2. ANALYSE AV DYPFORVITRING
2.2 Geologisk bakgrunn
Individualmente, cada modelo apresentou resultados consistentes, e comparativamente foram semelhantes entre si, sendo as pequenas diferenças de resultados devidamente compreendidas e justificadas. Apesar das várias simplificações adotadas, os resultados forem satisfatórios. Cada forma de abordagem, seja experimental, analítica ou numérica, complementa as lacunas deixadas pelas outras, dessa forma, podemos dizer que os 3 modelos se completam na busca de uma melhor compreensão do fluxo em meios granulares.
Conclui-se por fim, que para o material estudado, o gnaisse britado, podemos definir 3 padrões distintos de comportamento, em função de sua razão D/d. Para valores de razão D/d menores que 4, dificilmente ocorrerá fluxo granular, sendo portanto dispensáveis ensaios nesta faixa.
Para valores da razão D/d entre 4 e 5, entra-se numa zona de transição, na qual a ocorrência de fluxo é incerta. Nesta faixa, recomenda-se o uso da simulação numérica, através do método dos elementos discretos, pois este permite analisar os possíveis problemas de obstrução que podem ocorrer nesta faixa.
Por último, para razões D/d maiores que 5, a ocorrência de fluxo granular é praticamente certa, e desta forma, o modelo cinemático se torna a melhor opção, pois permite resultados rápidos, robustos, como campos vetoriais e perfis de velocidade, e é de fácil implementação. Todavia, em todos os casos, é necessário o conhecimento de parâmetros constitutivos do material, e estes devem ser medidos com critério para que sejam representativos.
Em trabalhos futuros, poderá ser abordado o tratamento tridimensional destes modelos, ou também a modelagem de materiais compostos por mais de uma faixa granulométrica, ou seja, materiais polidispersos. Pode-se também testar outras formas de obtenção de parâmetros constitutivos, como a densidade e ângulo de repouso. O ângulo de repouso, por exemplo, poderia ser estimado a partir de um ensaio de inclinação, também conhecido como tilt test. Por fim, como última sugestão, pode-se variar a geometria do silo, desde o ângulo de suas paredes à própria escala do modelo.
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A. TABELA DE DADOS DOS ENSAIOS DE DENSIDADE