frente de escavação e a queda de blocos. As funções de perigo foram estimadas em relação à intensidade da ameaça como razão de deslocamento da parede ou volume do bloco. No caso da convergência excessiva, um túnel circular profundo foi estudado com o intuito de comparar a qualidade de aproximação da técnica numérica (FLAC3D com acoplamento direto) em relação à solução exata. Erros inferiores a 0,1% foram encontrados na estimativa do índice de confiabilidade ß. Para o caso da estabilidade de frente foram comparadas duas soluções da análise limite da plasticidade contra a solução obtida numericamente. Já no caso de queda de bloco, verificou-se que as recomendações de parcialização do sistema de classificação geomecânica Q incrementa consideravelmente a segurança da escavação conduzindo a padrões da prática mais avançada, por exemplo, de um ß de 2,04 para a escavação a seção plena até 4,43 para o vão recomendado. No estudo de caso, a segurança da caverna da UHE-PAIV foi estudada perante a queda de blocos utilizando o software Unwedge. A probabilidade de falha individual foi integrada no comprimento da caverna e o conceito de sistema foi utilizado para estimar a probabilidade de falha global. A caverna apresentou uma probabilidade de falha global de 3,11 a 3,22% e um risco de 7,22x10-3 x C e 7,29x10-3 x C, sendo C o custo de falha de um bloco de grandes dimensões. O bloco mais crítico apresentou um ß de 3,63. No estudo de otimização foram utilizadas duas variáveis de projeto, a espessura do concreto projetado e o número de tirantes por metro quadrado. A configuração ótima foi encontrada como o par [t, nb] que minimiza a função de custo total. Também, um estudo de sensibilidade foi realizado para avaliar as influências de alguns parâmetros no projeto ótimo da escavação. Finalmente, os resultados obtidos sugerem que as análises quantitativas de risco, como base para a avaliação e gestão de risco, podem e devem ser consideradas como diretriz da prática da engenharia geotécnica, uma vez que estas análises conciliam os conceitos básicos de projeto como eficiência mecânica, segurança e viabilidade financeira. Assim, a quantificação de risco é plenamente possível. / In this thesis the author establishes a systematic method for quantifying the risk in underground structures in fractured rock masses using structural reliability concepts in an efficient way. The method is applied to the case study of the underground cavern of Paulo Afonso IV Hydroelectrical Power Station UHE-PAIV. Additionally, an optimization study was conducted in order to show a potential application of the method. The estimation of the risk was done according to the recommendations of the United Nations Disaster Relief Organization UNDRO where risk can be estimated as the convolution between the hazard, vulnerability and losses functions. FORM and SORM were used as approximation methods for the reliability quantification by means of Direct Coupling and Quadratic Polynomial Response Surfaces. A Monte Carlo simulation was also used to quantify the reliability of the cavern UHE-PAIV because of the presence of multiple failure modes in the numerical model. In this study 3 types of threads were evaluated: excessive wall convergence, face stability and wedge block fall. Hazard functions were built relative to the thread intensities such as wall convergence ratio or block size. In the case of excessive wall convergence a deep circular tunnel was studied meaning to compare the quality of the approximation of the reliability technique (FLAC3D with direct coupling) to the exact solution. Errors below 0.1% were found in the reliability index ß estimation. The reliability of the face stability was evaluated using two limit analysis solutions against the numeric estimation. For the block stability it was verified that the sequential excavation recommended by the Q system increases considerably the reliability of the excavation leading safety to modern standard levels, e.g. from a ß equal to 2.04 for a full section excavation to 4.43 for a partial excavation. In the case study of the UHE-PAIV, the reliability of the underground cavern was estimated using the commercial software Unwedge. The probability of failure of individual blocks was integrated along the length of the cavern and the concept of structural system was used to estimate the global probability of failure. The cavern presented a probability of failure of 3.11% to 3.22% and a risk of 7.22x10-3 x C and 7.29x10-3 x C - where C is the cost of failure of a large block. The critical individual block showed a ß equal to 3.63. The optimization was performed considering two design variables − liner thickness and number of bolt per square meter. The optimal design was found as the pair, [t, nb] which minimizes the total cost function. Also, a sensibility analysis was conducted to understand the influence of some parameters in the location of the optimal excavation design. Concluding, the results obtained here suggest that the quantitative risk analyses, as a base for the risk assessment and management, can and must be considered as a north for the practice of geotechnical engineering owing that these analyses reconcile the basic concepts of mechanical efficiency, safety and financial feasibility. Thus, risk quantification is fully affordable.

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2016-09-27T17:56:05Z No. of bitstreams: 1 Ingrid_Dias_Dissertacao_2016.pdf: 5728921 bytes, checksum: 2dfdfccf03dc2610f225c77cfbfd84d5 (MD5) / Made available in DSpace on 2016-09-27T17:56:05Z (GMT). No. of bitstreams: 1 Ingrid_Dias_Dissertacao_2016.pdf: 5728921 bytes, checksum: 2dfdfccf03dc2610f225c77cfbfd84d5 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências - Geoquímica. Niterói, RJ / As águas minerais do Parque Salutaris no município de Paraíba do Sul, região centro-sul do estado do Rio de Janeiro, consistem em um recurso explorado para consumo humano desde 1887. Essas águas são provenientes de aquíferos fissurais com litologias variadas, tais como gnaisse, granulito e diabásio que lhes conferem características hidroquímicas excepcionais. O objetivo desse trabalho foi compreender os processos geoquímicos responsáveis pela mineralização das águas subterrâneas do Parque Salutaris e identificar possíveis riscos quanto ao consumo dessa água pela população. Para tanto, dentro do parque, foi realizado um monitoramento das águas minerais durante 10 meses, a partir de 3 poços tubulares que captam as águas, nas fontes de distribuição dessas águas e em uma cava que acumula água subterrânea dentro de uma gruta. Também foram realizadas amostragens no rio Paraíba do Sul e em uma nascente a montante do parque, como medidas de background. Foram realizadas medidas físico-químicas “in situ” e análises laboratoriais dos íons maiores Na, K, Mg, Ca, Cl, SO4, HCO3, constituintes menores e traços Al, Mn, Fe, e F, dos nutrientes, SiO2, N-NO2, N-NO3 e P-PO4, de coliformes totais e termotolerantes. Para os materiais geológicos considerados produtos do intemperismo na região foram realizadas análises mineralógicas por DRX da fração argila e comparadas com a modelagem das espécies minerais, disponíveis em água através do PHREEQC. Os tipos hidroquímicos das águas foram: águas bicarbonatada sódica na gruta, bicarbonatada sódica a mista para o poço Nilo Peçanha, bicarbonatada mista no poço Alexandre Abraão e bicarbonatada magnesiana a mista no poço Maria Rita. Verificou-se que as concentrações dos íons dissolvidos teriam origens principais a partir do intemperismo químico de minerais como micas, feldspatos, piroxênio e plagioclásio, presentes no embasamento gnáissico e granulítico. A modelagem hidrogeoquímica permitiu identificar que as espécies minerais carbonáticas tendem ao equilíbrio, enquanto os argilominerais e óxidos de ferro tendem a saturação. Os minerais secundários, identificados através do DRX, estão de acordo com a modelagem no PHREEQC, sendo encontrados principalmente a caulinita, gibbsita, goethita, calcita e clorita no material geológico. Também foram confirmadas que concentrações dissolvidas do flúor e manganês possuem origens naturais. Não foi identificado contaminação por efluentes nos poços de captação das águas minerais. A pesquisa considerou a ingestão de flúor e manganês das águas minerais por receptores residenciais na avaliação de risco a saúde humana, sendo constatado que bebês e infantes podem estar submetidos a riscos crônicos no que tange o desenvolvimento de fluorose dentária. / The mineral waters of Salutaris Park, located at the south-central part of Rio de Janeiro State, are exploited for human consumption since 1887. Those waters come from fractured aquifers as gneiss, granulite and diabase, yielding a variety of hydrogeochemical features. The aim of this study was to understand the geochemical processes responsible for the groundwater mineralization of Salutaris Park and identify the possible risks for human health through the population consumption of those waters. The monitoring of mineral waters was carried out in 3 wells and their respective sources of distribution, besides an ancient pit lake located in cave, inside the park. In order to considerate background measures for the mineral waters, were also collected samples from the Paraíba do Sul River and a spring in upstream of the park. The physicochemical parameters were directly measured in the field. In laboratory, were carried out the measures of major ions Na, K, Mg, Ca, Cl, SO4, HCO3, minor and traces constituents as Al, Mn, Fe and F, nutrients, SiO2, N- NO2, N-NO3, P-PO4 and total and fecal coliforms. The mineralogical characterization of the geological materials were performed by DRX of the clay fraction, which was posterior compared to the mineral species indicated by the PHREEQC hydrogeochemical modeling, through the measure of the minerals saturation indexes. Three different hydrochemical water types were identified in the studied area, namely: 1) sodium bicarbonate type from the pit lake; 2) sodium and mixed bicarbonate types from the Nilo Peçanha well; 3) mixed bicarbonate type from Alexandre Abraão well and 4) magnesium bicarbonate and mixed types from Maria Rita well. It is noticed that the increase of the dissolved concentrations is due to the weathering processes of primary minerals, mainly micaceous minerals, K-feldspar, pyroxene and plagioclase, which are the main constituents of the regional rocks (gneisses and granulites). The hydrogeochemical modeling identified the carbonate species are in equilibrium with those waters, while the clay minerals and iron oxides trend to be supersaturated. The secondary minerals, estimated by the DRX, are in according to the PHREEQC modeling, identifying mainly kaolinite, gibbsite, goethite, calcite and chlorite. Based on the results, there was no identification of anthropogenic impacts by effluents in the minerals waters wells. The fluoride and manganese have natural sources, although they present concentrations above of the standard potability. For that reason, in order to the accomplishment of a risk assessment for the mineral waters consumption, considering the fluoride and manganese intake by human beings, it was found that the babies and infants may be subjected to chronic risks of dental fluorosis development.

Magister Scientiae - MSc (Environ & Water Science) / Groundwater in arid and semi-arid areas like the Karoo region of South Africa is an important source of domestic, agricultural and industrial source of fresh water. As a scarce resource, it requires extensive quality control and protection through innovative methods and efficient strategies. The town of Beaufort West and its vicinity use groundwater as a major source of municipal and private water supply. Forty nine groundwater samples were collected from spatially referenced boreholes located in and around the town of Beaufort West and were analyzed for EC, pH, TDS,TH, SAR, TA, Ca2+, Mg2+, Na+, K+, HCO3-, Cl-, NO3- and SO42- according to SANS 241 standards and tested for ionic balance. The groundwater of the study area was characterized using WHO and South African drinking water quality standards as well as TDS and Salinity hazard classifications. These comparisons and classifications characterized the groundwater of the study area as hard to very hard, with low to medium salinity hazard. These results are in accordance with the dominance of the ions Ca2+, Na+, HCO3 - and Cl- in the groundwater samples. Linear relationships between the hydrochemical variables were analysed through correlation and multiple regression analysis to relate the groundwater quality to the underlying hydrogeochemical processes. These linear relationships explained the contribution of the measured variables towards the salinity, hardness and anthropogenic contamination of the groundwater. The groundwater of the study area was also assessed using conventional trilinear diagrams and scatter plots to interpret the water quality and determine the major ion chemistry. The conventional methods highlighted the sources of the hydrochemical variables through analysis and interpretation of rock-water interaction and evaporations processes. To supplement these conventional methods and reveal hidden hydrogeochemical phenomenon, multivariate statistical analyses were employed. Factor analysis reduced the hydrochemical variables into three factors (Hardness, Alkalinity and Landuse) that characterize the groundwater quality in relation to the source of its hydrochemistry. Furthermore, combination of Cluster (CA) and Discriminant analyses (DA) were used to classify the groundwater in to different hydrochemical facies and determine the dominant hydrochemical variables that characterize these facies. The classification results were also compared with the trilinear diagrammatic interpretations to highlight the advantages of these multivariate statistical methods. The CA and DA classifications resulted in to six different hydrochemical facies that are characterized by NO3 -, Na+ and pH. These three hydrochemical variables explain 93.9% of the differences between the water types and highlight the influence of natural hydrogeochemical and anthropogenic processes on the groundwater quality. All the univariate, bivariate, multivariate statistical and conventional hydrogeochemical analyses results were analyzed spatially using ArcGIS 10.0. The spatial analysis employed the Inverse Distance Weighted (IDW) interpolation method to predict spatial distribution of unmeasured areas and reclassification of the interpolation results for classification purposes. The results of the different analyses methods employed in the thesis illustrate that the groundwater in the study area is generally hard but permissible in the absence of better alternative water source and useful for irrigation.

L’eau, par l’intermédiaire de la pression de fluides, est un phénomène déclencheur majeur de la déstabilisation des mouvements de terrain profonds. En conséquence, la caractérisation des mécanismes de déformation nécessite une bonne compréhension des processus hydrogéologiques contrôlant la déstabilisation. Les milieux fissurés et de surcroit les milieux instables présentent de fortes hétérogénéités, ce qui rend les études hydrogéologiques classiques peu adaptées. De plus, les mouvements de terrain profonds présentent des relations hydromécaniques complexes avec des évolutions significatives dépendantes du temps (déformation de type fluage). Cette thèse s’attache à caractériser les relations précipitations-déplacement du mouvement de terrain profond de Séchilienne. Un suivi saisonnier de traceurs naturels et artificiels a permis de définir un schéma conceptuel d’écoulement de l’eau souterraine sur l’ensemble du massif malgré un nombre limité de points d’intérêt hydrogéologiques. Les données de pression de fluides étant rarement mesurées, les paramètres indirects, tels que la recharge, sont souvent les seules données hydrogéologiques qui permettent de caractériser la relation précipitations-déstabilisation. Une méthode d’estimation de la recharge basée sur un calcul de bilan du sol a été développée afin d’estimer la recharge avec précision. En se basant sur le schéma conceptuel d’écoulement et le calcul de la recharge, une analyse en ondelettes couplée à un modèle numérique a permis de caractériser la relation précipitations-vitesse de déplacement. Cette modélisation tient compte de paramètres dépendant du temps et permet de simuler une déformation de type fluage (tendance pluriannuelle des vitesses de déplacement), conséquence des couplages hydro- mécaniques indirects. La caractérisation des processus hydrogéologiques contrôlant la déstabilisation a permis de définir un seuil statistique d’activation de la déstabilisation, basé sur une approche multi-dimensionnelle innovante. / Pore water pressure build-up by recharge of underground hydrosystems is one of the main triggering factors ofdeep-seated landslides. Consequently, the characterization of landslide deformation mechanisms requires athorough knowledge of the hydrogeological processes triggering the destabilization. Anisotropic andheterogeneous media combined with landslide deformation render classical hydrogeological investigationsunsuitable. Hydro-mechanical processes which lead to slope failure of deep-seated landslides are complex andare influenced by the evolution of the landslide deformation through time. This thesis aims at improving theunderstanding of the relationships between precipitation and displacement velocity based on the study of theSéchilienne deep-seated landslide. A time-related monitoring of natural and artificial tracers allows to define aconceptual groundwater flow model despite a limited number of hydrogeological points of interest. Fluid porepressures are rarely measured on landslide sites and, instead the groundwater recharge is generally used as themost relevant parameter. A parsimonious, yet robust, guideline workflow to calculate time series of groundwaterrecharge is developed. Based on the conceptual groundwater flow model and the recharge calculation, a waveletanalysis coupled to a numerical model integrating time-dependent parameters allows to characterize therelationship between precipitation and displacement velocity and to simulate the creep deformation resulting ofindirect hydro-mechanical coupling (multi-year trend of displacement velocities). The characterization of thehydrogeological processes controlling the destabilization allowed to define a statistical rainfall threshold basedon an innovative multi-dimensional approach.

Les transferts d’humidité dans les matériaux de construction ont une influenceimportante sur leur durabilité et sur les performances hygriques et thermiques desbâtiments. De nombreux mécanismes d’endommagement chimiques et physiquesde ces matériaux sont en effet dus à l’infiltration d’eau. En conséquence, leur structureporeuse peut évoluer au cours du temps, et des fissures microscopiques commemacroscopiques peuvent s’y développer. La description des matériaux à l’échelle microscopiqueest cependant une source d’erreur importante dans les codes de simulationactuels des transferts d’humidité et de chaleur, notamment en raison du faitque lesmilieux sont considérés comme homogènes, et que les effets du vieillissementdes matériaux sont négligés. Il importe donc de trouver un moyen d’inclure les effetsde l’endommagement dans les simulations de transferts d’humidité et de chaleurà l’échelle du bâtiment. Des méthodes existent pour la prédiction du comportementde milieux soumis à des sollicitations hygriques et mécaniques, mais supposent quel’ensemble des facteurs extérieurs influant sur l’endommagement soient connus toutau long des simulations.Une nouvelleméthodologie est proposée ici pour compléter ces approches prédictives,en combinant des mesures expérimentales d’endommagement avec la simulationde transferts couplés d’humidité et de chaleur. Une étude préliminaire a d’abordété menée, consistant à mesurer la perméabilité vapeur équivalente d’éprouvettes demortier multi-fissurées. Cette démarche a permis d’identifier les besoins expérimentauxet numériques de la suite du travail, visant à modéliser les écoulements dans unréseau discret de fissures sur la base de leur caractérisation. Une méthodologie expérimentalecombinant corrélation d’images numériques et émissions acoustiques aensuite été développée, permettant de disposer de cartographies d’endommagementet de proposer une démarche pour lamesure de réseaux de fissures dans lesmatériauxde construction en place. La méthode optique, associée à une procédure de traitementd’images, a permis de disposer de données précises de la géométrie de réseauxde fissures. De plus, une méthode a été proposée pour permettre l’interprétation desmesures d’émissions acoustiques en termes de quantification, localisation et identificationdes phénomènes d’endommagement.Un code de simulation a ensuite été écrit, permettant d’intégrer ces mesures defissuration dans la modélisation des écoulements couplés d’humidité et de chaleuren milieu poreux. Ce modèle a été validé sur la base de mesures expérimentales : lacorrélation d’images numériques a été appliquée durant la fracturation d’éprouvettesde béton, dans lesquelles l’infiltration d’eau a ensuite été suivie par radiographie auxrayons X. Les résultats numériques obtenus sont en bonne conformité avec lesmesuresexpérimentales en termes de prédiction de la concentration d’eau en deux dimensions.Enfin, laméthodologie a été appliquée à une série de cas test, dans le but demodéliserles performances hygrothermiques de parois multi-couches, incluant des matériauxendommagés, soumises à des conditions climatiques réelles. On a ainsi pu estimer les conséquences potentielles de l’endommagement sur l’accumulation d’eau dans desparois, sur l’amplitude des cycles de sorption et de séchage, ainsi que sur les transfertsthermiques. / An importantmatter in the field of building physics is the questioning of how wellbuildings sustain ageing, and how their overall efficiency evolves over their lifetime.Many causes for degradation are carried by moisture transfer through these porousmaterials. Indeed, infiltratedwatermay transport chemicals, altermechanical properties,and cause freeze thaw damage or mould development. It may also affect thermalproperties and energetic efficiency, as well as the health and comfort of the occupants.The understanding of how moisture transfer properties evolve during the lifespan ofbuildingmaterials is however far fromcomplete. The pore structure of amaterial itselfmay change over time, or be altered by cracks and defects caused bymechanical loadingand aggravated bymoisture-induced degradation. All sizes of fracturesmay have astrong impact on heat and moisture flow in the building envelope, and their influenceis to be accounted for in any long-termperformance assessment, not only of buildingand building components,but of any built structure in general. A considerable amountof work has already been performed in order to allow predicting the hygrothermal behaviourof buildings over longer periods of time. However, an accurate prediction of allranges of damage in a building component, from microscopic to macroscopic cracks,supposes an extensive knowledge of all damage-inducing, time-varying boundary conditionsof the problem during the simulation time. This also implies high computationalcosts, as well as important needs formaterial characterisation.As a complement to these predictive methods, a new approach was undertaken,combining experimental characterisation of crack patterns and numerical simulationsof coupled heat and moisture transfer. First, a preliminary study was conducted, consistingof measurements of the water vapour permeability of diffusely damaged constructionmaterials.This allowed identifying the experimental and numerical requirementsof the remainder of the work, which aimed at providing measurements of fracturenetwork geometries for their explicitmodelling in heat andmoisture transfer simulations.Digital image correlation and acoustic emission monitoring were then performedduring the degradation of cementitiousmaterials, in order to obtain quantitativedata on crack pattern geometries, and to assess the possibilities for damagemonitoringat the building scale. The optical technique, along with an appropriate imageprocessing procedure, was found suitable for providing precisemeasurements of fracturenetworks. Amethodwas also proposed for the interpretation of acoustic emissionrecordings in terms of damage quantification, localisation and identification.Then, a newmodel for coupled heat andmoisturemodelling in cracked porousmediawas developed, that allows including such measurements of fracture patterns intoa finite element mesh, and simulating flow accordingly. This model was validated onthe basis of experimentalmeasurements: digital image correlationwas performed duringthe fracturing of concrete samples, in which moisture uptake was then monitoredusing X-ray radiography. A good accordance was found between experimental and numericalresults in terms of 2-dimensional moisture concentration distributions. The validated code was then used for the simulation of test cases, in order to assess the hygrothermalperformance of damagedmulti-layered building components subjected toreal climatic conditions. The consequences of fractures on themoisture accumulationin walls, on the amplitude of sorption/desorption cycles and on the thermal performance,were observed.

Cette thèse est consacrée à l'étude mathématique d'un problème inverse en hydrogéologie : le but est d'identifier des fractures en milieu poreux, connaissant des mesures de l'écoulement dans le sous-sol. Le nombre, la localisation et les paramètres physiques des fractures sont recherchés. Ce problème est formulé comme la minimisation au sens des moindres carrés d'une fonctionnelle évaluant l'écart entre les mesures et les résultats du modèle direct. L'écoulement est celui d'un fluide monophasique incompressible (loi de Darcy). Un modèle traitant les fractures comme des interfaces est utilisé. Le problème direct est le modèle de fracture discrétisé par la méthode des éléments finis mixtes hybrides.Pour résoudre ce problème inverse, un nouvel algorithme itératif a été développé, basé sur l’utilisation d’indicateurs de fractures mis au point pendant la thèse. Ces indicateurs donnent une information au premier ordre concernant l'effet de l'ajout d'une nouvelle fracture. Comme ces indicateurs sont peu coûteux, un grand nombre de configurations de fractures sont testées à chaque itération. L’algorithme a été programmé, validé puis testé numériquement dans des situations variées, en utilisant des mesures synthétiques. Il donne des résultats très satisfaisants, bien que ce problème soit réputé difficile.Enfin, l’étude de l’identifiabilité du problème inverse a été amorcée. Pour un modèle simplifié de fractures (failles très perméables, cas le plus courant dans le sous-sol), on a montré que le problème. / This PhD is dedicated to the mathematical study of an inverse problem in hydrogeology: the goal is to identify fractures in porous medium, knowing measurements of the underground flow. The number, the location and the physical parameters of the fracture are looked for. This problem is formulated as the least squares minimization of a function evaluating the misfit between measurements and the result of the direct model. We used a model describing the flow of a monophasic incompressible fluid (Darcy's law), in a porous medium containing some fractures represented by interfaces. The direct problem is the fracture model discretized by the mixed hybrid finite element method. To solve this inverse problem, we developed an iterative algorithm, which is based on the use of fracture indicators that have been developed durig the thesis. These indicators give a first order information concerning the effect of the addition of a new fracture. As these indicators are inexpensive, a large number of configurations of new fractures is tested at each iteration. The algorithm was programmed, validated and tested numerically in various situations, using synthetic measurements. It gives very satisfactory results, although this problem is considered difficult. Finally, an early study of identifiability of the inverse problem of fractures in porous medium has been achieved. It allowed to prove the identifiability for a simplified model (very permeable faults, which is common in the underground). The question of identifiability for the full fracture model remains open.

(EN) Thesis deals with an approximation of static moduli in wells from dynamic moduli determined by acoustic well logging using T-matrix model. Proposed approach makes possible to determine moduli values, which are close to values of static moduli, which would be determined by loading tests. This approach is based on an idea, that an intact rock with sufficiently high compressional strength sc and sufficiently high value of static Young's modulus Es, manifests more or less linear elastic behaviour. In such case, the values of static and dynamic moduli are identical. This fact has been experimentally verified for rocks with values of sc and Es in order of higher tens of MPa and GPa respectively. In case of a rock damage presence in such rock, it's behaviour becomes nonlinearly elastic. The amount of nonlinearity is proportional to increasing amount of rock damage. This results in the difference between values of static and dynamic moduli. T-matrix model is used to quantify this difference. This model is based on an anisotropic rock matrix with ellipsoidal inclusions. These inclusions can affect each other. The result of this model calculation is a group of values of elastic constants, which we call effective moduli. These effective moduli include the effect of porosity in the rock as well and they...

Construction of rock slopes is needed in many civil work projects. It is for example very common in road and railway cuts, but other applications include excavation for tunneling or building foundations, where perhaps sensitive constructions are present in the immediate vicinity. In Sweden the majority of the rock is hard crystalline bedrock of relatively good quality, and the fracture orientation have a large effect of the stability of the rock slope.If the geology is not properly considered for when the design of the slope is carried out, it can result in slope failure, with severe consequences. This applies especially if the rock slope is high, but unwanted effects like increased excavation and construction costs, could occur also in smaller slopes if the risks are not identified and managed. However, it is difficult to standardize design of rock slopes in fractured hard crystalline rock because of the uncertainties and variations in the geological conditions during the design phase.Rock mass characterization systems like Rock mass rating, RMR (Bieniawski 1989) and the Qsystem (Barton, Lien och Lunde 1974) are commonly used to describe the general rock mass quality. Whilst a good rock mass quality is generally easier to construct in, stability problems do occur due to structural geology in rock slopes even in good rock mass quality. The application of these systems in rock slopes can be problematic as they do not describe the geometry of the slope and how the fractures daylight in the slope face. Instead, stereonets can be used to visualize this, but fracture parameters of large importance for stability (persistence, roughness and alteration) are traditionally not presented in a stereonet analysis. Additionally, these parameters and the structural geological conditions can be difficult to predict and can vary significantly over short distances, why it can be difficult to forecast and predict failure in the design face.Slope instability due to large sliding and wedge failures have been observed in a large number of slopes in crystalline rock, and a standard method for design of rock slopes is lacking. This has given rise to the research question of how best to describe rock mass conditions, how to design slopes in crystalline rock and how to manage these risks during construction.To investigate this, three rock slopes where large failure had occurred were selected for the case study and were mapped, characterized and analyzed. The results from the case study showed that all rock slopes investigated had in common that failure had occurred along fractures of large persistence. This highlights the importance of evaluating the geology in the correct scale and suggest that lineament studies and other elevation based interpretation are perhaps more useful than previously thought. It also came to light that the planning and design process is inflexible which in many cases lead to large risks being overlooked or left unnoticed.A flow chart for risk classification was produced and suggested for aid in decision making aiming at simplifying project management of rock slopes, as well as aiding in visualization of the risk that rock slopes can be associated to.

[pt] Meios porosos fraturados estão presentes em diferentes tipos de formações geológicas, como os maciços rochosos e os reservatórios de petróleo e gás. A modelagem adequada dos sistemas de fraturas presentes nesses meios é de grande relevância para o desenvolvimento de estratégias de exploração e produção dessas formações. Isso porque os processos de fluxo de fluido são fortemente influenciados pelas características dos sistemas de fraturas. Nesse contexto, diversas abordagens têm sido desenvolvidas para a modelagem desses problemas utilizando representações explícitas e implícitas para as fraturas. A representação explícita usando modelos de fraturas discretas fornece resultados precisos, mas possui um custo computacional elevado e apresenta dificuldades na construção de modelos mais complexos. Por outro lado, modelos de representação implícita, como o de dupla porosidade/dupla permeabilidade, são muito atrativos por incorporarem o efeito das fraturas nas simulações sem a necessidade de representá-las no modelo. No entanto, esses modelos são adequados para problemas envolvendo fraturas pequenas e conectadas, possuindo aplicabilidade limitada para representar fraturas principais de maior escala que podem dominar o fluxo. Assim, este trabalho apresenta algumas das abordagens disponíveis para a representação de formações porosas fraturadas. Diferentes cenários foram estudados para avaliar pontos fortes e limitações de cada método em diferentes aplicações. Além disso, uma nova formulação foi proposta para representar o efeito de fraturas isoladas, que se demonstrou eficiente em modelos com considerável número de fraturas. / [en] Fractured porous media are present in different types of geological formations as rock masses and oil and gas reservoirs. The proper modelling of the fractured systems present in these media is of high relevance to the development of production and exploitation strategies of these formations. This is because the fluid flow processes are strongly influenced by the fractured systems characteristics. In this context, several approaches have been developed to model these problems using explicit and implicit representations to fractures. The explicit representation using discrete fracture models provides accurate results, but has a high computational cost and exhibits difficulties to construct more complex models. On the other hand, implicit representation models, as the dual porosity/dual permeability, are very attractive because they incorporate the effect of fractures to simulations without the need to represent them explicitly in the models. However, these models are suitable to problems with small and connected fractures, and have limited capability to represent major fractures of larger scale that can dominate the flow. Therefore, this work shows some of the available approaches to represent fractured porous formations. Moreover, a new formulation was proposed to represent the effect of isolated fractures, which proved to be efficient in models with considerable number of fractures.

A model is developed to describe solute transport and retention in fractured rocks. It accounts for the fact that solutes not only can diffuse directly from the flowing channel into the adjacent rock matrix composed of different geological layers but can also at first diffuse into the stagnant water zone occupied in part of the fracture and then from there into the rock matrix adjacent to it. Moreover, the effect of radioactive decay-chain has also been studied in the presence of matrix comprising different geological layers. In spite of the complexities of the system, the analytical solution obtained for the Laplace-transformed concentration at the outlet of the flowing channel can conveniently be transformed back to the time domainby use of e.g. De Hoog algorithm. This allows one to readily include it into a fracture network modelorachannelnetwork model to predictnuclide transport through channels in heterogeneous fracturedmedia consisting of an arbitrary number of rock units withpiecewise constant properties. Simulations made in this study indicate that, in addition to the intact wall rock adjacent to the flowing channel, the stagnant water zone and the rock matrix adjacent to it may also lead to a considerable retardation of solute in cases with a narrow channel. The results further suggest that it is necessary to account for decay-chain and also rock matrix comprising at least two different geological layers in safety and performance assessment of the repositories for spent nuclear fuel. The altered zone may cause a great decrease of the nuclide concentration at the outlet of the flowing channel. The radionuclide decay, when accounted for, will drastically decrease the concentration of nuclides, while neglecting radioactive ingrowth would underestimate the concentration of daughter nuclides. / <p>QC 20140224</p>