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Étude théorique et numérique de l'endommagement thermo-hydro-mécanique des milieux poreux non saturésArson, Chloé 24 September 2009 (has links) (PDF)
Les déchets radioactifs sont stockés dans des milieux poreux multi-phasiques. Un nouveau modèle d'endommagement, formulé en variable indépendantes (contrainte nette, succion et contrainte thermique) est proposé pour ces géomatériaux. La variable d'endommagement est un tenseur d'ordre deux, dont les valeurs principales croissent avec la tension. Les relations contrainte/déformation sont dérivées de l'énergie libre, dont l'expression est postulée. Les rigidités dégradées sont calculées en appliquant le principe de l'Energie Elastique Equivalente pour chaque variable d'état. La fissuration est prise en compte dans les transferts d'humidité, au moyen de longueurs internes. Le modèle d'endommagement a été intégré dans le code d'Eléments Finis Θ-Stock. Le modèle mécanique a été validé en comparant des résultats numériques à des résultats expérimentaux et théoriques. Les tendances données par le modèle dans les études paramétriques sur des configurations réalistes complexes sont bonnes.
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And Through Flows the River : Archaeology and the Pasts of Lao PakoKällén, Anna January 2004 (has links)
<p>This is a story about Lao Pako. Lao Pako is located on a small hill on the southern bank of the river Nam Ngum in central Laos. Four seasons of archaeological fieldwork have yielded considerable amounts of pottery, metallurgical remains, glass beads, stone artefacts, spindle whorls as well as other material and structural information that have created a foundation for interpretation. The archaeological interpretation presents Lao Pako as a place where people came to perform rituals c. 1500 years ago. In these rituals, sophisticated combinations of pottery depositions, infant burials and iron production produced a narrative about what it means to be in the world. Things in and on the ground created, and continue to create, non-verbal sentences about life and death, fertility, decay and worldly reproduction. </p><p>The archaeological interpretation is, however, not the only valid story about Lao Pako. This is a place where spirits are; it is also a tourist resort and a national treasure. These other stories all work to create Lao Pako as a place of interest and are used in this thesis to define the archaeological story, and to visualize the aims and agendas inherent in the production of archaeological knowledge. </p><p>Using the conceptual apparatus of postcolonial and other critical theory, the thesis aims to critically deconstruct the archaeology performed by the author and others. It entails an explicit critique of the deterministic temporal unilinearity that is inherent in the archaeological narrative of the evolution of humankind, as well as against essentialist notions of culture and the dissociation of the past as exotic otherness. Thus, the stories about Lao Pako demonstrate the need to critically revise the role of archaeology in a postcolonial world, and create archaeological stories by which we are touched, moved and disturbed, without resorting to imperialist notions of time and progress.</p>
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And Through Flows the River : Archaeology and the Pasts of Lao PakoKällén, Anna January 2004 (has links)
This is a story about Lao Pako. Lao Pako is located on a small hill on the southern bank of the river Nam Ngum in central Laos. Four seasons of archaeological fieldwork have yielded considerable amounts of pottery, metallurgical remains, glass beads, stone artefacts, spindle whorls as well as other material and structural information that have created a foundation for interpretation. The archaeological interpretation presents Lao Pako as a place where people came to perform rituals c. 1500 years ago. In these rituals, sophisticated combinations of pottery depositions, infant burials and iron production produced a narrative about what it means to be in the world. Things in and on the ground created, and continue to create, non-verbal sentences about life and death, fertility, decay and worldly reproduction. The archaeological interpretation is, however, not the only valid story about Lao Pako. This is a place where spirits are; it is also a tourist resort and a national treasure. These other stories all work to create Lao Pako as a place of interest and are used in this thesis to define the archaeological story, and to visualize the aims and agendas inherent in the production of archaeological knowledge. Using the conceptual apparatus of postcolonial and other critical theory, the thesis aims to critically deconstruct the archaeology performed by the author and others. It entails an explicit critique of the deterministic temporal unilinearity that is inherent in the archaeological narrative of the evolution of humankind, as well as against essentialist notions of culture and the dissociation of the past as exotic otherness. Thus, the stories about Lao Pako demonstrate the need to critically revise the role of archaeology in a postcolonial world, and create archaeological stories by which we are touched, moved and disturbed, without resorting to imperialist notions of time and progress.
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Analyzing the Conceptual Integrity of Computing Applications Through Ontological Excavation and AnalysisHsi, Idris 19 July 2005 (has links)
In the world of commercial computing, consumers are being inundated with baroque, bloated, and difficult-to-use computing applications, tools that use computational methods and technologies to perform tasks. Market forces demand that new versions of these applications implement more features, the user-accessible behaviors and services implemented by the application, than their predecessors or competitors. Ensuring that planned features required for market competitiveness enhance a computing application without these side effects first requires that we understand how these features contribute to the overall design and conceptual integrity of the application
While conceptual integrity affects all aspect of the application, we are primarily interested in how an applications user-accessible features have been designed and implemented. To this end, we have developed a research framework, methodologies, and artifacts for measuring the conceptual integrity of a computing artifact from its theory of the world or its ontology. We use conceptual coherence, which we define as the degree to which an applications concepts are tightly related, as a first approximation for conceptual integrity.
We claim the following: any computing application has a central or core set of concepts that are essential to that applications ontology and can be identified through analytical means; and concepts that are not essential to an applications ontology either exist to support core concepts or are peripheral to the ontology. Peripheral concepts reduce an applications conceptual coherence.
We have developed the method of ontological excavation to identify the concepts in a computing application and model them as an ontology expressed as a semantic network. To identify core and peripheral concepts and to measure an ontologys conceptual coherence, we developed methodologies for ontological analysis.
If usefulness depends on the conceptual integrity of an applications ontology such that it ensures high fitness to a problem domain, then we would expect that users solving problems in that domain will invoke the concepts integral to the solution more often than those concepts that do not. Thus, to validate our structural measures, we claim the following: the probable use of the application will invoke core concepts more frequently than peripheral concepts in the ontology.
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Interventions On Immovable Archaeological Heritage As A Tool For New Formation ProcessSimsek, Gokce 01 June 2009 (has links) (PDF)
In the preservation discourse, interventions are generally viewed as technical issues. Considering that interventions cause variety of changes in the characteristics of archaeological edifices starting from the excavation, these changes constructs and shapes the archaeological edifices in terms of its appearance and meaning. In that respect, interventions act as tools for making changes in archaeological edifices by causing transformation of existing characteristics, loss of some others and adding new ones.
Based on this, the study aims to evaluate interventions by putting change at the center in order to understand how interventions affect archaeological edifice in constructing its appearance and meaning. The study is based on evaluation of intervention through a & / #8216 / new formation process& / #8217 / , which is based on two phases. The first phase deals with evaluation of changes in values through the & / #8216 / value formation process& / #8217 / . The second phase is related with the assessment of changes in the characteristics of archaeological edifice as a whole, in terms of its physical, functional and semantic characteristics. This approach enables the examination of the process of change starting from prior to excavation and the assessment of interventions through the principles of change (reliability, consistency, legibility) and the & / #8216 / value formation process& / #8217 / . The evaluation method is sampled on certain intervened archaeological edifices on the Curetes Street in Ephesus.
The study concludes that the interventions are significant tools for making changes in archaeological edifices throughout its new lifecycle. The & / #8216 / value formation process& / #8217 / and the & / #8216 / new formation process& / #8217 / approach can make it possible to predict changes in archaeological edifices, prevent value conflicts caused by interventions and improve the quality of change shaped by interventions. Approaching the intervention process as a change management problem necessitates to develop appropriate change strategies and to define this process as a & / #8216 / new formation process& / #8217 / .
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Design Of Excavation An Support Syaytems Of Cubukbeli Tunnel In AntalyaKarahan, Ercument 01 January 2010 (has links) (PDF)
In this thesis, suggestion of appropriate excavation and support systems and selection of rock mass strength parameters for the determination of these systems were carried out for the Ç / ubukbeli Tunnel in Antalya.
Ç / ubukbeli Tunnel is a twin tube flute shaped tunnel with 1985 m length, 12 m width, 10 m height and maximum overburden thickness of 130 m. The tunnel area consists of limestone, clayey limestone, claystone, marl and siltsone. Rock mass classification systems are used for evaluation of rock mass characteristics and estimation of strength parameters. Selection of appropriate numerical method and software tool, namely Phase2, is accomplished after an extensive literature survey.
The rock mass was divided into sections according to the RMR, Q, NATM and GSI classification systems along the tunnel and excavation and support systems were determined empirically along these sections. Thereafter, geomechanical parameters (i.e. modulus of deformation Em, Hoek-Brown material constants m and s etc.) were selected based on these classification systems.
Finite element analysis was carried out as the final step of the design in order to investigate deformations and stress concentrations around the tunnel, analyze interaction of support systems with excavated rock masses and verify and check the validity of empirically determined excavation and support systems.
As the result of design studies accomplished along tunnel route, B1, B2, B3 and C2 type rock classes are assumed to be faced during construction of Ç / ubukbeli Tunnel and appropriate excavation and support systems are proposed for these rock classes.
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DEFORMATION-BASED EXCAVATION SUPPORT SYSTEM DESIGN METHODIntsiful, Sekyi K 01 January 2015 (has links)
Development in urban areas around the world has steadily increased in recent years. This rapid development has not been matched by the ever decreasing open space commonly associated with urban centers. Vertical construction, thus, lends itself a very useful solution to this problem. Deep excavation is often required for urban construction. Unfortunately, the ground movements associated with deep excavation can result in damage to adjacent buildings. Thus, it is critically important to accurately predict the damage potential of nearby deep excavations and designing adequate support systems.
A new design method is proposed, as an attempt, to address the problem. The method is semi-empirical and directly links excavation-induced distortions experienced by nearby buildings and the components of the excavation support system. Unlike, the traditional limit equilibrium approach, the method is driven by the distortions in adjacent buildings. It goes further to propose a preliminary cost chart to help designers during the design phase. The benefit is that initial cost is known real time and will help speed up making business decisions. A new design flowchart is proposed to guide the designer through a step-by-step procedure.
The method is validated using 2D Plaxis (the finite element program) simulation. Though the nature of deep excavation is three-dimensional, a plane strain condition is valid when the length of the excavation is long. Hence, two-dimensional finite element simulation was considered appropriate for this effort. Five hypothetical cases were compared and the model performed very well. The lack of available literature on this approach made verification difficult. It is hoped that future case histories will be used to ascertain the veracity of the deformation-based design method.
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Investigating the Influence of Mechanical anisotropy on the Fracturing Behaviour of Brittle Clay Shales with Application to Deep Geological RepositoriesLisjak Bradley, Andrea 10 January 2014 (has links)
Clay shales are currently being assessed as possible host rock formations for the deep geological disposal of radioactive waste. However, one main concern is that the favourable long-term isolation properties of the intact rock mass could be negatively affected by the formation of an excavation damaged zone (EDZ) around the underground openings. This thesis investigated the deformation and failure process of a clay shale, namely Opalinus Clay, with particular focus on the influence of anisotropy on the
short-term response of circular tunnels. To achieve this goal, a hybrid continuum-discontinuum numerical approach was used in combination with new field measurements from the Mont Terri underground research laboratory. The response of Opalinus Clay during the excavation of a full-scale emplacement (FE) test tunnel was characterized by geodetic monitoring of wall displacements, radial extensometers
and longitudinal inclinometers. The deformation measurements indicated strong directionality induced by the combined effect of in situ stress field and presence of bedding planes striking parallel to the
tunnel axis, with the most severe deformation occurring in the direction approximately perpendicular to the material layering. Computer simulations were conducted using a newly-extended combined
finite-discrete element method (FEM/DEM), a numerical technique which allows the explicit simulation of brittle fracturing and associated seismicity. The numerical experimentation firstly focused on the
laboratory-scale analysis of failure processes (e.g., acoustic activity) in brittle rocks, and on the role of
strength and modulus anisotropy in the failure behaviour of Opalinus Clay in tension and compression.
The fracturing behaviour of unsupported circular excavations in laminated rock masses was then analyzed under different in situ stress conditions. Lastly, the modelling methodology was applied to the
aforementioned FE tunnel to obtain original insights into the possible EDZ formation process around emplacement tunnels for nuclear waste. The calibrated numerical model suggested delamination along bedding planes and subsequent extensional fracturing as key mechanisms of the damage process potentially leading to buckling and spalling phenomena. Overall, the research findings may have a potential impact on the constructability and support design of an underground repository as well as implications for its long-term safety assessment procedure.
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Investigating the Influence of Mechanical anisotropy on the Fracturing Behaviour of Brittle Clay Shales with Application to Deep Geological RepositoriesLisjak Bradley, Andrea 10 January 2014 (has links)
Clay shales are currently being assessed as possible host rock formations for the deep geological disposal of radioactive waste. However, one main concern is that the favourable long-term isolation properties of the intact rock mass could be negatively affected by the formation of an excavation damaged zone (EDZ) around the underground openings. This thesis investigated the deformation and failure process of a clay shale, namely Opalinus Clay, with particular focus on the influence of anisotropy on the
short-term response of circular tunnels. To achieve this goal, a hybrid continuum-discontinuum numerical approach was used in combination with new field measurements from the Mont Terri underground research laboratory. The response of Opalinus Clay during the excavation of a full-scale emplacement (FE) test tunnel was characterized by geodetic monitoring of wall displacements, radial extensometers
and longitudinal inclinometers. The deformation measurements indicated strong directionality induced by the combined effect of in situ stress field and presence of bedding planes striking parallel to the
tunnel axis, with the most severe deformation occurring in the direction approximately perpendicular to the material layering. Computer simulations were conducted using a newly-extended combined
finite-discrete element method (FEM/DEM), a numerical technique which allows the explicit simulation of brittle fracturing and associated seismicity. The numerical experimentation firstly focused on the
laboratory-scale analysis of failure processes (e.g., acoustic activity) in brittle rocks, and on the role of
strength and modulus anisotropy in the failure behaviour of Opalinus Clay in tension and compression.
The fracturing behaviour of unsupported circular excavations in laminated rock masses was then analyzed under different in situ stress conditions. Lastly, the modelling methodology was applied to the
aforementioned FE tunnel to obtain original insights into the possible EDZ formation process around emplacement tunnels for nuclear waste. The calibrated numerical model suggested delamination along bedding planes and subsequent extensional fracturing as key mechanisms of the damage process potentially leading to buckling and spalling phenomena. Overall, the research findings may have a potential impact on the constructability and support design of an underground repository as well as implications for its long-term safety assessment procedure.
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Modélisation de la stabilité des blocs rocheux isolés sur la paroi des excavations souterraines avec prise en compte des contraintes initiales et du comportement non linéaire des jointsGhazal, Rima 26 February 2013 (has links) (PDF)
L'instabilité des blocs situés à la surface des excavations souterraines est un problème courant dans les milieux rocheux fracturés. Comme les méthodes exactes prenant en compte tous les blocs et leurs interactions sont très lourdes, l'approche des Blocs Isolés est souvent adoptée. Elle consiste à étudier chaque bloc en considérant qu'il est rigide et que le reste de la masse rocheuse est rigide et fixe. Néanmoins, aucune des méthodes existantes adoptant cette approche ne prend en compte de façon rigoureuse les contraintes initiales et le comportement des joints. Dans cette thèse, on développe une nouvelle méthode qui apporte des améliorations importantes aux méthodes conventionnelles de Blocs Isolés. Connaissant les contraintes initiales, on rend compte du processus d'excavation par le déchargement de la face libre du bloc. Les efforts sur les faces du bloc en contact avec la roche sont alors modifiés en respectant l'équilibre des forces et des moments, la loi de comportement des joints et le mouvement de corps solide du bloc. On aboutit ainsi à un système linéaire où les seules inconnues sont les vecteurs translation et rotation du bloc. Deux modèles sont proposés : le premier considère un comportement linéaire élastique des joints et, par conséquent, la stabilité est évaluée a posteriori. Le deuxième modèle, plus pertinent, considère un comportement hyperbolique des joints dans la direction normale et élastoplastique dans la direction tangentielle avec prise en compte de la dilatance. La méthode numérique adoptée pour la résolution du problème non linéaire est une intégration explicite dans le temps cinématique avec des pas de déchargement constants. La technique d'intégration surfacique utilisée permet d'étudier toute forme géométrique de bloc. La méthode proposée a été validée puis comparée aux méthodes conventionnelles. Des études paramétriques ont montré l'influence des contraintes initiales et des propriétés mécaniques des joints sur la stabilité. Le soutènement a été aussi intégré dans le code développé. Finalement, la nouvelle méthode a été appliquée pour l'étude d'un assemblage de blocs autour d'une excavation souterraine et comparée à un modèle prenant en compte tous les blocs via la méthode des Éléments Distincts. Elle a été aussi utilisée pour restituer un cas réel de chute de blocs.
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