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.

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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.

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.

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.

This paper describes the results of rock and fluid property measurements and of the reservoir simulations associated with the demonstration of CO2-assisted oil recovery in the Cypress Sandstone reservoirs at Mattoon Field, Illinois. This work provided technical support for the field project. Results from core flood tests indicate that oil recovery from immiscible displacement of reservoir crude oil with carbon dioxide will increase with displacement pressure. Miscible displacement of oil with CO2 from the Cypress Sandstone reservoirs at Mattoon field is not possible. As shown by the slim-tube experiments, the minimum miscibility pressure (MMP) of Mattoon oil is close to the formation parting pressure of the Cypress Sandstone at Mattoon field. Nevertheless, phase behaviour experiments show that dissolved CO2 significantly enhanced oil recovery through oil swelling and viscosity reduction at pressures below miscibility conditions. Numerical simulations of CO2 injection into various reservoirs within the Sandstone were performed. A straight CO2injection program and a water alternating gas (WAG) injection program were simulated and compared in both the A-sandstone of the Pinnell Unit and E-sandstone interval of the Sawyer Unit. In the Pinnell Unit, the simulated results show an inefficient displacement of reservoir oil by CO2 and that neither of the two methods will be economically feasible because of the poor interwell communication and limited areal extent of the producing interval. This result is supported by the low oil recovery from the field CO2 injectivity tests in the Pinnell Unit. On the contrary, simulated results show that a significant amount of additional oil can be produced from the Sawyer Unit. The wateralternating- gas (WAG) injection program yielded more oil than water injection alone. The simulated results also indicate strategically- placed new wells will enhance the recovery of additional oil. Introduction This work provided technical support for a CO2-assisted oil recovery demonstration project funded by a cost-shared agreement (Cooperative Agreement number DE-FC22-93BCI4955) between the United States Department of Energy and American Oil Recovery, Inc. (AOR). The Mattoon Field, which is the site of the project (Figure 1), was discovered in June 1940. Development included approximately 420 producers and 90 dry holes drilled on a 4.05 ha (10 acre) well spacing. The principal reservoirs are found in the Cypress, Rosiclare and Aux Vases Sandstones of the Mississippian System (Figure 2). Secondary recovery was initiated in 1952 utilizing Pennsylvanian brine as well as treated municipal sewage water(1). The target intervals for additional oil recovery with CO2 are the Chesterian Cypress Sandstone reservoirs in the Mattoon field. In general, Cypress Sandstone reservoirs are the most prolific in Illinois(2). Recent studies(3,4,5) show that Cypress reservoir sandstones consist of four to five stacked layers having varying reservoir quality and often separated by thin shaly sandstone or calcareous beds. Because of the variations in reservoir quality, some layers are not as efficiently swept as others during water flooding. Such layers will contain more bypassed mobile oil than others. Furthermore, Cypress Sandstone reservoirs typically have high immobile oil saturation.

Phosphoric acid (H3PO4) is a product that can be used as a stabilizing additive for tropical soils in an exploratory manner by the construction industry. For the drying process of this grain, its husks are used as fuel for ovens, generating rice husk ash (RHA), which is considered an environmental liability if not reused. In this sense, this paper aimed to evaluate the resilient behavior and the simple compressive strength, at different curing ages, of the use of rice husk ash and phosphoric acid in a simple and combined mixture for the stabilization of lateritic soil. The lateritic soil was mixed with different contents of RHA, H3PO4, and water and compacted in intermediate and modified Proctor energies. Fractured soil samples in the mechanical compressive strength tests were analysed by scanning electron microscopy and X-ray diffraction. The results show the potential for stabilization of the lateritic soil in question in terms of resilience and simple compressive strength through the addition of RHA and H3PO4 at different curing ages. The insertion of only H3PO4 produced the most satisfying resilient behavior. By adding RHA, the strength properties were improved, and good mixtures were obtained for use in paving.

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