In view of the foreign mariculture is gradually diversified, and even has a trend that the fish cage aquaculture combines with algae culture at the same facility. A submersible single-point-mooring (SPM) cage system was modified and installed in-situ to investigate the feasibility of the cage system. A numercial model was established to simulate the cage dynamic motion as well as the mooring line tension. A detailed cage construction process was described in this study. Tension meter was used to keep track of mooring line tension, while the ADCP( Acoustic Doppler Current Profiler) was utilized to record the sea state during the test period. Those data were used to validate the numerical model. The field experiements were carried out at a location north to Xiaoliuqiu island. Since the testing period was in winter, the wave height was relativly calm and found to be between 0.5 and 1.2 m, wave period 4~7 seconds, and wave current about 0.2~0.6 m/s. The numerical results indicate that the maximum mooring line tension has good agreement with the meauresments of the tension meter. These comparisons verify that this numerical model is sufficient to simulate this kind of alage cage systems.

The dynamic properties of soil are normally inferred from laboratory tests on collected samples or from empirical relations. The soil properties measured in the field can be very different from those predicted from laboratory tests. It is very difficult to determine directly in the field the variation of the shear modulus and damping with the level of excitation (level of strains). This remains today a major gap in our knowledge and our ability to conduct reliable seismic analyses. The main objective of this study is to assess the feasibility of determining reliably in situ the shear modulus and damping of the soil as functions of the level of strains, developing a method to compute these properties from the measured data and providing practical recommendations for the use of the procedure. To achieve this objective, extensive and comprehensive sets of experimental and analytical studies were conducted in parallel. Some numerical analyses were performed to provide a better understanding for performing in situ tests with the newly developed vibroseis loading systems. In addition, the dynamic response of a surface foundation in vertical vibration were studied. This dissertation mostly focuses on the numerical aspects of the problem while some experimental data are also studied and utilized. Field tests were conducted to estimate shear moduli of silty sands at two sites, the Capital Aggregate Quarry and the Texas A&M University sites. Estimated nonlinear shear moduli presented very consistent trends regardless of the analysis methods and test sites. They showed larger elastic threshold shear strains, 1.5 × 10−3 % for the Capital Aggregate Quarry site and 2 × 10−3 % for the Texas A&M University site, than the mean of shear modulus curve for cohesionless soils proposed by Seed and Idriss (1970). Estimated moduli closely followed the mean of Seed and Idriss (1970) at strains larger than 6 × 10−3 % for both sites. Internal damping ratio can also be estimated if additional data are gathered from in situ tests in the future.

With the purpose of studying the mechanical properties of uncompacted rockfill and the creep deformation behaviour of rockfill under a load as well as finding a suitable method for estimation of creep deformation behaviour, a full scale embankment loading experiment was performed. The results of this experiment were then evaluated. During the course of this study it became evident to the author that the deformations which were seen in the collected data from the experiment could be classified as creep deformations due to the linear decrease of the deformation against the logarithm of time and the study therefore came to focus on creep. One constitutive equation and one model for estimation of creep deformations were studied, and parameters were obtained through back analysis of experiment data as well as calculation of soil stresses. The creep model was based on a logarithmic approximation of the creep deformations and the creep equation was based on a power function. The creep model could also be simplified and evaluated as an equation and when a comparison was made between the equations and the measured results this showed that the logarithmic equation resulted in estimates closer to the measured deformations than what the power function did, therefore a logarithmic function is a better approximation to the deformations of the rockfill at Norvik than the power function. When the creep model was evaluated as intended, based on the soil stresses, the resulting creep estimates were less accurate, they was however still within the limits of what can be considered as admissible. The conclusion is that a logarithmic function describes the creep deformation of the rockfill at Norvik better than a power function and that the creep model by Kristensen is suitable for estimating the creep deformations. This since the creep model also provides a way of estimating deformations occurring under stress conditions other than the ones for which the creep test was performed.

<p>Void growth and coalescence in a single layer model material with holes were visualized by the environmental electron scanning microscope coupled with in situ tensile test. Single sheet model materials were manufactured with a line of laser drilled holes through thickness. In order to investigate the effect of shear localization, the line of holes were oriented with the misorientation angle <em>θ </em>= 0°, 15°, 30°, and 45°. The α-brass samples were studied to introduce the work hardening effect in comparison with the pure copper samples.</p> <p>By taking images at intervals with small strain increments, the void growth behaviors were visualized during the interrupted tensile testing. The void coalescence (defined consistent with Hosokawa et al (2011), as the point at which the voids stopped shrinking laterally) was successfully captured for the first time in the two dimensional studies. The evolutions of void shape change and void rotation during deformation were also studied quantitatively. The results showed that the higher work hardening behaviors can suppress the void coalescence. It also showed that the effect of local volume fraction dominated the coalescence event rather than the void spacing and shear localization. A comparison of the classic models with the experimental results were also made.</p> / Master of Science in Materials Science and Engineering (MSMSE)

O principal objetivo deste trabalho é avaliar a aplicação da técnica híbrida de SPT Sísmico (S-SPT), ou seja, a realização da sísmica up-hole em conjunto com a sondagem de simples reconhecimento com medida de SPT, para uma melhor caracterização de solos tropicais. O ensaio híbrido mais empregado para determinação de parâmetros dos solos, inclusive o módulo de cisalhamento máximo (Go) é o de cone sísmico (SCPT). No entanto, sua realização exige equipamentos especiais e de custo elevado. A possibilidade de medir a velocidade de propagação da onda S (VS) em conjunto com o ensaio SPT empregando o a técnica up-hole é uma alternativa interessante. Essa técnica combinada, pouco empregada no Brasil, foi recentemente desenvolvida e testada. Neste trabalho, a determinação ao mesmo tempo e no mesmo furo dos valores de N do SPT e velocidade de onda S (Vs) permitiu calcular o módulo de cisalhamento máximo (Go) e avaliar as vantagens de se obter a relação Go/N, similar a relação entre Go/qc, para investigação de solos tropicais colapsíveis. As áreas de estudo são os campos experimentais da UNESP-Bauru, USP-São Carlos e UNICAMP-Campinas, onde ensaios S-SPT foram realizados. Os resultados desses ensaios foram comparados com valores de VS referência, determinados através de ensaios sísmicos cross-hole, down-hole e SCPT. A diferença entre os valores de VS foram, em média, 8,5, 9,0% e 16,0% respectivamente para os campos experimentais da UNESP-Bauru, USP-São Carlos e UNICAMP-Campinas. Considera-se que a técnica híbrida do S-SPT pode ser empregada para obter o perfil de Go, em conjunto com o ensaio SPT, rapidamente e a um custo relativamente baixo. Constatou-se que a relação Go/N é maior na camada de solo laterítico, e que ela diminui quanto menos evoluído é o perfil do subsolo. Observou-se essa a mesma tendência nos ensaios S-SPT, porém com menor nitidez. Este fato pode estar associado a maior dificuldade de interpretar os registros de ondas sísmicas pela técnica up-hole bem como pela variabilidade do perfil dos subsolos. / The main objective of this work is to assess the applicability of the hybrid test, the Seismic SPT (S-SPT), i.e. the up-hole seismic test carried out together with SPT test, in order to achieve a better site characterization of tropical soils. The most used hybrid test to determine the soil parameters, including the maximum shear modulus (Go), is the seismic cone test (SCPT). The possibility of measuring the S wave velocity together with the SPT test using the up-hole technique is an interesting alternative. This combined technique was scarcely used in Brazil and it has been recently developed and tested. In this work, the concomitant measuring of the SPT N value together with the S wave velocity in the same test allowed calculating the maximum shear modulus (Go) and assessing the advantages of obtaining the Go/N ratio, similar to the Go/qc ratio, for the site characterization of tropical collapsible soils. The research areas are the experimental sites of UNESP-Bauru, USP-São Carlos and UNICAMP-Campinas, where SPT tests were carried out. The results of these tests were compared with reference values VS, which were determined via cross-hole, down-hole and SCPT tests. The differences between VS values were, in average, 8.5%, 9.0% and 16.0% respectively for UNESP-Bauru, USP-São Carlos and Campinas-UNICAMP research sites. The hybrid S-SPT test can be used to define the Go profile, together with the N SPT values, with a relatively low cost. It was found that the Go/N ratio is higher in the lateritic soil layer and it gets lower as the soil profile is less developed. The same tendency was observed with the S-SPT tests, however with less distinctness. This fact can be associated to a higher difficulty on the interpretation of seismic wave traces with the up-hole technique as well as to soil variability.

L'érosion interne est le résultat de l'arrachement des particules d'un sol sous l'action d'un écoulement hydraulique. Ce phénomène est à l'origine des ruptures hydrauliques des barrages et des digues. Sur le plan mondial, 46% des désordres observés, sur les ouvrages en terre, ont pour origine l'érosion interne. En France, 70 cas critiques ont déjà été détectés. Malheureusement, à cause du phénomène d'érosion lui-même, la prévision du risque reste délicate et les autorités ont du mal à mettre en place des plans d'urgence. Compte tenu du risque potentiel, la compréhension des phénomènes à l'origine de l'érosion interne apparaît comme un enjeu scientifique majeur. L'objectif du travail de thèse est de mettre au point une méthode de diagnostic de l'érosion interne dans les digues et autres ouvrages en terre. Nous cherchons à établir un protocole qui nous guidera sur les essais à faire et qui nous aidera à interpréter les résultats. Cette méthode permettra d'expertiser les risques d'érosion interne. (i) Dans un premier temps, les principaux résultats des reconnaissances géomécaniques permettent d'identifier des couches géotechniques de sol de caractéristiques homogènes dans lesquelles sont réalisés les essais pressiométriques. L'analyse cluster des résultats des essais pressiométriques permet de déterminer le type, la nature de sol, ainsi que les caractéristiques géotechniques moyennes. (ii) Les résultats obtenus servent ensuite à déterminer si le sol est instable et quel est son seuil de sensibilité à l'aide du logiciel expert. Ce logiciel permet de calculer les critères d'érosion interne et de qualifier la sensibilité du sol à l'érosion en déterminant son seuil érosif. (iii) Un nouveau dispositif expérimental appelé l'Essai d'Erosion Transverse (Cross Erosion Test - CET) permet de caractériser expérimentalement le sol par rapport au risque d'érosion interne. Cet essai consiste à injecter de l'eau dans un forage, puis à pomper cette eau dans un forage parallèle au premier. L'eau extraite est chargée en particules produites par l'érosion interne du sol. L'érosion est estimée en se basant sur la mesure de l'évolution de la masse des particules recueillies au cours du temps. Les résultats montrent que cette expérience permet de caractériser l'érosion interne dans un sol spécifique. L'avantage de cette technique c'est qu'elle est transposable in situ et qu'elle peut être utilisée pour prédire le risque de suffusion dans les barrages et les digues. (iv) La validation de l'expérience est faite par un modèle numérique 3D réalisé avec le logiciel Comsol Multiphysics 4.3b. Ce modèle permet de montrer que sous les conditions de perméabilité observées, le gradient hydraulique se concentre autour des points d'injection et de pompage. Une modélisation de base en 2D est développée. Cette première approche permet de décrire le phénomène d'érosion et le transport des particules fines dans le milieu poreux du sol. / Internal erosion is the displacement of the fine particles of a soil under the action of an internal flow. This mechanism could be the origin of the damage on embankments and earth dams. In the word, 46% of failure observed on earthwork, are caused by internal erosion. In France, 70 critical cases have been detected. Unfortunately, due to internal erosion, the prediction of risk remains difficult. The understanding of this phenomenon of internal erosion appears as a major scientific challenge. The aim of this thesis is to develop a diagnostic method of internal erosion in dams and other earthworks. We seek to establish a protocol that will guide us to the test and help us to interpret the results. This method allows concluding about the risk of internal erosion appearance. (i) Initially, the main results of geotechnical survey allow identifying the layers of homogeneous characteristics of soil which are measured by the pressuremeter test. The results of cluster analysis of pressuremeter tests allow determining the localisation, the nature and the mean geotechnical characteristics of the soil. (ii) The results are used to determine the threshold of sensibility to internal erosion with the help of expert software. This software allows to calculate the criteria of internal erosion and to describe the sensitivity of the soil to internal erosion. (iii) A new experimental device is developed in our laboratory. This experiment called “Cross Erosion Test" (CET) allows determining the experimental resistance of the soil to the risk of internal erosion. The test consists of the injection, in a first drilling, of clear water and of the recovery, in another drilling, of water charged with eroded particles. For different initial state of the soils, it is possible to measure and to characterize the internal erosion by visualisation of the water flow and the measurement of the weight of the extracted eroded particles. The results show that this experience allows characterizing the internal erosion in a specific soil. The advantage of this technique is that it can be used in situ to predict the risk of suffusion in dams and dikes. (iv) A validation of experiences, with a 3D finite element method is carried out with the help of the Comsol Multiphysics 4.3b software. This model shows that under experiment hydraulic conditions, the hydraulic gradient is concentrated around the injection and the pumping. A finite element 2D model is developed to simulate erosion process. This approach describes the phenomenon of internal erosion and transport of fines particles in the porous medium of soils tested.

In any geotechnical design procedure, the fundemantal point to be initially clearified is the characterization of existing soil profile at a site. This requires a great deal of planning a suitable site investigation program including borings, sampling, laboratory and in situ testing etc. Laboratory and in-situ (field) tests are important tools leading to the estimation of soils properties in geotechnics. Beside laboratory tests, the measurement of engineering properties in situ is a continuously growing and developing trend, particularly in materials difficult to obtain perfect undisturbed samples. For the purpose of this study, two large volumed geotechnical investigation reports are collected from a wide archive of 30 years experiences. Different soil types are encountered during the study like alluvial deposits of soft to stiff cohesive materials, hard clays in appearance of highly weathered rocks. The in-situ tests mostly being focused and studied on are &ldquo / Pressuremeter Test&rdquo / and &ldquo / Standard Penetration Test&rdquo / on cohesive materails. Over 350 standard penetration test results are recorded together with the pressuremeter results of relevant soils. Besides, the corresponding laboratory test results of oedometer, triaxial loading and all index properties of soils are assembled. The results of in-situ tests are evaluated together with the results of laboratory tests performed on the samples obtained from related sites. The correlations between in-situ &amp / laboratory test results on shear strength, compressibility and deformation characteristics of soils are analysed and compared with the existing correlations in literature. The correlations are generally obtained to be in agreement with the ones in common literature in cases where the soil conditions, particularly saturation, are same in both laboratory and in-situ tests.

Ultra high performance fibre reinforced concrete (UHPFRC) is a relatively new fibre reinforced cementitious composite and has become very popular in construction applications. Extensive experimental studies have been conducted, demonstrating its superior properties such as much higher strength, ductility and durability than conventional fibre reinforced concrete (FRC) and high performance concrete. However, the material's damage and fracture mechanisms at meso/micro scales are not well understood, limiting its wider applications considerably. This study aims at an in-depth understanding of the damage and fracture mechanisms of UHPFRC, combining microscale in-situ X-ray computed tomography (µXCT) experiments and mesoscale image-based numerical modelling. Firstly, in-situ µXCT tests of small-sized UHPFRC specimens under wedge splitting loading were carried out, probably for the first time in the world, using an in-house designed loading rig. With a voxel resolution of 16.9µm, the complicated fracture mechanisms are clearly visualised and characterised using both 2D images and 3D volumes at progressive loading stages, such as initiating of micro-cracks, arresting of cracks by fibres, bending and pulling out of fibres and spalling of mortar at the exit points of inclined fibres. Secondly, based on the statistics of pores in the µXCT images obtained for a 20mm cube specimen, an efficient two-scale analytical-numerical homogenisation method was developed to predict the effective elastic properties of the UHPFRC. The large number of small pores were first homogenised at microscale with sand and cement paste, using elastic moduli from micro-indentation tests. 3D mesoscale finite element models were built at the second scale by direct conversion of the µXCT images, with fibres and large pores were faithfully represented. The effects of the volume fraction and the orientation of steel fibres on the elastic modulus were investigated, indicating that this method can be used to optimise the material micro-structure. Thirdly, 3D mesoscale finite element models were built for the specimen used in the in-situ µXCT wedge splitting test, with embedded fibre elements directly converted from the µXCT images. The fracture behaviour in the mortar was simulated by the damage plasticity model available in ABAQUS. Finally, 2D mesoscale finite element models were developed to simulate the fracture behaviour of UHPFRC using cohesive interface elements to simulate cracks in the mortar, and randomly distributed two-noded 1D fibres and connector elements to simulate the pull-out behaviour of fibres. This approach offers a link between the fibres pull-out behaviour and the response of the whole composite at the macroscale, thus it can be used to conduct parametric studies to optimise the material properties.

O principal objetivo deste trabalho é avaliar a aplicação da técnica híbrida de SPT Sísmico (S-SPT), ou seja, a realização da sísmica up-hole em conjunto com a sondagem de simples reconhecimento com medida de SPT, para uma melhor caracterização de solos tropicais. O ensaio híbrido mais empregado para determinação de parâmetros dos solos, inclusive o módulo de cisalhamento máximo (Go) é o de cone sísmico (SCPT). No entanto, sua realização exige equipamentos especiais e de custo elevado. A possibilidade de medir a velocidade de propagação da onda S (VS) em conjunto com o ensaio SPT empregando o a técnica up-hole é uma alternativa interessante. Essa técnica combinada, pouco empregada no Brasil, foi recentemente desenvolvida e testada. Neste trabalho, a determinação ao mesmo tempo e no mesmo furo dos valores de N do SPT e velocidade de onda S (Vs) permitiu calcular o módulo de cisalhamento máximo (Go) e avaliar as vantagens de se obter a relação Go/N, similar a relação entre Go/qc, para investigação de solos tropicais colapsíveis. As áreas de estudo são os campos experimentais da UNESP-Bauru, USP-São Carlos e UNICAMP-Campinas, onde ensaios S-SPT foram realizados. Os resultados desses ensaios foram comparados com valores de VS referência, determinados através de ensaios sísmicos cross-hole, down-hole e SCPT. A diferença entre os valores de VS foram, em média, 8,5, 9,0% e 16,0% respectivamente para os campos experimentais da UNESP-Bauru, USP-São Carlos e UNICAMP-Campinas. Considera-se que a técnica híbrida do S-SPT pode ser empregada para obter o perfil de Go, em conjunto com o ensaio SPT, rapidamente e a um custo relativamente baixo. Constatou-se que a relação Go/N é maior na camada de solo laterítico, e que ela diminui quanto menos evoluído é o perfil do subsolo. Observou-se essa a mesma tendência nos ensaios S-SPT, porém com menor nitidez. Este fato pode estar associado a maior dificuldade de interpretar os registros de ondas sísmicas pela técnica up-hole bem como pela variabilidade do perfil dos subsolos. / The main objective of this work is to assess the applicability of the hybrid test, the Seismic SPT (S-SPT), i.e. the up-hole seismic test carried out together with SPT test, in order to achieve a better site characterization of tropical soils. The most used hybrid test to determine the soil parameters, including the maximum shear modulus (Go), is the seismic cone test (SCPT). The possibility of measuring the S wave velocity together with the SPT test using the up-hole technique is an interesting alternative. This combined technique was scarcely used in Brazil and it has been recently developed and tested. In this work, the concomitant measuring of the SPT N value together with the S wave velocity in the same test allowed calculating the maximum shear modulus (Go) and assessing the advantages of obtaining the Go/N ratio, similar to the Go/qc ratio, for the site characterization of tropical collapsible soils. The research areas are the experimental sites of UNESP-Bauru, USP-São Carlos and UNICAMP-Campinas, where SPT tests were carried out. The results of these tests were compared with reference values VS, which were determined via cross-hole, down-hole and SCPT tests. The differences between VS values were, in average, 8.5%, 9.0% and 16.0% respectively for UNESP-Bauru, USP-São Carlos and Campinas-UNICAMP research sites. The hybrid S-SPT test can be used to define the Go profile, together with the N SPT values, with a relatively low cost. It was found that the Go/N ratio is higher in the lateritic soil layer and it gets lower as the soil profile is less developed. The same tendency was observed with the S-SPT tests, however with less distinctness. This fact can be associated to a higher difficulty on the interpretation of seismic wave traces with the up-hole technique as well as to soil variability.

Orientadores: Antonio Jose Ramirez, Rubens Caram Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-11T13:06:54Z (GMT). No. of bitstreams: 1 TorresLopez_EdwarAndres_M.pdf: 39783627 bytes, checksum: 03310e12f2969671a1edcad6da907e3b (MD5) Previous issue date: 2008 / Resumo: Foi desenvolvido um experimento para estudo in-situ dos processos de deformação a alta temperatura no interior do microscópio eletrônico de varredura, permitindo assim o estudo do fenômeno de trincamento a alta temperatura, denominado fratura por queda de ductilidade. Este experimento teve como finalidade o estudo específico das ligas de níquel AWS A5.14 ERNiCrFe-7 e ERNiCr-3AWS empregadas como metal de aporte para a soldagem de ligas de Ni. Instrumentação cientifica dedicada foi desenvolvida e modificada de modo a superar os desafios impostos pelas condições experimentais adversas associadas as elevadas temperaturas necessárias, à compatibilização do experimento com o nível de vácuo necessário na câmera do microscópio e finalmente, à estabilidade mecânica necessária para o acompanhamento do processo de deformação em escala micrométrica juntamente com os processos de aquecimento e de aplicação de forças elevadas. Utilizando esta instrumentação foram definidas as condições e procedimentos adequados para o acompanhamento do processo de deformação das ligas de Ni AWS A5.14 ERNiCrFe-7 e ERNiCr-3 em temperaturas entre 700 e 1000 °C, de forma a estudar as condições de inicio da fratura por queda de ductilidade nestes materiais. Porém, a instrumentação desenvolvida permite não apenas estudar o fenômeno de fratura por queda de ductilidade e avaliar o desempenho de ligas experimentais, mas também o estudo tanto qualitativo como quantitativo de diversos outros fenômenos de fratura e transformação de fase / Abstract: An in-situ high temperature deformation experiment was developed and adapted be performed within the vacuum chamber of a scanning electron microscope in order to study the high temperature cracking phenomenon known as ductility-dip cracking. This experiment was specifically applied to the study of Ni-base alloys AWS A5.14 ERNiCrFe-7 e ERNiCr-3, which are commonly used as filler metal to weld Ni- and Fe- based alloys. Dedicated scientific instrumentation was developed and modified to overcome the challenges imposed by the severe experimental conditions as elevated temperatures and forces, the compatibleness with the microscope vacuum chamber, and the required mechanical stability to track deformation processes at the micro scale. Using this instrumentation were defined and optimized the conditions to study the deformation of Ni-base alloys AWS A5.14 ERNiCrFe-7 e ERNiCr-3 alloys between 700 and 1000 °C and therefore, helps to elucidate the causes of ductility-dip cracking phenomenon . However, the developed instrumentation is a powerful tool to perform several other qualitative and quantitative studies of deformation, cracking phenomena and phase transformations in different materials / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica