Abstract Geotextile tubes can be used to dewater materials such as sludge, sediments or residues aiming at reducing their moisture contents to acceptable levels. The tube filling process can be carried out using one or several filling stages, and the number of stages can influence the tube behaviour in terms of dewatering rate, final shape and geotextile strains, for instance. In this research, laboratory tests were carried out on nonwoven geotextile tubes for the dewatering of a fine-grained material using different numbers of filling stages. The behaviour of the tube was monitored by instrumentation to assess tube geometry, pore pressures, total stresses at the tube base, geotextile strains and retention capacity. Evaluations of the accuracy of some available methods for the prediction of tube behaviour were also made. The results obtained showed that the increase in the number of filling stages resulted in larger final tube height, volume, geotextile strains as well as larger diameters of the soil particles that piped through the geotextile. Predictions of tube behaviour by available methods showed varying degrees of accuracy depending on the tube parameter considered. sludge levels rate instance research finegrained fine grained geometry pressures base capacity made height volume considered

Abstract Understanding the geotechnical properties of iron ore tailings is currently one of the major challenges in the mining industry. With transitions from drained to undrained conditions occurring in seconds, recent dam problems have been a challenge to solve with classical soil mechanics, which provides few means to explain how such phenomena develop. There is also an increasing propensity in technical and scientific circles to seek constitutive models that are based on critical state soil mechanics and that allow for the analysis of tailings behaviour. However, there is still a lack of knowledge and information about the critical state properties of iron ore tailings. The present research experimentally and numerically investigated the effectiveness of modelling the behaviour of iron ore tailings. The aim of these experiments was to assess the critical state parameters of tailings from a significant iron ore operation site in Quadrilátero Ferrífero (Minas Gerais state, Brazil). The results indicated that the selected numerical model (NorSand) was adequate to evaluate the behaviour of the studied mine tailings. The numerical results showed consistent adherence to the experimental results of both drained and undrained tests, with deformations below 5% and samples in which the state parameter had a small magnitude.

Atualmente o crescente aumento do volume de rejeitos gerados pelo aproveitamento de minerais com teor de ferro cada vez mais baixos tem motivado as mineradoras a adotar, como solução principal para disposição desses rejeitos, a técnica do aterro hidráulico aliada ao método de alteamento a montante. Essa metodologia pressupõe o aparecimento de incertezas relacionadas ao processo de deposição na praia e ao próprio rejeito, que é lançado de forma aleatória e sem controle das variáveis de descarga que influenciam nesse processo. Assim, podem formar-se regiões na barragem com alta concentração de ferro, o que tende a influenciar as propriedades geotécnicas desse material. Com base no relatado anteriormente, o objetivo desse trabalho constituiu em estudar o comportamento do rejeito, em função da porcentagem de ferro e sílica nele presente. Também foi verificada influência do rejeito na condutividade hidráulica saturada, através de ensaios de laboratório e ensaios de campo.

Nowadays the increased tailing volume, generated by the utilzation of minerals with low iron, has been motivating mining companies to adopt the technique hydraulic fill structures with upstream method as the main solution for tailings disposal. This methodology is influenced by the appearance of uncertainties related to the deposition process for the beach and to the tailing that is launched randomly and without control of the discharge variables that influence this process. As such, high iron concentration areas are formed in the dam, tending to influence the geotechnical properties of this material. Thus, the objective was to study tailing behavior in function of the percentage of iron and silica present and to verify their influence in the saturated hydraulic conductivity of this tailing through laboratory and field tests.

As diferenças nas características granulométricas e nos processos de disposição dos resíduos de mineração tendem a afetar, de forma significativa, o comportamento geotécnico das estruturas responsáveis pela sua contenção. Nesse sentido, algumas metodologias de controle da fase construtiva dos alteamentos foram propostas baseando-se em correlações entre as densidades e os parâmetros de resistência dos rejeitos. Entretanto essas metodologias apresentam limitações relacionadas à obtenção de amostras representativas, particularmente nos rejeitos granulares. Nesse contexto, o objetivo desse trabalho consistiu na proposição de uma metodologia alternativa para determinação da densidade in situ de rejeitos de minério de ferro com a utilização de um equipamento de penetração estática de pequeno porte denominado penetrologger. A realização conjunta de ensaios com o cilindro biselado e o penetrologger nas barragens de rejeitos do Quadrilátero Ferrífero permitiu atestar a aplicabilidade do equipamento.

The differences in the characteristics and the placement processes during the waste disposal tend to affect the geotechnical behaviour of tailings dams. Some methodologies of quality control during the construction phase have been proposed, which are based on the correlation between densities and strength parameters. Considering these methodologies, it is possible from field density analyses, to verify changes in the geotechnical parameters during construction phase. However, it has been observed that the field density measurements tend to present some problems due to the difficulties in obtaining representative samples, particularly for granular tailings. In this context, the proposal of this investigation was to evaluate an alternative methodology based on the static penetration equipment (penetrologger test). Some tests have been carried out on a tailings dam in the Minas Gerais State, Brazil, in the mining region known as "Quadrilátero Ferrífero". The tests were made during the construction phase using the penetrologger to evaluate field densities.