Agradeço a Deus, pois sem Ele nada é possível. A Marília, minha esposa, que abriu mão de tantas coisas para me acompanhar de perto nessa caminhada, como faz em todos os momentos da minha vida. Sempre fazendo o possível para me ver feliz, suas atitudes me fazem amá-la cada vez mais. Não há como recompensar tamanha dedicação. A Dilma Ottoni, minha sogra, por suas orações, dedicação e apoio incondicional. Agradeço também por estar presente em vários momentos importantes da minha vida. A meus pais, que, apesar da distância, acompanharam meus passos em mais esta etapa. Certamente, a disciplina e organização aprendidas em casa foram fundamentais para a conclusão desta tese. Aos primos Nevinha, Eliana, Abadia e César, por sua grande amizade em todo esse tempo. A Maria do Socorro Cavalcanti (Titia), pelo seu carinho, afeto e atenção em todos os momentos. A Tia Dinah, Rosemilton e sua família, por toda a consideração, cuidado e prontidão em momentos de dificuldade. Aos meus amigos Fernando, Letícia, Helena e Beatriz, pela amizade, ótimos momentos e acolhimento tão caloroso durante a minha estadia em Austin. Aos meus amigos de pós-graduação, pela amizade construída com a convivência em São Carlos. Ao Prof. Dr. Benedito de Souza Bueno, pela sua orientação, não apenas profissional, mas também pessoal. Aprendi muitas lições com ele e gostaria de deixar o meu sincero agradecimento. Ao Prof. Dr. Jorge Gabriel Zornberg por ter me acolhido tão amigavelmente em Austin e, ainda antes disso, por compartilhar suas sugestões que ajudaram a enriquecer esse trabalho. Ao Prof. Dr. Orencio Monje Vilar, por todo seu apoio, principalmente na etapa final para conclusão desta tese. Ao Prof. Edmundo Rogério Esquível, por sua amizade e companheirismo durante a minha pós-graduação na EESC/USP. Ao Prof. José Carlos Ângelo Cintra, por sua amizade, conversas e pelas oportunidades dadas durante a minha pós-graduação na EESC/USP. Ao Prof. Tarcísio Barreto Celestino, por sua amizade e pelos aconselhamentos em momentos de decisões a serem tomadas. Aos demais professores e funcionários do corpo técnico do Departamento de Geotecnia da EESC/USP. A boa convivência e prontidão em ajudar certamente são aspectos importantes do nosso departamento. À Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) pela bolsa de estudo cedida durante esta pesquisa e pelo financiamento da minha estadia em Austin, EUA, durante o Estágio no Exterior (PDEE). À Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) pelo apoio financeiro dado ao projeto ao qual esta pesquisa está relacionada.
The creep behavior of geosynthetics has commonly been determined using standardized creep tests, which are time consuming and very expensive. In addition, these tests involve the use of in-isolation specimens. Thus they are not likely to consider the overall effect of soil confinement. Confined creep tests conducted at elevated temperature can be used to address these negative aspects of standardized creep tests. This paper presents a pioneering laboratory apparatus developed in order to conduct confined, accelerated and confined-accelerated creep tests. In addition, preliminary tests were performed to assess the new equipment's capability of conducting confined and accelerated creep tests. These tests were performed using a biaxial geogrid, a woven geotextile, and a nonwoven geotextile. The new equipment allowed different conditions to be reproduced. The creep behavior of the nonwoven geotextile and the geogrid was found to be very sensitive to soil confinement. On the other hand, the woven geotextile presented a creep behavior independent of soil confinement. The geogrid results did not agree with reports in the technical literature. Accordingly, these results showed the importance of characterizing the effect of soil confinement in geosynthetics creep behavior. Additionally, these preliminary results showed the potential of the new device to overcome the main negative aspects of standardized creep tests on geosynthetics.
Deep mining operations require special measures in order to keep safe and economic aspects. After mine ore is extracted, voids are created and need to be filled with high-strength, low-cost materials. Cemented Paste Backfill (CPB) has recently become one of the main alternatives in filling stopes. Although numerous papers have mentioned the magnitudes of the strength of this material, its behavior under high confining pressures is still not well understood. Therefore, the purpose of this study is to increase the knowledge regarding the CPB behavior. Triaxial compression tests were performed using a Hoek Cell and Load Frame System under high confining pressures. Samples with two different binder contents were used in order to obtain the CPB strength improvement. Besides the self-weight consolidation curing method, samples were subjected to a different curing method that simulated a zero gravity condition (rotating wheel) in the first curing day to compare their mixture properties. The results suggested that both curing method and binder content have influenced the geomechanical properties of Cemented Paste Backfill. By increasing the curing time, the CPB shear strength has increased slightly, whereas specimens with higher binder content presented a significant increase in shear strength values.
Soil nailing is an efficient soil reinforcement technique which uses inclusions, namely nails, in soil slopes. Unit skin friction is one of the most important parameters used in soil nailing design. The definition of this parameter is commonly based on local experience and correlations to some in situ tests. This work presents the results obtained from the pullout test carried out in a soil nailed wall prototype built in laboratory. Forces acting in nails were measured by strain gage instrumentation. Soil displacement was measured in short and long terms. The pullout tests were carried out after the application of a uniform surcharge given by a compressed air bag. The results showed that unit skin friction was about 145 kPa, mobilized with little nail displacements. About 90% of nail length were solicited during pullout tests, according to tests performed in strain gage instrumented nails. Nail extraction showed a high level of nail integrity. Soil displacements were higher close to the wall top, near the face. These results demonstrate the feasibility of using of laboratory prototype studies to investigate the geotechnical behavior of soil nailing structures.
No abstract
This paper intends to evaluate changes in permeability of a soil sample from Formação Barreiras, in Natal, the capital city of Rio Grande do Norte State, related to the degree of compaction and the adding of clay to the soil sample. In field works, samples were collected and permeability and density tests were performed. In laboratory, grain size distribution, Attemberg limits and particle density tests were conducted. Afterwards, compaction and permeability tests fulfilled the set of laboratory tests, with changes in compactive energy and sample clay content. The results from field and laboratory tests were compared and the relationship between compaction energy and sample clay content were portrayed. The soil was classified as silty sand. Field and laboratory test results were quite similar. As expected, the tests indicated that permeability is inversely proportional to both compaction energy and sample clay content in the soil tested.
O modal mais utilizado para o transporte de cargas e pessoas no Brasil é o rodoviário. Entretanto, por vezes, não há disponibilidade de materiais que atendam aos requisitos de pavimentação, enfatizando a necessidade de técnicas de estabilização dos solos para o ajuste do material às especificações desejadas. Assim, o objetivo deste trabalho foi avaliar o comportamento de uma areia siltosa bem-graduada (SM-SW), da cidade de Natal/RN, cujas características são incompatíveis para o uso no pavimento. Esta foi estabilizada com emulsão asfáltica de ruptura rápida (RR-2C). Foram realizados ensaios de Índice de Suporte Califórnia (ISC) e de Penetrômetro Dinâmico de Cone (DCP) em três teores de emulsão (3%, 5% e 7%) e em três condições: sem cura e imersão; sem cura e com imersão; e com cura de 7 dias e imersão. Os resultados apontam uma redução da capacidade de suporte após mistura, embora as correlações entre ISC e DCP tenham apresentado ajustes mais adequados e melhores coeficientes de determinação (R²), com valores superiores a 0,80. Além disso, após a cura, houve uma tendência de aumento dos valores de ISC, mas ainda assim a emulsão mostrou-se pouco eficaz na estabilização do solo para uso na base e sub-base de um pavimento.
The coastline is constantly in undergoing change, in terms of its position (retreat) and form. The retreat of coastal cliffs is a physical, dynamic and complex process that is controlled mainly by the geology of the area, strength properties of materials, marine conditions and climatic aspects of the region. This process is directly related to basal erosion, which is basically the mechanical destruction and/or removal of soil particles from the toe of coastal cliffs, caused mainly by wave action. Basal cliff erosion decreases the stability of the slope and may trigger mass movements and coast retreats. The coastal area of Rio Grande do Norte (Brazil) consists predominantly of sandy beaches and cliffs of Barreiras Formation. In this area, the human occupation has been increasing; therefore, it potentiates the probability of occurrence of mass movement. The objective of this study is to analyze the direct influence of basal erosion on stability of typical cliffs of the district of Tibau do Sul / Rio Grande do Norte - Brazil. The results showed that tensions are generated above the basal erosion as notch extension increases.
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