Much of Brazil's massive infrastructure programme is having to be built on the very soft soils found along the country's coastline. Not least are venues and infrastructure required for the Rio 2016 Olympic and Paralympic Gamesin the city's Barra da Tijuca district, where soft soils can be over 20 m deep. One of these, the 13 ha Athletes' Park, is already successfully completed. This paper presents and discusses the results of various in situ and laboratory tests that were carried out to assess the soil properties at the site. It then describes how the ground was substantially improved with a recent technique developed in Brazil called deep radial consolidation.
RESUMO A escassez dos recursos naturais e a demanda por alternativas de reutilização de materiais tornou a reciclagem uma palavra de ordem no atual cenário da construção rodoviária mundial. A fresagem de pavimentos produz um material de alto valor econômico e com ótimas propriedades físicas e mecânicas que podem ser introduzidas na composição de novas misturas asfálticas. O presente trabalho avaliou o comportamento mecânico de misturas usinadas a quente com adição de diferentes teores de ligante novo, de 2,5% a 4,5%. O material de estudo é proveniente da Rodovia Brasileira 290 (BR-290), do trecho situado entre os municípios de Rosário do Sul e São Gabriel, no estado do Rio Grande do Sul (RS). Para caracterização do material fresado foram realizados os ensaios de granulometria, extração de betume, estabilidade e fluência Marshall e resistência à tração por compressão diametral com corpos de prova cilíndricos moldados conforme as misturas propostas. De acordo com os resultados, obtiveram-se valores de estabilidade, fluência e resistência à tração por compressão diametral satisfatórios para a aplicação de material fresado (50% e 100% de adição) em misturas asfálticas para camadas de rolamento. Portanto, a reutilização desse material, nas proporções avaliadas, proveniente do próprio pavimento, além de atender as especificações técnicas, também surge como solução para evitar deposição inadequada do mesmo, reduzindo o passivo ambiental.
The compression index, swelling index and preconsolidation stress values are essential for reliable settlement calculations. However, it is a challenge to obtain representative parameters for very soft, organic, high-plasticity clays, which are often found in the Jacarepaguá Lowlands, Rio de Janeiro, Brazil. In recent decades, several geotechnical correlations have been proposed for estimating the parameters to check oedometer test data. The compression index can be estimated based on simple laboratory index tests and the preconsolidation stress can be found by means of piezocone and vane tests. In this paper, data from 24 different investigation clusters located in the region are analysed. Undisturbed samples were collected from 20 different locations; 67 piezocone tests and 48 vane tests were carried out, which resulted in a comprehensive data bank. Then correlations were developed and compared with a number of equations to assess their reliability. Special emphasis was given to correlations between the compression index and soil water content, and also between the preconsolidation stress and the corrected cone resistance and shoulder pore pressure measured in the piezocone tests.
This article presents the study of the resilient behavior of three soil horizons from a deposit of lateritic soil employed in a pavement structure in Rio Grande do Sul, Brazil. The use of lateritic soils in pavement layers is a common practice in Brazil and due to its peculiarities, its behavior must be investigated. The methodology consisted of physical and chemical characterization and resilient modulus determination. Samples from the three horizons, compacted at standard, intermediate and modified energy, were analyzed. In addition, undisturbed samples extracted from the interior and top layer of the embankment were submitted to repeated load triaxial tests for resilient modulus determination. The results indicated that the soil exhibit good behavior for pavement subgrade applications, perhaps as subbase or base course layers. The compound and universal models yielded the best correlation coefficients. Furthermore, the results showed that as the compaction energy increased, the resilient modulus also increased, as long as they are within the optimum water content and compaction degree limit. However, when subjected to immersion in water for four days, the resilient behavior decreased about 73% in relation to unsaturated samples.
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