Esta dissertação apresenta em primeira etapa o trabalho desenvolvido para averiguar a adequação dos modelos reológicos de Mohr-Coulomb e de Endurecimento de solo, para representar as deformações e distorções que ocorrem no sistema soloestrutura, quando do processo de escavação de valas escoradas. Além disto, em uma segunda etapa fazem-se estimativas de previsão de danos causados em edificações, em decorrência das escavações de uma vala escorada da linha 1 do Metropolitano de São Paulo (Metrô S.P.). A primeira e a segunda etapa foram feitas através de 810 simulações numéricas, em elementos finitos utilizando-se o software PLAXIS, associadas a retroanálise por processo direto do módulo de deformabilidade a 50% da tensão de ruptura dos solos utilizando-se para isto o processo direto. Apresenta-se também uma síntese da formação e dos tipos de solos que constituem a bacia sedimentar de São Paulo, onde se localiza a seção experimental nº1 objeto de estudo desta dissertação. Faz-se uma breve revisão bibliográfica a respeito das técnicas de retroanálise. Apresentam-se critérios para escolha de intervalos de parâmetros geotécnicos que representem o sistema solo-estrutura no processo de escavação. Foram feitas análises paramétricas para determinar os parâmetros geotécnicos que mais influenciam o sistema solo-estrutura. Comparam-se os modelos constitutivos de Mohr-Coulomb e de endurecimento na previsão das deformações. Por fim, faz-se a previsão do nível de danos causados pelas escavações da vala, a um edifício hipotético / This dissertation presents, in a first part, the work done to verify how appropriate are the Mohr-Coulomb and hardening soil constitutive models to represent the strains and the distortions associated with escavations of braced wall process. In the second part, estimates are made of the damages in constructions due to the braced excavations of line one of Sao Paulo Subway (Metrô S.P.). In the two phases, 810 numeric simulations were made, in finite elements using the software PLAXIS, associated the back analysis for direct process. It is presented a synthesis of the formation and the types of soils that constitute the basin of the sediments of the city of São Paulo, where is located the section experimental nº1, object of study of this dissertation. It is presented an short bibliographical revision regarding the back analysis techniques. Criteria for choice of intervals of parameters geotechnical that represent the system soil-structure in the excavation process are presented. Parametric analyses are made to determine which the parameters have larger influence in the behavior of the system soil-structure. The behavior of the soil-structure system is simulated using the Mohr-Coulomb and hardening soil constitutive models. The Mohr-Coulomb and hardening soil constitutive models are compared in the forecast of the deformations. Finally, it is made the forecast of the level of damages to a hypothetical building caused by the braced excavations

[pt] Este trabalho de dissertação de mestrado apresenta a implementação da análise limite numérica com formulação mista-fraca, baseada no teorema do límite inferior, e sua aplicação em problemas de estabilidade axissimétricos. Aformulação com elementos finitos foi implementada no software Matlab, onde se estabelece o problema de otimização que compreende a definição da equação de equilibrio e a adaptação dos criterios de ruptura de Drucker-Prager e Mohr-Coulomb às programações cônica de segunda ordem e semidefinida, respectivamente, e que posteriormente é resolvido com o algoritmo Mosek Aps 9.2. Como resultado do problema de otimização o fator de colapso e o campo de velocidades podem ser obtidos, permitindo identificar o mecanismo de ruptura. O presente trabalho foca-se na análise de estabilidade de um poço que é executada em 3 fases, em função das condições consideradas no modelo. Os resultados obtidos da análise axissimétrica foram validados mediante analises em modelos tridimensionais e comparados com resultados dos softwares Plaxis 2D e Optum G2, também foram incluídos os resultados da modelagem MPM, com o sotware MPM-PUCRio. Por fim foi estudado o caso da capacidade de carga de uma fundação circular rasa, cujos resultados foram comparados com os apresentados por outros autores. / [en] This work dissertation presents the implementation of numerical limit analysis with mixed-weak formulation, based on the the lower bound limit theorem and its application in axisymmetric stability problems. The finite element formulation was implemented in Matlab, where the optimization problem is established, which comprises the definition of the equilibrium equation and the adaptation of the Drucker-Prager and Mohr-Coulomb rupture criteria to the second-order cone programming and semidefined programming, respectively, and which is later solved with the Mosek Aps 9.2 algorithm. As a result of the optimization problem, the collapse factor and the speed field can be obtained, allowing to identify the rupture mechanism.The present work focuses on the stability analysis of a well that is carried out in 3 phases, depending on the conditions considered in the model. The results obtained in the axissymmetric analysis were validated through analysis in three-dimensional models and compared with results of plaxis 2D and Optum G2 software, also included the results of MPM modeling, with the software MPM-PUCRio. Finally, the case of the load capacity of a shallow circular foundation is studied, the results of which are compared with those presented by other authors.

I samband med Förbifart Stockholm och Tvärförbindelse Södertörn förväntas en flaskhals skapas vid Vårbybron i södra Stockholm. För att förhindra överbelastning planeras en nybyggnation där pålgrundläggning med grävpålar föreslås. Markförhållanden är ovanliga i Stockholm, med över 100 meter ned till berg. Komplexa omständigheter i området gör det nödvändigt att analysera markrörelser som verkar på grundläggningen. Syftet med studien är att undersöka horisontella- och vertikala sättningar vid ett brolandfäste. Syftet är vidare att analysera vilken typ av numerisk konstitutiv modell som är lämplig med hänsyn till studiens specifika fall och område; Mohr-Coulomb (MC), Hardening Soil (HS) och Hardening Soil med small-strain stiffness (HSS). Slutligen ska jordparametrarnas väsentlighet avgöras i en parameterstudie. Sonderingsdata tillämpas i studien för att skapa en jordlagermodell i AutoCAD Civil 3D 2019 Metric och vidare simulering av sättningar i Plaxis 2D. Vid modellering av sättningar i förekommande geologi rekommenderas att en avancerad modell används, med fördel HSS. Däremot kräver mer avancerade modeller noggranna indata för tillförlitligt resultat och ytterligare tester för styvhetsparametrar bör utföras. I detta projekt kan dyrare tester tänkas sänka slutgiltig budget, eftersom underskattning av moduler i djupa och fast lagrade jordar baserade på konservativt valda moduler ger upphov till en dyrare konstruktion. / In conjunction with the opening of the Stockholm Bypass and Tvärförbindelse Södertörn, a bottleneck is expected at the bridge Vårbybron in southern Stockholm. To prevent traffic congestion, a new construction is planned where pile foundation consisting of bored piles is proposed. The ground conditions are unusual and not typical for Stockholm involving over 100 meters distance to rock. Complex circumstances in the area makes it complicated as well as necessary to analyze ground movements. The aim of the study is to investigate horizontal- and vertical settlements at a bridge abutment. The aim is further to analyze which type of numerical constitutive model that is appropriate with respect to the specific case and area; Mohr-Coulomb (MC), Hardening Soil (HS) and Hardening Soil with small-strain stiffness (HSS). Finally, the significance of the soil parameters is to be determined in a parameter analysis. Results from soundings are used to create a geological model in AutoCAD Civil 3D 2019 Metric. Furthermore, simulation of settlements in Plaxis 2D is performed. It is recommended to apply advanced models for this type of geology, advantageously HSS. However, more advanced models require accurate input data to obtain reliable results, and additional tests for stiffness parameters must be performed for accuracy in the results. In this project, more expensive tests can be thought of as lowering the final budget, as underestimation of modules in deep and stiff soils based on conservatively selected modules leads to an unnecessarily expensive construction.

La maintenance, la réparation et le renforcement de murs en maçonnerie par matériaux composites collés nécessitent le développement de méthodes et techniques d'évaluation de l'aptitude au service et de requalification tant pour leur restauration fonctionnelle que pour leur adaptation à de nouvelles contraintes (évolution du zonage sismique par exemple). Le présent travail de thèse a pour objectif de proposer un outil d'évaluation par calcul de l'état limite ultime de murs en maçonnerie, renforcés par composites collés, chargés dans leur plan.Les travaux effectués concernent la modélisation par homogénéisation de murs en maçonnerie et une campagne expérimentale de caractérisation du transfert de charge entre un renfort en tissu de fibres de carbone et un support en blocs creux de béton par le biais d'un joint de colle. Pour modéliser la résistance des murs maçonnés, nous proposons une loi élastique parfaitement plastique pour le comportement dans le plan d'une maçonnerie constituée de blocs liés par des joints de mortier. Le convexe de plasticité est obtenu par une technique d'homogénéisation périodique qui prend en compte la nature tridimensionnelle de la cellule de base. On obtient alors un convexe limité par plusieurs surfaces de charge. Un algorithme numérique original est ensuite proposé et programmé dans le logiciel aux Eléments Finis ABAQUS. Des simulations numériques utilisant le module développé sont présentées

Structures like transmission towers, tele-communication masts, dry-docks, tall chimneys, tunnels and burried pipelines under water etc are subjected to considerable uplift forces. The net effect of external loading on the foundations of these structures results in forces that try to pull the foundations out of the ground. Anchors are usually provided to resist such uplift forces. Earlier theoretical research of anchor behavior has focused on elastic response and ultimate pullout capacity. Many investigators have proposed techniques for determining the collapse load of anchors. Essentially the approaches involve the use of limit equilibrium concepts, with some assumptions regarding the shape of the failure surface and/or the influence of the soil above the anchor. The possible effect of dilatency and initial stress state are not considered in these methods. A number of investigators have used the results of small size model anchors to understand the behavior and extrapolated the results for predicting the behavior of large sized anchors. This has lead to unsatisfactory results. It has been clearly shown by Dickin (1989) that the failure displacements and load displacement curve patterns are very different for small and large sized anchors, i.e. they are not just proportional to the size of the anchor. Critical pullout load and the load displacement behavior are required for the complete analysis of anchor foundations. Though, many theories have been proposed to predict the uplift capacity within the limits of accuracy required at engineering level, at present no simple rational method is available for computing deformations. In the present investigation attempts have been made to analyze the load deformation behavior of large size strip anchors in sands, clays and layered soils using two-dimensional explicit finite difference program FLAG (Fast Lagrangian Analysis of Continua), well suited for geomaterials, by assuming soil to be a Mohr-Coulomb material in the case of sands and modified Cam-clay material in the case of clays. It is now well understood that the shearing resistance of a granular soil mass is derived from two factors frictional resistance and the dilatency of the soil. So the peak friction angle can be divided in to two components critical friction angle Фcv and dilation angle Ψ. Critical friction angle is the true friction angle as a result of frictional resistance at interparticle level when the soil is shearing at constant volume. If Фcv for a given soil remains constant, the value of Ψ has to increase with the increase in initial density of soil packing. The dilatency of a soil mass gradually decreases with continued shearing from its initial high value to zero after very large shear strains, when the soil finally reaches a constant, steady volume at critical states. Correspondingly the observed friction angle Ф reduces from its peak value to Фcv at a very large strain. In earlier days, clays used to be characterized by the strength parameters c and Ф. often, under undrained conditions, Ф would be even considered zero. But in the recent developments, it is understood that all the strength of clays is frictional. There is nothing like cohesion. The part of shear strength, which appears to be independent of normal stress, is shown to be the effect of over-consolidation and the resulting dilation. Thus although Cam-clay model uses zero cohesion for all clays, it reflects this component of strength through over-consolidation and in a more realistic way. Hence, it is appropriate to consider the pre-consolidation pressure as parameter in the analysis. More specifically, the various aspects covered in this investigation are as follows. Chapter 1 provides the general introduction. In chapter 2, the existing literature for the analysis of anchors for both experimental and analytical investigations on the pullout capacity of anchors in homogeneous and layered soils and the load deformation behavior of anchors under pullout are briefly reviewed. Chapter 3 deals with the features and the implementation of the two-dimensional explicit finite difference program, Fast Lagrangian Analysis of Continua (FLAC) and the constitutive modeling of soils. It discusses the background and implementation of Strain softening / hardening model. This model is based on the Mohr- Coulomb model with non-associated shear and associated tension flow rules. In this model the cohesion, friction, dilation and tensile strength may harden or soften after the onset of the plastic yield. Further the critical state concepts and implementation of the modified Cam-clay model have been discussed. Cam-clay model originally developed for clays reflects the hydrostatic pressure or density dependent hardening material response. Chapter 4 focuses on the analysis of load deformation behavior of large size anchors in granular soils. Two-dimensional explicit finite difference program (FLAC) is used for the simulations and the soil is modeled as a Mohr-Coulomb strain softening/hardening material In this chapter a series of simulations have been carried out on large size anchor plates, with parametric variation. By analyzing these results, a generalized load deformation relationship for different sizes of anchors and different types of soil have been proposed. The results are presented in the form of influence/design charts which can be used in hand calculations to obtain an estimate of anchor capacity and deformation for a wide range of soil types and size of anchors. Chapter 5 deals with the analysis of the drained and undrained behavior of large size horizontal strip anchors in clays using modified Cam-clay model. Earlier investigators have studied the undrained behavior of anchor plates in clays, but no studies are reported in literature for the drained behavior of anchors in clays. Further it is not clear whether, drained or undrained condition will be critical for an anchor. In this chapter the drained and undrained behavior of large size anchor plates in both normally consolidated and over-consolidated states have been made. It has been found that the undrained pullout capacity of an anchor in a soil of normally consolidated state will always be more than the drained capacity. This is contrast to the usual understanding that undrained behavior is more critical than the drained behavior. In Chapter 6 an attempt has been made to analyze the behavior of large size anchors in two layered sands and in conditions where backfill material has a higher or lower strength than the native soil, for different shape of excavations. Soil is assumed to be a Mohr-coulomb strain softening/hardening material. In Chapter 7 the entire investigation covered in earlier chapters has been synthesized and some specific conclusions have been highlighted.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-08-23T13:35:50Z No. of bitstreams: 1 DANIEL BESERRA COSTA - DISSERTAÇÃO (PPGECA) 2018.pdf: 3178699 bytes, checksum: cdb4fe8ec72383894c5c447ebe2853ae (MD5) / Made available in DSpace on 2018-08-23T13:35:50Z (GMT). No. of bitstreams: 1 DANIEL BESERRA COSTA - DISSERTAÇÃO (PPGECA) 2018.pdf: 3178699 bytes, checksum: cdb4fe8ec72383894c5c447ebe2853ae (MD5) Previous issue date: 2018-02-21 / Capes / A deformação permanente é definida como o acúmulo de pequenas quantidades de deformação não recuperáveis resultante da aplicação das cargas dos veículos. A deformação permanente na camada de revestimento asfáltico pode ser oriunda por três mecanismos: deformação permanente por densificação, por uso e por fluência da mistura. Dado que as temperaturas de serviço da camada de revestimento estão em torno de 40 a 60 °C, a mistura asfáltica nesse intervalo de temperatura se comporta como um material sólido. Sendo assim, é razoável supor que os mecanismos de falha aplicáveis aos materiais sólidos sejam válidos para as misturas de asfálticas. Sendo o critério Mohr-Coulomb amplamente utilizado para descrever as características de cisalhamento de materiais sólidos, poderá ser utilizado para obtenção do ângulo de atrito interno da mistura, bem como o seu intercepto coesivo. Este trabalho teve como objetivo a determinação de ângulos de atrito internos de diferentes misturas asfálticas e sua influência no comportamento mecânico, em especifico, na resistência à deformação permanente destas misturas. Como forma de atingir o objetivo da pesquisa foi desenvolvido um programa experimental visando à avaliação das propriedades mecânicas relacionadas ao ângulo de atrito interno das misturas asfálticas com CAP 50/70 e E – 55/75. Foi possível executar análises em laboratório a partir da determinação de parâmetros de ruptura por cisalhamento, com o auxílio da teoria de Mohr-Coulomb, tendo como inferência o desempenho de misturas estudadas em campo. Verificou-se que, a cada acréscimo de 5% de partículas graúdas em uma faixa granulométrica, as misturas estudadas apresentaram, em geral, um ganho de 1° (Grau) no ângulo de atrito interno para cada faixa estudada. Entretanto, deve ser observado o limite de 30 a 35% de partículas graúdas para cada mistura. Pode-se concluir que: os parâmetros de ruptura por cisalhamento, ângulo de atrito interno e intercepto coesivo são fatores determinantes no desempenho a deformação permanente de misturas asfálticas. Para os ligantes utilizados os resultados indicaram que o acréscimo do ângulo de atrito interno resulta numa maior resistência a deformação permanente. / Permanent deformation is defined as the accumulation of small amounts of non-recoverable deformation resulting from the application of vehicle loads. The permanent deformation in the surface layer of asphalt pavements can come from three mechanisms: permanent deformation by densification, by use and by creep of the mixture. Since the service temperatures of the pavement surface layer are around 40 and 60 ºC, the asphalt mixture, in this temperature range, behaves as a solid material. Therefore, it is reasonable to assume that failure mechanisms applicable to solid materials are valid for asphalt mixtures. As the Mohr-Coulomb criterion is widely used to describe the shear characteristics of solid materials, it can be used to obtain the internal friction angle of the asphalt mixture as well as to estimate its cohesive intercept. This work had as objective to determine the internal angles of friction of different asphalt mixtures and their influence on the mechanical behavior, in particular, on the resistance to permanent deformation of these mixtures. In order to achieve the objective of this research, an experimental program was developed to evaluate the mechanical properties related to the internal angle of friction of asphalt mixtures with the 50/70 asphalt binder and the E 55/75 asphalt binder. It was possible to perform laboratory analyses from the determination of shear rupture parameters, supported by the Mohr-Coulomb's theory, inferred by the performance of mixtures studied in the field. It was verified that, at each increment of 5% of coarse particles in a particle size range, the studied mixtures presented, in general, a gain of 1° (degree) in the internal angle of friction for each size range studied. However, the limit of 30 to 35% of coarse particles should be observed for each mixture. It can be concluded that: the parameters of shear rupture, internal angle of friction and cohesive intercept are determining factors in the permanent deformation performance of asphalt mixtures. For the asphalt binders used, the results indicated that the increment of the internal angle of friction results in a greater resistance to permanent deformation.

De nombreuses failles à faible pendage (pendage inférieur à 30°) ont été décrites en domaine continental extensif depuis leur mise en évidence dans la province des Basin and Range (USA). Bien que les observations de terrain suggèrent, dans plusieurs régions, que le jeu d'une faille se produit à faible pendage dans la croûte cassante (Apennins, Italie ; Basin and Range, USA; Alpes orientales), l'activité sismique liée à ces failles est presque inexistante et est en accord avec les angles de blocage des failles prédits par la mécanique andersonienne associée à la loi de Byerlee. L'étude des Metamorphic Core Complex et de l'exhumation de détachements dans les Cyclades permet d'obtenir un modèle figé de la croûte continentale en extension. Le Metamorphic Core Complex qui affleure sur l'île de Mykonos se caractérise par une intrusion granitique (laccolite) dans le dôme migmatitique, recoupé à son sommet par un système de détachements composé de deux branches. La branche inférieure ductile du détachement met en contact la Nappe Supérieure Cycladique, constituée de métabasites, et le laccolite. La branche supérieure cataclastique du détachement juxtapose une unité sédimentaire molassique sur la Nappe Supérieure Cycladique ou directement sur le laccolite. Le détachement cataclastique conditionne la sédimentation syn-tectonique dans les bassins. Associée au réseau de veines contemporain du jeu du détachement, la déformation dans l'unité sédimentaire montre que le détachement cataclastique de Mykonos a été actif à faible pendage et à faible profondeur, au moins au cours des derniers incréments de déformation. La synthèse des données collectées sur les îles d'Andros, de Tinos et de Mykonos montre que les détachements nord-cyladiques peuvent être considérés à différents stades d'évolution comme une seule et unique structure d'échelle crustale (le Système de Détachement Nord-Cycladique) pouvant accommoder l'extension régionale et l'exhumation des roches de l'unité inférieure. L'étude de l'Anisotropie de la Susceptibilité Magnétique (ASM) dans le laccolite, couplée aux observations de terrain, a permis de mettre en évidence une rotation de l'unité inférieure du détachement de Mykonos autour d'un axe vertical, compatible avec les données paléomagnétiques disponibles dans la littérature. Afin de réconcilier observations de terrain et mécanique des roches, nous proposons un nouveau modèle de réactivation de failles en considérant la faille comme une fine couche déformable plastiquement, contrairement au modèle classique suggérant une dislocation avec des propriétés frictionnelles. Notre modèle permet alors d'inclure les variations volumiques de la zone de faille au cours du cisaillement, et notamment, de prendre en compte des coefficients de dilatation faibles voir négatifs (faille compactante), souvent observés en laboratoire ou sur le terrain. Notre modèle permet, en particulier, de déterminer les quantités de déformation plastique que peuvent accommoder ces failles au cours du cisaillement avant leur blocage. Les angles de blocage obtenus dans notre modèle varient peu par rapport au modèle classique de réactivation de faille, qui apparaît comme un cas particulier de notre modèle. La réactivation d'une faille à faible pendage en extension est alors possible complètement ou partiellement et peut être associée à la formation de veines et de failles normales dans l'encaissant. La réactivation est alors favorisée lorsqu'il s'agit d'une faille compactante et se produit en régime durcissant, suggérant ainsi un comportement asismique de la faille.

Cette thèse traite le problème de la stabilité des ouvrages souterrains creusés en terrain meuble à faible profondeur. La stabilité de ce type d'ouvrages est normalement étudiée en utilisant des méthodes justifiées par l'expérience mais dont les hypothèses ne sont pas toutes cohérentes au plan mécanique. L'application systématique du calcul à la rupture et de l'analyse limite fournit des encadrements pour les chargements conduisant à la rupture d'un système donné. Le mémoire décrit la mise en oeuvre numérique d'une forme régularisée de l'approche cinématique de l'analyse limite pour l'étude de la stabilité des ouvrages souterrains. La résistance des sols est modélisée par des critères de Tresca, de Tresca tronqué en traction et de Mohr-Coulomb en conditions bidimensionnelles, et par des critères de Tresca et de Mohr-Coulomb pour les calculs tridimensionnels. Les calculs reproduisent les modes de rupture observés dans les travaux souterrains et sur modèles. Les charges limites calculées sont voisines des valeurs expérimentales.

Dans le cadre de cette thèse, on étudie le comportement mécanique de panneaux sandwich métalliques avec une âme à architecture gaufrée. Ces structures fournissent une alternative économiquement avantageuse aux nids d'abeilles hexagonaux car leur production de masse est réalisable par emboutissage progressif de tôles planes. Les différentes géométries possibles de la structure gaufrée sont limitées par des risques de rupture lors de la fabrication. Ainsi, l'étude de l'optimisation de la capacité portante des panneaux sandwich à âme gaufrée est contrainte par la rupture ductile du matériau de base. Le choix d'un modèle de rupture ductile approprié pour prédire le comportement à rupture du matériau de base joue donc un rôle central dans cette recherche. La première partie de cette thèse est entièrement consacrée aux évaluations expérimentale et numérique des capacités prédictives de deux versions du modèle de rupture de Mohr-Coulomb; l'une étant la version originale, l'autre intégrant un indicateur d'endommagement. En limitant notre attention aux contraintes planes induites par la traction uni-axiale et équi-biaxiale dans la tôle d'acier doux, on réalise des essais de rupture sur des éprouvettes entaillées et des essais de poinçonnement à l'aide d'un poinçon circulaire afin d'identifier les paramètres du modèle de rupture. Un test de Hasek et un essai d'emboutissage d'une structure gaufrée sont utilisés afin d'évaluer les capacités prédictives des deux modèles de rupture. Le modèle avec indicateur d'endommagement utilisant une fonction poids dépendant de l'état de contrainte prédit l'apparition de la rupture lors de l'essai d'emboutissage avec la meilleure précision. Dans la deuxième partie de cette thèse, pour l'étude de la fabrication de la structure gaufrée, on utilise le modèle de Mohr-Coulomb avec indicateur d'endommagement pour déterminer la profondeur d'emboutissage maximale en fonction de la géométrie de l'outil de mise en forme. Le comportement en grandes déformations est décrit par un modèle de plasticité quadratique avec écrouissage isotrope et une loi d'écoulement non associée. Des cartes de sensibilité aux principaux paramètres sont développées : rigidité au cisaillement de la partie cœur, résistance au cisaillement, résistance au délaminage et au flambement élastique des peaux en fonction de la géométrie de la structure cœur. Une méthode d'optimisation des performances des panneaux sandwich à âme gaufrée est développée pour les panneaux rectangulaires sur appuis simples soumis à un chargement latéral uniforme. Les résultats des expériences de flexion quatre points montrent que les panneaux sandwichs optimisés offrent des plus grandes résistance et rigidité (pour un moindre poids) que des panneaux avec une partie cœur en mousse de polyéthylène de haute densité. La dernière partie de cette thèse se concentre sur l'étude de la résistance à la perforation des panneaux sandwich métalliques à âme gaufrée. L'effet des paramètres décrivant la géométrie de la structure cœur et le l'influence du matériau constituant les peaux est étudié. On s'intéresse en particulier à un acier doux, un acier " dual-phase " DP780 et un acier martensitique à très haute résistance. Un nouveau modèle utilisant un indicateur d'endommagement avec une fonction poids basée sur le critère de Hosford est utilisé pour modéliser la réponse à la rupture de ces matériaux. Une étude paramétrique de la résistance à la perforation des panneaux sandwich pour différentes tailles de cellule élémentaire de la partie cœur est réalisée à l'aide d'un modèle éléments finis. La résistance à la perforation diminue avec la taille de la cellule et avec la hauteur de la partie cœur. Ainsi, le panneau sandwich le plus mince offre une résistance supérieure à la perforation. Des essais sont réalisés qui confirment ce résultat important.

The thesis deals with the back analysis of the instrumentated embankment on the subsoil, improved by prefabricated vertical drains. The first part is devoted to the theory of consolidation calculation. Furthermore, the author deals with a parametric study of the analytical calculation of prefabricated drains and the comparsion of the analytical and numerical solution. The last and the largest part of the work is a back analysis of the embankment which was built as a part of the subsoil improvement near the Suez Canal in Egypt by Keller GmbH.