Thesis (M.S. - Soils, Water and Engineering)--University of Arizona. / Includes bibliographical references.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1989. / Includes bibliographical references (leaves 114-118).

[pt] Simulações numéricas tendem a simplificar o comportamento de problemas reais, na maioria das vezes pela adoção de um modelo 2D para descrição da resposta hidráulico-mecânica de barragens de terra, escavações, fundações, etc., com base na maior facilidade da construção geométrica de malhas, rapidez de processamento, simplicidade na introdução das condições de contorno, menor dificuldade na obtenção dos parâmetros de engenharia, etc. Entretanto, para certos fenômenos como o fluxo através de barragem em vales estreitos ou no rebaixamento do lençol freático para execução de escavações para construção de fundações, os efeitos tridimensionais podem afetar consideravelmente os resultados obtidos com uma solução simplificada, seja em termos de vazão, cargas, gradientes hidráulicos ou fatores de segurança. Esta dissertação tem como objetivo principal analisar problemas de fluxo, na condição transiente e/ou permanente, considerando solos saturados e parcialmente saturados, em simulações 2D e 3D pelo método dos elementos finitos buscando destacar as principais diferenças entre as respostas obtidas, ressaltando as principais vantagens e dificuldades da realização de uma simulação 3D em relação a uma análise simplificada 2D. Os exemplos numéricos abordados neste trabalho se referem à barragem de terra Macusani, no Peru, à escavação realizada para construção das estruturas da Pequena Central Elétrica Canoa Quebrada - MT e ao rebaixamento do lençol freático para construção das fundações do shopping Brooklin na cidade de São Paulo - SP. / [en] Numerical simulations tend to simplify the behavior of real problems, mainly through the choice of 2D models to describe the hydromechanical responses of earth dams, excavations, foundations, etc., partly because it is easier to construct geometrical meshes, it is simpler to impose the required boundary conditions, the computer calculations are done more rapidly and the estimation of the engineering parameters, either through field or laboratory tests, are less difficulty than it would be if the problem was treated as a complete 3D case. However, for certain phenomena such as the flow of water through dams situated in narrow valleys or the water drawdown in excavations for construction of building foundations, 3D effects can considerably affect the results when compared to a simplified 2D solution, either in terms of quantity of flow, hydraulic heads and gradients, security factors, etc. The main goal of this dissertation is the analysis of flow problems, both in transient and permanent conditions, considering fully saturated or partially saturated soils, employing 2D and 3D numerical models based on the finite element method in order to highlight the main differences between the computed answers, emphasizing the advantages and difficulties of both approaches. The numerical examples studied in this work are the earth dam Macusani, situated in Peru, the excavation carried out for the construction of the structures in the small hydroelectric plant Canoa Quebrada - MT, and groundwater drawdown for the execution of the foundations of the Brooklin shopping mall, in the city of São Paulo - SP.

Phase change of the water in the soil skeleton under cold climate conditions (also known as frost action in soils) affects soil properties and can be responsible for serious alterations in a soil body; causing damages (due to the volumetric expansion known as frost heave) to structures on or below the ground surface such as foundations, roads, railways, retaining walls and pipelines, etc. In order to improve the current design methods for roads against frost action, the Swedish Transport Administration (Trafikverket) has initiated a research program. The main goals of the program are to revise the existing frost heave estimation methods and improve the frost susceptibility classification system for subgrade soils. Literature was reviewed to gather the details of different freezing test equipment around the world and to identify common trends and practices for laboratory freezing tests. Based on the literature review and the collaboration with the University of Oulu, Finland an experimental apparatus was assembled for studying frost action in the laboratory. A detailed description of the experimental apparatus is given. Top to down freezing of specimens (of 10cm height and diameter) can be monitored while keeping track of water intake, vertical displacements (heave) and the temperature profile within the sample. Loads can be applied at the top of the sample to study the effects of overburden. Moreover, the test setup was modified with a camera system to have the option of recording the experiments. Disturbed samples of two different soil types were tested. Experiments with fixed and varying temperature boundary conditions were conducted to assess the validity of the assumptions for the frost heave estimation methods currently in use in Sweden. To this end, a qualitative relationship between frost heave and heat extraction rates based on theoretical equations was established. It was shown that there is a significant difference between the preliminary findings of the experimental work and the current system being used in Sweden to quantify heave. Image analysis techniques were used on two experiments that were recorded by the camera system. Image recording and correlation analyses provided detailed information about frost front penetration and ice lens formation(s) under varying temperature boundary conditions. Thawing has also been regarded in further studies. Results of the image analyses were compared to readings from conventional displacement measurements during the same test. Significant agreement between the results of image analyses and displacement measurements has been found. Image analysis was shown to be a viable method in further understanding of frost heave mechanisms. Shortcomings and disadvantages of utilizing the theoretical equations as well as the image analysis techniques were discussed. Potential remedies for overcoming the drawbacks associated with each approach are suggested. The work is concluded by discussing the potential improvements, planned upgrades (addition of pore pressure transducers) and the future experiments to be conducted.

Phase change of the water in the soil skeleton under cold climate conditions (also known as frost action in soils) affects soil properties and can be responsible for serious alterations in a soil body; causing damages (due to the volumetric expansion known as frost heave) to structures on or below the ground surface such as foundations, roads, railways, retaining walls and pipelines, etc. In order to improve the current design methods for roads against frost action, the Swedish Transport Administration (Trafikverket) has initiated a research program. The main goals of the program are to revise the existing frost heave estimation methods and improve the frost susceptibility classification system for subgrade soils. Literature was reviewed to gather the details of different freezing test equipment around the world and to identify common trends and practices for laboratory freezing tests. Based on the literature review and the collaboration with the University of Oulu, Finland an experimental apparatus was assembled for studying frost action in the laboratory. A detailed description of the experimental apparatus is given. Top to down freezing of specimens (of 10cm height and diameter) can be monitored while keeping track of water intake, vertical displacements (heave) and the temperature profile within the sample. Loads can be applied at the top of the sample to study the effects of overburden. Moreover, the test setup was modified with a camera system to have the option of recording the experiments. Disturbed samples of two different soil types were tested. Experiments with fixed and varying temperature boundary conditions were conducted to assess the validity of the assumptions for the frost heave estimation methods currently in use in Sweden. To this end, a qualitative relationship between frost heave and heat extraction rates based on theoretical equations was established. It was shown that there is a significant difference between the preliminary findings of the experimental work and the current system being used in Sweden to quantify heave. Image analysis techniques were used on two experiments that were recorded by the camera system. Image recording and correlation analyses provided detailed information about frost front penetration and ice lens formation(s) under varying temperature boundary conditions. Thawing has also been regarded in further studies. Results of the image analyses were compared to readings from conventional displacement measurements during the same test. Significant agreement between the results of image analyses and displacement measurements has been found. Image analysis was shown to be a viable method in further understanding of frost heave mechanisms. Shortcomings and disadvantages of utilizing the theoretical equations as well as the image analysis techniques were discussed. Potential remedies for overcoming the drawbacks associated with each approach are suggested. The work is concluded by discussing the potential improvements, planned upgrades (addition of pore pressure transducers) and the future experiments to be conducted. / Modellering av tjällossningsförlopp vid vägdimensionering