Prestressed Concrete Cylinder Pipe (PCCP) is a large-diameter and high-pressure conduit for drinking water and wastewater transmission. Due to its large diameter, high pressure, and mode of breakdown, PCCP failures usually have catastrophic consequences. To mitigate failures, it is very important to assess the condition of the pipe and take proactive measures, such as repair, rehabilitation, or replacement. There are many challenges in assessing the condition of PCCP. PCCP has a complex structure with several layers of materials (e.g. mortar coating, prestressing wire, steel cylinder, and concrete core) working together under loading. This means that there are many factors that can cause pipe failure, and that failure mechanisms are complicated. Data collection could be difficult, and existing data are often unavailable or unreliable. Considerable research has been conducted by scholars and engineers in developing models to evaluate the condition of PCCP. There are mainly two types of models: statistical models, and numerical models using finite element method. Statistical models consider only a few factors, such as pipe age and failure rate, to predict the failure of PCCP. However, the failure of PCCP can be caused by many other factors including pipe material, and loading conditions. Models only considering a few factors are not robust enough for reliable results. The current numerical models assume that all broken wires are centrally distributed in the same location and broken wires have no prestress, thus all broken wires are completely removed from the model. These assumptions could be overly conservative when actual broken wires are distributed in different locations along the pipeline and broken wires have remaining prestress due to the bond between the wire and mortar coating. Therefore, a more comprehensive numerical model is needed to have a better understanding of the condition of PCCP. In this research, an extensive literature and practice review was conducted on PCCP failures to understand the critical factors that affect pipe condition. The available technologies commonly used to detect pipe defects were reviewed in order to better understand the accuracy and uncertainties of the collected data. Existing models were reviewed to better understand their limitations and to advance the research on condition analysis of PCCP using numerical models. Based on these comprehensive reviews, this dissertation proposed a numerical model to analyze the condition of PCCP for its long-term performance management. Detailed structural components such as concrete cores, prestressing wires, steel cylinder, and mortar coating were modelled. The interactions between different layers of pipe components were considered. An algorithm was proposed to account for the bond between the prestressing wire and mortar coating, which is a critical factor for the condition of PCCP with broken wires. A FORTRAN program was developed to assign linear stress distribution between the broken point and the full-prestress resuming point. The proposed numerical model was verified utilizing data from lab tests and forensic study. Lab test data helped to understand the functionality of the model and to verify the model parameters used in analyzing pipe components and the simulation of interactions between different layers. The forensic data helped to verify the model under actual field working conditions of the pipe. Validation of the proposed numerical model was conducted using a 66-inch Embedded Cylinder Pipe and two Lined Cylinder Pipes (42-inch and 48-inch, respectively) from a water utility. In the validation, field data were collected for model development. The simulation results were consistent with the field observation, which proved the validity and applicability of the proposed numerical model in practice. A series of sensitivity studies were conducted to investigate the impact of longitudinal and circumferential location on the structural integrity of the pipe. These investigations showed that considering the actual longitudinal and circumferential location of broken wires is very important to get accurate analysis of pipe condition, while assuming that all broken wires fail in one longitudinal location (assumptions by current numerical models for PCCP) will overestimate the actual damage to the pipe caused by broken wires. To consider the bedding condition, a critical factor for PCCP, the four most common bedding types found in practice were analyzed. Results show that poor bedding could lead to cracks in PCCP, which could cause corrosion in prestressing wires. Therefore, it is very important to account for bedding conditions in the PCCP analysis. The model presented in this dissertation is more comprehensive and robust compared with existing numerical models, and could provide a better understanding of the condition of PCCP. This is because the proposed model considers the contribution of remaining prestress in broken wires due to the bond between the wire and mortar coating. This model can consider the actual longitudinal and circumferential location of broken wires rather than centrally distribute them, and it can consider the actual bedding locations, and the interaction between different layers of materials. This model was calibrated using lab test data and forensic data, and was further validated using field data which showed consistence between simulation results and field observations. The proposed model does have limitations due to limited availability of data and assumptions. Material tests were not conducted to verify the material properties used in the model, which could cause accuracy issues in the results. A full-scale simulation of the interaction between prestressing wire and mortar coating was not considered because it could significantly increase the computation time. Lab tests were not conducted to verify the parameters used for the simulation of interaction between concrete core and steel cylinder which could lead to accuracy problems. Finally, it is acknowledged that the model was only validated in one water utility and validations in more geographically distributed utilities might further test the model's validity and robustness. Nonetheless, the comprehensiveness and robustness of this proposed model improved the analysis of the condition of PCCP. The findings and results of this research will provide guidance for better management of PCCP pipelines for water utilities, and provide reference for future research on numerical modeling of PCCP as well. / Ph. D.

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

京都大学 / 新制・課程博士 / 博士(理学) / 甲第25124号 / 理博第5031号 / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)教授 竹見 哲也, 教授 榎本 剛, 教授 向川 均 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第25253号 / 工博第5212号 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 川池 健司, 教授 山上 路生, 准教授 米山 望 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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.