Дисертації з теми "Fractured rock massif"
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El, Khattabi Mohamed. "Etude et gestion des risques liés aux glissements de terrain en milieu urbain : application à la ville d'Al Hoceima (Nord du Maroc)." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILN047.
Landslides represent highly hazardous phenomena influenced by various parameters and criteria commonly observed in different locations worldwide. Managing them proves challenging, especially in urban areas, due to the risks they pose to the population and structures, as well as the complexities involved in implementing corrective measures. This thesis focuses on landslide studies applied to the city of Al Hoceima in northern Morocco. The objective is to analyze their origins or reactivation, the predisposing factors triggering them, and to understand the mechanisms at play.To tackle this challenge, a methodology based on analyzing ground movements through a multidisciplinary approach, incorporating geology, hydrogeochemistry, and geotechnics, proved essential. The analysis of the studied slope reveals a complex morphology resulting from geology characterized by tectonic activity and often-altered lithology. Geotechnically, this translates into mechanical characteristics ranging from weak to moderate, further decreasing under the influence of water. Intense tectonic activity has resulted in faults and fractures that have structured the slope, creating block structures that further weaken the terrain. Inclinometric measurements localized sliding planes at average depths ranging from 15 meters to 25 meters. These measurements also revealed relative movements of blocks during sliding. Chemical analysis of groundwater indicates the presence of sodium sulfates, occasionally mixed with sodium chloride, indicating leaching of autochthonous formations (Triassic-Liassic and Jurassic), exacerbated by the influence of the rising water table. Additionally, wastewater, constituting additional volumes, further disrupts the slope's equilibrium by infiltrating from the surface, as evidenced by the detection of nitrates in the analyzed waters.These results prompted the implementation of simulations to deepen the understanding of landslide mechanisms. A model considering geological discontinuities and analyzing deformations, displacements, and friction within fractures was employed, primarily focusing on landslide-prone areas. This modeling confirmed the conclusions drawn from the analytical phase of the study while facilitating the planning of corrective actions
SAVELY, JAMES PALMER. "PROBABILISTIC ANALYSIS OF FRACTURED ROCK MASSES." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184249.
Min, Ki-Bok. "Fractured Rock Masses as Equivalent Continua - A Numerical Study." Doctoral thesis, KTH, Land and Water Resources Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3742.
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
ALVARENGA, JULIO ERNESTO MACIAS. "COMPUTATIONAL ANALYSIS OF THE STABILITY OF FRACTURED ROCK MASSES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1997. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1929@1.
O presente trabalho apresenta aplicações das técnicas de Relaxação Dinâmica e Análise Limite ao estudo da estabilidade de maciços rochosos fraturados. O maciço é modelado como um meio descontínuo formado por blocos rígidos com deformação concentrada nas juntas. A técnica de Relaxação Dinâmica é usada para a solução do problema de equilíbrio resultante, através do programa BLOCO. As expressões desenvolvidas para a matriz de rigidez tangente, usando o modelo de Barton & Bandis, foram implementadas no programa BLOCO. Exemplos para a validação do algoritmo são apresentados. A partir do trabalho de Faria (1992), foi implementado um procedimento automatizado e otimizado para a solução do problema de Análise Limite em um meio formado por blocos rígidos. O procedimento desenvolvido permitiu a solução de problemas de porte relatados na literatura.
This work presents some applications of the Dynamic Relaxation and Limit Analysis techniques, to the study of the stability of fractured rock masses. Rock mass is modeled as a discontinuum formed by rigid blocks with deformable joints. Dynamic Relaxation was applied to solve the resulting equilibrium problem, using the program BLOCO. Expressions obtained for tangent stiffness matrix, derived from Barton & Bandis model, were implemented into the BLOCO program. In order to extend Faria`s (1992) work, an automatic and optimized procedure, to solve the Limit Analysis problem of a media formed by rigid blocks was implemented. The developed procedure was applied to the study of relatively large dimensions problems, reported in the literature.
Este trabajo presenta aplicaciones de las técnicas de Relajación Dinámica y Análisis Límite al estudio de la estabilidad de macizos rocosos fracturados. EL macizo es modelado como un medio discontinuo formado por bloques rígidos con deformación concentrada en las juntas. La técnica de Relajación Dinámica se utiliza para resolver el problema de equilíbrio resultante, a través del programa BLOQUE. Las expresiones desarrolladas para la matriz de rígidez tangente, usando el modelo de Barton & Bandis, se implementaron en el programa BLOQUE. Se presentan algunos ejemplos para la evaluación del algoritmo. A partir del trabajo de Faria (1992), fue implementado un procedimiento automatizado y optimizado para la solución del problema de Análisis Límite en un medio formado por bloques rígidos. El procedimiento desarrollado permitió resolver problemas de porte relatados en la literatura.
Priscu, Doina Maria. "Double-porosity modelling of groundwater flow through fractured rock masses." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ37280.pdf.
Abdallah, Ghassan. "La convection thermique dans les milieux fracturés : modélisation avec la méthode des éléments distincts." Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL126N.
Baghbanan, Alireza. "Scale and Stress Effects on Hydro-Mechanical Properties of Fractured Rock Masses." Doctoral thesis, KTH, Teknisk geologi och geofysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4772.
QC 20100702
Saetta, Valeria. "Micro-seismicity and hydro-mechanics of fractured rock masses : experiments and numerical simulations." Vandoeuvre-les-Nancy, INPL, 2004. http://www.theses.fr/2004INPL039N.
This dissertation forms part of a larger research field which deals with using seismic monitoring systems to better understand the behavior of natural rock slope appealing to the laboratory and in-situ experiments and the numerical simulation. For this purpose, a small scale rock mass, former instrumented from the geo-hydro-mechanical point of view, bas been chosen for installing a seismic monitoring system. Ln this site, it is possible to easily induce a known hydraulic charging and to measure displacements and pressures in many meaningful points. The results of the in-situ experiments highlight the existence of micro-seismicity induced by a variation of water pressures and the repetitiveness either of the hydro-mechanical and micro-seismic behavior. From results, it bas been hypothesized that the micro-seismic activity onsets when water pressure increases in less permeable zones. The Finite Elements numerical modeling of the site allows to calculate the stress variations due to hydraulic charging and to assess if stress variations could generate seismic sources. Series of cores have been taken from the site in order to tested rock material and rock fractures in laboratory, associated with acoustic emissions. Lt results that little stress variations due to water pressure, calculated for the site, do not explain the micro-seismicity observed in laboratory. A micro-mechanical model using Boundary Elements Method (Displacements Discontinuity Method) which simulates the hydro-mechanical behaviour of rock joints sample under normal compression is proposed taking into account the joint topography. Results confirm the laboratory observations and show that the hydrostatic charging can induce instabilities, when contact areas open, comparable to the ill-situ micro-seismicity
Styles, Thomas Daniel. "Numerical modelling and analysis of slope stability within fracture dominated rock masses." Thesis, University of Exeter, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496103.
Mehrapour, Mohammad Hadi, and Mohammad Hadi Mehrapour. "Development of a Failure Criterion for Rock Masses Having Non-Orthogonal Fracture Systems." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625679.
Hamidi, Sahar [Verfasser]. "Numerical investigations of heat and mass transport in fractured porous rock masses / Sahar Hamidi." Bonn : Universitäts- und Landesbibliothek Bonn, 2019. http://d-nb.info/1177881721/34.
Pérez, Carreras Adrià. "T-H-M coupling with large advection in fractured rock masses using zero-thickness interface elements." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/671102.
El estudio de problemas hydro-mecánicos (HM) acoplados en diferentes áreas de ingeniería civil, ambiental o del petróleo es común en la literatura, pero los efectos térmicos del fluido transportando calor a través de fracturas o discontinuidades no se considera en las actuales herramientas de análisis, en las cuales el efecto de la diferencia de temperatura entre el fluido inyectado a través de las discontinuidades y la del medio in situ no se tiene en cuenta. No obstante, en algunos problemas geomecánicos los comportamientos mecánico, hidráulico y térmico del medio poroso fracturado pueden aparecer acoplados con fuertes interacciones entre ellos. En modelación geomecánica es importante distinguir el comportamiento hidráulico del medio poroso del de las discontinuidades, ambas generando un sistema de doble permeabilidad en el cual el medio poroso proporciona una pequeña permeabilidad al sistema, mientras que las discontinuidades establecen caminos preferentes y proporcionan gran permeabilidad al mismo. Debido a las elevadas velocidades de fluido que se pueden desarrollar en las discontinuidades, la advección (transporte) puede ser el modo dominante de transferencia de calor. Por ello, el estudio de procesos THM acoplados con advección térmica en discontinuidades es importante en problemas con un cierto grado de acoplamiento entre los campos mecánico, hidráulico y térmico, y en los cuales el flujo hidráulico puede transportar calor a gran velocidad a través de las discontinuidades. Por ello, es importante establecer un modelo numérico para estudiar el fenómeno advectivo que diferencie la contribución de la red de discontinuidades de la del medio continuo poroso. En este contexto, esta tesis está enfocada en el estudio, formulación, implementación numérica y verificación de un modelo THM acoplado monolítico con advección dominante que sea capaz de reproducir el comportamiento advectivo que ocurre en discontinuidades o fracturas, en las cuales el fluido transporta calor. Este estudio se lleva a cabo en el contexto geomecánico de un medio poroso fracturado, empleando el método de los elementos finitos (FEM) con elementos junta de espesor nulo para representar las discontinuidades o fracturas, suponiendo condiciones saturadas, un único fluido incompresible (con densidad constante) y pequeñas deformaciones. También se supone que todo el comportamiento no lineal se desarrolla en las juntas mediante el uso de una ley constitutiva elasto-plástica basada en mecánica de fractura, mientras que el medio continuo poroso se supone de comportamiento poro-elástico. Adicionalmente, la solución numérica del problema térmico advectivo presenta singularidades con respecto a los problemas de difusión pura. Cuando las velocidades del fluido son bajas, la formulación numérica se puede llevar a cabo mediante Elementos Finitos tradicionales (Galerkin). No obstante, cuando las velocidades del fluido son suficientemente elevadas y la advección domina el problema el método estándar de Galerkin conduce a resultados oscilantes, por lo que el término advectivo requiere un tratamiento especial para estabilizar la solución numérica. En este contexto, se presenta una revisión de diferentes metodologías para resolver el problema de advección dominante, seleccionando el método Streamline Upwind Petrov-Galerkin (SUPG) para resolver el problema en régimen permanente, un método bien conocido que conduce a soluciones estables con advección dominante. Para el régimen transitorio esta tesis empieza con el estudio del método de Características Galerkin explícito, un método existente en el que el fenómeno advectivo se estudia de modo Lagrangiano, siguiendo la partícula (o calor) con el movimiento del fluido, y estableciendo para ello un sistema de coordenadas móvil que depende de la velocidad del fluido y de su posición en el tiempo. Seguidamente se desarrolla la forma implícita de este método, y finalmente se propone una nueva variación del método, añadiendo un parámetro 𝛼�𝛼� que permite determinar diferentes posiciones de las derivadas temporales del volumen advectivo, concluyendo en el nuevo 𝛼�𝛼�-Implicit Characteristic Galerkin Method. Con esta nueva metodología se estabiliza el problema de gran advección en régimen transitorio si se cumple la condición de Courant. Con el fin de verificar el modelo THM monolítico acoplado con advección dominante se presentan diversos ejemplos de verificación, tanto para medio continuo poroso como para elementos junta de espesor nulo. Finalmente, se presenta un caso de aplicación a fractura hidráulica (HF), llevando a cabo el análisis numérico de una sola fractura en 2-D con el objetivo de entender los mecanismos térmicos que ocurren en problemas de HF y como éstos afectan sobre los comportamientos mecánico e hidráulico. Además, los resultados de la modelación se comparan con los obtenidos empleando un modelo HM, en el cual no se consideran efectos térmicos. Adicionalmente, con el objetivo de mejorar la eficiencia computacional del código de Elementos Finitos, se ha llevado a cabo la paralelización del mismo mediante una estrategia de partición de subdominios, resultando en una mejora sustancial de la velocidad de los cálculos y mostrando una buena escalabilidad de los mismos.
Min, Ki-Bok. "Determination of equivalent hydraulic and mechanical properties of fractured rock masses using the distinct element method." Licentiate thesis, KTH, Land and Water Resources Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1550.
The equivalent continuum approach uses equivalent propertiesof rock mass as the input data for a continuum analysis. Thisis a common modeling method used in the field of rock mechanicsand hydrogeology. However, there are still unresolvedquestions; how can the equivalent properties be determined andis the equivalent continuum approach suitable for modeling thediscontinuous fractured rock mass.
The purpose of this paper is to establish a methodology todetermine the equivalent hydraulic and mechanical properties offractured rock masses by explicit representations of stochasticfracture systems, to investigate the scale-dependency of theproperties, and to investigate the conditions for theapplication of the equivalent continuum approach for thefractured rock masses. Geological data used for this study arefrom the site characterization of Sellafield, Cumbria, UK. Aprogram for the generation of stochastic Discrete FractureNetwork (DFN) is developed for the realization of fractureinformation and ten parent DFN models are constructed based onthe location, trace length, orientation and density offractures. Square models with the sizes varying from 0.25 m× 0.25 m to 10 m × 10 m are cut from the center ofthe each parent network to be used for the scale dependencyinvestigation. A series of the models in a parent network arerotated in 30 degrees interval to be used for investigation oftensor characteristic. The twodimensional distinct elementprogram, UDEC, was used to calculate the equivalentpermeability and compliance tensors based on generalizedDarcys law and general theory of anisotropic elasticity.Two criteria for the applicability of equivalent continuumapproach were established from the investigation: i) theexistence of properly defined REV (Representative ElementaryVolume) and ii) existence of the tensor in describing theconstitutive equation of fractured rock The equivalentcontinuum assumption cannot be accepted if any one of the abovetwo criteria is not met. Coefficient of variation and meanprediction error is suggested for the measures toquantitatively evaluate the errors involved in scale dependencyand tensor characteristic evaluation.
Equivalent permeability and mechanical properties (includingelastic modulus and Poissons ratios) determined onrealistic fracture network show that the presence of fracturehas a significant effect on the equivalent properties. Theresults of permeability, elastic moduli and Poisson's ratioshow that they narrow down with the increase of scale andmaintain constant range after a certain scales with someacceptable variation. Furthermore, Investigations of thepermeability tensor and compliance tensor in the rotated modelshow that their tensor characteristics are satisfied at acertain scale; this would indicate that the uses of theequivalent continuum approach is justified for the siteconsidered in this study.
The unique feature of the thesis is that it gives asystematic treatment of the homogenization and upscaling issuesfor the hydraulic and mechanical properties of fractured rockswith a unified approach. These developments established a firmfoundation for future application to large-scale performanceassessment of underground nuclear waste repository byequivalent continuum analysis.
Keywords :Equivalent continuum approach, Equivalentproperty, Representative Elementary Volume (REV), DistinctElement Method, Discrete Fracture Network (DFN)
Bouteca, Maurice. "Fracturation hydraulique calcul de propagation d'une fracture induite dans un massif rocheux /." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37603363t.
Tran, Thi Thu Hang. "Combined application of structural geology, the mechanics of discrete media and the analysis of in situ stresses and displacements for the modelling of mechanical behaviour of fractured rock masses." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20018/document.
Aimed at studying the mechanical behaviour of rock mass and considering the presence of the discontinuity network in the intact rock, this research concentrates on how the rock can be represented in suitable geometrical models, on the basis of site measurements, and then appropriately analysed using computer tools developed for the study of granular media. The first chapter deals with a bibliographical study on fractured rock and tunnel engineering. Different computational methods of rock mechanics are introduced. Simultaneously, three principal approaches for tunnel structural design are recalled. These studies lead to the proposition of a methodology from the in situ investigation to in-door modelling and mechanical analysis, presented in the second chapters. The rock mass is first geometrically represented through the distribution of discontinuities in the rock mass and the use of the RESOBLOK code based on the Discrete Fracture Network method. Mechanical models of rock mass are then presented from the data of historical studies on the rock mass and from laboratory and in situ measurements. The 3D computational models are analysed using the LMGC90 based on the Non Smooth Contact Dynamics method. The first two applications of the methodology are introduced: the generation of the numerical rock for the simulation of the triaxial compression test, and the simulation of multi-phase excavation of rock tunnel. The proposed methodology has been applied on the white marble of Saint Béat (Haute Garonne, France) and the initial results are given in the third chapter. The mechanical responses of the numerical rock mass are analysed and the bulk behaviour of the rock is evaluated
Jeanpert, Julie. "Structure et fonctionnement hydrogéologiques des massifs de péridotites de Nouvelle-Calédonie." Thesis, La Réunion, 2017. http://www.theses.fr/2017LARE0047/document.
Water resources of hard-rock (gneisses or granites) aquifers have significantly been studied in the past two decades. The hydrogeological behavior and structure of these aquifers are thus relatively well understood. On the other hand, aquifers in mantle-type basements, such as peridotites, are poorly studied and understood, mainly because they are not common and of limited extent. In this context, New Caledonia is a great laboratory offering unique opportunity to improve the knowledge of these original types of hydrosystems in tropical climate. Thus, the objective of this thesis is to improve the knowledge of these aquifer systems within weathered peridotites. Firstly, the study focuses on the characterization of the weathered layers of the peridotites composed of, from top to bottom, iron oxides/ferricrete, laterite, coarse saprolite and saprock (ie. top of the bedrock, with up to 20 % of weathered material). More than 60 hydraulic tests are performed and results were compiled with existing data. Mean hydraulic conductivity (K) of laterites is estimated around 1.10-7 m/s while mean value in coarse saprolites and saprock is around 8.10-7 m/s. Heterogeneity of this altered layer is high; K varies between six orders of magnitude and hydraulic head data analysis reveals a hydraulic connection with the deep fractured bedrock. Secondly, the fresh rock part of peridotites is studied. Fracture network analysis is derived from outcrop structural measurements and from the description of about 1000 m of cumulated borehole cores. This work highlights the importance of serpentine network, because of its high density and its critical impact on weathering. Moreover, the observations reveal that hydraulic conductivity decreases with depth within the substratum, due to the vertical decrease of weathered fractures density. These new results allow defining a structural framework of the massifs. It is characterized by a primary decimetrical fracture network closely related to the serpentine network. This network is overprinted by a secondary weathering network which reveals decametric spacing (ca. 30 m) and in places K values of 10-5 m/s. At depth, spacing is hectometrical and fractures are sealed by lithostatic pressure and/or subsequent mineral precipitations. These deca- and hectometric fracture networks, which are also visible on the scale effect of hydraulic conductivity, are primarily vertical and are the result of dissolution instabilities occurring during weathering processes. However, low- angle fractures do occur and allow the percolation of the network. Finally, on the basis of these new results and the integration of all existing data from different massifs a new hydrogeological conceptual model is proposed at the scale of a massif. The model includes a homogeneous lateritic aquitard and a coarse saprolite and saprock aquifer which is about 50 m thick. The bedrock is subdivided into three layers whose hydraulic conductivity decreases from 2.10-7 m/s to 2.10-8 m/s, respectively 50 and 250 m below the aquifer base. Numerical modelling validates this unitary conceptual model and reveals that the saturation of the massifs depends on their morphology. At last, several aspects require further research. The role of the ferricrete layer must be specified and considered in the hydrological model. Moreover, distribution of the fracture network remains to be fully addressed and should be studied with care given the potential development of highly permeable structures that could conform to pseudo-karstic drains. The applied results of this work are available in a “Technical guide” and a “Technical report” of the “HYPERK” CNRT Project
Gaudreault, Michel. "Analyse numérique des phénomenes mécaniques et hydrauliques en périphérie d'excavations en massifs rocheux fractures : le cas de la mine niobec, St-Honore (Québec) /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1996. http://theses.uqac.ca.
Souley, Mountaka. "Modélisation des massifs rocheux fracturés par la méthode des éléments distincts : influence de la loi de comportement des discontinuités sur la stabilité des ouvrages." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL091N.
Loiseau, Philippe. "Etude structurale et geostatistique des gneiss de la region du cezallier : modelisation tridimensionnelle de reseaux de fractures, application a l'ecoulement des fluides." Orléans, 1987. http://www.theses.fr/1987ORLE2055.
Bethencourt, Lorine. "Etude des bactéries oxydantes du fer dans les aquifères hétérogènes : rôle dans le fonctionnement biogéochimique des zones d'interface." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1B025.
Bacteria of the Gallionellaceae family (β-proteobacteria) oxidise dissolved iron at circumneutral pH to fuel their energy metabolism. These bacteria are endemic of microaerobic habitats, where they can outcompete the rapid abiotic oxidation of iron with oxygen. They are thus generally found in the interface areas between the atmosphere and an anoxic iron-rich compartment, such as a resurgence of groundwater. However, in the last five years, several studies have shown the presence of Gallionellaceae at depth in some subsurface environments, at depths where they are generally anoxic. In several of these environments, such as some aquifers in the Armorican basement (Brittany, France), Gallionellaceae even seem to dominate the microbial communities. This suggests (i) that there are deep interface zones in these aquifers between an oxygen-containing compartment and an anoxic iron-rich compartment, and (II) that these interface zones can have a major role in maintaining microbial populations at depth. The objective of this thesis was to explore the diversity and the ecology of Gallionellaceae bacteria in these subsurface environments, for uncover their overall biogeochemical functioning. A multidisciplinary approach, involving metagenomic and hydrogeochemical analyses, was used to achieve this objective
García, Gian Franco Napa. "Análise de risco de obras subterrâneas em maciços rochosos fraturados." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-18082015-105621/.
In this thesis the author establishes a systematic method for quantifying the risk in underground structures in fractured rock masses using structural reliability concepts in an efficient way. The method is applied to the case study of the underground cavern of Paulo Afonso IV Hydroelectrical Power Station UHE-PAIV. Additionally, an optimization study was conducted in order to show a potential application of the method. The estimation of the risk was done according to the recommendations of the United Nations Disaster Relief Organization UNDRO where risk can be estimated as the convolution between the hazard, vulnerability and losses functions. FORM and SORM were used as approximation methods for the reliability quantification by means of Direct Coupling and Quadratic Polynomial Response Surfaces. A Monte Carlo simulation was also used to quantify the reliability of the cavern UHE-PAIV because of the presence of multiple failure modes in the numerical model. In this study 3 types of threads were evaluated: excessive wall convergence, face stability and wedge block fall. Hazard functions were built relative to the thread intensities such as wall convergence ratio or block size. In the case of excessive wall convergence a deep circular tunnel was studied meaning to compare the quality of the approximation of the reliability technique (FLAC3D with direct coupling) to the exact solution. Errors below 0.1% were found in the reliability index ß estimation. The reliability of the face stability was evaluated using two limit analysis solutions against the numeric estimation. For the block stability it was verified that the sequential excavation recommended by the Q system increases considerably the reliability of the excavation leading safety to modern standard levels, e.g. from a ß equal to 2.04 for a full section excavation to 4.43 for a partial excavation. In the case study of the UHE-PAIV, the reliability of the underground cavern was estimated using the commercial software Unwedge. The probability of failure of individual blocks was integrated along the length of the cavern and the concept of structural system was used to estimate the global probability of failure. The cavern presented a probability of failure of 3.11% to 3.22% and a risk of 7.22x10-3 x C and 7.29x10-3 x C - where C is the cost of failure of a large block. The critical individual block showed a ß equal to 3.63. The optimization was performed considering two design variables − liner thickness and number of bolt per square meter. The optimal design was found as the pair, [t, nb] which minimizes the total cost function. Also, a sensibility analysis was conducted to understand the influence of some parameters in the location of the optimal excavation design. Concluding, the results obtained here suggest that the quantitative risk analyses, as a base for the risk assessment and management, can and must be considered as a north for the practice of geotechnical engineering owing that these analyses reconcile the basic concepts of mechanical efficiency, safety and financial feasibility. Thus, risk quantification is fully affordable.
Oliva, Victor Hugo Gaitán. "Propagação de fraturas em juntas rugosas não-persistentes." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-01032005-172004/.
The present experimental study was conducted to investigate the effect of joint roughness on the fracture propagation of models with non persistent joints. For this approach the parameters investigated are : coalescence, the crack initiation angle, the compressive strength and deformation of the mortar samples containing non-persistent rough joints under biaxial loading. There are many works in specialized literature that study the behavior of non-persistent smooth joints, unfortunately, this kind of approach does not take into account the effect of the dilation and the increase of friction due to the joint roughness. In this study, a new method was developed to produce non-persistent rough joints inside the mortar models. With this method it was possible to compare the different paths of rupture generated for the smooth and for the rough joints. Each sample had 15 joints with 'alfa' = 54º; 'beta' = 60º; Lj = Lb = 50mm and d = 25mm. Where 'alfa' is the formed angle between the joint plane and the plane generated by two non coplanar joint tips, 'beta' is the joint inclination angle with the principal plane stress, Lb is the distance between coplanar joints, Lj is the length of the joint, d is the distance between two non-coplanar joints. These parameters remained constant in all the tests; the only variation permitted was in the joint roughness : from smooth joints (JRC = 0) to rough joints (JRC = 6,96 and JRC = 12,25). Using the mentioned parameters before it was always obtained the stepping failure. For the samples containing smooth joints, JRC = 0, the main mechanism of coalescence is tension. For these joints the average crack initiation angles, had resulted of 64º and 65º for left and right side, respectively. The average normalized compression strength ('sigma'nor = 'sigma'1 - 'sigma'2 / 'sigma'cs; where 'sigma'1 and 'sigma'2 are the principal stresses and 'sigma'cs is the average compression strength) of these tests resulted to have the lowest value, 'sigma'nor = 0,52, and the highest deformation, 'épsilon' = 0,0057. In the case of joints with JRC = 6,7; the mechanisms of coalescence are tension and shear, growing in a waving path between the joint tips. The average crack initiation angle was of 40º for the left side and 48º for the right side of the joint. The average normalized compression strength of these tests was of 'sigma'nor = 0,54 and deformation 'épsilon' = 0,0053. With joints having JRC = 12,3; the coalescence also presents both mechanisms, tension and shear, following a direction inclined in the beginning and a straight line in the middle of the way. The crack initiation angles had been : 5º in the left side and 20º of the right side. The highest values of average normalized strength resistant and the lowest average value of deformation were found in this type of joint, being of 'sigma'nor = 0,59 e 'épsilon' = 0,0045 respectively. With this approach, it was verified that the joint roughness influence the fracture propagation, affecting the coalescence, the crack initiation angle, the resistance and total deformation of the tested specimens
Jaunat, Jessy. "Caractérisation des écoulements souterrains en milieu fissuré par approche couplée hydrologie-géochimie-hydrodynamisme : application au massif de l'Ursuya (Pays Basque, France)." Phd thesis, Université Michel de Montaigne - Bordeaux III, 2012. http://tel.archives-ouvertes.fr/tel-00778427.
宋政輝, Cheng-hui Sung, and 宋政輝. "Investigation Technology for fracture parameters and permeability of fractured rock masses." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/7mbr6q.
國立臺北科技大學
資源工程研究所
100
Hydraulic models play the key roles for description of underground water flow and solute transport, and are also crucial for the development and application of water resources and underground. The natural rock include many discontinuities like crevasses, beddings, joints and schistosities, which cause the difficulty in simulation and analysis and even further difficulties of engineering design and construction resulting in its mechanical and hydraulic behaviors present heterogeneity and anisotropy. Therefore, how to get the hydrogeological characteristics of the site and select the appropriate hydraulic model to perform prediction analysis through the modest description of scale is the key point for hydrogeological study from conceptual model, description model towards hydraulics model and numerical model. This study designs a hydrogeological testing well site and a series of fracture parameters investigation and hydraulic parameters tests are performed, so as to get the equivalent hydraulic conductivity of fractured rock mass based on the site hydrogeological characteristics described by the discrete fracture network model (DFN) .To thoroughly obtain the parameters required by the DFN mode, laboratory experiments are conducted to obtain the characteristics of mechanical and geometric parameters. Based on the discrete fracture parameters from outcrop investigation, in-situ hydraulic test and lab test, this study established the fracture network by two-dimensional fracture network model to evaluate the site hydraulic conductivity. This research shows the site equivalent hydraulic conductivity obtained by different hydraulic test methods applied in siltstones with the difference exceeding two orders of magnitude and the dimensions range is from 10-5 to 10-7m/s .From single well hydraulic test results shows the maximum difference of hydraulic conductivity resolved by different fracture combinations drops from 10-5 to 10-9 m/s, exceeding four orders of magnitude, indicating that the fracture distribution significantly affects the site hydrogeological characteristics. This study utilize the discrete fracture network model to build the well sites after investigating the fracture surface parameters and further obtains the site hydraulic conductivity based on site hydrological tests, which is a feasible technique for the investigation of the hydrogeological characteristics of fracture rock mass. The simulation results show that, based on the fracture parameters measured nearby the well site, the numbers of fractures taken from the simulated discrete fracture network are similar to field measured data in wells. The calculated hydraulic conductivity dimension is from 10-5 to 10-7 m/s, which is very close to the average dimension of site hydraulic test results. This study demonstrates that using the discrete fracture network model to think about hydrogeological model can provide the references and applications for similar cases of investigation and analysis on hydrogeological properties by investigating procedure of fracture rock parameters and permeation parameters and statistical analysis. The procedure includes the wells site building, in-situ test, laboratory experiments and related simulation analysis technologies.
Fadakar, Alghalandis Younes. "Stochastic modelling of fractures in rock masses." Thesis, 2014. http://hdl.handle.net/2440/92338.
Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2014
Zheng, Hua-En, and 鄭華恩. "Mechanical behaviors of fractured rock masses based on synthetic rock mass simulation." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/ge7cn3.
國立中央大學
土木工程學系
107
This paper presents the mechanical behaviors of fractured rock masses for various geometrical conditions by using the Particle Flow Code (PFC3D). A specified rock mass size is assigned by software FracMan to generate discrete fracture network (DFN) then the fracture data were input into smooth joint model (SJM), combing with bonded particle model (BPM) by PFC3D to produce synthetic rock mass (SRM). SRM was used to simulate the mechanical behaviors based on macroscopically isotropic/anisotropic rock under triaxial test, calculating major principal stress, young's modulus, crack numbers, stress-axial strain relationship and volumetric strain-axial strain relationship. The research projects are including: (1) Set a series of parameters to study the effect of the fracture intensity and the fracture size on the mechanical behaviors of the fractured rock mass. (2) Select one set of in-situ fracture data which was uniformly random distribution (κ = 0) to generate isotropic rock for triaxial test then observe the failure process and the failure mode. Compare our result with the uniaxial test observations of Basu et al. (2013), and the triaxial test result of Bieniawski (1967), Wawersik and Fairhust (1970) and Elliott (1982). (3) Set up single fracture set of seven angles to generate anisotropic rock for triaxial test then observe the failure process and the failure mode. The experimental results of Tien et al. (2006) and Khanlari et al. (2014) were compared with the failure mode of the test, and the maximum principal stress of the test results was compared with the failure criteria proposed by Tien and Kuo (2006). (4) To verify the conceptual model proposed by Hoek and Brown (1980, 1988), generating SRM with one to four sets of fracture then act the uniaxial test. Furthermore, to verify the accuracy of the Young’s modulus of the transversely isotropic rock mass of one set of fracture, using the method proposed by Amadei (1983) to determine elastic constants of the transversely isotropic rock mass.
"Computational analysis of the stability of fractured rock masses." Tese, MAXWELL, 1997. http://www.maxwell.lambda.ele.puc-rio.br/cgi-bin/db2www/PRG_0991.D2W/SHOW?Cont=1929:pt&Mat=&Sys=&Nr=&Fun=&CdLinPrg=pt.
Chiang, Chih-Wei, and 江誌偉. "Study on discrete seepage model for fractured rock masses." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/35679182916854951015.
國立臺灣大學
土木工程學研究所
96
It is crucial to well know on the behaviors of rock masses for underground utilization, such as the tunnel, radioactive waste material store and the liquefied natural gas stores etc., all need to build the appropriate model for the description of behaviors of rock masses, so as to estimate, analyze, predict or control all sorts of project behaviors. Traditionally, the behavior of rock masses can be described specifically in accordance with the characteristic of handling problem such as thermal field, flow field, mechanical field or chemical field. However, the problems of flow field and mechanical field always lead the security of fractured rock engineering. Therefore, the appropriate prediction on the flow rate, stress and deformation of fractured rock masses, i.e., the hydro-mechanical coupled behavior, is not only the base for engineering design, but also the key point for its performance assessment. In this study, the 2-D discrete fractured networks (DFN) model was performed through MATLAB programming language. The discrete fractured networks model was generated according to geometric parameters of fractures, such as the locations of centers of fractures, trace lengths, orientations and apertures, and they also follow their own distribution type. Furthermore, the flow field in the rock was solved using Darcy’s Law and mass-balance equation with specified boundary conditions. Then, it based on the concept of equivalent continuum to obtain the hydraulic conductivity of a zone which was selected by users. On the basis of this model, this research considers the permeability of rock mass and to probe into their influences on the mechanical and hydraulic behaviors. Users can select the theories of hydraulic behavior or hydro-mechanical coupled behavior free in this 2-D discrete fractured networks model. Using the theory of hydraulic behavior, it will calculate with hydraulic apertures instead of mechanical apertures. Using the theory of hydro-mechanical coupled behavior, it not only employs mechanical apertures to advance the accuracy compared with using the theory of hydraulic behavior, but also probe into the variations of permeability of rock mass caused by stresses changing. Under analytic process, users also can freely choose the zone and size which they want to observe and obtain the hydraulic conductivity of rock mass in the zone. Utilizing this way which freely choose the zone and size, we can obtain the size of representative volume element (RVE) exactly. Additionally, the permeability of fractured rock mass would cause the permeability anisotropy with the change of stresses. Thus this research also probe into the change of permeability anisotropy caused by overburdenend and caused by parameters. The results of study show that when the compressed normal to the joint, JRC and JCS would affect the hydraulic conductivity. And the accuracy of JRC will be a key factor. Under shear loading, the residual friction angle affects the hydraulic behavior of VII joints hardly. The hydraulic conductivity tends toward stability when the overburden is deep to certain depth. Utilizing the way which the observed zone’s size and position cooperate each other, the size of representative volume element (RVE) would be obtained exactly. The observed zone’s size chooses smaller, the more variable hydraulic conductivity is. The observed zone’s size chooses larger, the more steady hydraulic conductivity tends toward. The density of spacing is lower, the larger range of steady size is. The density of spacing is higher, the higher k value is. The trace length is longer, the smaller range of steady size is. The trace length is shorter, the larger range of steady size is. The coefficient of lateral earth pressue and JRC could cause the permeability anisotropy with the change of overburdened, but the orientation of fractured rock mass influence the permeability anisotropy smaller.
Su, Chiou-Hua, and 蘇秋樺. "Numerical modelling of wellbore stress in fractured rock masses." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/73714710887245901956.
Farichah, Himatul, and 法麗佳. "Representative Elementary Volume of P32 and Hydraulic Conductivity of Fractured Rock masses." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/u97928.
國立中央大學
土木工程學系
105
This study presents the representative elementary volume (REV) of P32 (fracture intensity) and hydraulic conductivity of fractured rock mass. Discrete fracture network (DFN) generated by FracMan is adopted to create rock mass models. A series of parametric studies including dip angle, dip direction, Fisher constant κ, size of rock mass model, shape of rock mass model, specimen volume, fracture diameter, and P32 were investigated to study the REV of P32. Based on the results of the parametric studies, a novel equation to quantify the COV (Coefficient of variance) of P32 in terms of specimen volume, fracture diameter and P32 was established. A precise REV size can be obtained easily by assigning the acceptable COV. Thereafter, some case studies were used to verify the proposed novel equation. Conventional Oda and Oda gold were adopted to estimate the hydraulic conductivity of the fractured rock mass. By using Oda conventional, a series of parametric studies including specimen volume, fracture diameter, P32, transmissivity, and aperture were investigated to study the REV of hydraulic conductivity. Subsequently, that REV of hydraulic conductivity was compared with the REV of P32. In the other hand, by using Oda gold, only P32 was chosen as parametric study. Eventually, a proposed new method was conducted by examining the Monte Carlo simulation for REV of hydraulic conductivity determination.
HSU, CHE JUI, and 許哲睿. "The uncertainty of fracture intensity and mechanical properties of rock masses." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/x8a6av.
國立中央大學
土木工程學系
105
This paper presents the uncertainties of geometrical and mechanical properties based on macroscopically isotropic synthetic rock mass. In the geometrical section, the analytical approach used the probability of whether each fracture center point would be sampled or not. The coefficient of variance of P30 could then be calculated by binomial theorem. According to the relation between P30 and P32, the coefficient of variance of P32 could also be yielded. To verify the analytical solution, FracMan was used to generate the rock mass model and discrete fracture network (DFN) to simulate the measurements and access the coefficient of variance of P32. The analytical solution and numerical solution were very similar when the ratio of the fracture diameter and the length of the sample volume was smaller than 0.5. In the mechanical section, this paper adopted the concept of synthetic rock mass (SRM). FracMan was used to generate DFN in rock mass models and to execute the sampling. The SRM was generated by combining the fracture data from FracMan and the bonded particle model in PFC3D. The uniaxial compression test, which uses strain control, was conducted to investigate the mechanical behavior of SRM. The uncertainty in the mechanical behavior of SRM is derived from fracture permutation and sampled fracture intensity. In past studies, the effects of these two factors were studied at the same time, but the precise effect of each factor could not be obtained due to the methodology used in these studies. To quantify the effect of fracture permutation, the P32 of each sample must be the same. The direct-generate method and sample-modify method were therefore adopted to ensure that each sample’s P32 were the same. By using the analytical solution of P32 and the relation between P32 and the mechanical property, the effect of the sampled fracture intensity could be calculated. The results showed that the effect of fracture permutation and fracture intensity were almost the same for uniaxial compression strength, and that the effect of fracture intensity was larger than fracture permutation on Young’s modulus. The variance of the mechanical behavior of SRM was also equal to the combination of the variance affected by fracture permutation and sampled fracture intensity. This relationship could also be proven by the theory of analysis of variance. According to this paper, as P32 increases, the coefficient of variance of fracture intensity will decrease and the coefficient of variance of both uniaxial compression strength and Young’s modulus will increase. In the range of parameters adopted in this paper, when P32 was smaller than 1.8 m-1, the coefficient of variance of fracture intensity was larger than coefficient of variance of uniaxial compression strength, and Young’s modulus was the smallest among them. When P32 was greater than 1.8 m-1, the coefficient of variance of uniaxial compression strength was larger than the coefficient of variance of fracture intensity, and Young’s modulus was the smallest among them.
Deng, Bor-Wei, and 鄧博維. "The Relationships between Characteristics of Discontinuities and the Hydraulic Conductivity in Fractured Rock Masses - A Case Study of jointed Andesite Rocks in Lan-Yu Site." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/92246211745468931226.
國立成功大學
資源工程學系
85
ABSTRACT Fractures play an important role both in the engineering behaviors and groundwater movement of rock masses. A description of the fracture geometry pattern is a primary requirement to assess the hydraulic and mechanical behaviors of jointed rock masses. To enhance the reliability of fracture data, this paper firstly proposes some analytical techniques based on statistical approaches to characterize and analyze the variability of fracture pattern. In order to estimate the hydraulic conductivity, a fractured rock mass which contains a lot of fractures, is assumed to be a homogenous and anisotropic porous medium. On the basis of theoretical derivation, laboratory and field data obtained from outcrops, model of estimating the hydraulic conductivity of fractur rocks is presented. In this study an attempt is made to estimate the relationship between the hydraulic conductivity and fracture pattern. The new model includes effects of hydromechanical coupling, normal closure and fracture geometry. Finally, an actual rock mass of jointed andesite rock on the Lan-Yu site, Taiwan, was studied to predict the hydraulic conductivity with depth.