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Abstract(s)
Uma das principais funções da geotecnia é avaliar o comportamento de estruturas em contato com o solo. No entanto, a caracterização geotécnica dos maciços de terra não é sempre realizada de modo a refletir o comportamento global daquele material, já que os ensaios de caracterização são restritos a locais de extrema importância para o projeto da estrutura. A interação de estruturas de suporte de terra flexíveis com o maciço é um problema altamente indeterminado, as movimentações do maciço afetam as movimentações do paramento e vice-versa. Além disso, as movimentações horizontais estão extremamente relacionadas às pressões de terra e aos esforços que a estrutura está sujeita. Tendo isto em mente, esta dissertação tem como objetivo avaliar a maneira que os parâmetros de resistência do solo, a rigidez do paramento e o faseamento construtivo da estrutura afetam o comportamento de uma parede moldada com três níveis de ancoragens pré-esforçadas. A base da estrutura foi considerada encastrada em um estrato rígido e, portanto, está impedida de deslocar. Para isso, foram realizadas análises computacionais, utilizando diferentes metodologias de análise, método de Winkler e método dos elementos finitos (MEF), de forma a verificar os resultados obtidos por ambos os métodos. Através deste estudo foi possível concluir que o aumento da rigidez do paramento reduz os deslocamentos horizontais da estrutura e consequentemente aumenta as pressões de terra e esforços atuantes na estrutura. No entanto, para o MEF, altos valores de rigidez causam redução mínima do deslocamento, sendo que o deslocamento da estrutura começa a se assemelhar a uma rotação em torno da base. No MEF, o aumento dos parâmetros de resistência do solo geraram redução do deslocamento da estrutura e aumento da pressão de terra e esforços. O mesmo não foi observado para o método de Winkler, os resultados para resistências não drenadas de 25 kPa e 150 kPa foram próximos e para 75 kPa e 300 kPa também. O faseamento construtivo se mostrou indispensável para modelar o comportamento do solo no MEF, variações de 50% do deslocamento da estrutura foram observadas quando as fases construtivas intermediárias foram desconsideradas. Para o método de Winkler, os resultados foram pouco afetados, os esforços praticamente não sofreram alterações e o deslocamento sofreu uma variação de 8%.
One of the main functions of geotechnical engineering is assessing the behavior of structures in contact with the soil. However, the soil exploration isn’t always planed in a way that the results reflect the global behavior of the soil mass, as the plan is restricted to places of extreme importance for the structural project. The interaction between flexible earth-retaining structures with the soil is a highly indetermined problem, the horizontal displacements of the wall affect the displacement of soil and vice-versa. The horizontal displacement of the wall is also highly linked to the earth pressures acting on it. Having this in mind, the objective of this study is to assess the way in which the soil resistance parameters, the wall rigidity and the construction phases affect the behavior of a diaphragm wall with three levels of pre-stressed anchored bulkheads, the bottom of the structure was considered embedded on a firm stratum and therefore is restrained from moving. To do this several computational analyses were carried out, using different analysis methodologies, Winkler’s method and finite element method, so it was possible to check the results gathered from each methodology. Through this study it was possible to conclude that an increase in the wall rigidity reduces the horizontal displacements of the structure, therefore increasing the earth pressure and strains acting on the wall. However, for FEM, higher values of rigidity lead to a minimal reduction of the displacement and the movement of the wall starts resembling a rotation around the base. In FEM, the increase of the soil resistance parameters generates a reduction of the of the wall displacement and an increase of the earth pressures and strains. The same wasn’t observed for Winkler’s method, the results for undrained strength values of 25 and 150 were close and for 75 and 300 were also close. The construction phases were shown indispensable to model the soil behavior in the FEM method, a 50% variation rate was observed for the wall displacement when the intermediate construction phases were not considered. However, in Winkler’s method the results were affected a lot less, the strains obtained were practically the same and the displacement variation rate was 8%.
One of the main functions of geotechnical engineering is assessing the behavior of structures in contact with the soil. However, the soil exploration isn’t always planed in a way that the results reflect the global behavior of the soil mass, as the plan is restricted to places of extreme importance for the structural project. The interaction between flexible earth-retaining structures with the soil is a highly indetermined problem, the horizontal displacements of the wall affect the displacement of soil and vice-versa. The horizontal displacement of the wall is also highly linked to the earth pressures acting on it. Having this in mind, the objective of this study is to assess the way in which the soil resistance parameters, the wall rigidity and the construction phases affect the behavior of a diaphragm wall with three levels of pre-stressed anchored bulkheads, the bottom of the structure was considered embedded on a firm stratum and therefore is restrained from moving. To do this several computational analyses were carried out, using different analysis methodologies, Winkler’s method and finite element method, so it was possible to check the results gathered from each methodology. Through this study it was possible to conclude that an increase in the wall rigidity reduces the horizontal displacements of the structure, therefore increasing the earth pressure and strains acting on the wall. However, for FEM, higher values of rigidity lead to a minimal reduction of the displacement and the movement of the wall starts resembling a rotation around the base. In FEM, the increase of the soil resistance parameters generates a reduction of the of the wall displacement and an increase of the earth pressures and strains. The same wasn’t observed for Winkler’s method, the results for undrained strength values of 25 and 150 were close and for 75 and 300 were also close. The construction phases were shown indispensable to model the soil behavior in the FEM method, a 50% variation rate was observed for the wall displacement when the intermediate construction phases were not considered. However, in Winkler’s method the results were affected a lot less, the strains obtained were practically the same and the displacement variation rate was 8%.
Description
Mestrado de dupla diplomação com a FUMEC
Keywords
Método de Winkler Método dos elementos finitos Estruturas de suporte Pressões de terra Deslocamento Esforços Ancoragens Resistência do solo Rigidez Faseamento construtivo