Settlement-Induced Bending Moments (SIBM) are an important design condition that must be considered whenever battered piles are placed in settling soils. The objective of this research was to investigate various parameters which can affect SIBM in battered piles within a levee embankment. The results from the current study were compared and verified against those obtained from centrifuge testing and alternative numerical simulations. A series of centrifuge testing as well as finite difference numerical simulations in Fast Langrangian Analysis of Continua (FLAC) were conducted. Different parameters which may affect the bending moments were investigated including pile connection fixity, batter, and stiffness of the pile as well as the magnitude of settlement. The simulations show that these parameters can have large impacts on the magnitude and location of the bending moments. Findings of this research can be used to validate or identify the need for adjustment of the current modeling/design approach.

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第22815号 / 地環博第202号 / 新制||地環||39(附属図書館) / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 勝見 武, 教授 木村 亮, 准教授 高井 敦史 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24892号 / 工博第5172号 / 新制||工||1988(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 渦岡 良介, 教授 安原 英明, 教授 肥後 陽介 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

No description available.

Pile-supported T-walls, which are concrete floodwalls that are shaped like an inverted "T" and supported by batter piles, are commonly used by the United States Army Corps of Engineers (USACE) to protect low-lying portions of New Orleans and other areas. The design of a T-wall in southern Louisiana is complex, as the structure needs to resist both 1) large settlements caused by fill placed beneath and beside the T-wall before T-wall construction or by fill placed beside the T-wall after T-wall construction, and 2) large lateral flood loads that are imposed during a hurricane. As a result of these loading conditions, large bending moments can develop in the batter piles and these moments need to be accounted for as part of the T wall design. The goal of this research is to develop a more complete understanding of the pile bending moments in T wall systems, specifically for cross sections where large settlements may occur. As a first step towards this goal, Rensselaer Polytechnic Institute (RPI) performed a series of eight centrifuge tests to investigate and physically model the effects of settlement-induced bending moments on pile-supported T-walls. The centrifuge tests were evaluated and interpreted, and in order to better capture uncertainty, upper and lower bounds were estimated for the interpreted data. The centrifuge results offered some valuable insights on their own, but were ultimately used as the basis for validating and calibrating corresponding numerical models. The numerical models were developed following a rigorous modeling approach and using rational and reasonable assumptions based on widely-accepted and well-justified procedures. The numerical model results were in good agreement with the centrifuge results without the need for significant calibration or modifications. This good agreement indicates that similar numerical models can be developed to reliably analyze actual T-wall cross sections. Detailed recommendations were developed for using numerical models to analyze pile-supported T walls, and an example problem is presented herein that illustrates the application of this approach. These same techniques were then used to perform a parametric study to analyze the combined and separate effects of flood loading for a wide range of different T-wall cross sections. The range was selected in collaboration with the USACE in order to reasonably cover cross sections and conditions that 1) are typically encountered in practice, and 2) were expected to generate both upper and lower bound pile bending moments. In total, 3,648 cross sections were analyzed, and 29,184 sets of analysis results were generated since each cross section was analyzed for eight different loading conditions. Summary results are provided to show the influence of the loading conditions and parameters on T-wall response, including the influence of flood loading, new fill symmetry, pile fixity, number of piles, subsurface profile, pile batter, pile type, levee slope, T-wall elevation, and the presence of existing levee fill. In addition, the key results for all of the analyses are provided in the appendices and in an electronic database. Based on the parametric study results, a simplified analysis procedure was developed that can be used to calculated maximum pile bending moments for T walls installed directly on foundation soils due to settlements. In this procedure, the loads from new fill placed during or after T-wall construction are distributed onto the pile, and the pile response is analyzed using traditional p-y curves and a beam on elastic foundation formulation. This procedure shows good agreement with the numerical model results for a range of conditions. To demonstrate the application of the procedure, the same example problem that is analyzed numerically is reanalyzed using the simplified analysis procedure. Due to the complexity of the problem, it was not possible to modify this procedure or develop a similar procedure for T-walls installed on top of new or existing levees. Overall, this research demonstrates that numerical models can be used to calculate the bending moments that can develop in pile-supported T-walls due to settlements and flood loading, provides valuable insights into the behavior of T-walls and the influence of various parameters on T-wall response, presents a large database of T-wall analysis results, and recommends a simplified analysis procedure that can be used in some cases to calculate pile bending moments due to settlements. / Ph. D.

Microfabrication of ceramic features has become a critical issue in realizing the miniaturization of devices. Micromolding and sintering play critical roles in fabricating micron- and submicron-sized ceramic features using nanoparticles. Developed from soft lithography, replica molding has been proven a good method to prepare micron- and submicron-sized features. However, the fidelity of the features can be compromised by incomplete feature cavity filling and feature shrinkage during the forming process. In this study, centrifuge-aided micromolding is developed to prepare micron- and submicron-sized ZnO features. By introducing a centrifugal force, the shear-thinning behavior of the suspensions is utilized, and the cavity filling process and the diffusion of trapped air out of the features are accelerated. The drying shrinkage is decreased by increasing the density of the wet nanoparticle packing from the centrifugal process. The centrifugal force improves the fidelity of all the designed features. ZnO ridges from 0.4 μm to 2 μm size and rods of 1.6 μm size are prepared successfully. The wide applicability of this strategy has been demonstrated by preparing ZrO2 features via the same method. Sintering process has a significant influence on the morphology and microstructural evolution of micron-sized ceramic features. When ceramic features decrease to much smaller sizes, such as in the micron range, the dominating sintering mechanism(s) can be different from those of the bulk at large scales. However, limited effort has been devoted to understanding the sintering behaviors. In this study, the as-prepared micron-sized ZnO ridges and rods were sintered at 950oC for different time in air atmosphere. The sintering process destructs the ZnO features via abnormal grain growth and surface roughening. Destruction prediction of features using sintering time is established based on grain growth. Feature surface roughening is further analyzed with respect to thermodynamic fundamentals. Because of the evaporation tendency during zinc oxide sintering, sintering atmosphere has a significant influence on the sintering behavior and feature fidelity. In this study, micron-sized ZnO ridge features were sintered under air and argon atmospheres. Ridge size, line edge roughness, and grain size were characterized. Quantitative calculation of sintering behaviors was performed in order to obtain fundamental understating of the micron-sized ZnO feature sintering. It is found that oxygen partial pressure is the deciding factor for the ridge feature evolution. ZnO evaporation and defects diffusion are responsible for the ZnO bulk and ridge sintering behavior differences. / Master of Science / In order to produce portable devices with small sizes, novel techniques are required to make small components, which is called microfabrication. Since ceramic materials are widely used in various electronic devices, microfabrication of small ceramic features has become an important issue. When ceramic nanoparticles are used as the raw material, the fabrication of ceramic features mainly consists of two processes: micromolding and sintering, which are the problems that this thesis focuses on. In the micromolding process, the loose nanoparticles are packed to form features with specific shapes. In the sintering process, the nanoparticles in as-prepared features are bonded into a coherent and dense feature. For the micromolding process, a suspension made from the nanoparticles is poured into a mold with as-designed feature shape, and the dry feature is obtained after a drying process. In this study, the factors that will affect the shape of the features are studied. It is found that the major factors include completeness of the filling process and shrinkage during the drying process. By completing the micromolding process in a centrifugal machine, the micromolding process is accelerated, and the shrinkage during the drying process is decreased. Both the two aspects will benefit the feature quality. By using this technique, zinc oxide ridges from 0.4 μm to 2 μm size and rods of 1.6 μm size are fabricated successfully. It is also demonstrated that this technique can be applied to other ceramic materials. Sintering process can convert packed nanoparticles into a coherent object, which can help us to obtain dense ceramic features. However, the sintering process will cause the change in feature shape. For large size ceramic bulks, the sintering theory has been well established to explain these changes. When the size of ceramic materials decreases to very small scale, such as micron size, new sintering theory is needed to explain the change of ceramic features in the sintering process. In this study, micron-sized zinc oxide ridges and rods were sintered at 950oC for different time. It was found that the sintering process will distort the shape of the zinc oxide features. Based on thermodynamic views, the corresponding new theory was established. Because zinc oxide is relatively easy to evaporate during sintering, sintering atmosphere will also affect the shape of the features. In this study, micron-sized zinc oxide ridge features were sintered under air and argon atmospheres. It was found that oxygen content was the major factor that will affect the shape change. The corresponding theory was established to explain the effect of the sintering atmosphere based on thermodynamic views.

Soil improvement methods are used to minimize the consequences of liquefaction by changing the characteristics and/or response of a liquefiable soil deposit. When considering sites with previous development, the options for soil improvement are limited. Traditional methods, such as compaction and vibratory techniques, are difficult to employ because of adverse effects on adjacent structures. One potential method for soil improvement against soil liquefaction in developed sites is accelerated drainage through in situ vertical drains. Vertical drains expedite the dissipation of excess pore water pressures by reducing the length of the pore water drainage path. For more than thirty years, vertical gravel drains or stone columns have been employed to ensure the excess pore water pressure ratio remains below a prescribed maximum value. In recent years, the use of prefabricated vertical drains (PVDs) has increased because the drains can be installed with less site disruption than with traditional soil improvement methods. To date, little-to-no field or experimental verification is available regarding the seismic performance of sites treated with PVDs. The effectiveness of PVDs for liquefaction remediation was evaluated via small-scale centrifuge testing and full-scale field testing. A small-scale centrifuge test was performed on an untreated soil deposit and on a soil deposit treated with small-scale vertical drains. Compared to the untreated condition, the presence of the small-scale vertical drains provided numerous benefits including smaller magnitudes of excess pore water pressure generation and buildup, smaller induced cyclic shear strains, reduced times for pore pressure dissipation, and smaller permanent horizontal and vertical displacements. In addition, full-scale in situ field experiments were performed in an untreated soil deposit and in a soil deposit treated with full-scale PVDs using a vibrating mandrel as the dynamic source. In the untreated test area, the maximum induced excess pore pressure ratio reached about 0.95. In the treated test area, the vibratory installation of the first few drains generated significant excess pore pressures; however, significant excess pore pressures were not generated during the vibratory installation of additional drains because of the presence of the adjacent drains. Additionally, the vibratory installation of the drains caused significant settlement and significantly altered the shear wave velocity of the sand. Dynamic shaking after installation of all of the drains induced small accelerations, small cyclic shear strains, and negligible excess pore water pressures in the soil. The results of the field experiment indicate that the prefabricated vertical drains were effective at dissipating excess pore water pressures during shaking and densifying the site. / text

2007-2009 metais buvo tiriamas auksinio bulvinio nematodo ir blyškiojo bulvinio nematodo paplitimas Vilniaus regione. Tyrimai buvo atliekami Vilniaus regiono bulvių augintojų, dekoratyvinių, sodo ir miško augalų augintojų ir šiltnamių kontroliuojamuose ūkiuose. Iš vieno hektaro buvo imami 4 dirvožemio pavyzdžiai, o iš bulvių sėklininkystės ūkių ir ūkių, kuriuose auginama dauginimui skirta sodinamoji medžiaga, buvo imami 8 pavyzdžiai. Valstybinės augalų apsaugos tarnybos Fitosanitarinių tyrimų laboratorijoje pavyzdžiai buvo ištirti naudojant centrifugavimo Schuiling‘o centrifugos metodą. Apibendrinus 2007-2009 metų tyrimų duomenis nustatyta, kad buvo ištirtas dirvožemis 428-iuose kontroliuojamuose ūkiuose, kurių bendras tirtų laukų plotas buvo 877,51 ha. Iš viso buvo paimta 4343 pavyzdžiai. Iš kurių 652 buvo užkrėsti auksiniu bulviniu nematodu. Globodera pallida nebuvo identifikuota. Daugiausiai užkrėstų pavyzdžių nustatyta Švenčionių ir Trakų rajonuose (37,5 ir 33,6 % nuo tirtų tame rajone pavyzdžių). Mažiausiai užkrėstas Ukmergės ir Širvintų rajonų (12,03 ir 11,69 % nuo tirtų tame rajone pavyzdžių) dirvožemis. / The research of the spread of Globodera rostochiensis (Wollenweber) Behrens and Globodera pallida (Stone) Behrens was conducted in the Vilnius region in 2007 - 2009. It was done by potato cultivators of the Vilnius region, by cultivators of decorative, garden and forest plants as well as by controlled greenhouse farms. During the research 4 samples were taken from each 1 hectare and 8 samples from potato seed farms as well as farms where planting material was cultivated for the reproduction purposes. Each sample was tested in the Phytosanitary Research Laboratory of the State Plant Protection Service by using the Schuiling centrifuge method. When summarising the research data of 2007 - 2009 it was found out that the soil test was conducted in 428 controlled farms with the total tested field area of 877.51 ha. 4343 samples were taken in total, 652 of which were contaminated with the Golden Nematode. Pale cyst Nematode was not identifyed. The highest number of contaminated samples was found in Švenčionių and Trakų districts (37.5 % and 33.6 % of the tested samples respectively). Meanwhile the least contaminated soil was in Ukmergės and Širvintų districts (12.03% and 11.69% of the tested samples respectively).

A moagem e mistura rápidas e efetivas de materiais em pequenos volumes é uma necessidade nos laboratórios e na indústria moderna. Diversos tipos de métodos e equipamentos prestam este serviço, dentre eles o moinho e misturador planetário. Estes equipamentos são máquinas centrífugas que combinam movimentos rotacionais com translacionais e que utilizam os efeitos otimizados das forças, direções e movimentos dos materiais em processo. Para o moinho é otimizado e ampliado o poder dos mecanismos de moagem, sendo então considerado um processo de alta energia. No caso dos misturadores há a combinação do movimento planetário com um ângulo de inclinação entre o eixo de rotação do jarro com o eixo de translação que promovem vórtices helicoidais efetivos para promover a mistura. O presente trabalho objetiva o desenvolvimento de moinho e misturador planetário visando determinar condições otimizadas de moagem e mistura, o estabelecimento de limites de operação para ambas aplicações e a seleção de um sistema de transmissão simplificada. Inicialmente foram fabricados bancos híbridos de moagem e mistura para pequenas amostras (25 g para moagem e 100 g para mistura). O desempenho de moagem foi analisado pela determinação do tamanho de partículas antes e após o processo de moagem em pós de alumina de granulação grosseira com diâmetro médio de partícula em torno de 4,2 μm, variando-se as combinações de relação de transmissão, velocidade de translação e tamanho do meio de moagem. Para o misturador foi aplicado ângulo de inclinação de 30º e realizado ensaios nas misturas de massa plástica em diferentes rotações. Na configuração moinho, o melhor desempenho experimental resultou em pó de alumina submicrométrico de Øee ~ 0,9 mm em uma hora de moagem na rotação de translação de 450 rpm e relação de transmissão eixo principal/jarro de 1:-2. Na configuração misturador a condição otimizada foi com rotação de 2000 rpm e relação transmissão eixo principal/jarro de -2:1 que proporcionou mistura relativamente homogênea em 30 s. Para carregamentos de até 25 g de pós cerâmicos, em que o conjunto excêntrico (jarro, fixação, matéria prima e meios de moagem) são inferiores à 1 kg, utilizou-se a transmissão baseada em rodas de atrito que permitiu um projeto econômico e compacto, sendo o aço (AISI 4340 temperado e revenido) o material da roda de atrito que apresentou a melhor durabilidade e confiabilidade. Entretanto, apresentou limitação na moagem de amostras maiores (jarro acima de 1 kg) e nas misturas com rotações acima de 2000 rpm. A maior potência de transmissão exigida causou aquecimento excessivo na transmissão, ocasionando dilatação das rodas de atrito e consequentemente travamento do sistema. Para aumentar a capacidade de moagem para até 100 g de matéria prima, que reflete a conjuntos com massas superiores a 2 kg, um protótipo utilizando engrenagens foi projetado, construído e testado. Neste trabalho concluiu-se que, através de uma rápida reconfiguração, um único equipamento híbrido atende às ambas demandas. Entretanto observou-se que como as condições otimizadas de moagem e mistura ocorreram em condições opostas, ficou evidenciado que a condição ótima para um sistema, quando aplicado no outro sistema, oferece alto risco de acidentes, o que exige o desenvolvimento de um sistema de segurança inteligente sofisticado e oneroso que, em virtude do agregado financeiro dos componentes permanentes, para aplicações nos processos industriais, aconselha-se equipamentos individuais. / Fast and effective milling and mixing of materials in small volumes is a need for laboratories and modern industry. Several methods and equipment provide these services such as planetary mill and Dual Asymmetric Centrifuge (DAC). These pieces of equipment are centrifuge machines that combine rotation and revolution and use the optimized effects of forces, directions and movements of materials in process. In the mill, the power of the milling mechanisms is optimized, being considered a high-energy process. For the mixers there is a combination of planetary motion and a tilt angle between the axis of rotation of the jar and the revolution axis, which promote effective helical vortices for mixing. The present work aims at the development of planetary mill and mixer aiming to determine optimum grinding and mixing conditions, establishment of operating limits for both applications and transmission selection. Initially hybrid grinding and mixing benches for small samples (25 g for milling and 100 g for mixing) were manufactured. The planetary mill performance was analyzed by determining particle size before and after milling of coarse calcined alumina (initial median particle size of 4.2 mm) by varying combinations of transmission ratio, translation speed and media size. For the mixer, a tilting angle of 30º was applied and tests were performed on the modeling clay mixtures applied at different rotations. For the mill configuration, the optimized design with the best experimental setup resulted in sub micrometric alumina powder (Øee ~ 0.9 mm) in only one hour of milling (revolution of 450 rpm and speed ratio main axis/jar transmission ratio of 1:-2). For the mixer configuration, the optimized condition (revolution of 2000 rpm and speed ratio of -2:1) provided relatively homogeneous mixing in 30 s. For loadings up to 25 g of ceramic powders, where the eccentric assembly (jar, fixing, raw material and grinding media) is lighter than 1kg, the transmission based on friction wheels was used, which allowed an economical and compact design, being the steel (tempered AISI 4340) the material of the friction wheel that presented the best durability and reliability. However, there was a limitation in the grinding of larger samples (jar over 1 kg) and mixtures with rotations above 2000 rpm. The higher transmission power required caused excessive heat in the transmission, causing the friction wheels to dilate and consequently system malfunction. To perform loads greater than 100g of raw material, which reflects sets with masses over 2 kg, a prototype using gears was designed, built and tested. This work concluded that a quick reconfiguration allows a single device meets both demands. However, considering that optimized parameters of grinding and mixing occur at very different conditions, it is emphasizedthat the optimal operation for a system if applied in the optimal conditions of the other system offers high risk of accidents, which requires the development of a costly security system. Therefore, individual pieces of equipment for grinding and mixing are advised for industry application due to the financial aggregate of the permanent components.

No description available.