Navegando por Assunto "Solos moles"

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Acesso aberto (Open Access)
Análise comparativa das sensibilidades obtidas com o vane test e o mini vane em um depósito sedimentar na foz do rio Amazonas
(Universidade Federal do Pará, 2022-11-22) VIEIRA FILHO, Arudá Gomes; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The reed test has been used in field research for the elaboration of geotechnical projects and in the management of non-clay sedimentary deposits, due to the fact that it provides data such as undrained shear strength (Su) and sensitivity (St). The same results are obtained in the test with the laboratory straw (mini vane), but for that, it is necessary to extract samples considered undisturbed, which, in this research, were recommended by the ABNT NBR 9820 standard. vane shear test with the laboratory vane test, also called Mini Vane. The location of this analysis is in a port region located at the mouth of the Amazon River, in a natural sedimentary deposit, which presented two slope disruptions with characteristics peculiar to soils with high sensitivity. Landslides on slopes are usually predictable from a geotechnical point of view, however in this researched region the soil presented rapid landslides on the slope, showing signs of a soil with high sensitivity. The research pointed out that the laboratory vane test (mini vane) presented a greater (St) when correlated with the (St) of the simple compression tests, giving greater clarity that there is a very soft clayey soil with a depth between 30 and 40 meters, typical of a ground lens that performed with high sensitivity. Comparisons between the reed tests showed consistency in the results, even in soil layers with different consistency indices than the initial layers, the validations of the reed tests were validated with the tests performed by simple compression. Finally, the soil of this deposit had its sensitivity identified in the field straw test. The same identification was confirmed on the Mini Vane. However, at depths greater than the field vane. In this way, the tests carried out by the Vane Shear Test (VST) in situ were primordial in the identification of the sensitivity, having its confirmation with the laboratory reed test (Mini Vane).
Acesso aberto (Open Access)
Avaliação da sensibilidade de uma argila mole do Amapá por meio da correlação entre ensaios de CPTU e de laboratório
(Universidade Federal do Pará, 2022-11-03) GONÇALVES, Andrey da Costa; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The identification and mapping of sensitive soft clayey soils are of great interest for planning, design and protection purposes, as these materials can exhibit fragility, loss of strength and softening by deformation, in addition to being more prone to landslides. The occurrence of sensitive clays in the port region of the municipality of Santana, state of Amapá, region of the mouth of the Amazon River, motivated the study about the geological and geotechnical characteristics of the local soil. In this context, this research aims to evaluate the sensitivity of clays from a fluviomarine sedimentary deposit. The geotechnical investigation was divided into three areas, called investigation islands. On each island, piezocone tests (CPTU) were performed and undisturbed samples of high quality soil were collected for laboratory tests. Soil behavioral type abacuses (SBT), which use CPTU data, indirectly identified layers (lenses) of sensitive soft clays. Through the relationship between the undrained soil shear strengths (𝑆𝑢 and 𝑆𝑢𝑟), obtained by the unconfined simple compression test, the sensitivity values were directly obtained. The Atterberg limit tests, total granulometric analysis and moisture content, served to characterize the region's soil. The results showed that the sedimentary deposit is constituted mainly by silt and clay, of low resistance and high plasticity and compressibility, with moisture content close to 50%. The methods of Robertson (1990) and (2016) and Schneider et al. (2008) identified sensitive thin material. The clay showed 𝐵𝑞 values lower than 1.0. The results for 𝑆𝑢 were between 33.67 and 103.53 kPa, while for 𝑆𝑢𝑟 between 4.44 and 16.29 kPa. According to Skempton and Nortey's (1952) classification, 83.33% of the samples were classified as medium to extrasensitive clays, with a sensitivity range of 3.3 to 12.7 and an average of 7.06. Thus, the results were consistent with similar ones in the literature, evidencing the applicability of the geological geotechnical investigation for identifying and mapping sensitive soils in the Amazon region.