Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves 114-122).

No description available.

Thesis (Ph.D.)--University of Western Australia, 2006.

Thesis (Ph. D.)--Carleton University, 1996. / Also available in electronic format on the Internet.

Thesis (Ph.D.)--University of Wyoming, 2007. / Title from PDF title page (viewed on July 26, 2010). Includes bibliographical references.

Made available in DSpace on 2017-07-21T19:26:07Z (GMT). No. of bitstreams: 1 Sabrina Passoni.pdf: 6849418 bytes, checksum: 548846a6a7358d6de92338d9345d4f38 (MD5) Previous issue date: 2013-07-31 / The X-ray computed microtomography (CT) represents a non-invasive technique that can be used with success to analyze physical properties by the soil scientists without destroying the structure of the soil. The technique has as advantage over conventional methods the characterization of the soil porous system in three dimensions, which allow morphological property analyses such as connectivity and tortuosity of the pores. However, as the soil is a non-homogeneous and complex system, the CT technique needs specific methodologies for digital image processing, mainly during the segmentation procedure. The objectives of this work were: 1) to develop a methodology for microtomographic digital image processing; 2) to characterize the soil structure by using micromorphology analysis of samples submitted to non-tillage and conventional systems collected in three distinct layers (0-10, 10-20 and 20-30 cm); and 3) to identify possible changes in the porous system of the soil analyzed due to the effect of different management systems. The use of the CT technique and the procedures adopted for microtomographic digital image processing show to be efficient for the micromorphologic characterization of soil porous system. Soil under non-tillage system presented the best results from the agricultural point of view regarding porosity, total number of pores, connectivity and tortuosity in comparison to the conventional tillage. / A microtomografia computadorizada de raios X (μCT) é uma técnica não-invasiva, que pode ser usada com sucesso para analisar as propriedades físicas do solo pelos cientistas, sem destruir a estrutura do solo. A técnica apresenta vantagens sobre os métodos convencionais: a caracterização do sistema poroso do solo em três dimensões, a qual permite análises de propriedades morfológicas, tais como a conectividade e tortuosidade dos poros. No entanto, como o solo é um sistema não-homogêneo e complexo, a técnica de μTC necessita de metodologias específicas para o processamento de imagens digitais, principalmente durante o processo de segmentação. Os objetivos deste trabalho foram: 1) desenvolver uma metodologia de processamento digital de imagens microtomográficas; 2) caracterizar a estrutura do solo por meio de análise micromorfológica das amostras submetidas a sistemas plantio direto e plantio convencional coletadas em três camadas distintas (0-10, 10-20 e 20-30 cm) e 3), identificar possíveis alterações no sistema poroso do solo analisado, devido ao efeito de diferentes sistemas de manejo. O uso da técnica de tomografia computadorizada e os procedimentos adotados para o processamento de imagem digital microtomográfica mostrou-se eficiente para a caracterização micromorfológica do sistema poroso do solo. Os dados do solo sob sistema de plantio direto apresentou os melhores resultados do ponto de vista agrícola sobre a porosidade, o número total de poros, conectividade e tortuosidade em comparação com o plantio convencional.

The term ???Integral Abutment Bridges??? is used broadly all over the world these days. While the expansion joints used in bridges were once a scientifically proved cure to the problem of natural expansion and contraction, there are the excessive maintenance costs being accumulated annually due to the deterioration of essential functions from deicing chemicals and debris. This drawback triggered the advent of Integral Abutment Bridges. The performance of Integral Abutment Bridges at almost no extra costs in seasonal and daily cyclic contraction and expansion can be assessed as a monumental landmark of civil engineering technologies with respect to the massive budget reductions. However, since Integral Abutment Bridges are destined to expand or contract under the laws of nature, the bridge design became more complicated and sophisticated in order to complement the removal of expansion joints. That is why numerous researchers are attracted to Integral Abutment Bridges with deep interests. Accordingly, in designing the piled abutments of Integral bridges, it is essential to precisely predict the bridge???s behavior in advance. Researchers have been broadly carried out during the last several decades on the behavior of piled bridge abutments. However, most of the studies have been analyzed with focus on structural elements or soils, respectively for the static and dynamic loads such as thermal variations and earthquake loads. This presented research developed 3D numerical models with 3 m, 4 m, 5 m, 6 m, 7 m, and 8 m-tall abutments in the bridge using the finite element analysis software MIDAS CIVIL that simulate the behaviors of Integral Abutment Bridges to study the soil-structure interaction mechanism. In addition, this work evaluated and validated the suitability to the limit of the abutment height in Ontario???s recommendations for Integral Abutment Bridges by a parametric study under the combined static loading conditions. In order to be a balanced research in terms of a multidisciplinary study, this research analyzed key facts and issues related to soil-structure interaction mechanisms with both structural and geotechnical concerns. Moreover, the study established an explanatory diagram on soil-structure interaction mechanisms by cyclic thermal movements in Integral Abutment Bridges.