A presente dissertação aborda o estudo dos efeitos de escavações realizadas acima de túneis já executados. Os trabalhos mais relevantes envolvendo a interação entre escavações e túneis já existentes são apresentados e discutidos. São realizadas simulações numéricas de casos hipotéticos, em estado plano de deformações utilizando o modelo de Mohr-Coulomb, permitindo a identificação dos parâmetros mais relevantes para esse tipo de problema e suas influências nos resultados. É discutido o comportamento mais rígido do maciço durante as trajetórias de descarregamento, bem como qual o módulo de elasticidade mais adequado para representar o fenômeno. Modelagens numéricas de um caso real em São Paulo (a escavação dos subsolos do edifício Stan Paulista, acima de túneis do Metrô) são realizadas, utilizando o modelo e os conceitos estudados. Os resultados obtidos das simulações são discutidos e comparados com os valores de instrumentação. Constata-se que a metodologia utilizada para a análise dos efeitos de escavações acima de túneis já existentes pode ser utilizada na avaliação de outros casos. / The presented research approaches the study of excavations effects above existing tunnels. Some of the most relevant papers related to interaction between excavation and tunnels are presented and discussed. Numerical simulations of hypothetic cases assuming plane strain condition and Mohr-Coulomb model for soil behavior are performed, allowing the study of influence of input parameters in the results. It is discussed behavior of the soil in stress paths that indicates reduction of the mean stress, wich is more rigid than the triaxial compression path. It is also discussed wich is an appropriate elastic modulus to be used in this situation. A real case (basement excavation of Stan Paulista building, above Metrô tunnels) is analyzed with numerical models, utilizing the concepts studied. The results of the simulations are compared with field instrumentation data. It is concluded that the methodology used for the analysis of the effect of excavation above existing tunnels can be utilized in other cases.

The aim of this study is to develop new insights which pressure relief (PR) cushion designers can use to guide the design of new cushions with greater efficacy at preventing pressure ulcers than contemporary cushions. A methodological framework was formulated which incorporated a number of research techniques from the user-centred methodology USERfit, and included methodological triangulation. Exploratory interviews and observational work were conducted in a specialist unit for spinal cord injury (SCI). This involved ten patients, four physiotherapists, two nurses and an outpatient technician. Additionally, two questionnaires were designed and circulated amongst SCI patients and staff with completed responses from 41 patients and 31 staff. From the analyses of the data gathered from the literature, observational work, interviews and questionnaire responses, 28 recommendations for cushion design were formulated. These recommendations covered the principles which underpin cushion design, cushion usability and the future direction of cushion design.

The overall goal of this research is to improve the use of seated tilt to increase function, health and quality of life for people using power wheelchairs. Specifically, the objective of this dissertation is to evaluate the biomechanical responses to seated full body tilt and their relationships to the actual use of tilt-in-space wheelchairs. In the first phase of this study, researchers remotely monitored how 45 fulltime power wheelchair users used their tilt-in-space systems. Participants spent an average of 12.1 hours in their wheelchair each day. They spent more than 2 hours seated at positions greater than 15° and performed tilts of 5° or greater every 27 minutes, but rarely performed tilts past 30°. Two distinct types of tilt behavior were identified: uni-modal (staying at a single position more than 80% of the time) and multi-modal (staying at a single position less than 80% of the time). Participants in the multi-modal group tilted significantly more frequently (4 times per hour) than the uni-modal group, and did not have a single typical position. Participants without sensation were more likely to exhibit uni-modal behavior. In the second phase of this study, researchers used interface pressure measurements and laser Doppler flowmetry to study changes in localized loading and superficial blood flow at the ischial tuberosities across different amounts of tilt. Eleven participants with spinal cord injuries were studied in a laboratory setting. Results showed that biomechanical responses to tilt were highly variable. Pressure reduction at the ischial tuberosity was not present at 15°, but did occur with tilts to 30° and greater, and could be explained by the tilt position and upright pressure. Unlike pressure, blood flow increased with all tilts from an upright position, but did not increase when tilting from 15° to 30°. Only 4 of 11 participants had a considerable increase (≥10%) in blood flow at 30° tilt, whereas 9 participants did during maximum tilt (i.e., 45°-60°). Based on the results of this study, tilting for pressure reliefs as far as the seating system permits is recommended to maximize the potential for significant blood flow increases and pressure relief.

A presente dissertação aborda o estudo dos efeitos de escavações realizadas acima de túneis já executados. Os trabalhos mais relevantes envolvendo a interação entre escavações e túneis já existentes são apresentados e discutidos. São realizadas simulações numéricas de casos hipotéticos, em estado plano de deformações utilizando o modelo de Mohr-Coulomb, permitindo a identificação dos parâmetros mais relevantes para esse tipo de problema e suas influências nos resultados. É discutido o comportamento mais rígido do maciço durante as trajetórias de descarregamento, bem como qual o módulo de elasticidade mais adequado para representar o fenômeno. Modelagens numéricas de um caso real em São Paulo (a escavação dos subsolos do edifício Stan Paulista, acima de túneis do Metrô) são realizadas, utilizando o modelo e os conceitos estudados. Os resultados obtidos das simulações são discutidos e comparados com os valores de instrumentação. Constata-se que a metodologia utilizada para a análise dos efeitos de escavações acima de túneis já existentes pode ser utilizada na avaliação de outros casos. / The presented research approaches the study of excavations effects above existing tunnels. Some of the most relevant papers related to interaction between excavation and tunnels are presented and discussed. Numerical simulations of hypothetic cases assuming plane strain condition and Mohr-Coulomb model for soil behavior are performed, allowing the study of influence of input parameters in the results. It is discussed behavior of the soil in stress paths that indicates reduction of the mean stress, wich is more rigid than the triaxial compression path. It is also discussed wich is an appropriate elastic modulus to be used in this situation. A real case (basement excavation of Stan Paulista building, above Metrô tunnels) is analyzed with numerical models, utilizing the concepts studied. The results of the simulations are compared with field instrumentation data. It is concluded that the methodology used for the analysis of the effect of excavation above existing tunnels can be utilized in other cases.