Em túneis, a deformação do maciço e a pressão do solo no revestimento dependem das tensões e características do maciço, das tensões do maciço, da geometria, da rigidez, do instante da colocação do revestimento. A variação das tensões no revestimento e as deformações são causadas pelo avanço da escavação e as propriedades dependentes do tempo do maciço rochoso e revestimento. O objetivo desta dissertação é apresentar um modelo numérico para a análise tridimensional de túneis em maciços rochosos no programa ANSYS. Ele constitui uma ferramenta para calcular um túnel, revestido de concreto em diferentes situações de rigidez do revestimento, processo construtivo e características do maciço. O processo de escavação e colocação do revestimento é simulado pelo método da ativação/desativação de elementos em etapas sequenciais. O maciço apresenta comportamento elástico na primeira parte, e posteriormente uma lei viscoplástica. O concreto projetado e o concreto pré-moldado do revestimento são modelados como elásticos na primeira parte, e posteriormente, como materiais viscoelásticos utilizando o modelo da cadeia de Maxwell e de Kelvin, propostos por Bazant. Ambos os modelos foram calibrados por comparação com o Código Modelo fib 2010. A simulação do túnel é realizada através da incorporação de sub-rotinas para o concreto viscoelástico no programa ANSYS. Para validar o modelo são feitas comparações dos resultados obtidos no programa ANSYS com a solução analítica, com o programa GEOMEC91 e com o Novo Método Implícito, dependendo do caso. Um estudo paramétrico em elasticidade é realizado com o código ANSYS variando alguns parâmetros relevantes. Na segunda parte, o mesmo túnel revestido é modelado com dois diferentes tipos de revestimento e os dois modelos de cadeia citados. Finalmente, é comparado o comportamento com o túnel experimental Kielder, do qual se tem dados disponíveis da instrumentação. A comparação destes dados com os resultados do programa ANSYS mostra uma aproximação muito boa. / Stabilizing underground openings such as tunnels excavated in rock mass remain a major concern of geotechnical engineers dealing with this kind of structures. In tunnels, the rock mass strain and the ground pressure on lining depend on the stress and characteristics of the rock mass as well as of the geometry, the stiffness and the moment of the lining installation. Pressure variation on lining and strain are caused by the advance of excavation and the time-dependent properties of the rock mass and lining. This dissertation describes the numerical implementation of constitutive laws in the numerical code ANSYS. It is performed a numerical simulation with 3D finite elements of a tunnel. The rock mass presents elastic behavior in the first part and then a viscoplastic law. The shotcrete and precast concrete are modeled as elastic in the first part and then viscoelastic material with the constitutive laws of the Maxwell and the Kelvin chain model, proposed by Bazant. So the characteristics of the viscoelastic concrete changes with time until the stabilization. Both chain models had to be calibrated by comparing with de fib Model Code 2010. The finite elements simulation is performed by incorporating subroutines for the viscoelastic concrete model in the ANSYS code. The method to simulate the tunnel excavations is by activating and deactivating elements in sequential steps. In the first part of the dissertation two validations are performed. The analytical solution and the deformation achieved on the stabilization in the ANSYS code are compared for the validation of an unlined tunnel. For a lined tunnel, with an elastic and viscoplastic rock mass and elastic lining, validation is performed by comparing the results of the GEOMEC91 code with the ANSYS code. The results show a very good approximation in viscoplasticity and agree perfectly in elasticity. Also a parametric study is undertaken with the ANSYS code varying some relevant parameters. In the second part, it is compared the same tunnel with the two different concrete lining and the two chain models. Finally, it is compared with the Kielder experimental tunnel, which in situ measured data is available. The comparison of this data with the results from the ANSYS code shows a very good approximation.

A busca por novos modelos matemáticos e técnicas inovadoras para análises numéricas tem sido tema de muitas pesquisas. Em análises de modelos que possuem domínios infinitos e semi-infinitos, o Método dos Elementos de Contorno (MEC) sobressai-se como uma das mais eficientes ferramentas numéricas. Por outro lado, em análises não-lineares o MEC requer a avaliação de integrais de domínio, diminuindo as vantagens de uma discretização apenas do contorno do modelo analisado. Neste trabalho apresenta-se uma técnica inovadora que trata as integrais de domínio, não adequadas para uma representação pura do contorno, em análises de modelos com materiais viscoplásticos. Na abordagem proposta, utiliza-se um novo algoritmo de visualização proposto por Noronha & Pereira para detectar as regiões de plastificação automaticamente. Este procedimento de detecção é realizado de forma incremental por meio de predições (gradiente como direção de busca) e iterações (Newton-Raphson). Uma vez que as regiões sejam obtidas, torna-se possível transformar as integrais de domínio em integrais de contorno de forma direta. Obtém-se assim uma abordagem baseada apenas na discretização do contorno dos modelos, mantendo uma das principais vantagens da utilização do MEC. Foram realizados neste trabalho alguns exemplos numéricos que apresentaram excelentes resultados em comparação com o Método dos Elementos Finitos (MEF) e com resultados encontrados na literatura. / The search for new mathematical models and innovative techniques for numerical analyses has been subject of many research studies. In analysis of models with infinite and semi-infinite domains, the Boundary Element Method (BEM) has been proved to be one of the most efficient numerical tools. On the other hand, in nonlinear analyses the BEM requires the evaluation of domain integrals, diminishing the advantages of a discretization only of the boundary of the model. This work presents an innovative technique that treats the domain integrals, not suitable for pure boundary representations, in analyses of models with viscoplastic materials. The proposed approach is based on a new post-processing algorithm developed by Noronha & Pereira to detect the plastic regions automatically. The detection procedure herein proposed is an incremental technique that uses prediction (along the gradient direction) and iteration (Newton-Raphson) loops. Once the plastic regions are found, it becomes possible to transform the domain integrals in boundary integrals in a straightforward manner. The proposed approach results in a pure boundary discretization, preserving the main advantage of the BEM. The numerical examples presented in this work are in good agreement with the Finite Element Method (FEM) and with results found in the literature.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Permanent deformation or rutting is a major distress in asphalt pavements. To predict permanent deformation of asphalt mixtures the dynamic creep test is often used in laboratory, with the result presented in terms of the so called flow number. However, for this work it was performed the triaxial repeated permanent deformation load test, a confined test that better represents field conditions. The models that incorporate the flow number do not represent the main zone of the dynamic creep test result, denoted secondary region, in which the permanent deformation rate of growth is constant. In this work the Shift Model was used, which is a viscoplastic model that accesses the permanent deformation from the superposition principles, i.e., time-temperature superposition and time-stress superposition. Thus, the asphalt mixtures were tested under different loading conditions, temperature, load time and rest period, in order to assess three parameters of the test: parameter C, which indicates where the secondary region begins (parameter that governs the primary region of the test); the parameter α (alpha) is the slope of the secondary region; and the parameter B represents the level of permanent deformation of the secondary region. The results show that the TRLPD test is more severe than the conventional dynamic creep test. Nevertheless, the use of TRLPD test represents an advance in the understanding of the behavior of asphalt mixtures with respect to rutting performance, and has the advantage of allowing the use of results in computational simulations. / A deformaÃÃo permanente à um dos principais defeitos em pavimentos asfÃlticos. Para prever esta falha em revestimentos, por meio de ensaios laboratoriais, à frequentemente utilizado o ensaio de creep dinÃmico cujo resultado final à apresentado em termos do chamado flow number. No entanto, para este trabalho foi realizado o triaxial repeated load permanent deformation (TRLPD) test, que à um ensaio sob condiÃÃes de confinamento, a fim de melhor se aproximar das condiÃÃes encontradas em campo. Os modelos que incorporam o flow number nÃo representam a principal regiÃo de ensaio de creep dinÃmico, denominada regiÃo secundÃria, na qual o incremento de deformaÃÃo permanente cresce em valor constante. No presente trabalho utilizou-se o Shift Model, o qual à um modelo viscoplÃstico que avalia a deformaÃÃo permanente a partir da superposiÃÃo dos efeitos tempo-temperatura e tempo-tensÃo. Dessa forma, as misturas asfÃlticas foram testadas sob diferentes condiÃÃes de carregamento, temperatura, tempo de aplicaÃÃo de carga e perÃodo de repouso. Foram avaliados trÃs parÃmetros do ensaio em questÃo: o parÃmetro C, que fornece os dados de onde a regiÃo secundÃria se inicia (parÃmetro que governa a regiÃo primÃria do ensaio); o parÃmetro α (alfa), que à o aclive da regiÃo secundÃria; e o parÃmetro B, que representa o nÃvel de deformaÃÃo permanente da regiÃo secundÃria. Os resultados obtidos mostram que o ensaio TRLPD à mais severo do que o ensaio convencional de creep dinÃmico, porÃm considera-se que a utilizaÃÃo de ensaios confinados representa um avanÃo para o entendimento do comportamento das misturas asfÃlticas quanto à resistÃncia à deformaÃÃo permanente das mesmas, e este traz a vantagem de poder ser usado em simulaÃÃes computacionais.

Em túneis, a deformação do maciço e a pressão do solo no revestimento dependem das tensões e características do maciço, das tensões do maciço, da geometria, da rigidez, do instante da colocação do revestimento. A variação das tensões no revestimento e as deformações são causadas pelo avanço da escavação e as propriedades dependentes do tempo do maciço rochoso e revestimento. O objetivo desta dissertação é apresentar um modelo numérico para a análise tridimensional de túneis em maciços rochosos no programa ANSYS. Ele constitui uma ferramenta para calcular um túnel, revestido de concreto em diferentes situações de rigidez do revestimento, processo construtivo e características do maciço. O processo de escavação e colocação do revestimento é simulado pelo método da ativação/desativação de elementos em etapas sequenciais. O maciço apresenta comportamento elástico na primeira parte, e posteriormente uma lei viscoplástica. O concreto projetado e o concreto pré-moldado do revestimento são modelados como elásticos na primeira parte, e posteriormente, como materiais viscoelásticos utilizando o modelo da cadeia de Maxwell e de Kelvin, propostos por Bazant. Ambos os modelos foram calibrados por comparação com o Código Modelo fib 2010. A simulação do túnel é realizada através da incorporação de sub-rotinas para o concreto viscoelástico no programa ANSYS. Para validar o modelo são feitas comparações dos resultados obtidos no programa ANSYS com a solução analítica, com o programa GEOMEC91 e com o Novo Método Implícito, dependendo do caso. Um estudo paramétrico em elasticidade é realizado com o código ANSYS variando alguns parâmetros relevantes. Na segunda parte, o mesmo túnel revestido é modelado com dois diferentes tipos de revestimento e os dois modelos de cadeia citados. Finalmente, é comparado o comportamento com o túnel experimental Kielder, do qual se tem dados disponíveis da instrumentação. A comparação destes dados com os resultados do programa ANSYS mostra uma aproximação muito boa. / Stabilizing underground openings such as tunnels excavated in rock mass remain a major concern of geotechnical engineers dealing with this kind of structures. In tunnels, the rock mass strain and the ground pressure on lining depend on the stress and characteristics of the rock mass as well as of the geometry, the stiffness and the moment of the lining installation. Pressure variation on lining and strain are caused by the advance of excavation and the time-dependent properties of the rock mass and lining. This dissertation describes the numerical implementation of constitutive laws in the numerical code ANSYS. It is performed a numerical simulation with 3D finite elements of a tunnel. The rock mass presents elastic behavior in the first part and then a viscoplastic law. The shotcrete and precast concrete are modeled as elastic in the first part and then viscoelastic material with the constitutive laws of the Maxwell and the Kelvin chain model, proposed by Bazant. So the characteristics of the viscoelastic concrete changes with time until the stabilization. Both chain models had to be calibrated by comparing with de fib Model Code 2010. The finite elements simulation is performed by incorporating subroutines for the viscoelastic concrete model in the ANSYS code. The method to simulate the tunnel excavations is by activating and deactivating elements in sequential steps. In the first part of the dissertation two validations are performed. The analytical solution and the deformation achieved on the stabilization in the ANSYS code are compared for the validation of an unlined tunnel. For a lined tunnel, with an elastic and viscoplastic rock mass and elastic lining, validation is performed by comparing the results of the GEOMEC91 code with the ANSYS code. The results show a very good approximation in viscoplasticity and agree perfectly in elasticity. Also a parametric study is undertaken with the ANSYS code varying some relevant parameters. In the second part, it is compared the same tunnel with the two different concrete lining and the two chain models. Finally, it is compared with the Kielder experimental tunnel, which in situ measured data is available. The comparison of this data with the results from the ANSYS code shows a very good approximation.

No presente trabalho é descrita uma formulação para modelos constitutivos elastoviscoplásticos, considerando deformações infinitesimais e finitas. Os modelos são formulados em um contexto da termodinâmica de variáveis internas usando fundamentos de análise convexa. As equações de evolução são obtidas a partir do princípio da máxima dissipação, o qual desempenha um importante papel na abordagem adotada, a qual consiste na generalização do modelo reológico de Bingham. O problema constitutivo de valor inicial local é solucionado por um esquema de integração implícita combinado a um algoritmo de mapeamento de retorno. O problema de valor no contorno e inicial global, considerando casos quasi-estáticos, é solucionado por meio do método dos elementos finitos (MEF) empregando também um método de integração implícita. Esta estratégia é implementada empregando os modelos constitutivos viscoplásticos linear e não linear de Perzyna e o modelo de Perié. A implementação computacional é avaliada por meio da comparação dos resultados numéricos a soluções analíticas e também a problemas padrões disponíveis na literatura. Os resultados obtidos são importantes para avaliar o comportamento e as características dos modelos viscoplásticos na análise dos fenômenos de dependência da taxa de deformação e de relaxação de tensão. Embora os três modelos se mostrem adequados à captura destes fenômenos, uma atenção especial deve ser dada ao modelo não linear de Perzyna, pois este não recupera o modelo invíscido como um caso limite, além disso, apresenta mal condicionamento no algoritmo de mapeamento de retorno. / In this work an elastic-viscoplastic constitutive formulation is described, considering infinitesimal and finite deformations. The models are formulated inside a thermodynamic with internal variables framework using fundamentais from convex analysis. The evolution equations are obtained from the maximum dissipation principie, which plays an important role on the approach adopted, which is the generalization of the Bingham rheological model. The local initial value problem is solved by an implicit integration scheme with a return mapping algorithm. The global initial boundary value problem is solved by the finite element method (FEM) also employing an implicit integration method. The strategy is implemented employing the linear and nonlinear Perzyna and the Perié viscoplastic models. The computational implementation is evaluated by comparing the numerical results with analytical solutions and with benchmarks available in the literature. The results obtained are important to evaluate the behavior and the characteristics of the models on the analysis of rate-dependency and stress relaxation. The three models were suitable to predict these phenomena. However, a special attention is needed on the nonlinear Perzyna model, because it does not recover the inviscid model as a limit case. Further, it presents ill-conditioning in the return mapping algorithm.

O presente trabalho trata da formulação de modelos constitutivos viscoelásticos e elasto-viscoplásticos nos apectos relativos à verificação da consistência termodinâmica, pela aplicação do Método do Estado Local, e de verificação da resposta numérica decorrente da utilização de um procedimento implícito de integração. No contexto da verificação da consistência termodinâmica, são revistos alguns arranjos unidimensionais de elementos reológicos básicos, analisando-se, com maior destaque, um arranjo misto denominado modelo elasto-viscoplástico completo. Nas análises numéricas em campo unidimensional e multiaxial, realiza-se um confronto entre as respostas obtidas com procedimentos de integração Explícito e Implícito, bem como um estudo para a definição do passo de tempo, de modo a garantir precisão nas respostas. / The present work treats of the formulation of viscoelastics and elastoviscoplastics constitutive models, on the aspects related to verification of the thermodynamic consistency, by the Method of Local State, and of numerical responses of a implicit integration scheme. In the context of the thermodynamic consistency, some unidimensional arrangements of basics rheological elements are reviewed, where a named elasto-viscoplastic extended model is enhanced. On what concerns to unidimensional and multiaxial numerical analysis, confront is showed between the results obtained from the explicit and implicit integration algorithms, and a study for time step definition aiming a good precision of the responses is presented as well.

Les estuaires sont généralement soumis à des phénomènes de comblement sédimentaires. Dans cette partie des systèmes fluviaux du territoire, l'accumulation des matériaux fins modifie radicalement la morphologie de l'estuaire, et conditionne la présence des espèces animales et végétales et on distingue un impact fort sur le plan économique, social et industriel. Les comblements compliquent la circulation dans les estuaires, compliquent les activités de pêches, de loisirs, modifient les propriétés des écoulements et constituent un facteur risque sur les zones d'habitations voisines. Des solutions temporaires consistent à curer les estuaires et des solutions d'aménagement des estuaires peuvent être envisagées. Néanmoins, il ressort de la littérature un manque important sur la caractérisation des mélanges liquides-solides et sur les mécanismes de structuration. Ce travail s'inscrit dans le contexte de l'étude des mécanismes de structuration des matériaux sédimentaires dans les estuaires afin de mieux comprendre les remplissages des zones estuariennes et surtout d'envisager des solutions durables de « nettoyage » de ces zones. L'estuaire de la Rance est particulièrement ciblé par notre étude. Le but est de donner des éléments de réponse sur le comportement rhéologique des vases naturelles en distinguant les échelles les plus significatives afin de détecter les facteurs structurants qui influencent les paramètres rhéologiques. La rhéologie des sédiments est ainsi étudiée à l'aide du rhéomètre Kinexus, géométrie plan-plan. On a pu alors détecter un comportement visco-plastique Bighamien. L'influence du diamètre moyens et de la fraction volumique solide sur la viscosité et le seuil de la contrainte de cisaillement dynamique du modèle de Bingham sont ainsi analysés. Ensuite, nous avons étudié grâce à des sédiments sans sel et sans matière organique, l'influence de ces deux composés chimiques sur le comportement rhéologiques des sédiments et puis leurs influences sur le vieillissement des sédiments. Une étude statique est également réalisée à l'aide du Va ne test permettant le calcul de la contrainte de cisaillement seuil. •Enfin, une assimilation du piège du Lyvet est réalisée grâce à des colonnes de sédimentation dans des conditions assez proches des conditions naturelles. Un processus de sédimentation-tassement-consolidation sous poids propre est recréé en laboratoire. Les sédiments sont amenés à vieillir cette fois pour des longues durées allant jusqu'à 9 mois. Au terme de périodes de vieillissement retenues, le massif créé est caractérisé depuis l'interface fluide-sédiments. Cela nous a permis d'étudier la répartition granulaire des sédiments après structuration et la variation de la contrainte de cisaillement seuil selon la profondeur de la colonne et la durée du vieillissement. Ce type d'essai est aussi réalisé pour les sédiments sans sel et sans matières organiques. / Estuaries are generally subject of sedimentary filling phenomena that alter their morphology and affect subsequently the economic, social and industrial plans. In this part of the fluvial systems of the territory, the accumulation of fine materials radically modifies the morphology of the estuary, and conditions the presence of animal and plant species and cause a strong impact on the economic, social and industrial. Filling complicates navigation in estuaries, fishing, recreational activities and modifies flow properties and is a risk factor in neighboring housing areas. Temporary solutions consist of cleaning estuaries and estuarine management solutions can be considered. Nevertheless, the literature shows a significant lack of characterization of liquid-solid mixtures and structuring mechanisms. This work is in the context of the study of structuring mechanisms of sedimentary materials in estuaries to better understand the fillings estuarine areas and specially to consider sustainable solutions of "cleansing" of these areas. The Rance estuary is particularly targeted by the study. The aim is to provide answers on the rheological behavior of natural vessels by distinguishing the most significant scales to detect structural factors influencing the rheological parameters. The rheology of the sediments is studied using the Kinexus rheometer, plan-plan geometry. A Bighamien visco-plastic behavior was then detected. The influence of the mean diameter and the solid volume fraction on the viscosity and the threshold of the dynamic shear stress of the Bingham model are thus analyzed. Then, using sediments without salt and organic matter, we studied the influence of these two chemical compounds on the rheological behavior of the sediments and their influence on the aging of the sediments. A static study is also carried out using the Vane test allowing the calculation of the threshold shear stress. Finally, an assimilation of the natural filling phenomenon is achieved in columns under conditions similar to natural conditions. These columns are then filled with natural sediments, washed sediments and sediments free of organic material and left for ages ranging from one week to 9 months. Then, the columns will be disassembled and rheological tests with the Brookfield Rheometer will be performed throughout the depth of the columns as well as measurements of water content and grain size. These tests allow us to study sediment structuring in the long term and also to identify the effect of salt and organic matter on sedimentation.

Ce mémoire présente une étude sur la caractérisation des propriétés mécaniques dépendantes du temps par nanoindentation instrumentée à différentes températures.Ce sujet de recherche porte sur l’adaptation des méthodes d’indentation classiques aux problématiques de la caractérisation à hautes températures. Les méthodes développées dans ces travaux ont pour premier objectif d’apporter une meilleure compréhension des phénomènes dépendants du temps et de la température par une approche locale. Le second objectif est d’apporter des éléments de comparaison entre le comportement à l’échelle microscopique et macroscopique.Les méthodes proposées sont principalement fondées sur l’essai de relaxation en indentation. Ses développements et applications aux matériaux polymères et métalliques sont étudiés de manière analytique puis expérimentale. L’étude analytique nous montre que ce type d’essais en indentation peut être directement comparé à un essai uniaxial. Elle montre également que la cinétique de chargement a une grande influence sur la qualité des résultats obtenus en relaxation.L’étude expérimentale proposée, en température, permet d’extraire la sensibilité à la vitesse de déformation ainsi que l’énergie d’activation des phénomènes visqueux. Cependant, la dérive thermique limite la durée des essais – la durée maximum du segment de relaxation reste inférieure à quelques minutes. Une autre étude réalisée à température ambiante ouvre la voie à des durées de caractérisation plus longues. Celle-ci se fonde sur l’équivalence entre aire et raideur de contact pour un matériau homogène. Un maintien de l’aire de contact constante pendant 10 heures est effectué sans signes de dérive.Finalement, l’application de la nanoindentation à hautes températures à la caractérisation in situ des changements microstructuraux pour un alliage d’aluminium est étudiée. Les résultats de l’étude montrent qu’il est possible d’obtenir la cinétique de recristallisation avec un seul échantillon et en un temps limité. / This manuscript presents a study on the mechanical properties’ characterization of time dependent phenomena using instrumented nanoindentation at different temperatures.This research subject treats the development of methods dealing with the adaptation of classical indentation methodologies to high temperature characterizations. Bringing a better understanding of time and temperature dependent phenomena at a local scale is the first aim of the methods developed. The second objective is to compare materials behaviors measured at micro and macro-scale.The proposed methods are based on indentation relaxation tests. Their development and applications to polymers and metals characterization are studied analytically and experimentally. The analytical study shows that the indentation relaxation test is equivalent to the uniaxial one. This study also highlights the great influence of loading kinetics on the measured relaxation behavior.The proposed experimental study in temperature permits the extraction of the strain rate sensitivity and the activation energy of the viscous phenomena. However, thermal drift limits the characterization duration – i.e. the maximum experimental time remains limited to a couple of minutes. Another experimental study configuration, at room temperature, opens the way to longer test durations. It is based on the equivalence of contact area and stiffness for a homogeneous material. With this configuration, we successfully hold the contact area constant for 10 hours without any evidences of drift.Eventually, the high temperature nanoindentation application to in situ microstructural changes characterization of an aluminum alloy is studied. Measurements and limitations are carefully discussed for a better understanding of the studied phenomenon. The results show that the recrystallization kinetics can be successfully described with reduced test duration and samples’ set.

Cette thèse a été réalisée dans le cadre d’une convention entre le Cerema (Centre d’Etude et d’Expertise sur les Risques, l’Environnement, la Mobilité et l’Aménagement) et l’ENTPE (Ecole Nationale des Travaux Publics de l’Etat). Ce travail concerne l’étude et la modélisation du comportement des enrobés bitumineux, dans les domaines des petites et grandes déformations, soit respectivement les comportements viscoélastique et viscoplastique.Après une étude bibliographique portant sur les propriétés mécaniques des enrobés bitumineux en petites et grandes déformations et la présentation des modèles de comportement viscoélastique linéaire et viscoplastique, ce mémoire s’organise en cinq chapitres. Les deux premières parties concernent le développement du modèle DBN, et la description de la version introduite dans cette thèse : la version EPPI (Elastique Parfaitement Plastique Isotrope). Cette formulation tridimensionnelle vise à décrire les comportements viscoélastique et viscoplastique des enrobés bitumineux avec un formalisme unique, suffisamment simple pour être implémenter dans un code de calcul aux éléments finis. Le modèle est ensuite développé et implémenté dans un code de calcul homogène, permettant ainsi de réaliser des simulations d’essais expérimentaux classiques.Les deux chapitres suivants traitent de la campagne expérimentale réalisée dans cette thèse. Il s’agit d’abord de décrire l’ensemble des procédures et conditions d’essais. Deux types d’essais sont réalisés : module complexe pour la caractérisation du comportement viscoélastique et traction simple pour la caractérisation du comportement viscoplastique. Ensuite, l’ensemble des résultats expérimentaux et observations issus de cette campagne sont présentés et permettent de dessiner quelques conclusions.Enfin, le dernier chapitre traite des simulations réalisées à partir du modèle DBNEPPI. Ces résultats permettent dans un premier temps de tester la validité du modèle (essais de module complexe, essais cycliques de traction-compression). Enfin une étude des effets transitoires lors des essais de module complexe est présentée. / The thesis has been realized within the framework of a partnership between the Cerema (Center for Studies and Expertise on Risks, Environment, Mobility, and Urban and Country Planning) and the ENTPE (National School for Public State Works). This work deals with the study and the simulation of the behavior of bituminous mixtures, in the domains of small and large amplitudes of solicitations. These domains correspond to the viscoelastic and viscoplastic behavior.First a bibliographical review on mechanical properties of the bituminous mixtures under small and large amplitudes of solicitations and a review of the several models describing the viscoelastic and viscoplastic behavior of bituminous mixtures is presented. This thesis is then composed of 5 main chapters.The two first deals with the development of the DBN model and mainly with the introduction of its new version EPPI (Elastic Perfectly Plastic and Isotropic). This formulation aims at describing the viscoelastic and viscoplastic behaviors together in a unique formalism, but simple enough to be implemented in a finite elements calculation program. This version of the DBN model is then implemented in a homogeneous computation code so as to be able to simulate classical experimental test.The two following chapter are devoted to the experimental campaign made during this research work. First a global description of the experimental procedures and test conditions is presented. Two kinds of tests are performed: complex modulus tests so as to characterize the viscoelastic behavior and simple traction tests for viscoplastic behavior. Finally results and observations issued from this campaign are detailed and some conclusions can be drawn.Finally the last chapter deals with the simulations performed thanks to the DBNEPPI model. These results aim at verifying the validity of the model introduced. Then a study about the transient effects during complex modulus tests on bituminous mixtures is detailed.

Ceramic Matrix Composites (CMC) are attractive material systems for structural applications where resistance to intermediate (700 0C-950 0C) and high temperatures (900 0C-1400 0C) is required and low density is desired. There are currently barriers to a more widespread adoption of CMCs which include less robust simulation tools, which this dissertation seeks to address. A novel unified reduced order homogenization model for initial quasi-static, creep, and fatigue loading of SiC/SiC CMCs at intermediate and high temperatures is proposed. Driven by a single set of parameters, the model can seamlessly transition between initial quasi-static, creep, and fatigue regimes while capturing the complex material response of SiC/SiC CMCs. The reduced order homogenization approach provides a robust and efficient computational platform for analyzing composite behavior. Continuum damage mechanics provides the basis for the initial brittle CMC behavior while a hybrid damage-viscoplasticity model combined with an oxidation driven crack sealing effect drives the time-dependent brittle-ductile material behavior at high temperatures. A temporal multiscale approach extends the spatial multiscale model into fatigue regime at high temperatures, avoiding the computational complexity of modeling each cycle individually. At intermediate temperatures, a one-dimensional model based on the slow crack growth model originally proposed by Iyengar and Curtin is generalized to three dimensions focusing on a woven composite architecture. For this oxidation-assisted rupture model, the constitutive equation in the axial tow direction is governed by the continuum damage mechanics variant of the slow crack-growth model and the availability of oxygen to fibers, which in turn depends on the initial matrix pores and subsequent matrix cracking. The model is verified on two SiC/SiC material systems, S200H and GEA SMI, in both initial quasi-static and time-dependent loading regimes at both high and intermediate temperatures.