Avaliação experimental de protótipos de estruturas de contenção em solo reforçado com geotêxtil
Data
2017-11-15
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
Resumo
Descrição
Apesar das vantagens relacionadas ao uso de estruturas de contenção em solo reforçado, a maioria das obras em nosso país ainda é executada por soluções convencionais. A ausência de um conhecimento mais profundo sobre o real comportamento das estruturas em solo reforçado, principalmente em termos de deslocamentos, certamente impede uma utilização mais intensa desse tipo de obra no Brasil. Com isso, para contribuir para um melhor entendimento do desempenho de estruturas em solo reforçado, foram construídos oito protótipos de estrutura de contenção em solo reforçado com geotêxtil, com 4,0 m de altura cada. Todas as estruturas foram instrumentadas, principalmente visando os deslocamentos, para avaliar o comportamento de campo. Adicionalmente, foi realizada a análise, em longo prazo, de um talude íngreme com 15,3 m de altura, construído no estado americano de Idaho, em que foram realizadas leituras até cinco anos após o fim da construção. Esse trabalho apresenta os resultados de cada protótipo construído, juntamente com os resultados do talude íngreme em Idaho, tanto em curto, quanto em longo prazo. As análises desenvolvidas compreendem, além da avaliação dos resultados individuais de cada estrutura, uma análise paramétrica entre todos os protótipos, investigando entre outros fatores, o tipo de solo, tipo de geossintético e geometria interna das estruturas. Além disso, foi realizada uma abordagem especial sobre a análise em longo prazo do protótipo 7. Dentre as conclusões mais importantes obtidas nesta pesquisa, podem-se citar as grandes deformações de fluência registradas no protótipo 7, a tendência de formação de uma superfície potencial de ruptura linear para os protótipos construídos com solo granular e de espiral logarítmica para os protótipos construídos com solos coesivos, a importância da coesão no bom comportamento das estruturas e a redução das movimentações verticais das estruturas com o acréscimo do teor de areia na granulometria do solo
Despite the important advantages associated with the use of geotextiles as reinforcement, most retaining walls in Brazil still use more conventional. The lack of field monitoring data regarding the internal and face displacements of these structures has certainly prevented broader use of this reinforced soil technology. This study addresses several aspects related to the behavior of geotextile-reinforced soil structures, such as the deformability of reinforcement materials under the confinement of soil, and quantification of the actual failure mechanisms. To achieve these goals, eight 4.0 m high geotextile-reinforced soil retaining wall prototypes were built and instrumented in order to quantify their behavior under ambient atmospheric conditions. Granular and poorly draining backfills were used in this study. Innovative construction methods and instrumentation were developed specifically for this research program. A significant laboratory testing program was conducted to quantify the stress-strain properties of the soils and geosynthetics involved in the construction of the walls. As a reference, the behaviors of these prototype structures were compared with that of a long term analysis of a steep slope in Idaho, USA. This wall is 15.3 m high, with displacement measurements carried out until five years after the end of the construction. A parametric analysis was conducted for the prototypes, in order to investigate the effects of soil type, reinforcement type and internal geometry of the structures. Among the most important conclusions obtained in this research, it is the large creep strains observed in prototype 7, the tendency of a linear potential slip surface observed for the walls constructed with granular backfills, and a log spiral slip surface for the prototypes constructed with cohesive backfills, the importance of the apparent cohesion in the behavior of the structures, and the reduction of the vertical movements of the structures with the increase of the amount of sand in the grain size distribution of the soil
Despite the important advantages associated with the use of geotextiles as reinforcement, most retaining walls in Brazil still use more conventional. The lack of field monitoring data regarding the internal and face displacements of these structures has certainly prevented broader use of this reinforced soil technology. This study addresses several aspects related to the behavior of geotextile-reinforced soil structures, such as the deformability of reinforcement materials under the confinement of soil, and quantification of the actual failure mechanisms. To achieve these goals, eight 4.0 m high geotextile-reinforced soil retaining wall prototypes were built and instrumented in order to quantify their behavior under ambient atmospheric conditions. Granular and poorly draining backfills were used in this study. Innovative construction methods and instrumentation were developed specifically for this research program. A significant laboratory testing program was conducted to quantify the stress-strain properties of the soils and geosynthetics involved in the construction of the walls. As a reference, the behaviors of these prototype structures were compared with that of a long term analysis of a steep slope in Idaho, USA. This wall is 15.3 m high, with displacement measurements carried out until five years after the end of the construction. A parametric analysis was conducted for the prototypes, in order to investigate the effects of soil type, reinforcement type and internal geometry of the structures. Among the most important conclusions obtained in this research, it is the large creep strains observed in prototype 7, the tendency of a linear potential slip surface observed for the walls constructed with granular backfills, and a log spiral slip surface for the prototypes constructed with cohesive backfills, the importance of the apparent cohesion in the behavior of the structures, and the reduction of the vertical movements of the structures with the increase of the amount of sand in the grain size distribution of the soil
Palavras-chave
estruturas de contenção, solo reforçado, instrumentação de campo, geotêxteis, geossintéticos, taludes íngremes, geotextiles, geosynthetics, reinforced soils, retaining walls, steep slopes field instrumentation