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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A geoestatística como ferramenta para estimar o rock mass rating em modelos tridimensionais

Vatanable, Henri Yudi January 2018 (has links)
A caracterização geotécnica de maciços rochosos é um dos aspectos mais importantes para o sucesso de um empreendimento mineiro. Desta forma é preciso ter um investimento significativo para a aquisição de dados durante a fase de pesquisa mineral, bem como um grande esforço para manipular os dados obtidos. Para se determinar as propriedades de um maciço, é necessário estabelecer, primeiramente, as diferenças entre rochas intacta e maciço rochoso. O comportamento mecânico destas duas classes pode apresentar grandes diferenças quando analisadas em laboratório. Um dos métodos mais utilizados no ambiente mineiro para classificar o maciço rochoso é o Rock Mass Rating (RMR), sistema que consiste em ranquear os seguintes parâmetros: Rock Quality Designation (RQD), espaçamento entre fraturas, resistência a compressão simples (UCS), qualidade das descontinuidades e presença de água no maciço. Este trabalho tem por utilizar a geoestatística para primeiro se conhecer algumas das particularidades destas variáveis, tais como a não linearidade, o comportamento em diferentes direções e a união de diferentes populações e posteriormente usar as técnicas de krigagem para criar um modelo geotécnico tridimensional. A geoestatística nos permite obter uma estimativa mais precisa e ter um maior conhecimento da incerteza do fenômeno, entretanto o RMR, por não ser uma variável aditiva, não se pode aplicar diretamente o uso das técnicas de krigagem. Assim uma metodologia é proposta para se estimar cada um dos parâmetros, ranqueá-los de acordo com seus valores e por fim obter a classificação RMR através do somatório destes ranques. Os resultados são comparados com a geologia estrutural da região de estudo, para se analisar a relação desta com a qualidade do maciço. A metodologia proposta apresentou uma melhora significante na qualidade de informações no local estimado e mostrou ser uma tentativa consistente para se criar um modelo geotécnico 3D. / The geotechnical characterization of rock masses is one of the most important aspects for the success of a mining enterprise. In this way, it is necessary to have a significant investment to acquire data during the mineral research phase and to make a great effort to manipulate and interpret the obtained data. In order to know a rock, it is necessary to establish the differences of properties between rock intact and rocky mass. The mechanical behavior of these two classes can present great differences when analyzed in the laboratory. One of the methods most used in the mining environment to classify the rock mass is the Rock Mass Rating (RMR) system, which consists of ranking the following parameters: Rock Quality Designation (RQD), fracture spacing, simple compression strength (UCS) quality of the discontinuities and presence of water in the massif. This work has to use geostatistics to first know some of the peculiarities of these variables, such as nonlinearity, behavior in different directions and the union of different populations and later to use kriging techniques to create a three - dimensional geotechnical model. The geostatistics allows us to obtain a more accurate estimate and to have a better knowledge of the uncertainty of the phenomenon, however, the RMR is not an additive variable, so cannot be directly applied the use of kriging techniques. Thus a methodology is proposed to estimate each of the parameters, rank them according to their values and finally obtain the RMR classification through the sum of these ranks. The results are compared with the structural geology of the study region, in order to analyze its relation with the quality of the rock mass. The proposed methodology presented a significant improvement in the quality of information at the estimated site and proved to be a consistent attempt to create a 3D geotechnical model.
2

Shear and compression behaviour of undegraded municipal solid waste

Langer, Ulrich January 2005 (has links)
To ensure stability of a construction the physical properties of its components have tobe well known. In a landfill, waste presents the largest structural element and controlsboth the stability and integrity of the lining system. In spite of this critical role there is adearth of knowledge on behaviour of waste as an engineering material. Wastevariability and changes in waste stream aggravate the assessment of wastemechanical properties.In a literature review the main influences on shear behaviour of municipal solid waste(MSW) were identified. Design values and recommendation for shear parameter weresummarised. To assess mechanical behaviour in a systematic way the use of aclassification system was deemed crucial for a comparison of different findings fromliterature and a categorisation of waste in regard to its composition. A framework for aclassification system was introduced. Main elements of a comprehensive classificationsystem were identified in a literature review and discussed, and data from literaturewas applied to the classification framework. For the validation of a classificationsystem, municipal solid waste was examined in an in-situ waste sorting analysis andalso applied to the framework.The findings from the waste sorting and the classification system were also used todevelop a family of synthetic waste to gradually examine the influencing factors onwaste mechanical behaviour. For this, the materials, size ranges and shapes of wastecomponents identified in the waste sorting analysis were reduced to a minimum butstill representative amount. A range of synthetic waste compositions was engineeredand tested in a large-scale shear device. Compression tests were also conducted in alarge compression cell. The results from the laboratory testing were compared tovalues from the literature and MSW mechanical behaviour was subsequentlydiscussed in view to potential changes from changing waste streams.The results from shear and compression tests (constrained and shear modulus) onsynthetic waste were linked to the classification system and trends of the mechanicalbehaviour in relation to the tested synthetic waste compositions were identified.A framework for classifying MSW and comparing waste mechanical behaviour waspresented and demonstrated. A family of synthetic wastes was engineered and testedin shear and compression tests. The results were comparable to values from theliterature. Further research is recommended to refine the synthetic waste and theclassification.

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