Current fire induced burnthrough models of aluminum typically rely solely on temperature thresholds and cannot accurately capture either the occurrence or the time to burnthrough. This research experimentally explores the fire induced burnthrough phenomenon of AA6061-T651 plates under multiple sized exposures and introduces a new burnthrough model based on the near melting creep rupture properties of the material. Fire experiments to induce burnthrough on aluminum plates were conducted using localized exposure from a propane jet burner and broader exposure from a propane sand burner. A material melting mechanism was observed for all localized exposures while a material rupture mechanism was observed for horizontally oriented plates exposed to the broader heat flux. Numerical burnthrough models were developed for each of the observed burnthrough mechanisms. Material melting was captured using a temperature threshold model of 633 deg C. Material rupture was captured using a Larson-Miller based creep rupture model. To implement the material rupture model, a characterization of the creep rupture properties was conducted at temperatures between 500 and 590 deg C. The Larson-Miller curve was subsequently developed to capture rupture behavior. Additionally, the secondary and tertiary creep behavior of the material was modeled using a modified Kachanov-Rabotnov creep model. Thermal finite element model accuracy was increased by adapting a methodology for using infrared thermography to measure spatially and temporally varying full-field heat flux maps. Once validated and implemented, thermal models of the aluminum burnthrough experiments were accurate to 20 deg C in the transient and 10 deg C in the steady state regions. Using thermo-mechanical finite element analyses, the burnthrough models were benchmarked against experimental data. Utilizing the melting and rupture mechanism models, burnthrough occurrence was accurately modeled for over 90% of experiments and modeled burnthrough times were within 20% for the melting mechanism and 50% for the rupture mechanism. Simplified burnthrough equations were also developed to facilitate the use of the burnthrough models in a design setting. Equations were benchmarked against models of flat and stiffened plates and the burnthrough experiments. Melting mechanism burnthrough time results were within 25% of benchmark values suggesting accurate capture of the mechanism. Rupture mechanism burnthrough results were within 60% of benchmark values. / Ph. D.

Following the DWH oil spill event, crude oil reaching the shoreline of Gulf of Mexico produced petroleum oil deposit with a range of distinct geometries, including sphere tar balls and horizontal tar sheets. Numerical models were developed based on the Deep Water Horizon oil spill conditions to evaluate the influence of deposit geometry on long term persistence of residual NAPL oil. Two extreme deposit geometries were modeled in this study: the horizontal tar sheet and the spherical tar ball. Both two-dimensional modeling approach and three-dimensional modeling approach were applied to compare two contrasting geometries. The two-dimensional model results showed that sheet geometry deposits exhibited a greater obstruction to groundwater flow relative to the spherical deposits and induced a larger sulfate reducing zone downgradient of the NAPL source, resulting in significantly greater sulfate-based biodegradation of benzene. Three-dimensional models were constructed to assess the influence of key geometry parameters on oil deposit fate and persistence. Three parameters affecting deposit's geometric structure were recognized, including the upper horizontal area of the sheet deposit, the thickness of the sheet deposit, and the radius of the sphere deposit. The three-dimensional model results suggested that thickness of the sheet deposit and radius of the sphere deposit were important geometry factors impacting the fate and long term persistence of residual NAPL oil in the coastal environment. However, the influence of deposit geometry differed depending on the solubility of the different NAPL components. When high solubility compound and low solubility compound both exist in the oil deposit, the influence of deposit geometry on benzene degradation was significant, while the influence on naphthalene was almost negligible. / Master of Science

Hydrothermal processes play a major role in transporting mass and energy in Earth’s crust. These processes rely on hydrothermal fluid, which is dissolving, transporting and precipitating minerals and distribute heat. The composition of the hydrothermal fluid is specific for various geological settings, but in most cases it can be approximated by H₂O-NaCl-CO₂ fluid composition. The flow of hydrothermal fluid is controlled by differences in temperature, pressure and/or density of the fluid and hydraulic conductivity of the rock. In my work, I was focused on modeling of the hydrothermal fluid properties and experimental characterization of fluid that formed emerald deposit in North Carolina, USA. The dissertation based on the result of three separate projects. The first project has been dedicated to characterization of the H₂O-NaCl hydrothermal fluid ability to transport mass and energy. This ability of the fluid is defined by a change in fluid density and enthalpy in response to changing pressure or temperature. In this project we quantified the derivatives of mass, enthalpy and SiO₂ solubility in wide range of pressure, temperature and composition (PTx) of H₂O-NaCl fluid. Our study indicated that the PT region in which fluid is most efficiently can transport mass and energy, located in the critical region near liquid-vapor phase boundary and the sensitivity to changing pressure-temperature conditions decrease with increasing salinity. In second project we developed the revised H₂O-NaCl viscosity model. Revised model to calculate the viscosity of H₂O-NaCl reproduces experimental data with ±10% precision in PTx range where experimental data available and follows expected trends outside of the range. This model is valid over the temperature range from the H₂O solidus (~0 °C) to ~1,000 °C, from ~0.1 MPa to ≤500 MPa, and for salinities from 0-100 wt.% NaCl. The third project has been focused on the characterization of formation conditions of the emerald at North American Emerald Mine, Hiddenite, North Carolina, USA. The emerald formation conditions defined as 120-220 MPa, 450-625 °C using stable isotope, Raman spectrometry, and fluid inclusion analysis. Hydrothermal fluid had a composition of CO2-H2O±CH4, which indicates mildly reducing environment of emerald growth. / Ph. D.

Free-Fall Penetrometer (FFP) testing is an easy and rapid test procedure for seabed sediment characterization favorable to conventional geotechnical testing mainly due to its cost-effectiveness. Yet, FFP testing results are interpreted using empirical correlations, but difficulties arise to understand soil behavior under the high-strain rate (HSR) loading effects during rapid FFP penetration. The numerical simulation of FFP-soil interaction is also challenging. This study aims to numerically analyze FFP testing of saturated loose sands using the particle-based Material Point Method (MPM). The numerical analysis was conducted by simulating calibration chamber FFP tests on saturated loose quartz sand. The numerical results using quasi-static properties resulted in a reaction of the sand softer than the actual calibration chamber test. This implied the necessity of considering HSR effects. After performing parametric analyses, it was concluded that dilation plays an important role in the response of sand-water mixtures. Comparison of dry and saturated simulations showed that FFP penetration increases when the soil is dry and tends to develop a general bearing capacity failure mechanism. This is because the pore water increases the stiffness of the system and due to the increased strength that develops in saturated dilative sands when negative pore pressures develop. Local bearing failure mechanism is observed in all saturated simulations. Finally, numerical CPT (quasi-static) and FFP tests were used to examine the strain rate coefficient used in practice (K); and a consistent range between 1 to 1.5 was obtained. / Master of Science / Accurate characterization of seabed sediments is crucial to understand sediment mobilization processes and to solve nearshore engineering problems such as scouring around offshore structures. Its portability, low testing effort, and repeatability make FreeFall Penetrometer (FFP) testing a highly cost-effective sediment characterization test. Nevertheless, due to the complex penetration mechanism of FFPs in soils (e.g., high-strain rate effects due to rapid FFP loading), converting FFP output into practical information is complicated, and it heavily relies on empirical correlations. This thesis presents a numerical analysis of FFP testing on saturated sand using the Material Point Method. First, the simulation results were compared with laboratory tests. Later, a parametric study was performed to understand the effect of different material parameters on the FFP response and to highlight in a simplified manner the effects of rapid loading on the sand behavior. Additional simulations in dry sand (without water) revealed that dry conditions provide larger FFP penetrations than saturated ones for the same material parameters. Lastly, the strain rate coefficient, which is a parameter required in one of the most common empirical methods for converting FFP output into geotechnical parameters, was back-calculated. The results were consistent with values used in practice for similar conditions.

This thesis describes the creation of RECOVERY-RD, a numerical model capable of representing the biotransformation processes associated with Polychlorinated Biphenyl (PCB) compounds in contaminated sediments for a variety of aquatic environments, including rivers and marine systems. RECOVERY-RD is intended as a screening tool for evaluating the impact of engineered sediment caps on contaminant remediation. The two key components that provided the framework for RECOVERY-RD are RECOVERY, a model for contaminant transport in stratified sediment, and SEAM3D, a numerical transport model for contaminated groundwater systems. The predictions made by RECOVERY-RD are verified using a series of test cases organized to test each phase of the modification process individually. The results show that the processes simulated by RECOVERY-RD are reasonably represented when compared to alternative calculation methods that have been previously verified. A hypothetical application of the initial version of the model provides evidence of the usefulness as a screening-level tool for the assessment of remedial efficacy. / Master of Science

Coarse-grained beaches are particularly prevalent in the UK, composed of accumulations of either gravel, or mixed sand and gravel sediments. The aim of the work presented in this thesis is to improve capabilities for predicting coarse-grained beach 2D profile development. In particular, the effects of infiltration and sediment sorting are considered. In this study, the public domain numerical model, XBeach (v12) is developed further. This model was initially developed for studying sandy environments especially for the case of dune erosion. Here, the model is modified to enhance its capability to predict beach profile change on coarse-grained beaches. Improvements include: use of Lagrangian interpretation of velocity in place of Eulerian for driving sediment movement; introduction of a new morphological module based upon Soulsby’s sediment transport equation for waves and currents; incorporation of Packwood’s infiltration approach in the unsaturated area of the swash region; and implementation of a multiple sediment fraction algorithm for sediment sorting of mixed sediments. These changes are suggested and justified in order to significantly improve the application of this model to gravel and mixed beaches, especially with regard to swash velocity asymmetry which is responsible for development of the steep accretionary phase steep berm above waterline and sediment sorting. A comparison between model simulation and large scale experiments is presented with particular regard to the tendency for onshore transport and profile steepening during calm conditions; offshore transport and profile flattening during storm conditions; and sediment sorting in the swash zone. Data used for this and the model calibration comes from the Large Wave Channel (GWK) of the Coastal Research Centre (FZK) in Hannover, Germany. The results are found to agree well with the measured experimental data on gravel beach profile evolution. This is due to the inclusion of infiltration in the model which weakens the backwash volume and velocity in a more satisfying manner than through the use of asymmetric swash friction and transport coefficient. The model also simulates sediment sorting of a mixed sediment beach. However, the profile comparisons were not satisfactory due to limitations of the numerical model such as the constant permeability rate used throughout the simulation and the non-conservation of the sediment volume in the laboratory data by an order of 50%. From the simulation, it was found that the fine sediment moves offshore and the coarser sediment moves onshore. This is because of infiltration weakens the backwash velocity; the coarser sediment moving onshore barely moves back offshore while the fine sediment remains in motion. This pattern agrees with the pattern obtained from sediment samples analysis in the experiment and provides an explanation for the existence of composite beaches. The model is also shown to be capable of switching from accretionary to erosive conditions as the wave conditions become more storm-like. Again, the model simulations were in a good agreement with the observations from the GWK dataset. Numerical model simulations on the effects of the tidal cycle on coarse-grained beach profile evolution were also carried out. This preliminary investigation showed that the model was able to predict the anticipated profile change associated with a coarse-grained beach under such wave and tidal forcing. Tidally forced accretion and erosion were compared with those predicted under similar beach sediments and wave conditions for constant water level. The main differences are that the affected area is wider and the berm is located on the upper beach during flood for both gravel and mixed beaches. Therefore, the model developed in this study can be seen to be a robust tool with which to investigate cross-shore beach profile change on coarse-grained beaches and sediment sorting on mixed beaches. Further work is also indicated.

Lors des accidents de la route, les lésions de l’abdomen mettent des vies en jeu et nécessitent un traitement médical long et coûteux. Il est important d’offrir une meilleure prévention des lésions abdominales traumatiques. Des modèles numériques de corps humain ont été développés afin de comprendre les mécanismes lésionnels. L’objectif de cette thèse est de contribuer au développement d’un modèle numérique de foie humain pour la prédiction de lésions hépatiques en cas de choc.Dans un premier temps, une caractérisation morphologique du foie a été réalisée sur 78 scanners et a mis en évidence l’existence de 4 morphotypes. Ensuite, des expérimentations ont mis en évidence l’influence de la pressurisation des vaisseaux sur la déformation de la capsule et ont permis d’identifier la déformation à rupture locale lors d’un choc.Enfin, les modèles numériques des 4 morphotypes identifiés ont été construits pour simuler les essais de décélération réalisés dans la partie expérimentale. / In road accidents, lesions of the abdomen are life-threatening, and require a long and expensive medical treatment. It is important to offer a better prevention of traumatic abdominal injuries. Numerical models of the human body have been developed to understand the mechanisms of injury. The aim of this thesis is to contribute to the development of a numerical model of human liver for the prediction of liver lesions in case of shock.First, a morphological characterization of the liver was performed on 78 healthy patient scanners and highlight the existence of 4 morphotypes.Then, experiments were carried out to highlight the influence of this pressurization of the vessels on the strain state of the Glisson capsule and to identify the local ultimate strain during an impact.Finally, the numerical models of the 4 identified morphotypes were constructed and used to simulate the deceleration tests performed in the experimental part.

A presente tese versa sobre ampla investigação em torno da distribuição das ações verticais entre paredes de alvenaria estrutural dentro de um edifício. O edifício foi caracterizado como pertencente ao sistema complexo de paredes, o qual é de uso mais comum no Brasil. Desenvolveu-se análise numérica no edifício, com objetivo de predizer o comportamento na análise experimental, assim como na comparação entre os próprios modelos numéricos. Serviu de modelo experimental um edifício em escala real, o qual foi monitorado, durante sua execução e depois dela, com ensaio de prova de carga. Realizou-se monitoramento mediante uso de unidades especiais de alvenaria instrumentadas para se converterem em células de carga, nas quais as tensões em cada ponto de análise puderam ser determinadas. Tabelas e gráficos foram montados para tornarem possível a verificação das diferenças entre todos os modelos analisados. Como principais conclusões uma se mostrou de grande importância e foi esta: as paredes sofrem efeito da flexão e a causa são as rotações nas lajes apoiadas por elas. / The present thesis contemplated a wide investigation about the vertical action distribution among structural masonry walls within a building. The building was characterized as related to the complex system of walls, which practice is the most customary in Brazil. It was developed a numerical analysis in the building aiming to predict the structural behavior on the experimental analysis, as well as a comparison among numerical models themselves. The experimental model consisted on a real scale building, which was monitored during its execution and after that, with a live load test. The monitoring was done with the usage of special masonry units, which were instrumented to convert itself in a load cell, on which the stress in each point of analysis could be determined. Tables and graphics were mounted to make feasible to verify the differences among all models analyzed. As main conclusions observed, one showed to be of great importance, which was the effect of bending on the walls caused by the rotations on the slabs supported by them.

A Plataforma Continental do Estado do Ceará (PCCE) foi dividida em: Plataforma Continental Externa (PCE), Plataforma Continental Média (PCM) e Plataforma Continental Interna (PCI). Os critérios físicos adotados levaram em consideração intrusões mais ou menos intensas de água tropical (AT) transportada pela Corrente Norte do Brasil (CNB) em direção à costa; a intensificação dos gradientes de salinidade superficial; e a mistura entre diferentes massas de água. Durante a estação de chuva, observamos que na região da PCE a massa de Água Tropical (AT) ficou aprisionada em níveis verticais maiores que 60 m, enquanto que na PCI observamos a formação de uma pluma estuarina que ocupou os dois primeiros metros da coluna de água e provocou o rebaixamento do topo da massa de água costeira (AC), chegando a 6 km da linha de costa. A variação espaço-temporal das correntes na frequência submaregráfica mostram que a tensão de cisalhamento do vento (TCV) foi o principal agente na transferência de momentum para as águas da PCCE, gerando uma corrente de deriva polarizada para NW, paralela à direção das isóbatas, em resposta ao empilhamento de água na costa. Este comportamento, associado a espessura da camada de Ekman muito maior que a profundidade local, mostra que a dinâmica do primeiro modo de oscilação (barotópico) é dominante, gerando correntes na direção do vento forçante, como resposta à sua ação. O modo barotópico também foi dominante nas correntes de maré, com as componentes semi-diurnas (M2 e S2) caracterizando-se como as mais energéticas. A orientação normal das elipses de maré associada ao sentido horário de rotação, foram responsáveis pelas maiores velocidades de corrente na frequência maregráfica. Os resultados obtidos com o modelo numérico mostram a res\\-posta barotrópica das águas da PC a um vento estacionário com correntes para NW. Os maiores valores das corrente e elevação do nível do mar ocorreram na região mais próxima à costa. As correntes de maré e a orientação das elipses de maré obtidas com a modelagem corroboram o o comportamento dos dados observacionais. Para o estuário do Rio Jaguaribe (CE), o período de grandes descargas fluviais resultou em fluxos unidirecionais transportando volumes de 97 x 106 m3, advectando os processos de mistura para a região da PCI. Entretanto, na estação seca, a minimização dos fluxos fluviais resultou na maior atuação da maré na região, controlando a posição espacial da zona de máxima turbidez. Nesta época do ano o estuário foi classificado de acordo com parâmetros de estratificação e circulação como do tipo 2a, parcialmente misturado. / The Continental Shelf of Ceará State was divided in: External (ECS), Middle (MCS) and Inner (ICS) Continental Shelf. The physical criteria of classification considered intrusions of Tropical Water (TW) transported onshore by the North Brazil Current (NBC); intensification of surface saline gradient; and mixing of different water masses. During the rainy season, the TW was retained the ECS at levels higher than 60 m, while an estuarine plume formation was observed in the PCI, occupying the two first meters of the water column, sinking top of the coastal water mass (CW) to 6 km off coast. The space-time variation of the currents in the subtidal frequency shows that wind stress was the main agent in the momentum transfer to continental shelf waters, generating a current to NW, parallel to the direction of the isobaths, in response to the stacking of water on the coast. This behavior associated to the thickness of the Ekman layer much larger than local depth, shows the dominance of the barotropic dynamic, generating currents in the wind direction, as response to its action. The barotropic mode was also dominant in the tidal currents, with semi-diurnals components (M2 e S2) characterized as the most energetic. The normal orientation of tidal ellipses, associated to clockwise rotation, were responsible for the highest current velocities in tidal frequency in MCS. Numerical model results show a barotropic response of waters to a stationary wind, with currents to NW, and highest values of currents and sea level ocurring closer the coast. Tidal currents and tidal ellipses orientation obtained by numerical model support the observations. In relation to Jaguaribe River estuary, the period of great river input led to unidirectional flows, which transport volumes of 97 x 106 m3, advecting the mixing process to the ICS region. However, during the dry season, river input decrease resulted in a larger tide influence in the region, controlling the spatial position of the mixing zone. For this time, the estuary was classified according to the parameters of estratification and circulation as a 2a type, partially mix

A utilização de concreto projetado como suporte de túneis é uma prática amplamente difundida no mundo inteiro. Este tipo material possui a característica de começar a agir estruturalmente desde pequenas idades. Apesar disso, os correntes processos de dimensionamento de suportes negligenciam o desenvolvimento de suas propriedades com o tempo, em acoplamento aos efeitos tridimensionais da região onde se localiza a frente de escavação. O presente trabalho tem a finalidade de relatar os procedimentos utilizados na análise da influência de alguns parâmetros da interação maciço - suporte, sobre os esforços solicitantes e os deslocamentos radiais finais do suporte de um túnel, tanto para o caso de concreto projetado, com suas propriedades dependentes do tempo, quanto para materiais com propriedades constantes. São elaboradas soluções adimensionais para o problema da quantificação de esforços solicitantes no suporte e de deslocamentos radiais na interface entre maciço e suporte. Além disso, é proposta uma forma de se determinar, através destas soluções adimensionais, coeficientes de alívio de tensões que auxiliam em simulações bidimensionais de escavações subterrâneas. / The utilization of shotcrete as tunnel support is a widely diffused practice in the whole world. This kind of material has the feature of beginning to act structurally since early ages. Nevertheless, the current processes of support design neglect the development of its properties after some time in connection to the 3D effects of the region where the face of the tunnel is located. The present work relates the procedures adopted in analyzing the influence of some ground-support interaction parameters on the support internal forces and interface radial displacements of a tunnel, not only when shotcrete is used, with its time-dependent properties, but for materials with constant properties as well. Dimensionless solutions are developed for the support thrust and radial displacement quantification problem. Moreover, through this dimensionless solution, a way of quantifying stress relief factors, which are intermediate steps in 2D simulations of underground excavations, is proposed.