<p>In this thesis, fractured rock masses are treated asequivalent continua for large-scale analyses of rockengineering projects. Systematic developments are made for thedetermination of equivalent mechanical and hydraulic propertiesof fractured rock masses using a hybrid discrete fracturenetwork - distinct element method (DFN-DEM) approach. Thedetermined equivalent properties are then used for a far-fieldfinite element analysis of the thermo-mechanical impacts on thestress, deformation and permeability of fractured rockssurrounding a hypothetical geological repository of nuclearwaste. The geological data were extracted from the results ofan extensive site investigation programme at Sellafield, UK,conducted by Nirex UK Ltd.</p><p>The scale dependencies of the hydraulic and mechanicalproperties were investigated by using multiple realizations ofthe fracture system geometry with increasing model sizes untilproperly defined hydraulic and mechanical representativeelementary volumes (REVs) were reached. The validity of thesecond order permeability tensor and the fourth-ordermechanical compliance tensor were tested for continuum analysesat larger scales. The REV was determined to be around 5 m formechanical and hydraulic data in this study.</p><p>Analysis of the stress-dependent mechanical and hydraulicproperties shows that the effect of rock stresses is crucial.The elastic moduli increase significantly with the increase ofstress and an empirical equation of stress-dependent elasticmodulus is suggested based on results of numerical experiments.Calculations of the Poisson's ratios suggest greater valuesthan are normally assumed in practice. Depending on the stateof stress, permeability decreases or increases with increasingcompressive stress. Stress-induced flow channeling effect iscaptured by numerical modeling for the first time and detailedmechanisms of shear dilation of fractures are provided. Basedon the numerical experiments, a set of empirical equations wassuggested for the stress-dependent permeability, consideringboth normal deformation and shear dilation of fractures.</p><p>Thermo-mechanical impact on the performance of ahypothetical repository at a far-field scale (5 km by 1 km) wasinvestigated with the stress-dependent equivalent propertiesdetermined at the REV scale. This analysis shows thatmechanical responses vary significantly depending on how themechanical properties were determined. The change ofpermeability due to the thermal loading is, however, notsignificant in this particular case.</p><p>The thesis provides a framework for systematic analysis oflarge-scale engineering applications in fractured rock masses,such as geological repositories of nuclear wastes.</p><p><b>Keyword:</b>Fractured rock masses, Equivalent Continuum,Discrete Fracture Network (DFN), Distinct Element Method (DEM),Finite Element Method (FEM), Nuclear Waste Disposal, CoupledThermo-Hydro-Mechanical Processes</p>

Die zunehmende Einsatzvielfalt von Hard- und Softwaresystemen führt zu einem wachsenden Bedarf, Betriebssysteme als (Software-) Infrastrukturen für Anwendungen zweckorientiert anzupassen bzw. herzustellen. Das Anwendungsgebiet reicht dabei über das der universellen Betriebssysteme für universelle Rechensysteme hinaus. Anwendungsentwicklung findet nicht mehr notwendigerweise ausschließlich im Anwendungsbereich statt, sondern kann sich auch auf unterliegende Systemschichten beziehen. Infrastruktur muß dafür einerseits offen sein, und andererseits muß es auch dort geeignete Strukturen geben, welche die Herstellung bzw. Anpassung von Infrastrukturkomponenten für Anwendungshersteller auch geeignet unterstützen. Dem Gesamtsystem sollte eine Architektur zugrunde liegen, welche strukturell, funktional und methodisch alle Systembereiche bzw. verschiedenartige Zielsysteme in einer einheitlichen, durchgängigen Weise erfaßt und heute vorhandene Strukturbrüche überwindet. Gleichzeitig muß der Spezifik unterschiedlicher Systemumgebungen Rechnung getragen werden. In dieser Dissertation wird eine dafür geeignete Architektur aus der Analyse des Gegenstandsbereichs dynamischer ablaufender Systeme hergeleitet und begründet. Die praktische Umsetzbarkeit wird anhand der Implementierung des CheOps-Kerns gezeigt und bewertet. Um der Verschiedenartigkeit von Systemen bzw. Systembereichen gerecht zu werden, ist ein hohes Maß an Skalierbarkeit der Architekturmerkmale erforderlich. Dies wird durch Trennung universeller Merkmale von konkreten Ausprägungen in jeweiligen Zielumgebungen erreicht. In der generalisierten Architektur wird das unterlegte, durchgängig anwendbare Architekturkonzept festgelegt. Es ist durch Schichten als vertikale Grundstruktur gekennzeichnet. Innerhalb von Schichten bilden (Verarbeitungs-) Instanzen das zentrale Strukturelement, um semantisch zusammengehörige Teilverarbeitungen identifizierbaren, aktiv dienstausführenden Elementen zuzuordnen. Das Vorbild dafür ist das aus dem Anwendungsbereich bekannte Client-Server-Modell. Die Anpassung an jeweilige Systemumgebungen erfolgt dann durch explizites Ableiten spezieller Ausprägungen von Elementen und Beziehungen aus den generellen Architekturmerkmalen und der Zuordnung jeweils geeigneter Ausführungs- und Ablaufeigenschaften. In dieser hier explizit vorgenommenen Differenzierung liegt ein wesentlicher Unterschied zu anderen Architekturvorschlägen. Erst dadurch wird das Grundmuster des Client-Server-Modells auf alle Infrastrukturschichten in speziell angepaßten Ausprägungen übertragbar und damit Anwendungsanpaßbarkeit strukturell auch für Infrastruktur unterstützt. Mit der Implementierung des CheOps-Kerns konnte gezeigt werden, daß sich das Strukturmuster von Instanzen selbst für die unterste Systemschicht der Unterbrechungsverarbeitung anwenden läßt und sich daraus neben strukturellen auch vorteilhafte Ablaufeigenschaften ergeben. Dieses neuartige Implementierungsprinzip auf Basis sogenannter iproc-Instanzen wird im zweiten Teil der Dissertation im Detail vorgestellt und bewertet.

This work explains the effect of failure on permeability anisotropy and dilation in sands. Shear failure is widely observed in field operations. There is incomplete understanding of the influence of shear failure in sand formations. Shear plane orientations are dependent on the stress anisotropy and that view is confirmed in this research. The effect of shear failure on the permeability is confirmed and calculated. Description of permeability anisotropy due to shear failure has also been discussed. In this work, three-dimensional discrete element modeling is used to model the behavior of uncemented and weakly cemented sand samples. Mechanical deformation data from experiments conducted on sand samples is used to calibrate the properties of the spherical particles in the simulations. Orientation of the failure planes (due to mechanical deformation) is analyzed both in an axi-symmetric stress regime (cylindrical specimen) and a non-axi-symmetric stress regime (right cuboidal specimen). Pore network fluid flow simulations are conducted before and after mechanical deformation to observe the effect of failure and stress anisotropy on the permeability and dilation of the granular specimen. A rolling resistance strategy is applied in the simulations, incorporating the stiffness of the specimens due to particle angularity, aiding in the calibration of the simulated samples against experimental data to derive optimum granular scale elastic and friction properties. A flexible membrane algorithm is applied on the lateral boundary of the simulation samples to implement the effect of a rubber/latex jacket. The effect of particle size distribution, stress anisotropy, and confining pressure on failure, permeability and dilation is studied. Using the calibrated micro-properties, simulations are extended to non-cylindrical specimen geometries to simulate field-like anisotropic stress regimes. The shear failure plane alignment is observed to be parallel to the maximum horizontal stress plane. Pore network fluid flow simulations confirm the increase in permeability due to shear failure and show a significantly greater permeability increase in the maximum horizontal stress direction. Using the flow simulations, anisotropy in the permeability field is observed by plotting the permeability ellipsoid. Samples with a small value of inter-granular cohesion depict greater shear failure, larger permeability increase and a greater permeability anisotropy than samples with a larger value of inter-granular cohesion. This is estimated by the number of micro-cracks observed. / text

Στη διδακτορική αυτή διατριβή διερευνάται κατά πόσον η τηλεσκόπηση μπορεί να χρησιμεύει ως αρωγός για την κοιτασματολογική έρευνα και ειδικότερα για την εύρεση "στόχων" επιθερμικής μεταλλοφορίας πολύτιμων μετάλλων μέσω της αναγνωρίσεως ηφαιστειακών και τεκτονικών δομών και ζωνών υδροθερμικών εξαλλοιώσεων από αέρος. Το πεδίο έρευνας είναι το μειοκαινικό ηφαιστειακό-γεωθερμικό πεδίο της νήσου Λέσβου. Ερευνάται η ορυκτολογία των μεταλλικών ορυκτών και συνοδευόντων ορυκτών εξαλλοίωσης. Γίνονται πάραυτα μικροθερμομετρικοί προσδιορισμοί, προσδιορισμοί χρυσού-αργύρου, ιχνοστοιχείων- ιχνηλατών και άλλων ιχνοστοιχείων στις περιοχές-στόχους και τα γεωχημικά δεδομένα τίθενται σε περιβάλλον GIS (θεματικοί χάρτες). / In this phd dissertation it is investigated if remote sensing techniques can be used successfully as an aid in the ore deposits research and specifically for the localization by air "target" areas of epithermal mineralization of precious metals through the recognition of volcanic and tectonic structures and detection of hydrothermal alteration zones. The research area is the miocene volcanic-geothermal field of the island of Lesvos. The research includes also identification of ore and alteration minerals microthermometric measurements, measurement of the Au-Ag parts, of pathfinder and other trace elements in the target areas. The geochemical data are subsequently placed in a GIS environment for future research and/or mineral exploration purposes.

No description available.

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.

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.

This thesis presents a systematic numerical modeling framework to simulate the stress-deformation and coupled stress-deformation-flow processes by performing uniaxial and biaxial compressive tests on fractured rock models with considering the effects of different loading conditions, different loading directions (anisotropy), and coupled hydro-mechanical processes for evaluating strength and deformability behavior of fractured rocks. By using code UDEC of discrete element method (DEM), a series of numerical experiments were conducted on discrete fracture network models (DFN) at an established representative elementary volume (REV), based on realistic geometrical and mechanical data of fracture systems from field mapping at Sellafield, UK. The results were used to estimate the equivalent Young’s modulus and Poisson’s ratio and to fit the Mohr-Coulomb and Hoek-Brown failure criteria, represented by equivalent material properties defining these two criteria. The results demonstrate that strength and deformation parameters of fractured rocks are dependent on confining pressures, loading directions, water pressure, and mechanical and hydraulic boundary conditions. Fractured rocks behave nonlinearly, represented by their elasto-plastic behavior with a strain hardening trend. Fluid flow analysis in fractured rocks under hydro-mechanical loading conditions show an important impact of water pressure on the strength and deformability parameters of fractured rocks, due to the effective stress phenomenon, but the values of stress and strength reduction may or may not equal to the magnitude of water pressure, due to the influence of fracture system complexity. Stochastic analysis indicates that the strength and deformation properties of fractured rocks have ranges of values instead of fixed values, hence such analyses should be considered especially in cases where there is significant scatter in the rock and fracture parameters. These scientific achievements can improve our understanding of fractured rocks’ hydro-mechanical behavior and are useful for the design of large-scale in-situ experiments with large volumes of fractured rocks, considering coupled stress-deformation-flow processes in engineering practice. / <p>QC 20141111</p>

Trois méthodes de télédétection (Lidar, interférométrie radar satellitaire et photogrammétrie aérienne) ont été appliquées pour quantifier les évolutions spatiales et temporelles de deux glissements argileux (Harmalière et Avignonet, situés dans la région du Trièves, Alpes françaises) en complément d'instrumentation in-situ. Une analyse géomorphologique a été réalisée à partir d'ortho-photos (depuis 1948) et du MNT Lidar filtré. Couplée à des reconnaissances géophysiques, elle a montré que la cinématique différente des deux glissements contigus était partiellement contrôlée par la paléotopographie sur laquelle s'est déposée la couche d'argile. La rugosité directionnelle a permis de distinguer les processus d'érosion résultant de mouvements gravitaires et de ravinement. Une technique de corrélation d'images adaptée aux MNT a été développée pour obtenir les vecteurs de déplacement 3D entre deux acquisitions Lidar (2006 - 2009), avec une attention particulière portée à l'évaluation de la qualité des mesures. La carte des déplacements obtenue montre que la zone la plus active du glissement de Harmalière entre 1981 et 2001 est maintenant relativement lente (déplacement <0.4 m en 3 ans), contrairement à d'autres zones proches montrant des mouvements importants atteignant 3m avec une composante rotationnelle. Pour le glissement d'Avignonet, les déplacements déduits augmentent généralement vers le pied du glissement et peuvent atteindre 1 m. La technique des réflecteurs permanents en interférométrie radar a permis de déterminer de nouvelles valeurs de taux de déplacements (entre 1992 et 2000) en 16 points du glissement, qui sont cohérentes avec les données GPS existantes. Le taux moyen de recul à long terme de l'escarpement principal a été estimé à 1-5 cm/an à Avignonet et entre 7 et 14 cm/an à l'Harmalière. La régression du glissement d'Avignonet semble contrôlée par l'érosion du sommet de la couche d'alluvions compactes reposant sur le substratum. La présence d'une paleovallée du Drac sous le pied du glissement de l'Harmalière pourrait expliquer cette différence de cinématique entre les deux glissements.

Soil landscape characterization into landform elements for precision agriculture has become an important issue. As soil properties and crop yields change over the landscape, delineating landform elements as a basis for site-specific application of crop inputs has become a reality. Two different methods of delineating landform elements from agricultural fields were tested and compared. The first method delineated landform elements from digital elevation maps with the use of the LandMapR(tm) software, the second method delineated classes from IKONOS high resolution panchromatic images using an unsupervised classification algorithm. The LandMapR(tm) model delineated landform elements from true elevation data collected in the field and was considered the reference dataset to which the image classification maps were compared to. The IKONOS imagery was processed using a combination of one filtering algorithm and one unsupervised classification method prior to being compared to the classified DEM. A total of 20 filtering algorithms and two unsupervised methods were used for each of the five study sites. The study sites consisted of four agricultural fields covered with crop stubble and one field in summer fallow. Image classification accuracy assessment was reported as overall, producer’s and user’s accuracy as well as Kappa statistic. Results showed that filtering algorithms and classification methods had no effects on image classification accuracies. Highest classification accuracy of image map to landform element map comparison achieved for all study sites was 17.9 %. Classification accuracy was affected by the heterogeneity of the ground surface cover found in each field. However, the classification accuracy of the fallow field was not superior to the stubble fields.