Dissertações em Engenharia de Barragem e Gestão Ambiental (Mestrado) - PEBGA/NDAE/Tucuruí

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/9396

Navegar

Agora exibindo 1 - 5 de 5

Acesso aberto (Open Access)
Análise numérica da estabilidade de taludes utilizando o método de Galerkin livre de elementos
(Universidade Federal do Pará, 2017-05-03) SILVA, Davi Barbosa Costa da; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The safety of dams is associated to the stability of the structures that compose them. In a earthfill dam, there are mentioned the slopes, which are surfaces that form an angle with the horizontal one. Its study using numerical methods, like the finite element method (FEM), makes possible the estimate of displacements, stresses and strains. It is aimed in this study to contribute in the efficiency of the numerical analysis devoted to the slopes. Through the development of a resource turned specifically to dams, the objective in the present work is to present an algorithm able to check the stability of slopes in the period of its construction using a numerical method without mesh. For the proposed analyses, there was used the element free Galerkin method (EFGM), applying it in the strength reduction method (SRM). After the idealization of a model and solution using the limit equilibrium method and the strength reduction method with the help of the FEM, both in commercial software (GeoStudio), there were obtained and were compared the results of a model in which there is applied the strength reduction method with the use of the EFGM. The analysis by the strength reduction method was divided in determination of the in situ stresses of the foundation, construction of the landfill and strength reduction of the soil. Numerically, in the stage of getting the in situ stresses, the EFGM presented better result when compared to FEM, taking as a reference the classic mathematical model of the soil mechanics for subhorizontal surfaces. In the stages of construction of the landfill and of strength reduction, the relative approximation error the EFGM regarding the FEM was nearly always superior to 5%. However, it noticed if that in the main answers, i.e. in the determination of the slip surface and of the strength reduction factor, the results were similar, as in the strength reduction method, with the EFGM regarding the FEM, as that regarding the limit equilibrium method. In the comparison with the FEM, there were obtained more conservative strength reduction factors. In spite of being an information not available openly, it concluded if that the elastoplastic constitutive model used in the commercial software is not the linear elastic perfectly plastic model, which was hypothesis adopted for the EFGM. Besides the differences due to the behavior idealized for the material, the application of meshfree method also requires more studies related to the definition of the representation of the domain. The main advantage of the adoption of the proposed method is the possibility to test more parameters in less time, which makes it useful in preliminary construction studies. For that, it must be observed that, in spite of the limitations in displacement estimation, which are useful to associate numerical results to the observations in field, the conditions in which there is slip at slope can be appreciated in satisfactory, conformable way when it was shown in comparisons with the most used methods.
Acesso aberto (Open Access)
Avaliação de alternativas para projetos de descaracterização de uma barragem de rejeito de mineração utilizando análise comparativa multicritério
(Universidade Federal do Pará, 2024-10-10) OLIVEIRA, Pedro Lucas Louzada de; SILVA, Adriano Frutuoso da; http://lattes.cnpq.br/3321059172343690; https://orcid.org/0000-0003-1710-8862
The decharacterization of tailings has become an extremely relevant and urgent topic in the contemporary global scenario. Given the recent disasters and environmental tragedies resulting from the collapse of mining dams in Brazil in 2015 and 2019, the need to implement efficient and safe processes for the deactivation and recovery of these structures has become imperative. The complexity inherent to this type of enterprise demands a careful and comprehensive approach in evaluating the available options. The simple selection of an alternative based on a single criterion, such as financial cost or deadline, for example, can result in adverse consequences and negative impacts from both a technical, economic, environmental and social point of view. Given the above, this dissertation aims to explore the importance of analyzing alternatives considering multiple criteria in the process of choosing the best solution for the mining dam decharacterization project. Through a literature review and presentation of a case study of the decharacterization of a Manganese dam using the assessment of technical, environmental, economic and socioeconomic requirements as a decisive element in choosing the solution to be detailed. The methodology consists of analyzing the proposed alternative scenarios, including the definition and weighting of the multiple variables to be evaluated. The result obtained demonstrates that the adoption of multiple criteria, which encompass not only economic aspects, but also environmental, social, technical and safety aspects, was fundamental to guarantee a well-informed and sustainable decision. It was evidenced that the analysis of multiple criteria was also able to favor the decision-making process in mining dam decharacterization solutions, facilitating traceability and understanding between the stakeholders involved in projects of this nature.
Acesso aberto (Open Access)
Dimensionamento de barragem de acumulação de água para sistema de irrigação de plantio de cacau no sudeste do estado do Pará
(Universidade Federal do Pará, 2024-04-25) SILVA, Cleveland Gustavo Canto; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
The Amazon region has high water potential and large natural reservoirs of water existing in the most diverse forms (springs, aquifers, lakes, etc.), however the distribution and access to the resource by the population are unequal, making the demand for water much greater than its availability in certain regions, which leads to water stress. In the Amazon, family farming is a relevant activity in regional sustainable development, and demands part of this resource, which is a limiting factor for regional development. Faced with this reality, water capture, storage and conservation technologies are used, with dams being one of the available technologies that play an important role in the democratization of water use. Therefore, through this research, we seek to design a dam that will serve as an artificial reservoir for water storage, intended for agricultural consumption of cocoa plantation on an agro-family scale on a farm located in the municipality of Novo Repartimento, to optimize its cultivation cycles, combined with the use of new technologies that use local resources and renewable energy sources available in the Amazon. For this, the water demand necessary for the agricultural activity of the enterprise was evaluated, comprising the Water Balance of the location, as well as delimiting the watershed of direct contribution of the dam, allowing the dimensioning of the artificial reservoir to meet the volume of water needed in the activity.
Acesso aberto (Open Access)
Estudo de caso de execução de aterros com misturas de argila e rejeito de bauxita
(Universidade Federal do Pará, 2023-06-05) EÇA JUNIOR, José Roberto Guimarães; ALENCAR JÚNIOR, Júlio Augusto de; http://lattes.cnpq.br/3663658632717465
The reuse of mining tailings is a real demand due to the search for sustainable exploitation of resources. Brazil is the holder of one of the largest mineral assets and, as such, is one of the largest producers and exporters of minerals on the planet. The search to meet the demand for the production and extraction of minerals has been growing every day and, along with this growth, the search for the reduction of environmental impact without loss of profitability has also been increasing. Currently, research with these objectives is extremely necessary in the search for solutions to these problems. Several studies seek alternatives for the reuse of the waste on a large scale, and one of the alternatives that make this application feasible are landfills within the enterprise itself. With the continuous updating of the regulations that govern dams, it is often necessary to reinforce old structures in order to increase the safety factor. This paper sought to analyze the applicability of mixing clay with bauxite tailings, in different proportions, for feasibility of its use in controlled landfills. In addition, it aimed to make feasible analyses regarding the research that evidenced the reuse of ore tailings and additions of other tailings materials. A case study was carried out in a mining company, collecting clay and tailings samples, and after being characterized, a pilot and an auxiliary mix were defined. As results, the mixture of 50% bauxite tailings with 50% clay resulted in a material that achieved California Support Index (CSI) values higher than those required by the Dnit 108 of 2009 standards, besides considerably improving the geomechanical characteristics when compared to the pure tailings. Thus, this research contributed to evaluate the applicability of compositions of clay and bauxite tailings in an experimental embankment in a mining area.
Acesso aberto (Open Access)
Verificação de desempenho dos sistemas de filtragem de resíduo bauxita por tambor e prensa como alternativa para barragens
(Universidade Federal do Pará, 2023-02-26) PANTOJA, Ronaldo Guimarães; SILVA, Adriano Frutuoso da; http://lattes.cnpq.br/3321059172343690; https://orcid.org/0000-0003-1710-8862
Tailings dams generally function as a reservoir of tailings and water, due to existing disposal methods, this is due to the characteristics of the processing processes of mining companies and refineries, which use a very high concentration of water in this process, resulting in tailings with low solids contents and that offer risks in the disposal and that also directly impact the environment in which they are inserted. In view of the occurrence of accidents involving tailings dams in Brazil and worldwide and the need to reduce the impacts caused, mining companies and ore processing industries have invested in innovative technology that promote waste dewatering, making them drier and providing a safer form of disposal. However, in this direction, this study presents the methods of disposal of wet and dry tailings in the form of landfills, obtained from filtration systems, highlighting the advantages and disadvantages of the use of the filter press compared to the drum filter for the disposal of bauxite residue. Experimental landfills of bauxite residues from an alumina refinery, located in the state of Pará, were used, which allowed the knowledge of the material behavior after filtering by filter press, when submitted to compaction by track tractor and compactor roller. A qualitative risk analysis of the FMEA type was also analyzed to identify the risks involved in the method of disposal of the filtered residue by drum filter. The residue dewatered through the drum filter reaches an average solids content of 60% at the end of the process and per filter press up to 80%. The compaction tests allowed the knowledge of dry density, optimum humidity and degree of compaction of the material dewatered by filter press, when arranged in the form of a controlled landfill. The two waste filtration systems (Drum Filter and Press Filter) were compared considering the operational, safety and environmental aspects, allowing to know the advantages and disadvantages of each system and the safer disposal method, less impacting on the environment and less susceptible to structural problems. The FMEA analysis identified the main triggers and failure modes related to geotechnical risks in the operation of the waste system with drum filter, for disposal via construction of platforms. The aspects of "insecurity" and "dam galling" were analyzed and generated the risk matrices and their consequences / effects. The results "High Risks" helped to define the change in the filtering system and arrangement method.

Navegar

Navegando Dissertações em Engenharia de Barragem e Gestão Ambiental (Mestrado) - PEBGA/NDAE/Tucuruí por CNPq "CNPQ::ENGENHARIAS::ENGENHARIA CIVIL::GEOTECNICA::OBRAS DE TERRA E ENROCAMENTO"