EM - Escola de Minas

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6

Notícias

A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.

Navegar

Filtros

2016 - 20182

Configurações

Assunto: search.filters.subject.Clayey barriers

Resultados da Pesquisa

Agora exibindo 1 - 2 de 2
  • Nenhuma Miniatura Disponível
    Item
    On the compatibility and theoretical equations for mixtures of tropical soils and bentonite for barrier purposes.
    (2018) Morandini, Thiago Luiz Coelho; Leite, Adilson do Lago
    Vast regions of the globe are covered by tropical soils, increasing the perspective of using them for barrier design at solid/liquid disposal facilities. They comprise diverse pedological taxonomies, but have common features, specially the dominant mineral composition of quartz, kaolinite clay and Fe-Al-Mn oxides/hydroxides. Despite the vast occurrence, sometimes tropical soil samples may not be suitable for barrier purposes, which can be overcome using bentonite as additive, provide that technical evaluations are adopted. An important technical issue to be addressed is the compatibility between the barrier materials and the liquids to be disposed. Compatibility studies usually involve laboratory testing using direct and indirect methods, which were involved in this research. The indirect studies involved modified Atterberg limits and the direct approach was developed using direct permeation. The tropical soil samples were selected to be in different weathering stages, considering the laterization degree. The chosen bentonite content to compose the mixtures was 3, 6, 9 and 12% on a dry weight basis. The elected chemical solutions for these studies were: calcium chloride (CaCl2), nitric acid (HNO3), sodium hydroxide (NaOH), ethanol (C2 H5OH) and tap water. As a summary, the main research objectives were: (1) comparison between direct and indirect methods for compatibility evaluation; (2) assessment of the influence of the bentonite content on the compatibility of tropical soil samples; (3) investigation of the influence of the laterization degree on compatibility and (4) evaluation of theoretical equations to predict the compatibility of these samples through back analysis. The results indicate that: indirect and direct methods are similar from a qualitative point of view; bentonite is more sensitive to chemicals than the natural soil components; the laterization degree is not so influent on the compatibility and good compatibility predictions were obtained with the proposed theoretical equations.
  • Nenhuma Miniatura Disponível
    Item
    Shear strength of tropical soils and bentonite mixtures for barrier design.
    (2016) Morandini, Thiago Luiz Coelho; Leite, Adilson do Lago
    Compacted clayey tropical soils have great potential to be used as barriers in waste disposal facilities, considering that some technical requirements are fulfilled (e.g. hydraulic conductivity; compatibility after disposal; shear strength; swelling/cracking, etc). In turn, the bentonite addition is relevant for the cases where the hydraulic conductivity must be lowered, and therefore investigations on the changes of the mechanical parameters of tropical soils induced by the bentonite addition are of great interest. This paper presents the results of a laboratory investigation on the shear strength of different samples of tropical soils and their mixtures with bentonite in the proportions of 0, 3, 6, 9 and 12% (dry weight basis). The tropical soil samples were collected considering the lateritic, transitional and non-lateritic behavior according to the MCT-M (Modified-Miniature-Compacted-Tropical) classification. The laboratory tests consisted of CU (Consolidated- Undrained) triaxial tests under the confining stresses of 100, 200 and 400 kPa. The results have showed that the addition of bentonite produced a significant increase in the plasticity of the tropical soil samples (PI increases 4 to 6 times), considerably reduced their friction angle (by as much as 11o) and stiffness at peak (modulus reductions of 2.5 to 4 MPa) and gave rise to a slight increase in their cohesion (up to 12 kPa). These facts must be considered in the barrier stability analyses when heavy loads are applied. The important role of the shear strength on barrier design is highlighted.