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Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

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A static cone penetrometer was modified to incorporate a small diameter triaxial geophone package. This instrument was evaluated by obtaining downhole shear wave velocity profiles at selected research sites on the Fraser River Delta near Vancouver B.C. for the purpose of determining in-situ dynamic shear moduli. A second geophone package was added to the instrument to assess the accuracy of shear wave velocity measurements, and to determine a practical instrument configuration for routine field use. Shear wave characteristics, downhole velocities, signal repeatability and signal amplitude were studied, to evaluate the energy source and downhole receiver response, and to develop a rational testing procedure. Plank type signal sources were used exclusively and were found to be both satisfactory and convenient. Geophone response and receiver to soil coupling were excellent and identifiable shear waves were obtained to depths of 40 metres. Down rod signal transmission, signal repeatability and problems with high background noise levels were overcome by selective testing procedures and interpretation techniques. The results of this study indicate that a static cone penetrometer containing just a single geophone can provide a rapid and accurate method for carrying out a downhole shear wave velocity survey. The cone testing procedure allows superior shear wave records since it minimizes soil disturbance, provides excellent soil to receiver coupling and controlled receiver orientation. Combined with data from the cone bearing, friction and pore pressure measurement elements, the interpretation of in-situ static and dynamic soil properties, using a single test hole, is greatly enhanced. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

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Orientador: George de Paula Bernardes / Banca: Edmundo Rogério Esquivel / Banca: Heraldo Luiz Giacheti / Resumo: As propriedades geomecânicas do solo são dados imprescindíveis na elaboração e execução de um projeto de engenharia geotécnica. Para isso, diversos métodos são comumente utilizados na prática tais como o ensaio à percussão (SPT) e o ensaio de cone (CPT), entre outros. Cada tipo de equipamento vai apresentar vantagens e desvantagens em função da geologia, das condições de acesso e área de montagem e trabalho. O Penetrômetro Dinâmico Leve modificado por Nilsson (2001), com medida de torque, é um equipamento leve e simples que apresenta grande mobilidade, permitindo realizar ensaios em regiões de difícil acesso, como relevo acidentado, florestas e áreas inundadas. Esse equipamento é pouco difundido no Brasil e a interpretação dos seus resultados é feita através do índice N10 que fornece uma ideia da resistência do solo, assim como o NSPT faz com o SPT. Este trabalho procurou interpretar racionalmente os resultados do DPL aplicando os mesmos conceitos de energia e propagação de onda unidimensional de tensão, hoje amplamente usados para interpretar o SPT. Foi investigada a influência da geometria de ponta no atrito mobilizado, constatando que pode-se substituir a ponteira de 90° do DPL por uma com 60° de ápice, como as usadas no CPT. É proposto uma nova formula relacionando o torque medido no DPL com o atrito lateral da ponteira, considerando as contribuições da luva cilíndrica e da ponta cônica. Ensaios de campo mostraram que esta fórmula proposta contabiliza mais adequadamente o... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Geotechnical properties of soil are given essential in the preparation and execution of a geotechnical engineering design. For this, several methods are commonly used in practice such as percussion test (SPT) and cone test (CPT), among others. Each type of equipment will have advantages and disadvantages depending on the geology, the conditions of access and mounting area and work. The Dynamic Light Penetrometer modified by Nilsson (2001), to measure torque, is a lightweight and simple tool that exhibits high mobility, allowing perform tests in areas of difficult access, such as rugged terrain, forests and wetlands. This equipment is not yet widespread in Brazil and the interpretation of results is done via the N10 index that provides an idea of the strength of the soil, as well as the NSPT makes the SPT. This study sought to rationally interpret the DPL results of applying the same concepts of energy and one-dimensional wave propagation of tension, now widely used to interpret the SPT. The influence of the tip geometry the mobilized friction was investigated, noting that one may substitute the tip 90 of the DPL by a 60 ° apex, as used in CPT. It is proposed a new formula relating the torque measured in DPL with the lateral friction of the tip, considering the contributions of the cylindrical sleeve and the conical tip. Field trials have shown that this accounts for proposed formula more suitably the lateral friction, especially when using the measurement of the residual torq... (Complete abstract click electronic access below) / Mestre

published_or_final_version / abstract / Civil Engineering / Doctoral / Doctor of Philosophy