Thesis (M. Sc.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 150-162).

Le sous-sol urbain est aujourd’hui reconnu comme un espace riche en ressources, espace disponible, eau, géo-matériaux et géothermie jouant un rôle fondamental dans l’aménagement durable des territoires mais dont la réglementation reste lacunaire. Dans un contexte de développement urbain vertical, l’eau souterraine peut être impactée. L’objectif de la thèse est de développer une compréhension quantitative des impacts des ouvrages souterrains sur l’ eau souterraine urbaine afin de proposer des éléments d’aide à la décision destinés aux aménageurs du territoire. Ces travaux de thèse ont permis d’améliorer la compréhension du rôle joué par différents types ouvrages souterrains à une échelle de prise de décision. Les résultats montrent que les ouvrages impliquant des systèmes de pompages sont responsables d’une fragmentation des systèmes d’écoulement. Dans des conditions de faible gradient hydraulique, les ouvrages imperméables ont un impact marginal sur la position de la surface libre. Le comportement hydrodispersif des ouvrages a également été étudié et un effet de mélange dispersif a été mis en évidence au droit des ouvrages souterrains. Il favorise la migration verticale des contaminations urbaines. L’impact des ouvrages souterrains sur la temperature de l’eau souterraine urbaine a également été étudié. Le transfert de thermique entre les ouvrages et l’aquifère urbain a été quantifié et a mis en évidence l’ampleur des zones thermiquement impactées. Enfin, la compréhension des impacts des aménagements souterrains sur l’eau souterraine urbaine a permis de formuler des recommandations afin de prévenir les risques et nuisances inhérents à la construction de nouveaux ouvrages : risque d’inondation par remontée de nappe, risque d’altération qualitative de la ressource, menace et opportunité vis-à-vis du potentiel géothermique d’un aquifère urbain. / Urban subsoil provides space, groundwater, geothermal energy and geomaterials, and the importance underlying the management of this strategic space is well-known. In the context of vertical urban growth, groundwater management, is a crucial issue. The aim of the PhD thesis was to improve the knowledge related to the impacts caused by underground structures on groundwater resource in order to provide a basis for the decision making dedicated to urban planners. The understanding of the role played by numerous types of underground structures was improved at the decision-making scale. Underground structures involving pumping devices were shown to be responsible for the fragmentation of flow systems, which can modify the urban groundwater regime. Under low gradient conditions, impervious structures were confirmed to have a nonsignificant effect on water table elevation. Regarding quality, reservoir theory was applied to assess the impact of underground structures on groundwater quality. This theory allows to take into account the advective and dispersive part of groundwater flow. A dispersive piston effect is shown to occur under the structures, favoring the vertical spreading of pollutants. In addition, the impacts of underground structures on urban groundwater temperature were investigated. The annual heat from underground structures were computed deterministically, highlighting the significant thermally affected zones. Finally, the impacts of underground structures on groundwater flow quality and temperatures were analyzed in order to prevent risks and disturbances : flood risk, degradation of groundwater quality, jeopardizing geothermal potential.

The multi-utility tunnel has received increased attention as an alternative method for the installation of subsurface infrastructure for the distribution of electricity, water, sewage and district heating. In previous research, the multi-utility tunnel (MUT) has been described as a more sustainable technology compared to the conventionally used technique where the cables and pipes are placed with open-cut excavation (OCE), especially when the entire life cycle is taken into account. This thesis aims to contribute to an improved understanding of MUT's sustainability performance in relation to conventional installation using open-cut excavation. This is done by using literature study, interview study and quantitative sustainability assessments to gain an understanding of the current state of knowledge. Furthermore, this thesis also focuses on how knowledge can be deepened with the help of quantitative sustainability assessments and the challenges of conducting this type of assessment. This thesis shows that the state of knowledge regarding MUT's sustainability performance is low and scattered, with a lack of a holistic approach. Direct economic performance has gained the most attention, followed by indirect and social impact, and the environmental impact has so far barely been assessed. The sustainability performance depends to a large extent on the conditions of the specific case, and these should be considered when assessing the technology. Quantitative assessments have the potential to help deepen the knowledge of the sustainability implications of using MUT. The characteristics of MUT have some similarities with other types of physical infrastructure. Similarities are that the systems are long-lived, have project conditions that affect sustainability performance, and impact a broad spectrum of actors. One difference to typical infrastructure systems is that the owner and management structure of MUT is, by design, more complex as several types of utility systems are in use. The characteristics of MUT give some practical considerations that need to be addressed: data availability, including practitioners; detailed data; transparency; and flexibility. This thesis highlights the complexity of assessing MUT´s sustainability performance and advocates that future studies should have a learning-oriented approach so that the knowledge level can collectively and gradually improve over time rather than focusing on decision-oriented studies. / <p><strong>Funding agencies:</strong> Kampradstiftelsen</p>

A caracterização de um maciço rochoso constitui um passo essencial na geologia de engenharia, proporcionando a possibilidade de previsão do comportamento deste maciço frente às inúmeras solicitações de qualquer obra a ser realizada. No caso de obras subterrâneas urbanas, como linhas metroviárias, por exemplo, a caracterização geológico-geotécnica de maciços rochosos é fundamental para a identificação de condicionantes geológicos associados à sua estabilidade, sendo eficaz na determinação de parâmetros geotécnicos que influenciarão no projeto de escavação desse maciço, seja este através do método convencional (NATM) ou mecanizado, com o uso de tuneladoras (TBM). Feições estruturais como planos de foliação, dobras, falhas e sistemas de fraturas merecem atenção especial por estarem associadas a zonas de fraqueza, além de todas as características geomecânicas do maciço. Em zonas urbanizadas como a Região Metropolitana de São Paulo (RMSP) as condições geológicas, geomorfológicas e de ocupação dificultam a exposição e a identificação destas feições em superfície. Neste contexto foram desenvolvidas novas técnicas para facilitar o acesso às feições supracitadas. Dentre estas se encontra o televisionamento óptico (OPTV, OTV, Optical Televiewer), que consiste na obtenção de imagens 360º das paredes dos furos de sondagem, fornecendo o que pode ser considerado um testemunho virtual de sondagem. O televisionamento óptico é uma tecnologia introduzida no Brasil desde 2001, entretanto apenas recentemente tendo sido introduzido no manual de sondagens da ABGE (2013), contudo não havendo especificações sobre metodologia de aquisição, de interpretação e possibilidades de aplicação. Este trabalho apresenta sugestões para a aquisição destas imagens, sua interpretação e sugestões de aplicações em obras de engenharia, tendo como exemplo a aplicação em projetos de obras subterrâneas do Metrô de São Paulo. No caso específico de escavações subterrâneas urbanas, o conhecimento do subsolo é essencial, já que sua construção é uma atividade a ser desenvolvida dentro do contexto urbano, podendo provocar interferências significativas com a comunidade, implicando em um alto risco à população lindeira. Somado a isto há o fato de que um maciço pouco conhecido poderá implicar em contenções superdimensionadas, aumentando o custo da obra ou subdimensionadas, aumentando o seu risco. Conforme citado em ISRM (1978), à medida que as descrições de maciços rochosos e suas descontinuidades se tornem mais completas e unificadas, será viável projetar estruturas de engenharia em rocha reduzindo os gastos e aumentando a confiabilidade da interpretação e extrapolação dos resultados. / The rock mass characterization is an essential step in engineering geology, providing the possibility of performance prediction of this massive due to numerous requests of any work to be done. In the case of urban underground works, such as subway lines, for example, geological and geotechnical characterization of rock masses is critical for identifying geological conditions linked to its stability, being effective in determining the geotechnical parameters that influence the design of massive excavation, whether by the conventional method (NATM), or mechanized, using tunneling boring machines (TBM). Structural features such as foliation planes, folds, faults and fracture systems deserve special attention as they are associated with weakness zones in addition to all the geomechanical characteristics of the massif. In urbanized areas, such as São Paulo Metropolitan Region (RMSP), geological, geomorphological and occupation hinders exposure and identification of these features on the surface. In this context, new techniques have been developed to facilitate access to the above features. Among these new techniques is the optical televiewer (OPTV, OTV), which is to obtain 360° images of the borehole walls, providing what might be considered a virtual core of a borehole. The optical televiewer has been a technology introduced in Brazil since 2001, but only recently has been published in ABGE 1 Borehole Manual (2013), however, there are no specifications on the acquisition methodology, interpretation and application possibilities. This paper presents suggestions for the acquisition of these images, their interpretation and suggestions of applications in engineering works, taking as an example the design in projects of underground works of the São Paulo Metro. In the specific case of urban underground excavations ground knowledge is essential, since its construction is an activity to be developed within the urban context, which could cause significant interference with the community, resulting in a high risk to neighboring population. Added to this is the fact that a little-known mass can result in oversized contention, increasing the cost of the work or undersized, increasing its risk. As mentioned in ISRM (1978), as the descriptions of rock masses and discontinuities become more complete and unified, it will be feasible to design engineering structures in rock reducing the costs and increasing the reliability of the interpretation and extrapolation of the results.

A caracterização de um maciço rochoso constitui um passo essencial na geologia de engenharia, proporcionando a possibilidade de previsão do comportamento deste maciço frente às inúmeras solicitações de qualquer obra a ser realizada. No caso de obras subterrâneas urbanas, como linhas metroviárias, por exemplo, a caracterização geológico-geotécnica de maciços rochosos é fundamental para a identificação de condicionantes geológicos associados à sua estabilidade, sendo eficaz na determinação de parâmetros geotécnicos que influenciarão no projeto de escavação desse maciço, seja este através do método convencional (NATM) ou mecanizado, com o uso de tuneladoras (TBM). Feições estruturais como planos de foliação, dobras, falhas e sistemas de fraturas merecem atenção especial por estarem associadas a zonas de fraqueza, além de todas as características geomecânicas do maciço. Em zonas urbanizadas como a Região Metropolitana de São Paulo (RMSP) as condições geológicas, geomorfológicas e de ocupação dificultam a exposição e a identificação destas feições em superfície. Neste contexto foram desenvolvidas novas técnicas para facilitar o acesso às feições supracitadas. Dentre estas se encontra o televisionamento óptico (OPTV, OTV, Optical Televiewer), que consiste na obtenção de imagens 360º das paredes dos furos de sondagem, fornecendo o que pode ser considerado um testemunho virtual de sondagem. O televisionamento óptico é uma tecnologia introduzida no Brasil desde 2001, entretanto apenas recentemente tendo sido introduzido no manual de sondagens da ABGE (2013), contudo não havendo especificações sobre metodologia de aquisição, de interpretação e possibilidades de aplicação. Este trabalho apresenta sugestões para a aquisição destas imagens, sua interpretação e sugestões de aplicações em obras de engenharia, tendo como exemplo a aplicação em projetos de obras subterrâneas do Metrô de São Paulo. No caso específico de escavações subterrâneas urbanas, o conhecimento do subsolo é essencial, já que sua construção é uma atividade a ser desenvolvida dentro do contexto urbano, podendo provocar interferências significativas com a comunidade, implicando em um alto risco à população lindeira. Somado a isto há o fato de que um maciço pouco conhecido poderá implicar em contenções superdimensionadas, aumentando o custo da obra ou subdimensionadas, aumentando o seu risco. Conforme citado em ISRM (1978), à medida que as descrições de maciços rochosos e suas descontinuidades se tornem mais completas e unificadas, será viável projetar estruturas de engenharia em rocha reduzindo os gastos e aumentando a confiabilidade da interpretação e extrapolação dos resultados. / The rock mass characterization is an essential step in engineering geology, providing the possibility of performance prediction of this massive due to numerous requests of any work to be done. In the case of urban underground works, such as subway lines, for example, geological and geotechnical characterization of rock masses is critical for identifying geological conditions linked to its stability, being effective in determining the geotechnical parameters that influence the design of massive excavation, whether by the conventional method (NATM), or mechanized, using tunneling boring machines (TBM). Structural features such as foliation planes, folds, faults and fracture systems deserve special attention as they are associated with weakness zones in addition to all the geomechanical characteristics of the massif. In urbanized areas, such as São Paulo Metropolitan Region (RMSP), geological, geomorphological and occupation hinders exposure and identification of these features on the surface. In this context, new techniques have been developed to facilitate access to the above features. Among these new techniques is the optical televiewer (OPTV, OTV), which is to obtain 360° images of the borehole walls, providing what might be considered a virtual core of a borehole. The optical televiewer has been a technology introduced in Brazil since 2001, but only recently has been published in ABGE 1 Borehole Manual (2013), however, there are no specifications on the acquisition methodology, interpretation and application possibilities. This paper presents suggestions for the acquisition of these images, their interpretation and suggestions of applications in engineering works, taking as an example the design in projects of underground works of the São Paulo Metro. In the specific case of urban underground excavations ground knowledge is essential, since its construction is an activity to be developed within the urban context, which could cause significant interference with the community, resulting in a high risk to neighboring population. Added to this is the fact that a little-known mass can result in oversized contention, increasing the cost of the work or undersized, increasing its risk. As mentioned in ISRM (1978), as the descriptions of rock masses and discontinuities become more complete and unified, it will be feasible to design engineering structures in rock reducing the costs and increasing the reliability of the interpretation and extrapolation of the results.