For the design of deep excavations, codes and standards advise to base estimates of wall deflections and ground movements on empirical data. Due to the limited number of case studies on circular excavations it is nearly impossible to find comparable projects under similar conditions. Therefore designers have to adopt conservative approaches, which predict larger ground movements than probably occur in reality and thus lead to more expensive structures and protective measures. Further uncertainty is induced for diaphragm wall shafts. The discontinuous nature of the wall due to the joints between the individual panels may cause anisotropic wall behaviour. There is a complete lack of understanding if, and how, the design of diaphragm wall shafts should consider anisotropic wall stiffness. The construction of Thames Water's Abbey Mills shaft in East London provided a unique opportunity to monitor the structural performance and the ground movements of one of the largest shafts ever built in the UK. The 71 m deep excavation penetrates a typical London strata and one third is in unweathered medium to hard Chalk. The monitoring scheme included distributed fibre optic strain sensing instrumentation and conventional inclinometers in the shaft wall to measure bending and hoop strains, as well as wall deflections during several construction stages. Further inclinometers and extensometers were installed around the shaft to monitor surface and sub-surface ground movements. The monitoring results were then compared to the initial PLAXIS design predictions. A further numerical investigation was conducted in FLAC2D which allowed a more flexible parametric study. The measured bending moments during shaft excavation exceeded the predictions mainly in the wall sections in the Chalk group. It was found that this was caused by assigning a low cohesion to the Chalk to induce conservative ground movements, so that the Chalk yielded in the analysis. In reality however, it remained elastic and hence induced larger bending moments in the wall. For future excavations in Chalk it is recommended to investigate the effect of a low and a high cohesion of the Chalk on the wall bending moment. The hoop strain measurements indicate that the shaft has undergone a three-dimensional deformation pattern during a dewatering trial prior to shaft excavation. The parametric study on wall anisotropy suggests that the shaft wall behaved like a cylindrical shell with isotropic stiffness, where the joints between the panels do not reduce the circumferential stiffness. Further numerical simulations varied the shaft wall thickness and the at rest lateral earth pressure coefficient in the Chalk. The results showed that the wall thickness has a minor influence on its deflection and hence thinner walls might be feasible for future shafts. The at rest lateral earth pressure coefficient of the Chalk appeared to be appropriately picked with 1.0 in the initial design. Above all, it was shown that wall deflections were very small with less than 4 mm. Correspondingly small ground movements were measured throughout shaft excavation. Empirical formulas on the other hand predict large settlements between 40 and 105 mm. Numerical predictions were much closer to the measurements and showed that small heaves occurred due to soil swelling caused by removal of overburden pressure. For future shaft designs it is hence advised against the use of empirical formulas derived from case studies under different conditions. It may furthermore not be necessary to implement expensive large-scale monitoring schemes, as it has been confirmed that ground movements around diaphragm wall shafts are minimal and that risks are low. The findings from this study provide valuable information for future excavations, which can be applied to the shafts constructed for the forthcoming Thames Tideway Tunnel project.

This study deals with tilt sensors. Besides others methods, accelerometers and gyroscopes are also convenient to solve this problem. Tilt sensors which are described in this thesis are working with capacitive, piezoresistive and thermal method. Capacitive accelerometers from producer Analog Devices, STmicro and Freescale, piezoresistive accelerometers from producer Panasonic Matsushita and gyroscope ADXRS300 are tested by practical measurement. Parameters of these accelerometers are found and they are compared with parameters from producer. Measurement reliability in this study is analysed as well. This thesis is divided in chapters theoretically describing principles of particular accelerometers and the chapters containing measured data evaluation.

Made available in DSpace on 2016-06-02T20:18:18Z (GMT). No. of bitstreams: 1 4592.pdf: 4567380 bytes, checksum: cf72712eb4eca85bb9df273f4e2fde10 (MD5) Previous issue date: 2012-06-21 / Financiadora de Estudos e Projetos / Manual material handling (MMH) is a common task in occupational environments and has been associated with musculoskeletal disorders at low back and upper limbs. Studies have shown that the correct hand/box coupling can minimize the risks for upper limb disorders, suggesting the use of handles as a way to reduce the physical demand required by the task. However, even when the boxes have handles, the workers not always use them during handling, suggesting the need for new boxes and handles designs. In order to improve the knowledge in this area, this thesis was composed by three studies: the first study was exploratory and the main objective was to descriptively and objectively evaluate how experienced workers performed cardboard boxes handling activities in an industry setting. The range of movements for wrists, forearms and elbows were objectively evaluated through electrogoniometry. The boxes had already received an ergonomic intervention, implemented six months before the data collection. The ergonomic intervention evaluated was the insertion of cutout handles in the cardboard boxes. The main results indicated that the way the worker grasps the box is crucial to the upper limbs movements during handling tasks. Thus, one hypothesis was that the positioning of the hands close to the bottom face would give workers greater control and biomechanical advantage regarding the load. In this sense, the second and third studies were performed. These studies had been carried out both experimentally in a laboratory setting, and followed the same data collection methodology. Inclinometers and electromyography equipments were added to the data collection. The aim of the second study was to evaluate a new prototype cardboard, developed as an alternative design to the one evaluated in the first study. The results showed that cardboard prototypes were resistant for reuse in internal transport, comfortable and safer for wrist and elbow movements, as well had promoted a reduced muscle demand on electromyography activity for wrist extensors and biceps brachii, when compared to the commercial boxes. Considering that the cardboard boxes are limited to the transportation of dried products, it is suggested the need for new boxes designs using other types of materials. In this sense, new plastic prototypes have been developed. The aim of the third study was: to compare the common commercial boxes with plastic prototypes boxes regarding their effect on upper limb posture, muscle electrical activity and perceived pleasantness of volunteers about their perception of upper limbs comfort during handling tasks. The prototypes allowed changes in handle position (top and bottom) and inclination (0 °, 15° and 30°). The prototypes with handles positioned at 30° were positive for the elbow flexion, shoulders elevation and ulnar deviation of the wrists. The results of present thesis showed that the best box to be used depends on conditions such as the type of conveyed material and height of the handling surfaces at the work environments. The evaluated prototypes showed good durability and costeffective, and can be used in industrial environments, especially for internal transportation. The studies have increased our understanding of safer conditions and more comfortable grips, promoted safer movements and required less electrical muscle activity when compared to commercial boxes. In future studies, we suggest that individuals with experience in manual handling tasks were also evaluated and new joints and muscle groups are also evaluated. / O manuseio de materiais e comum em ambientes ocupacionais e está associado a lesões na coluna lombar e membros superiores. Estudos indicam o uso de alças como uma forma de minimizar a demanda física exigida pela atividade, melhorando o acoplamento entre as mãos do trabalhador e o objeto manuseado. No entanto, mesmo quando as caixas possuem alças, este recurso não e utilizado pela maioria dos trabalhadores, sugerindo a necessidade de novos designs de alças e caixas. Na tentativa de ampliar o conhecimento nessa área, a presente tese foi composta por três estudos. O primeiro estudo teve caráter exploratório e o principal objetivo foi avaliar descritivamente e objetivamente, através da eletrogoniometria de punho, antebraço e cotovelo, como funcionários experientes realizavam o manuseio de caixas de papelão em um setor industrial. As caixas manuseadas haviam sido alteradas por uma intervenção ergonômica, implantada no setor seis meses antes da coleta de dados. A intervenção ergonômica avaliada foi a presença de alças, na forma de perfurações laterais. Os principais resultados apontaram que a forma como o individuo apreende a caixa interfere no movimento das articulações avaliadas durante o manuseio. Apesar da grande aceitação dos trabalhadores pelo uso de alças nas caixas, não foram todos os funcionários que as utilizaram em todos os manuseios. Sendo assim, uma hipótese levantada foi de que o posicionamento das mãos próximas a face inferior pudesse proporcionar ao individuo maior controle e vantagem biomecânica sobre a carga. Assim, foram realizados dois outros estudos. Estes estudos tiveram caráter experimental e foram realizados em laboratório, seguindo o mesmo método. Equipamentos de inclinometria e eletromiografia foram acrescidos a analise, ampliando o numero de articulações avaliadas tendo como objetivo de entender melhor a sobrecarga imposta aos membros superiores. O principal objetivo do segundo estudo foi avaliar um protótipo de caixa de papelão, desenvolvido como alternativa ao design avaliado no primeiro estudo (caixa de papelão comercial com alças). Os resultados demonstraram que os protótipos foram resistentes para a reutilização extensiva em transportes internos, favoreceram pegas mais confortáveis e movimentos mais seguros de punho e cotovelo, bem como exigiram menor atividade eletromiografica dos extensores do punho e bíceps braquial, quando comparadas as caixas comerciais sem alças. Tendo em vista que as caixas de papelão apresentam a limitação de permitir apenas o transporte de produtos secos, novos designs utilizando material plástico foram desenvolvidos. O objetivo do terceiro estudo foi: comparar o manuseio de uma caixa comercial com alças e de protótipos com alças ajustáveis confeccionados em plástico, avaliar seus efeitos na postura, atividade elétrica muscular e percepção de agradabilidade dos membros superiores, durante atividades de manuseio. Os protótipos testados possibilitavam a mudança do posicionamento (superior e inferior) e angulação das alças (0°, 15° e 30°). Os protótipos com alças anguladas em 30° apresentaram as melhores avaliações para os movimentos de flexão dos cotovelos, elevação dos ombros e desvio ulnar do punho. Os achados da presente tese mostraram que o melhor design de caixa a ser utilizado depende de características como o tipo de material transportado e das alturas das superfícies de manuseio presentes no ambiente de trabalho. Se as superfícies de manuseio puderem ser padronizadas no ambiente de trabalho, sugerimos pegas próximas as superfícies superiores da caixa para manuseios entre o solo e a altura do trocanter maior do fêmur e, pegas próximas a superfície inferior da caixa (fundo) para manuseios entre o trocanter maior do fêmur e acrômio do trabalhador. Os protótipos avaliados apresentaram boa durabilidade e custo-benefício, e podem ser utilizados em ambientes industriais, principalmente para o transporte interno. Os estudos permitiram aumentar a compreensão sobre condições mais seguras e confortáveis de manuseio, promoveram movimentos mais próximos a postura neutra e exigiram menor atividade elétrica muscular quando comparados a caixas comerciais. Em estudos futuros, sugerimos que sujeitos com experiência em manuseio também avaliem os novos protótipos e que novas articulações e grupos musculares também sejam avaliados.

The majority of the power generated today is produced using fossil fuels,emitting carbon dioxide and other pollutants every second. Also, fossil fuels will eventually run out. For the increasing worldwide energy demand, the use f reliable and environmentally beneficial natural energy sources is one of the biggest challenges. Alongside wind and water, the solar energy which is clean, CO2-neutral and limitless, is our most valuable resource. Concentrated solar power (CSP) is becoming one of the excellent alternative sources for the power industry. The successful implementation of this technology requires the efficient design of tracking and operation system of the CSP solar plants. A detailed analysis of components needed for the design of cost-effective and optimum tracker for CSP solar systems is required for the power plant modeling, which is the primary subject of this thesis. A comprehensive tracking and operating system of a parabolic trough solar power plant was developed focusing primarily on obtaining optimum and cost effective design through the simplified methodology of this work. This new model was implemented for a 50 kWe parabolic trough solar power plant at University of South Florida, Tampa.

The effects of seismic forces and thermal expansion on bridge performance necessitate an accurate understanding of the relationship between passive force and backwall deflection. In past case studies, skewed bridges exhibited significantly more damage than non-skewed bridges. These findings prompted studies involving numerical modeling, lab-scale tests, and large-scale tests that each showed a dramatic reduction in passive force with increased skew. Using these results, a correlation was developed between peak passive force and backwall skew angle. The majority of these tests had length to height ratios of 2.0; however, for several abutments in the field, the length to height ratio might be considerably higher than 2.0. This change in geometry could potentially affect the validity of the previously found passive force reduction correlation. To explore this issue, laterally loaded, large-scale pile cap tests were performed with densely compacted sand at a length of 11 ft (3.35 m) and a height of 3 ft (0.91 m), resulting in a length to height ratio of 3.7. The backwall interface was adjusted to fit three various skew angles including: 0°, 15° and 30°. The behavior of both the pile cap and adjacent soil backfill were monitored under these conditions. The peak passive force for the 15° and 30° tests were found to be 71% and 45%, respectively, of the peak passive force for the 0° skew test. These findings are relatively consistent with previously performed tests. Passive forces peaked at deflections between 2% and 5% of the backwall height, decreasing with skew angle. All skews exhibited a log spiral failure plane that transitioned into a linear plane. These results also agreed with previously reported values for large-scale passive force-deflection tests. Rotation of the pile cap was detected in the direction opposite to the skew. Higher pressures were found to be on both corners of the pile cap than in the middle portion, as is suggested by the elastic theory.

No description available.

[pt] Nos últimos anos na cidade de Lima as escavações profundas alcançaram uma presença maior, devido à recente demanda pela construção de edifícios altos e centros comerciais com vários níveis de subsolos, onde utilizam-se preferencialmente as cortinas atirantadas para a contenção dos solos. No entanto, a técnica de solo grampeado mostra-se como uma alternativa interessante, dado que também permite fornecer suporte lateral e limitar os movimentos do solo. A técnica consiste em reforçar o bloco do solo atrás da parede através das inclusões passivas, criando uma estrutura de gravidade consistente que permite aumentar a resistência geral ao cisalhamento e restringir os deslocamentos. Este estudo de caso procura avaliar os deslocamentos horizontais em uma escavação de 15m de altura em um entorno urbano, onde o solo é predominantemente de pedregulho denso mal graduado, parte do depósito aluvial do Conglomerado de Lima. A estimativa dos parâmetros de resistência baseou-se em ensaios de cisalhamento direto in situ em grande escala e ensaios de arrancamento encontrados na literatura. O acompanhamento dos deslocamentos ao longo do processo construtivo, foi realizado a través de inclinômetros instalados no perímetro, em locais estratégicos para avaliar os deslocamentos mais críticos na escavação. A avaliação de erros sistemáticos em inclinômetros é também abordada no estudo. Complementarmente, realizaram-se análises numéricas com programas de equilíbrio limite e elementos finitos, que permitiram avaliar os fatores de segurança e os deslocamentos com o objetivo de comparar os dados de campo com os resultados calculados. Através de análise paramétrica e calibração do modelo foi possível conhecer a influência dos parâmetros geotécnicos e geométricos de escavações profundas grampeadas. / [en] In recent years in the city of Lima, the execution of deep excavations growth, due to the recent demand for the construction of high-rise buildings and shopping malls having various levels of basements, where anchorage walls systems are preferably used to soil retention. However, the soil nailing technique is an interesting alternative, by reason to provide lateral support and limit movements. The soil nailing technique consists of reinforcing the soil block behind the wall through passive inclusions, producing a consistent gravity structure that allows the increas of the shear strength and restricting displacements. This case study aims to evaluate the horizontal displacements generated in a 15m high deep excavation in an urban environment, where the existing soil is predominantly of poorly graded dense gravel, component of the alluvial deposit of the Lima Conglomerate. The estimate of strength parameters for this type of soil was based on large-scale in situ direct shear tests and pullout tests found in the literature. The monitoring of displacements throughout the construction process was carried out using vertical inclinometers installed on the perimeter, in strategic locations to assess the most critical displacements that the excavation could experience. The evaluation of systematic errors in inclinometers is also approached in the study. In addition, numerical analyzes were carried out with limit equilibrium and finite element programs, which allowed evaluating the safety factors and displacements in order to compare the field data with the calculated results. Through parametric analysis and model calibration, it was possible to know the influence of geotechnical and geometric parameters of nailed deep excavations.

A landslide occurred during the construction of the Giresun &ndash / Espiye road between Km: 1+030 &ndash / 1+170 in April 2003. Investigating the causes and mechanism of this slope failure along with suggesting a proper stabilization technique is aimed in this study. For that purpose, a detailed site investigation study, including engineering geological mapping, drilling work, in situ and laboratory tests, was performed. Weathered tuffite, tuffite, flysch and dacitic tuffite, from top to bottom, are the major units in the study area. A &ldquo / translational slide&rdquo / occurred in completely weathered tuffite owing to the disturbance of the stability of the slope by the excavations performed at the toe of the slope / particularly the foundation excavation for the restaurant building and for the road cut for the Giresun &ndash / Espiye road. After establishing the model of the landslide in detail, shear strength parameters of the failure surface were determined by the back analysis method as &quot / cohesion&quot / =2.5 kN/m2 and &quot / friction angle&quot / =9&deg / . Toe buttressing, ground water and surface water drainage options were considered for stabilizing the slope. For the back analysis calculations, the Morgenstern-Price and Spencer methods were used with the aid of the SLOPE/W computer program.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O processo mais utilizado para a união de tubos de aço para o transporte de óleo e gás é a soldagem. Embora ainda se utilize a soldagem manual, a soldagem mecanizada e até mesmo a automatizada vem ganhando espaço. Assim, este trabalho comtempla a soldagem circunferencial em meia cana de tubos API 5L X65 de 8” de diâmetro nominal e 8,0 mm de espessura, junta de topo com chanfro estreito (abertura de 30°) e preparação em V, por meio de dispositivo de deslocamento (soldagem mecanizada) e com variação de parâmetros (soldagem automatizada). São apresentados os parâmetros de soldagem encontrados para a confecção da junta soldada em dois passes (um de raiz e outro de enchimento/acabamento). Os parâmetros selecionados para o passe de raiz foram retirados de um estudo anterior servindo também como forma de validação de resultados, ora obtidos na soldagem em chapas e, agora em tubos. Foram avaliados os processos GMAW com transferência metálica por curto-circuito em modo convencional e controlado (processos derivativos) utilizando fontes comerciais com diferentes tecnologias (RMD, STT e CMT). Logo após a determinação dos parâmetros de enchimento, foram realizados ensaios mecânicos voltados para sua validação (tração uniaxial, dobramento de face e raiz, nick break, impacto, dureza e macrografia,). Os resultados obtidos para o RMD e CMT foram adequados inicialmente em todos os ensaios e, em um, segundo momento foram também adequados para o STT. Entretanto, os ensaios realizados para processo convencional revelaram a existência de falta de fusão o que levou a necessidade de determinação de novos parâmetros de enchimento. Assim, foi projetado e construído um Sistema de Variação de Parâmetros para Soldagem Circunferencial (SVP) que permite a variação, em função da posição angular (inclinômetro), dos parâmetros mais adequados para cada uma das três posições angulares (plana, vertical e sobrecabeça). Para o processo convencional com variação de parâmetros foi possível obter ganhos em termos de tempo para execução da soldagem da ordem de 38% para a raiz e 30% para o enchimento. / Welding is one of the most employed process for joining steel pipes. Although, manual welding is still the most used one, mechanized version and even automatized one have increased its demand. Thus, this work deals with girth welding of API 5L X65 pipes with 8” of nominal diameter and 8.0 mm thickness, beveled with V-30º narrow gap. Torch is moved by a bug carrier (mechanized welding) and further the parameters are controlled as a function of angular position (automatized welding). Welding parameters are presented for filling the joint with two-passes (root and filling/capping passes). Parameters for the root pass were extracted from previous author´s work with weldments carried out in plates, but validated in this work for pipe welding. GMAW processes were assessed with short-circuit metal transfer in both conventional and derivative modes using different technologies (RMD, STT and CMT). After the parameter determination, mechanical testing was performed for welding qualification (uniaxial tension, face and root bending, nick break, Charpy V-notch impact, microhardness and macrograph). The initially obtained results for RMD and CMT were acceptable for all testing and, in a second moment, also for the STT. However, weld beads carried out by using the conventional process failed and revealed the existence of lack of fusion, which required further parametrization. Thus, a Parameter-Variation System for Girth Welding (SVP) was designed and built to allow varying the welding parameters as a function of angular position by using an inclinometer. The parameters were set for each of the three angular positions (flat, vertical downhill and overhead). By using such equipment and approach, the conventional process with parameter variation allowed reducing the welding time for joint accomplishment of the order of 38% for the root pass and 30% for the filling/capping pass. / Tese (Doutorado)

Geothermal energy is one of the oldest forms of energy on our planet. Its use by humanity dates back to the beginning of the ages. The forms of this energy gradually changed from the direct heat of the hot springs, through the heating of the buildings and the baths to the later use of superheated steam for industrial use. Nowadays, there is a large share of the use of large number of ground geothermal boreholes with heat exchangers drilled in the matrix. The geometric arrangement of such system has a considerable impact on its operation. Specific examples show that, unlike the design, actual boreholes in such system can often be drilled non vertically or even curved. These imperfections then usually deteriorate the thermal properties of the system. This thesis demonstrates the influence analysis of the borehole geometry distortion on the system thermal properties, it also informs about the development of a special measuring device designed to obtain information about the actual geometric shape of the investigated borehole and about the development of software for in situ rapid borehole system properties evaluation. The theoretical part of thesis contains the derivation of a simplified numerical model of heat conduction in the vicinity of the borehole system. Its results serve to compare the different borehole variants and the inaccuracy of borehole shaping. Using the simulations, the influence of inaccuracies in the borehole system on its thermal properties is demonstrated in several model configurations. This effect does not occur in a single borehole, but it is significantly visible in organized geothermal borehole systems. It may deteriorate system properties, but under certain circumstances its properties may improve. Verification of the results of these simulations was performed by the FEFLOW simulation software. In the practical part the development of a special instrument for measuring the shape of a geothermal energy borehole is documented. ....