According to the Mine Health and Safety Administration (MSHA), between 2006 and 2016, the underground stone mining industry had the highest fatality rate in 4 out of 10 years, compared to any other type of mining in the United States. Additionally, the National Institute for Occupational Safety and Health (NIOSH) stated that structurally controlled instability is a predominant failure mechanism in underground limestone mines. This type of instability occurs when the different discontinuity sets intercept with each other forming rock blocks that displace inwards the tunnel as the excavation takes place, posing a great hazard for miners and overall mine planning. In recent years, Terrestrial laser scanning (TLS) has been used for mapping and characterizing fractures present in a rock mass. TLS is a technology that allows to generate a three-dimensional multimillion point cloud of a scanned area. In addition to this, the advances in computing power throughout the past years, have allowed numerical modeling codes to represent more realistically the behavior of a fractured rock masses. This work presents and implements a methodology that integrates laser scanning technology along with Discrete Element Modeling as tools for characterizing, preventing, and managing structurally controlled instability that may affect large-opening underground mines. The stability of an underground limestone mine that extracts a dipping ore body with a room and pillar (and eventual stoping) mining method is analyzed with this approach. While this methodology is proposed based on a specific case study that does not meet the requirements to be designed with current NIOSH published guidelines, this process proposes a general methodology that can be applied in any mine experiencing similar failure mechanisms, considering site-specific conditions. The aim of this study is to ensure the safety of mine workers and to reduce accidents that arise from ground control issues. The results obtained from this methodology allowed us to generate Probability Density Functions to estimate the probability of rock fall in the excavations. These models were also validated by comparing the numerical model results with those obtained from the laser scans. / M.S. / According to the Mine Health and Safety Administration (MSHA), between 2006 and 2016, the underground stone mining industry had the highest fatality rate in 4 out of 10 years, compared to any other type of mining in the United States. Additionally, the National Institute for Occupational Safety and Health (NIOSH) stated that structurally controlled instability is one of the main causes of rock falls in underground limestone mines. This type of instability occurs when the fractures present in the rock mass intercept each other forming rock blocks that displace into the tunnel as the excavation takes place and poses a great hazard for miners. In recent years, Terrestrial laser scanning (TLS) has been used for mapping and characterizing fractures present in a rock mass. TLS is a technology that allows to generate a three-dimensional multimillion point cloud of a scanned area. In addition to this, the advances in computing power throughout the past years, have allowed simulation softwares such as the Discrete Element Model (DEM) to represent more realistically the behavior of a fractured rock mass under excavation. The aim of this work was to develop and evaluate a methodology that could complement already exisiting design guidelines that may not apply to all kind of underground mines. The presented methodology evaluates rock failure due to presence of discontinuites, through the integration of TLS with DEM and considers site specific conditions. An area of a case study mine was assessed with this methodology, where several laser scans were performed. Information extracted from this laser scans was used to simulate the response of the rock mass under excavation by running Discrete Element Numerical Models. Results from these models allowed us to estimate the probability of rock failure in the analized areas. These, rock block failure probability estimations provide engineers a tool for characterizing, preventing, and managing structurally controlled instability, and ultimately improving workers safety.

[pt] Em uma mina a céu aberto, a estabilidade dos taludes rochosos é um dos maiores desafios na engenharia das rochas devido aos processos geodinâmicos que formaram o depósito de minério, fazendo de cada depósito complexo e único. Algumas das complexidades encontradas comumente são: a geologia nos arredores do depósito, a alta variabilidade das propriedades, os complexos defeitos estruturais, o grau de alteração das rochas, a informação geomecânica limitada, etc. Antes de avaliar a estabilidade de taludes devemos caracterizar o maciço rochoso. Para caracterizá-lo se têm construído os modelos geológico, estrutural e do maciço rochoso para formar o modelo geotécnico como recomenda o projeto Large Open Pit (LOP), um projeto de pesquisa internacional relacionado à estabilidade de taludes de rocha nas minas a céu aberto. Uma vez construídos os domínios geotécnicos, a estabilidade de taludes rochosos pode ser avaliada para cada domínio pelos métodos de equilíbrio limite ou numéricos como o método dos elementos finitos ou o método dos elementos discretos. O uso do método depende de diversos fatores, como a influência dos elementos estruturais, a importância da análise, a informação disponível, etc. Os métodos de equilíbrio limite como os tradicionais de Bishop e Janbu podem ser usados na avaliação de estabilidade de grandes taludes de rocha que são susceptíveis a falhas rotacionais do maciço rochoso. Já o método de elementos finitos se tem desenvolvido rapidamente e tem ganhado popularidade para a análise de estabilidade de taludes no caso em que o mecanismo de falha não esteja controlado por estruturas discretas geológicas. Os métodos de elementos finitos estão baseados em modelos constitutivos de tensão – deformação para rochas intactas e têm dificuldades em simular famílias com um número grande de descontinuidades dentro do maciço rochoso. O método dos elementos discretos permite simular um número grande de descontinuidades assim como também permite a simulação de grandes deformações. A presente dissertação usa o modelo SRM (Synthetic Rock Mass) para avaliar a estabilidade de taludes de uma mina a céu aberto no Peru. O SRM é uma nova técnica para simular o comportamento mecânico de maciços rochosos fraturados e permite simular a propagação de fraturas e os efeitos da anisotropia. Está técnica usa o modelo BPM (Bonded Particle Model) para representar a rocha intacta e o SJM (Smooth - Joint Contact Model) para representar as estruturas do maciço rochoso dentro do programa PFC. Para a modelagem estrutural se utilizou o método DFN (Discrete Fracture Network). Para a determinação dos modelos geológicos e estrutural se utilizou o programa Petrel e para a análise de estabilidade de taludes usando o modelo SRM se utilizou o programa PFC 4.0 na versão 2D. / [en] In an open pit mine, stability of rock slope is one of the most challenges in rock mechanics due to geodynamic processes that formed the ore deposit, making each deposit complex and unique. Some of the complexities commonly encountered are: the geology in the vicinity of the deposit, the high variability of properties, the complex structural defects, the rock alteration degree, limited geomechanical data, etc. Before evaluating the slope stability we should characterize the rock mass. To characterize it we have built the geological model, structural model and rock mass model to form the geotechnical model as it recommends the Large Open Pit project (LOP), an international research project related to stability of rock slope in open pit mines. Once constructed geotechnical domains, the stability of rock mass slope can be evaluated for each domain by using some known methods like limit equilibrium, the finite elements and discrete element methods. The use of the method depends of different factors like influence of structural elements (defects), importance of analysis, available information, etc. Limit equilibrium traditional methods like Bishop and Janbu can be used to evaluate the stability of large rock slopes that are susceptible to rotational failure of rock mass. Since the finite element method has developed rapidly and has gained popularity for the slope stability analysis in the case where failure mechanism is not controlled by discrete geological structure. Finite element method is based on constitutive models of stress-strain for intact rocks and has difficulties in simulating sets with a large number of discontinuities within the rock mass. The discrete element method allows to simulate a large number of discontinuities and also allows the simulation of large deformations. This dissertation uses the SRM (Synthetic Rock Mass) model to evaluate the stability of slopes in an open pit mine in Peru. The SRM model is a new technique that allows the simulation of the mechanical behavior of fractured rock mass taking into account propagation of fractures and anisotropic effects. This technique uses two well established techniques like BPM (Bonded Particle Model) for representation of intact rock and the SJM (Smooth-Joint Contact Model) to represent the structural fabric within the PFC program. For structural modeling it was used DFN method (Discrete-Fracture Network). To determine the geological and structural model it was used the Petrel program (Version 2010.1) and for slope stability analysis with the SRM model it was used the version 2D of the PFC 4.0 program.

In this research, a novel, unique systematic procedure was implemented to investigate the influence of the fracture networks and confining stresses on the jointed coal mass strength (JCMS). Both a laboratory experimental scheme and a numerical modeling scheme were carried out at the 3-D level. The laboratory experiments were performed to achieve the following three goals. Firstly, the geomechanical properties for the intact coal and coal discontinuities were estimated through the laboratory geomechanical property tests. Secondly, naturally existing fracture networks in the cubic coal blocks were first detected by the industrial Computed Tomography (CT) scanning technique and then quantified by the fracture tensor based methodology. Thirdly, polyaxial tests were conducted on the same cubic coal blocks to obtain the JCMS values under different confining stresses. With respect to the numerical modeling, PFC^3D and 3DEC software packages were used to simulate the polyaxial compression tests for intact and jointed cubic coal blocks, respectively. From more than twenty intact rock strength criteria, nine criteria were selected for this research. The intact coal strength data bank obtained from PFC^3D modeling was used to evaluate the applicability of nine different intact rock strength criteria. A modified grid search (MGS) procedure is proposed and used to find the best fitting parameter values and calculate the coefficient of determination (R²) values for each criterion. These criteria are compared in detail using the following features: R² values, σ₁ - σ₂ plots for different σ₃, shapes on the deviatoric planes, linearity or nonlinearity on the meridian planes. The regression analysis and the MGS procedure were found to be equivalent in finding the best fitting parameter values for a certain intact rock strength criterion. Through the comparisons, the modified Wiebols-Cook and modified Lade criteria were found to provide the highest R² values and fit the intact coal strength data best on the σ₁ - σ₂ coordinate plane and meridian planes. Based on the appearances on the deviatoric plane, the nine intact rock strength criteria are categorized into three types: the single shear stress criteria, the octahedral shear stress criteria and the criteria incorporating the maximum principal shear stress and partial intermediate principal shear stress. The relative positions of the different criteria on two specific meridian planes are also discussed. The geometric model of the jointed coal block was first set up by incorporating the fracture network constructed from the CT scanning into the intact coal block using a modified fictitious joint procedure. The numerical parameter values of intact coal and coal discontinuities were then calibrated and validated through a trial and error procedure using the laboratory test results of some selected samples. Next the JCMS data bank was consummated by performing a four-phase numerical investigation on several jointed coal blocks having selected fracture networks and five additional artificial fracture networks under different confining stress combinations. Finally, a new empirical coal mass strength criterion was developed to estimate the JCMS values at the 3-D level. The developed new model is capable of capturing the scale effect and anisotropic strength behaviors. It can also be applied to rock masses having approximately orthogonal fracture systems or for masses where fracture system can be reduced to an equivalent orthogonal fracture system.The following new contributions were made in this dissertation to advance the existing state-of-art on the dissertation topic: (a) A new, unique methodology as shown in Fig. 1.1 incorporating the following aspects was used to develop a new 3-D coal mass strength criterion: a complete set of geomechanical property tests, fracture network detection and quantification, polyaxial compression tests, numerical decomposition techniques; (b) A new procedure was developed to construct the fracture network in the coal cubes starting from CT scans to perform numerical modeling using 3DEC. In this procedure, a modified fictitious joint framework was also proposed to extend the applicability of the original fictitious joint framework, which allows incorporating a large quantity of non-persistent joints with acceptable numerical calculation effort; (c) A new 3-D coal mass strength criterion was developed to incorporate the fracture network and 3-D confining stress system to capture the anisotropy and scale effect of coal mass strength. The proposed criterion not only includes the influence of the intermediate principal stress, which is ignored by some existing strength criteria, but also includes the intensity and orientation and size probability distributions of the fracture system explicitly by a fracture tensor based methodology, which is far more advanced than most of the current criteria that are based on rock mass classification systems having only scalar indices; (d) A modified grid search procedure was proposed and used to evaluate the applicability of nine different intact rock strength criteria. The best intact rock strength criteria applicable for the intact coal data obtained through PFC^3D modeling were found by performing the most detailed intact rock strength criteria evaluation incorporating σ₁ - σ₂ - σ₃ plots and behaviors on the deviatoric and meridian planes, which improves the understanding of the available intact rock strength criteria.

Jointed rock masses are formed of intact rock and joints. There-fore, proper characterization of rock mass behavior has to consid-er the combined behavior of the intact rock blocks and that of the joints. This thesis presents the theoretical background of the Synthetic Rock Mass (SRM) modeling technique along with example applica-tions. The SRM technique is a new approach for simulating the mechanical behavior of jointed rock masses. The technique uses the Bonded Particle Model (BPM) for rock to represent intact ma-terial and the Smooth-Joint Contact Model (SJM) to represent the in situ joint network. In this manner, the macroscopic behaviour of an SRM sample depends on both the creation of new fractures through intact material, and slip/opening of pre-existing joints. SRM samples containing thousands of non-persistent joints can be submitted to standard laboratory tests (UCS, triaxial loading, and direct tension tests) or tested under a non-trivial stress path repre-sentative of the stresses induced during the engineering activity under study. Output from the SRM methodology includes pre-peak properties (modulus, damage threshold, peak strength) and post-peak proper-ties (brittleness, dilation angle, residual strength, fragmentation). Of particular interest is the ability to obtain predictions of rock mass scale effects, anisotropy and brittleness; properties that can-not be obtained using empirical methods of property estimation. Additionally, the nature of yielding and fracturing can be studied as the rock mass fails. This information can improve our understand-ing of rock mass failure mechanisms. / QC20100720

Simuler les réservoirs souterrains permet d’optimiser la production d’hydrocarbures. Les réservoirs naturellement ou hydrauliquement fracturés détiennent une part importante des réserves et exhibent un degré élevé d’hétérogénéité : les fractures, difficiles à détecter, impactent fortement la production via des réseaux préférentiels d’écoulement. Une modélisation précise de ces forts contrastes permettrait d’optimiser l’exploitation des ressources tout en maîtrisant mieux les risques environnementaux. L’enjeu est de prédire les processus d’écoulement multi échelles par un modèle simplement paramétrable. Une stratégie de simulations, qui améliore la fiabilité et les temps de calculs est mise au point dans cette thèse. Elle permet de simuler numériquement ou analytiquement la complexité d’un réservoir fracturé à grande échelle. Ces techniques dont l’intérêt est démontré sur un réservoir de roche mère trouvent des applications en géothermie ou dans la gestion des ressources en eau. / Fluid flow simulation is used to optimize oil and gas production. Naturally or hydraulically fractured reservoirs hold a significant part of reserves, difficult to assess. Fractures may create preferential flow paths heavily impacting fluid flow. Accurate modeling of fractured media accounting for strong contrasts would allow operators to optimize resources exploitation while better controlling environmental risks. Integrating sparse available data, we aim at predicting fluid flow processes occurring in the earth’s subsurface accounting for multi-scale fractures with a simply parameterized model. Improving the computational time and results reliability, we propose a full integrated strategy suitable for fractured reservoir specificities by simulating the fractures complexity on large scales. The techniques developed in this thesis, whose interest is demonstrated in an unconventional field case study, can find other applications in geothermal engineering and water resources management

Water ingress into rock tunnels is a problematic phenomenon – especially in urban areas – as a lowered groundwater table may cause harmful settlements. Furthermore, too much ingress can be an incentive for the environmental court to halt the tunnel process, in order to protect the nature as part of a national interest.Water ingress is normally lowered by injecting a water and cement mixture into boreholes in the rock mass – a process called rock grouting – thus sealing the rock fractures. Very little information and research has been on the subject of how the rock fracture orientation interact with the orientation and geometry of the grouting holes. The purpose of this thesis is to investigate whether or not it is possible and feasible to select a grout fan geometry that will have the most intersections with the rock fractures, based on fracture information gained in an early pre-investigation stage. The suitability of different grout fan geometries will be determined by analyzing the amount of fracture intersections that each geometry has in a discrete fracture network, generated based on data obtained from rock cores in the Stockholm Bypass project. The assumption is that more fracture intersections means a higher chance of sealing the rock mass. The results show that there is no clear difference in number of intersections between the analyzed grout fan geometries, indicating that focus should not be on analyzing the grout fans as whole units, but rather on the scale of individual grouting holes and fractures. This thesis also highlights the importance of monitoring according to the observational method. / Vatteninläckage i bergtunnlar är ett problem, speciellt inom tätbebyggda områden, eftersom en sänkt grundvattennivå kan orsaka sättningar i jordlagren och följaktligen skada infrastruktur. Dessutom kan ett för högt vatteninläckage vara ett incitament för miljödomstolen att stoppa tunneldrivningen i ett försök att skydda den allmänna miljön i dennas roll som ett nationalintresse.Vatteninträngning i tunnlar minskas normalt genom att injicera en blandning av vatten och mikrocement i borrhål lokaliserade i bergmassan – en process som kallas för sprickinjektering – och genom detta täta bergmassan. Idag finns mycket lite information tillgänglig om hur sprickors och injekteringshålens orienteringar interagerar med varandra.Syftet med denna uppsats är att undersöka huruvida det är genomförbart att i ett tidigt förundersökningsskede bestämma en skärmgeometri som kommer ha så många sprickskärningar som möjligt. Olika skärmgeometriers lämplighet bedömdes genom att analysera mängden sprickskärningar som varje geometri hade i ett diskret spricknätverk, baserat på indata från utvalda kärnborrningar från Förbifart Stockholm. Analysen utfördes under antagandet att fler sprickskärningar ger en större chans att täta berget.Resultaten visar att det inte finns en klar skillnad i antalen skärningar olika skärmgeometrier emellan, vilket indikerar att framtida fokus inte bör läggas på att analysera skärmgeometrier som enheter, utan snarare att analysen bör utföras på individuella injekteringshål och sprickor. Denna uppsats markerar också vikten av observationer under utförandet av berguttag och sprickinjektering i enlighet med observationsmetoden.

Comprendre l'altération du verre nucléaire dans un réseau de fracture au sein d'un bloc de verre vitrifié est important pour la sûreté du conditionnement des déchets nucléaires (quantification des risques associés au relâchement des radionucléides). L’évaluation de la performance du stockage géologique des déchets nucléaires passe obligatoirement par la modélisation de l’altération aqueuse d’un bloc de verre nucléaire fracturé, l’échelle de temps envisagée (plusieurs milliers d’années) dépassant toute possibilité d’expérience directe. Cette thèse vise donc à combler le fossé entre les simulations d'écoulement et de transport à l'échelle du réservoir et la modélisation à l'échelle micrométrique des processus interfaciaux verre-eau, en apportant l'évaluation quantitative de la dégradation aqueuse du verre à l'échelle d’un bloc.Pour aborder ce problème, les objectifs principaux de cette thèse ont été fixés comme suit : (i) la reproduction des résultats expérimentaux obtenus précédemment (pour quelques fractures modélisées de manière discrète en mode diffusif), (ii) l’analyse de l'impact des géométries de fractures sur la quantité de verre altéré pour quelques fissures modélisées de manière discrète, (iii) l’étude de la possibilité d'adaptation du modèle géochimique à la modélisation dans le cadre de l’approche milieu équivalent, (iv) la mise au point d'une méthodologie de caractérisation, (v) la modélisation géostatistique et géométrique de réseau de fractures à l’échelle d’un conteneur de verre, (vi) le calcul des paramètres équivalents diffusifs, hydrauliques et les paramètres qui contrôlent la cinétique de dissolution de verre, et au final, (vii) la modélisation de transport réactif à l’échelle d’un conteneur.À titre illustratif, la méthodologie de la caractérisation de réseau fracturé proposée, basée sur le traitement des images, a été appliquée aux images bidimensionnelles (2D) de haute résolution de deux blocs de verre. Cette application a permis de mettre en œuvre à la fois les données directes obtenues par mesures des paramètres d’un réseau fracturé de verre vitrifié et les données indirectes explicatives issues des simulations thermomécaniques. L’application a abouti à la création de multiples réalisations de tessellation de réseaux fracturés équivalents qui ont ensuite été utilisées comme représentations physiques pour les calculs de la perméabilité équivalente, de la diffusion équivalente et des paramètres contrôlant la cinétique de dissolution de verre borosilicaté. L'évolution de la quantité de verre altéré obtenue en effectuant la modélisation de transport réactif appliquée à plusieurs réalisations de la tessellation de réseau fracturé équivalent a été comparée aux données expérimentales d’un essai d'altération aqueuse d'un conteneur non radioactif de verre nucléaire. Les résultats montrent que la méthodologie conçue offre une opportunité pour mieux comprendre l'impact de la fracturation sur l'altération aqueuse du verre vitrifié et constitue un outil fiable permettant de prendre en compte différents scénarios d'évolution du stockage. / Understanding the alteration of nuclear glass in a fracture network of a vitrified glass block is important for the safe conditioning of nuclear waste (quantification of the risks associated with radionuclide release). Performance assessment of geological nuclear waste repositories entails modelling of the long-term evolution of the fractured nuclear glass block aqueous alteration, because the considered time scale, of several thousands of years, is beyond the range of any direct experimental perspectives. This dissertation aims then to bridge the gap between the reservoir-scale flow and transport simulations and the micron-scale modeling of the glass-water interfacial processes, by bringing the quantitative evaluation of the glass aqueous degradation at the block scale.To tackle this issue, the main objectives of this thesis were fixed as follows: (i) reproduction of the experimental results previously obtained (for some fractures modeled in a discrete way in the diffusive mode),(ii) analysis of the impact of fractures geometries on the quantity of altered glass at the scale of some fractures modeled in a discrete way, (iii) investigation of the possibilities of the geochemical model adaptation for the equivalent homogenous modeling, (iv) establishment of a methodology for glass block fracture network characterization, (v) geostatistical and geometric modeling, (vi) calculation of the equivalent diffusive, hydraulic and glass dissolution kinetics controlling properties and (vii) upcoming reactive transport modeling at the scale of one canister.As an illustrative example, the proposed image processing-based fracture network characterization methodology was applied to two-dimensional (2D) high-resolution images of two blocks of vitrified glass. This application brought into service both hard data obtained by direct measurement of the fracture network and soft physics-based explanatory data and resulted in the creation of multiple realizations of fracture network equivalent tessellation that were further used as physical representation for the calculation of the equivalent hydraulic, diffusive, and alteration kinetics - controlling properties. The evolution of the quantity of altered glass obtained by conducting reactive transport modeling applied to several realizations of the equivalent fracture network tessellation was compared with the experimental data of the aqueous alteration test of a non-radioactive full-scale nuclear glass canister. The results show that implementation of the devised procedure presents an opportunity for better understanding the impact of fracturing on aqueous alteration of borosilicate glass and provides a reliable tool enabling different scenarios of repository evolution to be accounted for.

<p>One of many applications of geohydraulic modelling is assessing the suitability of a site to host a nuclear waste repository. This modelling task is complicated by scale-dependent heterogeneity and coupled thermo-hydro-mechanical (THM) processes. The objective here was to develop methods for (i) upscaling flow and transport in fractured media from detailed-scale data and (ii) accounting for THM-induced effects on regional-scale transport. An example field data set was used for demonstration.</p><p>A systematic framework was developed where equivalent properties of flow, transport, and stress-effects were estimated with discrete fracture network (DFN) modelling, at some block scale, and then transferred to a regional-scale stochastic continuum (SC) model. The selected block scale allowed a continuum approximation of flow, but not of transport. Instead, block-scale transport was quantified by transit time distributions and modelled with a particle random walk method at the regional scale.</p><p>An enhanced SC-upscaling approach was developed to reproduce the DFN flow results more simply. This required: (i) weighting of the input well-test data by their conductivity-dependent test volumes and (ii) conductivity-dependent correlation structure. Interestingly, the best-fitting correlation structure resembled the density function of DFN transmissivities. </p><p>Channelized transport, over distances exceeding the block scale, was modelled with a transport persistence length. A linear relationship was found between this persistence length and the macroscale dispersion coefficient, with a slope equal to a representative mean block-scale dispersion coefficient.</p><p>A method was also developed to combine well-test data and rock-mechanical data in estimating fracture transmissivities, and its application was demonstrated.</p><p>Finally, an overall sequential THM analysis was introduced allowing the estimation of the significance of waste-related thermo-mechanical (TM) effects on regional transport; here TM effects are calculated separately and their impact on fracture transmissivities were incorporated into the hybrid framework. For the particular case, their effects on regional-scale transport were small.</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. 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. 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. 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. The thesis provides a framework for systematic analysis oflarge-scale engineering applications in fractured rock masses,such as geological repositories of nuclear wastes. Keyword:Fractured rock masses, Equivalent Continuum,Discrete Fracture Network (DFN), Distinct Element Method (DEM),Finite Element Method (FEM), Nuclear Waste Disposal, CoupledThermo-Hydro-Mechanical Processes

One of many applications of geohydraulic modelling is assessing the suitability of a site to host a nuclear waste repository. This modelling task is complicated by scale-dependent heterogeneity and coupled thermo-hydro-mechanical (THM) processes. The objective here was to develop methods for (i) upscaling flow and transport in fractured media from detailed-scale data and (ii) accounting for THM-induced effects on regional-scale transport. An example field data set was used for demonstration. A systematic framework was developed where equivalent properties of flow, transport, and stress-effects were estimated with discrete fracture network (DFN) modelling, at some block scale, and then transferred to a regional-scale stochastic continuum (SC) model. The selected block scale allowed a continuum approximation of flow, but not of transport. Instead, block-scale transport was quantified by transit time distributions and modelled with a particle random walk method at the regional scale. An enhanced SC-upscaling approach was developed to reproduce the DFN flow results more simply. This required: (i) weighting of the input well-test data by their conductivity-dependent test volumes and (ii) conductivity-dependent correlation structure. Interestingly, the best-fitting correlation structure resembled the density function of DFN transmissivities. Channelized transport, over distances exceeding the block scale, was modelled with a transport persistence length. A linear relationship was found between this persistence length and the macroscale dispersion coefficient, with a slope equal to a representative mean block-scale dispersion coefficient. A method was also developed to combine well-test data and rock-mechanical data in estimating fracture transmissivities, and its application was demonstrated. Finally, an overall sequential THM analysis was introduced allowing the estimation of the significance of waste-related thermo-mechanical (TM) effects on regional transport; here TM effects are calculated separately and their impact on fracture transmissivities were incorporated into the hybrid framework. For the particular case, their effects on regional-scale transport were small.