O estudo do comportamento mecânico dos solos é muitas vezes feito por meio de ensaios de campo, cujos resultados permitem a definição do perfil estratigráfico, posição do nível d\'água e estimativa realista dos parâmetros dos materiais envolvidos, bem como a avaliação de sua variabilidade. Os solos tropicais apresentam comportamento peculiar, devido aos processos geológicos e/ou pedológicos inerentes a sua formação e sua condição não saturada. Por isso, a Mecânica dos Solos Clássica apresenta limitações para prever seu comportamento, principalmente quando se leva em conta a variabilidade sazonal. Neste contexto, este trabalho tem como objetivo estudar o comportamento não convencional de perfis de solos tropicais não saturados, com ênfase a influência da variabilidade sazonal na estimativa de parâmetros geotécnicos considerando o efeito da sucção. Os ensaios de campo realizados foram os de Cone (CPT) e de Dilatômetro (DMT), em conjunto com sísmica downhole. Os locais estudados foram os Campos Experimentais da USP de São Carlos e da Unesp de Bauru. Resultados desses ensaios foram reavaliados com o intuito de melhor compreender a variabilidade espaçotemporal. Foi possível verificar que as variações sazonais nos perfis de umidade, e consequentemente da sucção, afetaram os resultados dos ensaios de campo, destacando a importância de considerar a variabilidade sazonal na interpretação dos mesmos. Novas campanhas de ensaios de campo, sempre com a determinação de perfis de umidade e curvas de retenção de água no solo para a estimativa de sucção foram realizadas nesses dois campos experimentais. A interpretação dos resultados desses ensaios considerando o efeito da sucção e microestrutura presentes nos solos tropicais possibilitou avaliar a aplicabilidade das metodologias existentes para a definição do perfil estratigráfico e, em especial, para a estimativa de parâmetros geotécnicos de projeto. Os perfis de qc, KD e ED foram normalizados considerando o efeito da sucção nas tensões efetivas, o que possibilitou uma avaliação mais adequada dos perfis de solo estudados. Concluiu-se que para o entendimento do comportamento mecânico desses solos tropicais é necessário compreender a influência da variabilidade sazonal, bem como identificar a presença de microestrutura nos mesmos. O emprego de técnicas híbridas, como o SCPT e o SDMT, em conjunto com perfis de umidade e curvas de retenção de água no solo permitiram uma melhor caracterização dos perfis investigados. / The study of the mechanical behavior of tropical soils is quite often carried out by in-situ tests. In-situ test data allow defining the stratigraphic profile, position of the ground water level and a realistic estimative of the geomaterials parameters, as well as assessing their variability. Tropical soils present a peculiar behavior due to the geological and/or pedological processes inherent to their formation and to its unsaturated condition. For this reason, the Classical Soil Mechanics has limitations to predict such behavior. In this context, this work aims to study the unusual behavior of unsaturated tropical soils with emphasis on the influence of the time-spatial variability in the estimative of geotechnical parameters caused by soil suction. The in-situ tests were the Cone (CPT) and Dilatometer (DMT) together with downhole seismic tests. The experimental research sites are the Unesp-Bauru and USP-São Carlos. CPT, DMT and downhole seismic tests data were reinterpreted for better understanding the time-spatial variability. It was possible to verify that the seasonal variations in the water content profiles, and consequently on the soil suction, caused changes in the in-situ test data. As a result, the seasonal variability should be considered in the interpretation of the in-situ tests carried out in unsaturated tropical soils. Further in-situ test campaigns, always together with water content profiles determination and soil water retention curves, were carried out in both research sites. The interpretation of the tests data considering the influence of the soil suction and cementation effects in tropical soils allows evaluating the applicability of the classical methodologies for the definition of the stratigraphic profile and the estimative of geotechnical parameters. The qc, KD e ED were normalized considering the soil suction influence on the effective stresses. This procedure allowed a proper site characterization of the studied soil profiles. It was concluded that for the understanding of the mechanical behavior of the studied tropical soils it is necessary to figure out the influence of the seasonal variability, as well as identifying the presence of microstructure on these soils. The use of hybrid techniques, such as SCPT and SDMT, together with moisture content profiles and soil water retention curves allowed a better site characterization of the investigated soil profiles.

Cette thèse a pour objectif la compréhension fine du rôle de la microstructure sur les propriétés mécaniques de composites à matrice céramique oxydes, en vue de l’introduction de ce type de matériau dans les futurs moteurs d’aviation civile. L’influence des hétérogénéités induites par la mise en forme de ce matériau est particulièrement investiguée. Ces hétérogénéités semblent favoriser l’apparition et la propagation de mécanismes d’endommagement conduisant à la ruine du matériau. L’étude est réalisée sur trois nuances de composites oxydes à tissage bidimensionnel générées à partir de trois procédés de fabrication différents. Ces procédés conduisent à la mise en place de trois types de microstructures. Des caractérisations morphologiques par porosimétrie et par μ-tomographie sont réalisées afin d’estimer la répartition des hétérogénéités et ainsi d’établir les microstructures représentatives de chaque nuance. En se basant sur ces analyses, une étude du comportement mécanique des nuances d’étude est réalisée à plusieurs échelles. Dans un premier temps, une étude des propriétés mécaniques à l’échelle macroscopique, représentative du matériau est effectuée à l’aide d’essais de traction dans le plan de tissage. En parallèle, des essais in-situ sont mis en place afin d’observer l’évolution de l’endommagement des microstructures. Ces observations permettent d’améliorer la compréhension du rôle des hétérogénéités sur l’activation des mécanismes d’endommagement. Le suivi de l’EA (Emission Acoustique) des essais est utilisé pour analyser la cinétique d’endommagement des nuances de composites oxydes. En plus de l’analyse globale de l’activité acoustique, des classifications des signaux d’EA sont réalisées. Ces classifications se basent sur la détection de signaux d’EA à l’aide de deux types de capteurs présentant des caractéristiques différentes. Une labellisation des classes est proposée en confrontant les activités de ces classes aux mécanismes d’endommagement observés lors des essais in-situ. Le couplage de l’ensemble de ces informations permet de constituer le scénario d’endommagement de chaque nuance. Il est ainsi possible d’établir le rôle de chaque type d’hétérogénéités sur le comportement mécanique des composites oxydes. / The aim of this thesis is the fine understanding on the influence of the microstructure on oxide-based ceramic matrix composites mechanical properties. These materials are good candidate for new generation of civil aircraft engines. The aim of this work is to establish a relationship between the microstructural defects generated by the manufacturing process and the mechanical behavior of the composite. These heterogeneities seem to influence the appearance and the propagation of damage mechanisms. This study is realized on three kinds of bi-dimensional oxide composites generated from three different manufacturing processes. These processes create three kinds of microstructure. Porosimetric and μ-tomographic analyses allow estimating the distribution of microstructural defects and establish typical microstructure of each oxide composite. Based on these preliminary analyses, mechanical behavior of each kind of oxide composites is studied through several representative scales. On the one hand, mechanical tensile tests are carried out in order to estimate the mechanical properties of the studied materials in the weaving plane. On the other hand, the implementation of in-situ mechanical tests allows the visualization of damage mechanisms appearance and propagation. These observations improve the understanding of the role of microstructural defects on the activation of damage mechanisms. Damage kinetics of each mechanical test are inspected through AE (Acoustic emission) analysis. This monitoring helps to link mechanical behavior with microstructural damage. In parallel with global AE analysis, AE clustering is achieved. These classifications are based on two kinds of AE sensor with different properties. Data fusion from the two sensors is accomplished. This technique allows more robust AE clustering. Cluster labelling is proposed thanks to damage mechanisms observed during in-situ mechanical tests. Damage scenarios are set up owing to macroscopic mechanical test, in-situ analysis and AE labelling. Thus, it is possible to establish the influence of each kind of microstructural defect on oxide-based CMCs mechanical behavior.

O desempenho das fundações pode ser avaliado da maneira clássica através de provas de carga estáticas ou dinâmicas. Estas provas de carga são, em geral, caras e demoradas, além de que é necessário que o elemento de fundação já esteja pronto. Outra forma de avaliar o desempenho de fundações é determinar os parâmetros de deformabilidade do solo, em especial os módulos de deformabilidade. Em geral, esses módulos são estimados através de correlações empíricas com o N do SPT ou qc do CPT. Poucas vezes ensaios de laboratório (como o triaxial), ou especiais de campo (como o pressiômetro), são executados para determinação desse parâmetro. Uma possibilidade de contornar esse problema é realizar uma prova de carga no cone elétrico (o ensaio CLT) simultaneamente ao ensaio CPT. Neste trabalho apresenta-se como o ensaio CLT pode ser realizado e como seu resultado pode ser interpretado. Uma campanha de ensaios CLT foi realizada no campo experimental da Unesp de Bauru. Os resultados desses ensaios foram utilizados para calcular o módulo ECLT na região elástica linear inicial da curva, de modo similar como se determina o módulo de Young para o aço. Os valores dos módulos ECLT foram comparados com os módulos de deformabilidade determinados a partir de ensaios de pressiômetro. Também foi possível representar a curva de degradação do módulo de cisalhamento para o local estudado. Apresenta-se também a correlação obtida para estimativa de ECLT a partir dos valores da resistência de ponta do cone (qc) para os solos da área estudada. Conclui-se que o ensaio CLT é uma técnica rápida e econômica que pode ser utilizada como um complemento ao ensaio CPT para um melhor entendimento do comportamento tensão-deformação do solo. Com o ensaio CLT é possível estimar um parâmetro de deformabilidade, o ECLT, bem como representar a degradação do módulo com o nível de deformação. Este ensaio híbrido, CPT+CLT, tem potencial para uso na investigação de solos não convencionais, onde quase sempre não existem parâmetros de referência para estimativa de recalques de fundações. / The performance of foundations can be evaluated the classical way, through static and dynamic load tests. Such load tests are generally time-consuming and expensive, besides that it is necessary that the foundation system be already in place. Another way to evaluate the performance of foundations is to determine the deformability parameters of the soil, especially the the deformability moduli. Ordinarily such moduli are estimated through empirical correlations with N of SPT or qc of CPT. Seldom laboratory tests (such as the triaxial) and field tests (such as the pressiometer) are employed to determine such parameters. One way to solve this problem is to perform a load test on the electric cone (the Cone Loading Test) simultaneously with the CPT test. The work presented here shows how the Cone Loading Test (CLT) can be performed and how its results can be interpreted. A campaign of Cone Loading Tests was conducted at the research site of Unesp-Bauru, São Paulo, Brazil. The CLT results were used to calculate the modulus ECLT in the linear elastic region of the stress-strain curve, in the same manner how the modulus of Young for steel is obtained. The values for ECLT moduli were compared to the deformability moduli obtained from pressiometer (PMT) tests. It was also possible to generate the degradation curve for shear modulus of the soil in the area of study. Presented here are the correlations obtained in the estimation of ECLT from values of cone tip resistance (qc) for the studied soils. From the results obtained, it can be concluded CLT is a fast and inexpensive technique that can be used as a complement to the CPT in improving the understanding of the stress-strain behavior of soils. With CLT it is possible to estimate the deformability parameter ECLT, as well as to represent the degradation of the modulus with increasing levels of strain. Such a hybrid test, CPT+CLT, has potential use in the investigation of non-conventional soils, which lack reference parameters for the estimation os settlement of foundations installed in them.

L’introduction des composites dans des pièces structurelles critiques pour les aéronefs représente une réelle rupture technologique et nécessite des études spécifiques afin de maîtriser leur comportement et leur durabilité. Ce travail a pour objectifs de caractériser et de comprendre les mécanismes de vieillissement de composites interlock 3D à fibres de carbone et à matrice polymère lorsqu’ils sont soumis à des cycles thermiques.Dans ce but, un essai de cyclage thermique (-55°C/120°C), dont l’environnement thermique et gazeux est totalement maitrisé, a été mis en place pour le vieillissement d’échantillons composites représentatifs du motif interlock élémentaire. L’analyse des mécanismes de dégradation induits a été réalisée grâce i/ à la mise au point d’une méthode de caractérisation quantitative 3D de l’évolution des microfissures au cours du cyclage, basée sur des observations par microtomographie RX et sur le développement d’une procédure de traitement d’images spécifique, ii/ au développement d’un essai de cyclage thermique in situ synchrotron couplé à une technique de corrélation d’images volumiques 3D, et iii/ à des simulations par éléments finis prenant en compte l’architecture réelle des échantillons à l’échelle mésoscopique et le comportement thermo-viscoélastique de la matrice.Les résultats obtenus mettent en évidence des couplages thermo-chimio-mécaniques complexes,qui s’expriment à travers quatre paramètres influents : le temps (et le nombre de cycles),l’architecture de l’interlock, la ténacité de la matrice et sa sensibilité à la thermo-oxydation. / The introduction of composite materials in critical structural parts for aircrafts represents a real technological breakthrough and requires specific studies to understand their behavior and durability. This work aims to characterize and understand the ageing mechanisms incarbon/epoxy 3D interlock composites when they are submitted to thermal cycling.For this purpose, a thermal cycle test (-55°C/120°C), whose heat and gaseous environment istotally mastered, was set up for the ageing of composite samples of elemental interlock pattern dimensions. Analysis of induced degradation mechanisms was achieved by i/ the development ofa 3D quantitative characterization method of the evolution of microcracks during cycling, basedon observations by microtomography RX and the development of a specific image processing procedure, ii/ the development of an in situ thermal cycle test under synchrotron light, coupled to a digital volume correlation technique, and iii/finite elements simulations taking into account the actual mesoscopic architecture of the samples and the thermo-viscoelastic behavior of thematrix.The results reveal complex thermo-chemo-mechanical couplings that are linked to four important parameters: time (and the number of cycles), the interlock architecture, the matrix toughness andits sensitivity to thermo-oxidation.

Cette thèse CIFRE a été réalisée dans le cadre d'un partenariat entre l'ENTPE Université de Lyon, AREA et EIFFAGE Travaux Publics. Les méthodes actuelles de détermination et de prévision de l'endommagement des structures de chaussées autoroutières sont peu fiables et nécessitent d'être améliorées. L'objectif de la thèse est de mettre en place une procédure d'analyse inverse donnant accès aux paramètres de comportement des matériaux de chacune des couches de chaussées à partir des mesures de déflexion. Une première étape vise à définir plus précisément les états de contraintes et de déformations existants dans les différentes couches de chaussées. Pour cela, une instrumentation de chaussée autoroutière située proche d'Aix les Bains a été réalisée. 47 capteurs de déformation et de température ont été implantés dans la structure à trois niveaux différents lors de travaux d'entretien effectués en août 2012. En parallèle, des matériaux de chaussée ont été prélevés sur autoroutes pour caractériser leur comportement en laboratoire. Des essais de module complexe ont permis de déterminer les propriétés thermo-visco-élastiques des matériaux. Ces résultats ont permis de modéliser la déformation de la chaussée et de la comparer avec les mesures. Des mesures de déflexion ont également été réalisées sur la chaussée instrumentée à l'aide d'un curviamètre. Les résultats ont pu être comparés à la modélisation. Les différences observées ont permis de proposer une analyse critique des mesures de déflexion. / This thesis was conducted into a parnership between ENTPE university of Lyon, AREA and Eiffage Travaux Publics. Current methods of determination and prediction of damage to highway pavement structures are unreliable and need to be improved. The aim of the thesis is to establish an back analysis procedure from the deflection measurements fiving access to material behavior parameters of each pavement layers. A first step is to define more precisely the states of stress and deformation existing in the different layers of pavement. For this reason, a motorway pavement instrumentation was performed near Aix les Bains in France. 47 strain sensors and temperature were implanted into the structure in three layers during maintenance works in August 2012.In parallel, pavement materials were collected on motorways to characterize their behavior. Complex modulus tests were used to determine the thermo-viscoelalstic properties of materials. These results were used to modeling the deformation of the pavement and compared with measurements. Deflection measurements were also performed on the instrumented pavement with a curviameter device. The reseults were compared to modeling. The observed differences have helped to provide a critical analysis of deflection measurements.

The results of the measurements presented in this manuscript show that none of the coatings has a significant impact on the performance degradation over the course of cell reversal cycling. However, for the EOL polarization curves, the voltage is significantly decreased for the carbon coatings compared to the Au coating. Further experiments should be performed here to determine if these are measurement inaccuracies or if the trend is confirmed. The BIP coatings Cr/a-C also perform worse in the resistance measurements of the HFR and ICR, with the pre-coat variant having the highest values after the tests. The surface changes, which can be seen in the area of the BIP deflections, probably also have an influence here. These appear to be more distinct for the BIP coating Cr/a-C pre-coat. Here, it should be analyzed in more detail how the surface changes and whether metal ions can emerge. The use of the BIP coatings Cr/a-C post- and pre-coat offers a lot of potential, both economically and technically, but cannot be recommended without reservation, as further investigations are still required. / Die Ergebnisse der in diesem Manuskript vorgestellten Messungen zeigen, dass keine der Beschichtungen einen signifikanten Einfluss auf die Leistungsverschlechterung im Verlauf der Cell Reversal Zyklen hat. Bei den EOL Polarisationskurven ist die Spannung bei den Kohlenstoffbeschichtungen jedoch deutlich niedriger als bei der Au-Beschichtung. Hier sollten weitere Experimente durchgeführt werden, um festzustellen, ob es sich um Messungenauigkeiten handelt oder ob der Trend bestätigt wird. Die BIP-Beschichtungen Cr/a-C schneiden auch bei den Widerstandsmessungen des HFR und ICR schlechter ab, wobei die pre-coat nach den Tests die höchsten Werte aufweist. Wahrscheinlich haben auch hier die Oberflächenveränderungen, die im Bereich der BIP Umlenkungen zu sehen sind, einen Einfluss. Diese scheinen bei der BIP Beschichtung Cr/a-C pre-coat deutlicher ausgeprägt zu sein. Hier sollte noch genauer analysiert werden, wie sich die Oberfläche verändert und ob Metallionen austreten können. Der Einsatz der BIP Beschichtungen Cr/a-C post- und pre-coat bietet sowohl wirtschaftlich als auch technisch viel Potenzial, kann aber nicht uneingeschränkt empfohlen werden, da noch weitere Untersuchungen erforderlich sind.

Dynamic penetration tests are frequently used as geotechnical site investigation methods. In Sweden, the main reason to choose a dynamic penetration method is to investigatedepth to bedrock, strength and deformation properties of soil, compaction, or pilingdepth. The advantage of dynamic penetration methods is that they have a betterpenetration ability than static methods and it is therefore easier to penetrate hardmaterial or rock.The most common dynamic penetration method in Sweden is soil-rock sounding. Duringsoil-rock sounding, a metal rod is drilled into the ground and measurements are taken ofdepth, drilling resistance, sinking speed, feeding force, hammer pressure, and rotationalspeed and pressure. The method is conducted in different classes with varying accuracies.Soil-rock sounding is mainly used to determine depth to bedrock, but as the drilling rodpenetrates the whole soil layer profile, there may be opportunities to gain moreknowledge about the penetrated material using the same process.The scope of this licentiate research project was to investigate whether vibrationmeasurements on the ground surface performed simultaneously with soil-rock soundingcan yield additional information about the soil layer profile and the thin layers within amaterial. Measurements were conducted in various building and infrastructure projectsin eastern Sweden between Norrköping and Stockholm/Solna and the results wereanalyzed. It was investigated whether there is a relationship between the vibration resultsand soil properties as determined by other geotechnical investigation methods in thesame area.The results show that soil-rock sounding with simultaneous vibration measurementsconstitutes a promising extension of the conventional soil-rock sounding method whichcan provide additional information about the soil layer profiles at the investigation site.Furthermore, indications can be made about overall soil layer profiles. However, thevibration signals must be adjusted due to distance attenuation before results fromdifferent depths, boreholes and sites are comparable. The different penetrated materials and their properties are correlated to the frequencycontent of the vibration signal. In this way, more information about the penetratedmaterial can be gained from the vibration measurements. The results show thatheterogeneities in the penetrated soil layer can clearly be seen in the vibration results andpatterns in these heterogeneities identified. Furthermore, the results indicate that thevibration signals can help to distinguish silt from sand/gravelly soil and boulder from rock,and the ground water table can be seen in the frequency spectrogram for granular soils. / Dynamiska sonderingsmetoder är vanliga geotekniska undersökningsmetoder. Den främsta anledningen till att välja dynamiska sonderingsmetoder i Sverige är när djup till berggrund, hållfasthets- och deformationsegenskaper av olika jordar, packning eller påldjup ska undersökas. Fördelen med dynamiska sonderingsmetoder är den bättre genomträngningsförmågan jämfört med statiska metoder. På så sätt är det enklare att sondera genom hårt jordmaterial eller berg. Den mest vanliga dynamiska sonderingsmetoden i Sverige är jord-berg-sondering. Vid jord-berg-sondering används en borrstång för att sondera marken och parametrar som djup, borrmotstånd, sjunkningshastighet, matningskraft, hammartryck liksom rotationshastighet och -tryck registreras. Metoden genomförs i olika klasser med olika noggrannheter. Jord-berg-sondering används huvudsakligen för att bestämma djup till berggrund men med tanke på att metoden genomtränger hela jordlagerprofilen vid undersökningsplatsen finns det en stor möjlighet att erhålla mer information om det genomträngda materialet i samband med jord-berg-sondering. Målet med detta forskningsprojekt var att undersöka om man kan erhålla ytterligare information om jordlagerföljden och förekomsten av tunna lager inom ett material när vibrationsmätningar på marken genomförs samtidigt som jord-berg-sondering. Mätningar genomfördes i ett flertal byggnads- och infrastrukturprojekt mellan Norrköping och Stockholm/Solna i östra Sverige och resultaten analyserades. Korrelationen mellan resultaten av vibrationsmätningarna och jordegenskaperna som utvärderades genom andra geotekniska undersökningsmetoder vid samma försöksplats. Resultaten visar att jord-berg-sondering med parallella vibrationsmätningar utgör ett lovande tillägg till den konventionella metoden där man kan erhålla ytterligare information om jordlagerprofilen vid undersökningsplatsen. Vibrationssignalerna måste dock justeras på grund av avståndsdämpning innan resultaten från olika djup, olika borrhål och olika undersökningsplatser kan jämföras mot varandra. De olika genomträngda materialen och deras egenskaper korreleras mot frekvensinnehållet av vibrationssignalen. På det sättet kan ytterligare information om det genomträngda materialet erhållas från vibrationsmätningarna. Resultaten visar att heterogeniteter av det genomträngda jordlagret ses tydligt i vibrationsresultaten och att olika mönster kan identifieras. Utöver det indikerar resultaten att vibrationssignalerna kan hjälpa till att skilja mellan silt och sandiga/grusiga jordar och mellan block och berg. Grundvattennivån kan identifieras i frekvensspektrogrammen för friktionsjordar. / <p>QC 20220329</p>