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Статті в журналах з теми "Fractured rock massif":
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Rozov, Konstantin, Vyacheslav Rumynin, Anton Nikulenkov, and Polina Leskova. "Sorption of 137Cs, 90Sr, Se, 99Tc, 152(154)Eu, 239(240)Pu on fractured rocks of the Yeniseysky site (Nizhne-Kansky massif, Russia)." E3S Web of Conferences 98 (2019): 10007. http://dx.doi.org/10.1051/e3sconf/20199810007.
Анотація:
The study demonstrates the effect of sorption properties of fractured host rocks from the Yeniseysky site (Nizhne-Kansky rock massif, Krasnoyarsk region) on the migration of dissolved radioactive components (137Cs, 90Sr, 79Se, 99Tc, 152(154)Eu, 239(240)Pu) in the deep geological conditions of a high-level radioactive waste repository. Estimates of radionuclide distribution coefficients between the aqueous solution and fractured rocks obtained from sorption experiments. The influence of various petrographic types and fracture-filling substances on the retardation of radioactive components has been investigated. Based on the results of sorption experiments, we concluded that the type and attributes of rock discontinuities, as well as the mineral composition of the material in fractures, are crucial for the immobilization of radionuclides during their migration through a geological environment.
2
Malkovsky, Victor I., Vladislav A. Petrov, Sergey V. Yudintsev, Michael I. Ojovan, and Valeri V. Poluektov. "Influence of Rock Structure on Migration of Radioactive Colloids from an Underground Repository of High-Level Radioactive Waste." Sustainability 15, no. 1 (January 3, 2023): 882. http://dx.doi.org/10.3390/su15010882.
Анотація:
Studies of leaching of vitrified simulated high-level radioactive waste (HLW) evidence that most of actinides or their simulators enter leaching water in a colloidal form. In this paper, we consider a mechanism of colloid-facilitated migration of radionuclides from an underground repository of HLW located at a depth of a few hundreds of meters in fractured crystalline rocks. The comparison between data of field and laboratory measurements showed that the bulk permeability of the rock massif in field tests is much greater than the permeability of rock samples in laboratory experiments due to an influence of a network of fractures in the rock massif. Our theoretical analysis presents evidence that this difference can take place even in a case when the network is not continuous, and the fractures are isolated with each other through a porous low-permeable matrix of the rock. Results of modelling revealed a possibility of mechanical retention of radionuclide-bearing colloid particles in the frame of rock during their underground migration.
3
Gabov, Viktor V., Denis A. Zadkov, Andrey Yu Kuzkin, and Aleksandr S. Elikhin. "Fractured-Laminar Structure of Formations and Methods of Coal Loosening." Key Engineering Materials 836 (March 2020): 90–96. http://dx.doi.org/10.4028/www.scientific.net/kem.836.90.
Анотація:
The paper analyzes the structure of coal beds. It is noted that coal beds belong to laminar massifs with characteristic oriented structure and pronounced anisotropy of strength properties, and include rock layers and consolidated hard inclusions. The quality criteria of the coal loosening process are highlighted. A selective method of separating coal from a massif by cutting along weakened surfaces is proposed as an alternative to the existing combine technology with continuous cutting of a massif from the surface.
4
Vergelska, N. V., L. І. Pуmonenko, and I. M. Skopychenko. "MINING AND GEOLOGICAL FEATURES OF FORECASTING DYNAMIC PHENOMENA IN COAL MINES." Mining Geology & Geoecology, no. 1(4) (June 8, 2022): 5–15. http://dx.doi.org/10.59911/mgg.2786-7994.2022.1(4).273777.
Анотація:
The issues of forecasting and preventing dynamic phenomena in coal mines, despite decades of research, remain insufficiently studied. The nature of dynamic phenomena is far from being known, and as the depth of mining of coal seams increases, the phenomena become more and more formidable and, as a rule, unpredictable.Most of the dynamic phenomena are related to the stress state of the massif and the peculiarity of its gas saturation, which is partly explained by the state of sedimentary rocks. In sedimentary rocks or crystalline fractured, the number of parameters characterizing the stress state of rocks at depth increases.Studying the dynamic processes of different intensity in the coal rock massifs of the Donets Basin, it was found that the main factors that provoke them should include anomalously high formation pressures, stress state and gas content of the massif.
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Kazakov, Aziz, Bobur Bobarakhimov, Muzaffar Haqberdiyev, Shuhrat Muhitdinov, and Hasan Qurbonov. "Rating assessment of rocks and ores in the conditions of the Kyzyl-alma deposit of Angren mine department." E3S Web of Conferences 462 (2023): 03028. http://dx.doi.org/10.1051/e3sconf/202346203028.
Анотація:
A comparative analysis of assessing the stability of rock masses was carried out based on rating indicators that are used at foreign underground mining enterprises. An assessment of the state of the rock mass at the Razvedochnaya and Kyzyl Alma mines of the Angren mine was carried out. The method for determining the category of disturbance of an ore and rock massif is effective, gives a quick assessment of the state of the massif - the international Barton rating system is recommended to be used in problem areas (unstable, stressed, weakened, fractured, disturbed (tectonic faults), watered massif, etc.) during excavation, fastening and maintaining workings, for qualitative and quantitative assessment of the state of the ore and rock mass.
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Ait-Ssi, Lahcen, Jean-Pierre Villeneuve, and Alain Rouleau. "Utilisation d'un modèle stochastique de réseaux de fractures pour étudier les propriétés hydrauliques d'un massif fissuré." Canadian Geotechnical Journal 26, no. 2 (May 1, 1989): 313–23. http://dx.doi.org/10.1139/t89-040.
Анотація:
This study of the hydraulic properties of a fractured rock mass is based on data from field injection tests and fracture measurements, and on simulations of the fracture system in the bedrock upstream from the Daniel Johnson dam at Manic 5. Analysis of water injection tests indicates that the bedrock can be divided into two zones with respect to the permeability. The more permeable zone, which is the object of this study, shows a log-normal distribution of the hydraulic conductivities.Using several stochastic simulations of fracture networks, the fracture aperture has been adjusted gradually to reproduce the rock mass permeability estimated from injection tests. The results show that the fracture system geometry, as well as the fracture porosity and the fracture lengths and densities, influences widely the hydraulic properties of a fractured medium and particularly the fracture porosity. Also, the estimation of the fracture porosity is sensitive to a number of other factors, including the assumed hydraulic boundary conditions, the field estimation of the hydraulic conductivities, and the orientation of the simulation planes. Key words: fissured media, fracture porosity, stochastic model, simulation, sensitivity analysis, dam.
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Rodionova, Anastasiya A., Vladimir G. Petrov, Irina E. Vlasova, Konstantin B. Rozov, Iurii M. Nevolin, Vasiliy O. Yapaskurt, Vyacheslav G. Rumynin, and Stepan N. Kalmykov. "Sorption and Spatial Distribution of 137Cs, 90Sr and 241Am on Mineral Phases of Fractured Rocks of Nizhnekansky Granitoid Massif." Energies 15, no. 19 (October 10, 2022): 7440. http://dx.doi.org/10.3390/en15197440.
Анотація:
The sorption behavior and spatial microdistribution of Cs-137, Sr-90 and Am-241 onto the surface of a fractured rock sample from the R-11 borehole of the exocontact zone of the Nizhnekansky granitoid massif were studied. The sorption efficiency of the fractured sample increases in the row of Sr < Cs < Am, where americium is the most retained radionuclide. Based on the image processing of radiograms and scanning electron microscopy data, the mineral relative sorption efficiency (RSE) values were determined to quantify the contribution of the mineral phases of the fractured sample to radionuclide retention. It was established that cesium and strontium are predominantly retained in cracks filled with secondary mineral chlorite. Zeolite is a less effective sorbent with respect to cesium and strontium. Americium sorption is uniform over the whole surface of the fractured sample, with close RSE values for all mineral phases (RSE ~1). The behavior of cesium in heterogeneous and monomineral systems of crushed mineral phases of quartz, biotite and zeolite NaA imitating minerals of the fractured rock sample R-11 was determined. It was shown that the fraction of the sorbed cesium in a heterogeneous system of two mineral phases—biotite and quartz—was larger than the sum of sorption values for the same separated mineral phases. Based on the models of radionuclide sorption on illite–smectite minerals, it was able to estimate the depth of the penetration of solution into the fractured rock sample R-11. The variations of penetration depths for solutions of specific radionuclide into the fractured rock sample were established.
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Colegial-Gutiérrez, Juan Diego, María Camila Forero-Quintero, María Alejandra Fuentes-Rueda, and Sully Gomez Isidro. "Characterization of weathering profiles of the crystal rocks of eastern Bucaramanga and definition of hydrogeological properties." Boletín de Ciencias de la Tierra, no. 41 (January 1, 2017): 16–30. http://dx.doi.org/10.15446/rbct.n41.59347.
Анотація:
In the process of improving the knowledge of the hydrogeological potential of weathered zones in crystalline rocks and compounds that can behave as aquifers, this article is performed whose area of study is located east of the metropolitan area of Bucaramanga, Santander Massif consists of two main lithological units; the Neis of Bucaramanga and Santander Group plutonic (diorite, granodiorite-tonalite gray quartz monzonite and monzogranite). These rocks have undergone brittle deformation, physico-chemical weathering mainly influenced by the tropical atmosphere of the area also are jointed and fractured creating conditions that facilitate the flow of water and in turn be optimized weathering processes in the region. He appealed to the identification and location of field weathering profiles made a detailed study of outcrops, presenting a thickness of 90.4 m for the profile of the Gneisic rock weathering and 68.5 m for the profile of granodiorite rock, made up 6 steps weathering of which samples each were taken and carry out macroscopic analysis, petrographic and geochemical using thin films, determining the percentage of porosity, humidity, dry unit weight, X-ray fluorescence, electron microscopy Sweeping and Grading; base characterizing weathering profiles and properties, highlighting the potential hydrogeological found in the Range II: Slightly weathered rock and interval V: Completely weathered rock profile of granodiorite rock and Rock Gneisic profile, the interval III : Moderately weathered rock and the range V: Completely weathered rock, since these stages of weathering, moisture peaks present, regular micro fractures and high porosities.
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Deline, P., W. Alberto, M. Broccolato, O. Hungr, J. Noetzli, L. Ravanel, and A. Tamburini. "The December 2008 Crammont rock avalanche, Mont Blanc massif area, Italy." Natural Hazards and Earth System Sciences 11, no. 12 (December 15, 2011): 3307–18. http://dx.doi.org/10.5194/nhess-11-3307-2011.
Анотація:
Abstract. We describe a 0.5 Mm3 rock avalanche that occurred in 2008 in the western Alps and discuss possible roles of controlling factors in the context of current climate change. The source is located between 2410 m and 2653 m a.s.l. on Mont Crammont and is controlled by a densely fractured rock structure. The main part of the collapsed rock mass deposited at the foot of the rock wall. A smaller part travelled much farther, reaching horizontal and vertical travel distances of 3050 m and 1560 m, respectively. The mobility of the rock mass was enhanced by channelization and snow. The rock-avalanche volume was calculated by comparison of pre- and post-event DTMs, and geomechanical characterization of the detachment zone was extracted from LiDAR point cloud processing. Back analysis of the rock-avalanche runout suggests a two stage event. There was no previous rock avalanche activity from the Mont Crammont ridge during the Holocene. The 2008 rock avalanche may have resulted from permafrost degradation in the steep rock wall, as suggested by seepage water in the scar after the collapse in spite of negative air temperatures, and modelling of rock temperatures that indicate warm permafrost (T > −2 °C).
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Lahmili, A., L. Ouadif, A. Akhssas, and L. Bahi. "Rock stability analysis – A case study." MATEC Web of Conferences 149 (2018): 02072. http://dx.doi.org/10.1051/matecconf/201814902072.
Анотація:
The problems of the stability of the mineral-bearing structure ST2 at 560 m of depth in the east zone of Bou-azzer mine disturbs the advance of the exploitation. The geological and structural study based on field observations and the analysis of core drilling shows the presence of altered and fractured diorite surmounted by cobalt mineralization. Based on the empirical methods of Barton (Q-system) and Bieniawski (RMR) the bed rock is classified as poor quality. The analytical study made it possible to dimension supporting by bow-pieces and bolting. The existence of several types of discontinuities (fault, diaclases and joints) has made the realization of numerical simulation by the finite elements method very difficult. These discontinuities create a network of natural fractures which cut out the blocks in various forms likely to be detached or slip into the excavation, thus encouraging the infiltration of water creating pressure on the massif. The classical studies show their limits in practice for installation of supporting because they must take into account the characteristics of discontinuities. Hence a structural analysis of the massif is essential. The cracking survey of ST2 at 560 m of depth in the east zone of Bou-azzer mine at 560m of depth, and their processing by the DIPS software, showed the existence of three main families of discontinuity NW-SE with a dip of 75SW, NS subverticale and NE-SW with a dip of 57NW, and two families of minor joints NW-SE and NE-SW with successive dips of 40SW and 75SE. The analysis of fracturing surveys allowed us to evaluate the risks of falling blocks and the families of discontinuity responsible for them, and to limit the zones presenting a risk of slip and the families responsible for them. The importance of this study is of knowing how and where to put supporting to be opposed to the risk of fall and tilting of the blocks, caused by the network of discontinuities of the massif.
Дисертації з теми "Fractured rock massif":
1
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.
Анотація:
Les glissements de terrain représentent des phénomènes extrêmement dangereux, influencés par divers paramètres et critères fréquemment observés dans différents endroits dans le monde. Leur gestion se révèle complexe, d'autant plus s'ils sont localisés en milieu urbain, en raison des risques qu'ils présentent pour la population et les habitations, ainsi que de la difficulté des mesures correctives à mettre en place. Cette thèse se concentre sur l'étude des glissements de terrain appliquée à la ville d'Al Hoceima, au nord du Maroc. L'objectif est d'analyser leurs origines ou leur réactivation, les facteurs prédisposants qui les déclenchent, et de comprendre les mécanismes en jeu.Pour relever ce défi, une méthodologie basée sur l'analyse des mouvements de terrain à travers une approche pluridisciplinaire, combinant géologie, hydrogéochimie et géotechnique, s'est avérée essentielle. L'analyse du versant étudié révèle une morphologie complexe, résultant d'une géologie caractérisée par une activité tectonique et une lithologie souvent altérée. Du point de vue géotechnique, cela se traduit par des caractéristiques mécaniques variant de faibles à moyennes, et qui diminuent encore sous l'effet de l'action de l'eau. L'activité tectonique intense a engendré des failles et des fractures qui ont structuré le versant, créant des structures en blocs qui fragilisent davantage le terrain. Les mesures inclinométriques ont permis de localiser les plans de glissement à des profondeurs moyennes comprises entre 15 mètres et 25 mètres. Ces mesures ont également révélé des déplacements relatifs des blocs pendant les mouvements. L'analyse chimique des eaux souterraines indique la présence de sulfates de sodium, parfois mêlés à du chlorure de sodium, témoignant d'un lessivage des formations autochtones (Trias-Lias et Jurassique), aggravé par l'influence de la nappe phréatique montante. De plus, les eaux usées, représentant des volumes additionnels, viennent encore perturber l'équilibre du versant en s'infiltrant depuis la surface, comme en témoigne la détection de nitrates dans les eaux analysées.Ces résultats ont motivé la réalisation de simulations visant à approfondir la compréhension des mécanismes des glissements de terrain. Un modèle prenant en compte les discontinuités géologiques et analysant les déformations, les déplacements et les frottements dans les fractures a été utilisé, en se focalisant principalement sur les zones sujettes aux glissements. Cette modélisation a confirmé les conclusions tirées de la phase analytique de l'étude tout en permettant de planifier des actions correctivesLandslides 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
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SAVELY, JAMES PALMER. "PROBABILISTIC ANALYSIS OF FRACTURED ROCK MASSES." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184249.
Анотація:
Stability analysis of rock masses composed of small, discrete rock blocks that are in-place and interlocked should consider four components of failure: (1) Sliding between blocks. (2) Shearing through rock blocks. (3) Rolling blocks in a shear zone. (4) Crushing of rock blocks. Statistical rock mass description is used to define the characteristics of the rock blocks and the block assemblage. Clastic mechanics is one method of predicting stresses produced by the arrangement of rock blocks and the loading conditions. Failure begins at a point of maximum stress behind the slope. Progression of the failure is assumed if the first block fails because adjacent blocks will become overstressed. The location of the point of maximum stress is determined from the shape and arrangement of the constituent rock blocks. Because strength is mobilized block-by-block rather than instantaneously along a continuous shear surface, sliding between blocks shows less stability than a soil rotational shear analysis or a rigid block sliding analysis. Shearing through rock blocks occurs when maximum shear stress exceeds rock shear strength. Crushing of rock blocks is predicted if the normal stress exceeds the compressive strength of the rock block. A size-strength relationship is combined with the rock block size distribution curve to estimate crushing strength. Rotating blocks in a shear zone have been observed in model studies and as a mechanism in landslides. Stability analysis assumes that the rock mass is sufficiently loosened by blasting and excavation to allow blocks to rotate. The shear strength of rolling blocks is dynamic shear strength that is less than static sliding shear strength. This rolling mechanism can explain release of slope failures where there are no other obvious structural controls. Stability of each component of rock mass failure is calculated separately using capacity-demand reliability. These results are combined as a series-connected system to give the overall stability of the rock mass. This probability of failure for the rock mass system explicitly accounts for the four components of rock mass failure. Criteria for recognizing rock mass failure potential and examples applying the proposed method are presented.
3
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.
Анотація:
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
4
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.
Анотація:
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO 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.
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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.
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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.
Анотація:
L’étude des phénomènes couplés thermo-hydro-mécaniques intéresse la communauté scientifique aujourd'hui confronté au problème du stockage des déchets. La modélisation est un outil essentiel pour prédire l'évolution complexe du milieu hôte et de ces déchets. Parmi les approches numériques existants, on distingue les approches de types éléments finis et les approches de type éléments distincts. Si la première, plus ancienne, a déjà donné lieu à de nombreux développement et applications, elle rend mal quelquefois la réalité du massif rocheux fracturé. Nous avons souhaité cette dernière approche en la rendant capable de modéliser les échanges thermiques convectifs liés à la circulation d'un fluide dans les fissures de roche. Nous suspectons en effet que ce phénomène peut être important si le gradient hydraulique est suffisamment élevé. Une étude bibliographique nous a permis de mettre en évidence les paramètres qui déterminent ce phénomène dont le principal est le coefficient de transfert thermique h entre la roche et le fluide. Les nombreuses formulations recensées ne sont pas totalement suffisantes à expliciter la réalité de ses effets. D’autres mesures, in situ et en laboratoire, s'avèrent nécessaires. Nous avons pu établir des expressions pour les termes d'échange thermique entre le fluide et la roche et à l'intérieur du fluide lui-même. Souhaitant donc modéliser le phénomène à l'aide d'une approche adaptée au milieu discontinu, notre choix s'est porte sur le logiciel UDEC (Universal Distinct Element Code) dont la structure permettait moyennant quelques modifications d'accueillir les développements envisagés. Les algorithmes de calcul sont basés sur les différences de vitesse entre les transferts thermiques convectifs et conductifs. Nous avons testé notre modèle dans le cas de l'écoulement d'un fluide froid entre 2 blocs. Dans le cas d'une modélisation thermohydraulique, les échanges thermiques calculés sont cohérents et s'accordent avec ceux calculés par une autre approche numérique. On observe en effet que la convection thermique croit avec l'ouverture hydraulique de la fracture, la vitesse du fluide et décroit avec sa viscosité. Des calculs thermo-hydromécaniques ont montré la nécessité d'alterner les calculs thermiques et les calculs hydromécaniques suffisamment fréquemment pour rendre compte de la réalité du couplage. Notre modèle a été utilisé à grande échelle et a permis également d'interpréter les anomalies thermiques mesurées sur le site géothermal du Cézallier
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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.
Анотація:
In this thesis, the effects of size and stress on permeability, deformability and strength of fractured rock masses are investigated. A comparison study was carried out to examine the effects of considering, or not considering, the correlation between distributions of fracture apertures and fracture trace lengths on the hydro-mechanical behavior of fractured rocks. The basic concepts used are the fundamental principles of the general theory of elasticity, Representative Elementary Volume (REV), the tensor of equivalent permeability, and the strength criteria of the fractured rocks. Due to the size and stress dependence of the hydro-mechanical properties of rock fractures, the overall effective (or equivalent) hydro-mechanical properties of the fractured rocks are also size and stress-dependent. However, such dependence cannot be readily investigated in laboratory using small samples, and so numerical modeling becomes a necessary tool for estimating their impacts. In this study, a closed-form relation is established for representing the correlation between a truncated lognormal distribution of fracture apertures and a truncated power law distribution of trace lengths, as obtained from field mapping. Furthermore, a new nonlinear algorithm is developed for predicting the relationship between normal stress and normal displacement of fractures, based on the Bandis model and the correlation between aperture and length. A large number of stochastic Discrete Fracture Network (DFN) models of varying sizes were extracted from some generated large-sized parent realizations based on a realistic fracture system description from a site investigation programme at Sellafield, UK, for calculating the REV of hydro-mechanical properties of fractured rocks. Rotated DFN models were also generated and used for evaluation of the distributions of directional permeabilities, such that tensors of equivalent permeability could be established based on stochastically established REVs. The stress-dependence of the permeability and the stress-displacement behaviour were then investigated using models of REV sizes. The Discrete Element Method (DEM) was used for numerical simulation of the fluid flow, deformability properties and mechanical strength behavior of fractured rocks. The results show significant scale-dependency of rock permeability, deformability and strength, and its variation when the correlation between aperture and trace length of fractures are concerned, with the overall permeability and deformability more controlled by dominating fractures with larger apertures and higher transmissivity and deformability, compared with fracture network models having uniform aperture. As the second moment of aperture distribution increases, a fractured rock mass shows more discrete behavior and an REV is established in smaller value of second moment with much larger model size, compared with the models with uniform fracture aperture. When the fracture aperture pattern is more scattered, the overall permeability, Young’s modulus and mechanical strength change significantly. The effect of stress on permeability and fluid flow patterns in fractured rock is significant and can lead to the existence or non-existence of a permeability tensor. Stress changes the fluid flow patterns and can cause significant channeling and the permeability tensor, and REV may be destroyed or re-established at different applied stress conditions. With an increase in the confining stress on the DEM models, the strength is increased. Compared with the Hoek-Brown criterion, the Mohr-Coulomb strength envelope provides a better fit to the results of numerical biaxial compression tests, with significant changes of the strength characteristic parameters occurring when the second moment of the aperture distribution is increased.QC 20100702
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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.
Анотація:
Un massif rocheux fracturé, dont le comportement géo-hydromécanique a été étudié depuis plusieurs années, a été instrumenté sismiquement. L'intérêt du site réside dans le fait qu'on peut induire artificiellement une charge hydraulique connue et mesurer des déplacements, des pressions hydrauliques sur plusieurs points significatifs. Les résultats des essais in-situ mettent en évidence l'existence d'une micro-sismicité induite par une variation de pression avec une grande repétitivité. A partir des résultats des essais in-situ, a été formulée l'hypothèse que l'activité micro-sismique est associée à l'augmentation de la pression d'eau dans les zones moins perméables du massif rocheux. Une modélisation numérique du site avec la méthode des Eléments Finis a été réalisée pour determiner l'amplitude des variations de contraintes induites par la mise en charge hydraulique et vérifier si elles pouvaient engendrer des sources sismiques. Des échantillons prélevés ont permis de déterminer, en laboratoire, le comportement mécanique de la roche intacte et des joints rocheux et la sismicité associée. Il s'avère que les variations de contrainte calculées pour le site ne sont pas suffisantes pour générer la sismicité observée au laboratoire. Une modélisation micromécanique à l'échelle du joint rocheux avec la méthode des Eléments de Contour (Discontinuités de Déplacement) a été réalisée pour simuler le comportement hydro-mécanique tenant compte de la morphologie du joint. Les résultats numériques sont en accord avec les obsenTations de laboratoire et montrent que la mise en charge hydraulique d'un joint rugueux peut engendrer des instabilités lors de l'ouverture des aires de contact compatibles avec la micro-sismicité observée sur le siteThis 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
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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.
Анотація:
Numerical modelling of rock slopes can involve a number and variety of techniques, the selection and requirement of which depends on the factors deemed to control the potential for Instability. This thesis presents a number of case studies involving slopes in fractured rock, encompassing a range of scales. The case study slopes have provided a means to question the way in which particular slope instabilities should be analysed. Currently there are few methods available for analysing the complex behaviour within slopes of fractured rock. A review of available techniques is given within this thesis, with the use of limit equilibrium, finite element and hybrid methods, to highlight their specific advantages and limitations for the chosen case study slopes. By modelling slope Instability within fractured rock, the understanding of both discrete and mass behaviour increases considerably. Numerical modelling can therefore be used as a tool to help improve both the safety and efficiency of open pit mining and the management of natural rock slopes.
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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.
Анотація:
Two new three-dimensional rock mass strength criteria are developed in this dissertation by extending an existing rock mass strength criterion. These criteria incorporate the effects of the intermediate principal stress, minimum principal stress and the anisotropy resulting from these stresses acting on the fracture system. In addition, these criteria have the capability of capturing the anisotropic and scale dependent behavior of the jointed rock mass strength by incorporating the effect of fracture geometry through the fracture tensor components. Another significant feature of the new rock mass strength criterion which has the exponential functions (equation 6.7) is having only four empirical coefficients compared to the existing strength criterion which has five empirical coefficients; if the joint sets have the same isotropic mechanical behavior, the number of the empirical coefficients reduces to two in this new strength criterion (equation 6.10).
The new criteria were proposed after analyzing 452 numerical modeling results of the triaxial, polyaxial and biaxial compression tests conducted on the jointed rock blocks having one or two joint sets by the PFC3D software version 5. In this research to have several samples with the same properties a synthetic rock material that is made out of a mixture of gypsum, sand and water was used. In total, 20 joint systems were chosen and joint sets have different dip angles varying from 15 to 60 at an interval of 15 with dip directions of 30 and 75 for the two joint sets. Each joint set also has 3 persistent joints with the joint spacing of 42 mm in a cubic sample of size 160 mm and the joints have the same isotropic mechanical behavior. The confining stress combination values were chosen based on the uniaxial compressive strength (UCS) value of the modeled intact synthetic rock. The minimum principal stress values were chosen as 0, 20, 40 and 60 percent of the UCS. For each minimum principal stress value, the intermediate principal stress value varies starting at the minimum principal stress value and increasing at an interval of 20 percent of the UCS until it is lower than the strength of the sample under the biaxial loading condition with the same minimum principal stress value.
The new rock mass failure criteria were developed from the PFC3D modeling data. However, since the joint sets having the dip angle of 60 intersect the top and bottom boundaries of the sample simultaneously, the joint systems with at least one of the joint sets having the dip angle of 60 were removed from the database. Thus, 284 data points from 12 joint systems were used to find the best values of the empirical coefficients for the new rock mass strength criteria. λ, p and q were found to be 0.675, 3.16 and 0.6, respectively, through a conducted grid analysis with a high R2 (coefficient of determination) value of 0.94 for the new criterion given by equation 6.9 and a and b were found to be 0.404 and 0.972, respectively, through a conducted grid analysis with a high R2 value of 0.92 for the new criterion given by equation 6.10.
The research results clearly illustrate how increase of the minimum and intermediate principal stresses and decrease of the joint dip angle, increase the jointed rock block strength. This dissertation also illustrates how different confining stress combinations and joint set dip angles result in different jointed rock mass failure modes such as sliding on the joints, failure through the intact rock and a combination of the intact rock and joint failures.
To express the new rock mass strength failure criteria, it was necessary to determine the intact rock strengths under the same confining stress combinations mentioned earlier. Therefore, the intact rock was also modeled for all three compression tests and the intact rock strengths were found for 33 different confining stress combinations. Suitability of six major intact rock failure criteria: Mohr-Coulomb, Hoek-Brown, Modified Lade, Modified Wiebols and Cook, Mogi and Drucker-Prager in representing the intact rock strength was examined through fitting them using the aforementioned 33 PFC3D data points. Among these criteria, Modified Lade, Modified Mogi with power function and Modified Wiebols and Cook were found to be the best failure criteria producing lower Root Mean Square Error (RMSE) values of 0.272, 0.301 and 0.307, respectively. Thus, these three failure criteria are recommended for the prediction of the intact rock strength under the polyaxial stress condition.
In PFC unlike the other methods, macro mechanical parameters are not directly used in the model and micro mechanical parameter values applicable between the particles should be calibrated using the macro mechanical properties. Accurate calibration is a difficult or challenging task. This dissertation emphasized the importance of studying the effects of all micro parameter values on the macro mechanical properties before one goes through calibration of the micro parameters in PFC modeling. Important effects of two micro parameters, which have received very little attention, the particle size distribution and the cov of the normal and shear strengths, on the macro properties are clearly illustrated before conducting the said calibration. The intact rock macro mechanical parameter values for the Young’s modulus, uniaxial compression strength (UCS), internal friction angle, cohesion and Poisson's ratio were found by performing 3 uniaxial tests, 3 triaxial tests and 5 Brazilian tests on a synthetic material made out of a mixture of gypsum, sand and water and the joint macro mechanical parameter values were found by conducting 4 uniaxial compression tests and 4 direct shear tests on jointed synthetic rocks with a horizontal joint. Then the micro mechanical properties of the Linear Parallel Bond Model (LPMB) and Modified Smooth Joint Contact Model (MSJCM) were calibrated to represent the intact rock and joints respectively, through the specific procedures explained in this research. The similar results obtained between the 2 polyaxial experiments tests of the intact rock and 11 polyaxial experimental tests of the jointed rock blocks having one joint set and the numerical modeling verified the calibrated micro mechanical properties and further modification of these properties was not necessary.
This dissertation also proposes a modification to the Smooth Joint Contact Model (SJCM) to overcome the shortcoming of the SJCM to capture the non-linear behavior of the joint closure varying with the joint normal stress. Modified Smooth Joint Contact Model (MSJCM) uses a linear relation between the joint normal stiffness and the normal contact stress to model the non-linear relation between the joint normal deformation and the joint normal stress observed in the compression joint normal stiffness test. A good agreement obtained between the results from the experimental tests and the numerical modeling of the compression joint normal test shows the accuracy of this new model. Moreover, another shortcoming associated with the SJCM application known as the interlocking problem was solved through this research by proposing a new joint contact implementation algorithm called joint sides checking (JSC) approach. The interlocking problem occurs due to a shortcoming of the updating procedure in the PFC software related to the contact conditions of the particles that lie around the intended joint plane during high shear displacements. This problem increases the joint strength and dilation angle and creates unwanted fractures around the intended joint plane.
Книги з теми "Fractured rock massif":
1
Bouteca, Maurice. Fracturation hydroulique: Calcul de propagation d'une fracture induite dans un massif rocheux. Paris: Éditions Technip, 1987.
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Bles, J. L. Fracturation profonde des massifs rocheux granitiques. Orléans: Editions du Bureau de recherches géologiques et minières, Service géologique national, 1986.
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Loiseau, Philippe. Etude structurale et géostatistique des gneiss de la région du Cézallier, Massif central français: Modélisation tridimensionnelle de réseaux de fractures : application à l'écoulement des fluides. Orléans, France: Editions du BRGM, 1988.
Частини книг з теми "Fractured rock massif":
1
Mackie, Bruce E. "Interconnectivity Study of a Fractured Rock Aquifer." In Remediation in Rock Masses, 56–67. Reston, VA: American Society of Civil Engineers, 2000. http://dx.doi.org/10.1061/9780784400159.ch05.
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Bai, M., H. I. Inyang, C. C. Chien, and C. Bruell. "Factors for Assessing Flow and Transport in Fractured Porous Media." In Remediation in Rock Masses, 12–27. Reston, VA: American Society of Civil Engineers, 2000. http://dx.doi.org/10.1061/9780784400159.ch02.
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Reitsma, Stanley, and Bernard H. Kueper. "Alcohol Flooding to Remediate Rock Fractures Containing a DNAPL." In Remediation in Rock Masses, 220–36. Reston, VA: American Society of Civil Engineers, 2000. http://dx.doi.org/10.1061/9780784400159.ch16.
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Li, Chunhong, and John L. Wilson. "Heuristic Theory on Diffusive Mixing Behavior at Fracture Junctions." In Remediation in Rock Masses, 28–41. Reston, VA: American Society of Civil Engineers, 2000. http://dx.doi.org/10.1061/9780784400159.ch03.
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Bai, M., Y. Abousleiman, H. I. Inyang, H. Mo, and J. C. Roegiers. "Analysis of Capture Zone and Pump-and-Treat Method in Fractured Rocks." In Remediation in Rock Masses, 42–55. Reston, VA: American Society of Civil Engineers, 2000. http://dx.doi.org/10.1061/9780784400159.ch04.
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Mackiewicz, Scott M., Bruce H. Kjartanson, and John M. Pitt. "Gasoline Transport and Air Venting Removal in a Fractured Clayey Till: A Laboratory Study." In Remediation in Rock Masses, 124–36. Reston, VA: American Society of Civil Engineers, 2000. http://dx.doi.org/10.1061/9780784400159.ch10.
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Paillet, Fredrick L. "Using Borehole Wireline Methods to Delineate Fracture Flow Paths in Bedrock Formations." In Remediation in Rock Masses, 83–100. Reston, VA: American Society of Civil Engineers, 2000. http://dx.doi.org/10.1061/9780784400159.ch07.
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Middleman, Bruce, and Rob Earle. "Development of a Conceptual Groundwater Recovery System in a Fractured Bedrock Aquifer: A Case Study from the Wissahickon Formation." In Remediation in Rock Masses, 68–82. Reston, VA: American Society of Civil Engineers, 2000. http://dx.doi.org/10.1061/9780784400159.ch06.
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Zhang, Fengshou, Branko Damjanac, and Jason Furtney. "Hydraulic Stimulation of Naturally Fractured Reservoirs." In Coupled Thermo-Hydro-Mechanical Processes in Fractured Rock Masses, 161–80. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-25787-2_6.
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Zhang, Fengshou, Branko Damjanac, and Jason Furtney. "3D Lattice Modeling of Hydraulic Fracturing in Naturally Fractured Reservoirs." In Coupled Thermo-Hydro-Mechanical Processes in Fractured Rock Masses, 237–51. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-25787-2_9.
Тези доповідей конференцій з теми "Fractured rock massif":
1
Bulegenov, Kanat, Sayat Rais, and Daulet Muratkhanov. "GEOLOGY OF PERMIAN GRANITES OF THE KARATAU-NARYN ZONE AND THEIR PROSPECTIVE FOR RARE METALS (SOUTH KAZAKHSTAN)." In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/1.1/s01.07.
Анотація:
The studied intrusive massif is an ellipse elongated in the sublatitudinal direction. Only the eastern part, 2.2x4 km in size, is exposed on the earth surface. Under the sediments, the intrusion was traced by boreholes and aeromagnetic survey. The intrusion is a sheetlike body of a fractured nature, inclined to the southwest. A zone of marmorized limestones, as well as tremolite and wolastonite hornfelses, formed at the contact with the intrusion. Among the intrusive rocks that make up the massif, three successive igneous phases are distinguished. The first phase is represented by pyroxenites, biotite pyroxenites, alaskites, hornblendites, pyroxene-hornblende shonkinites and pseudoleucite facies, in which mesocratic and melanocratic syenites are distinguished. The rocks of the second phase are pyroxene-biotite and hornblend-biotite-pyroxene shonkinites, monzonites, syenites, which have gradual transitions. The rocks of the third intrusive phase are represented by biotite-pyroxene-hornblend syenites. A characteristic feature of syenites is the abundance of xenoliths of rocks of the first and second phases and marbles. The main rock-forming minerals of these rocks are orthoclase, hornblend, diopside-augite, minor ones: biotite, acidic or intermediate plagioclase, nepheline. The rocks of the intrusion are enriched in zinc, yttrium, copper, tin, molybdenum, vanadium, and lead. In addition, they contain increased amounts of cobalt and silver. Intrusions have been studied and their prospects for rare metals and rare earth elements have been evaluated.
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Gupalo, T. A., V. P. Beygul, and V. Yu Konovalov. "Comparative Quantitative Estimation of Engineered and Natural Barriers Influence on Ecological Safety of Long-Lived Radwaste Underground Disposal." In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4533.
Анотація:
The paper presents quantitative estimations of the effect of containers, matrix materials, bentonite barrier and hard rock massif on ecological safety during geologic isolation of longlived RW. The estimations were obtained on the basis of mathematical modelling of radionuclides (Np-237, Tc-99, Pu-239, Zr-93) migration in bentonite barrier, forecasting contaminated underground water migration in fractured zones, experimental data on leaching rates of radionuclides immobilized in boron silicate glasses and mineral-like ceramics. Preliminary data obtained at one of the sites of the Nizhnekansky massif were used in calculations. Is was shown that choice of optimum performances of multibarrier system can ensure safe final isolation of long-lived, not heat-generating RW fractions in geologic disposal located at 600 m depth.
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Karimi, Omid, Marie-Helene Fillion, and P. Dirige. "A quantitative numerical assessment of blast-induced damage in an open pit bench blast using a propagating gas pressure boundary condition." In The IV Nordic Symposium on Rock Mechanics and Rock Engineering. Jarðtæknifélag Íslands og Jarðgangafélag Íslands, 2023. http://dx.doi.org/10.33112/nrock2023.7.
Анотація:
"One of the cost-effective methods used for rock breakage in mining is drilling and blasting. In open pit mining, blast-induced damage can reduce the level of stability of benches and pit slopes, which is a concern for the safety of mine personnel. Rock fracturing and fragmentation by blasting is the result of the coalescence of existing and new fractures (created by the blast) in the rock mass. The stress waves affect the rock mass in a few milliseconds while the effects of gas pressure last in the scale of hundreds of milliseconds and have a greater effect on rock fragmentation. The presence of in-situ fractures can have a significant impact on the extent of blast-induced damage beyond the intended area of the blast. These fractures are generally preferential paths of least resistance for the explosive energy. It is therefore necessary to account for the effect of the in-situ fracture network to reliably characterize fracture development and blast-induced damage. Discrete fracture networks (DFN) are representations of joint systems and can estimate the distribution of insitu fractures within a rock mass. The combined finite (FEM)/discrete (DEM) element method (or FDEM) is a useful tool to simulate the complex rock blasting process. FEM is used for calculating stress distribution and displacements before fracturing (static phase) and, once the fracture process begins, DEM is used for simulating the fractured medium (large displacement phase). The principal objective of this paper is to develop a DFN-based numerical FDEM model to assess the influence of gas pressure on blast-induced damage using a propagating boundary condition, which simulate the effect of gas pressure on a growing network of fractures. A two-holes open pit bench blast was simulated in 2D environment. In this simulation, gas pressure was applied on a propagating boundary (boundary of developed fractures). The numerical model is simulated based on rock and blast properties obtained from an operating open pit mine. The level of blast-induced damage was quantified based on the area of the blast damage zone and the intensity of blast-induced fractures. The results show that the propagating boundary condition provides a realistic simulation of blast holes interaction and blast-induced fracture development."
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Gao, Jingyao, Guangqi Chen, and Yasuhiro Mitani. "Hydro-Mechano-Chemical Analysis of the Reactive Transportation Process Using the Extended DDA Method." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0144.
Анотація:
ABSTRACT The waste repositories or mining activities interfere with the chemical equilibrium of natural underground water, enhancing the hydro-chemical erosion and widening the flow passage, which may lead to serious geohazard. Understanding the evolution of this hydro-mechano-chemical (HMC) coupling process is helpful to the forecast and mitigation of the influence brought by the human activities. This study extends the original DDA method by embedding the discrete seepage network and considering the widening of fracture flow passage by using the finite difference method. After being validated by comparing the numerical results with those of the laboratory test on a single fracture, the extended DDA method is applied to the analysis of a real reactive tailings case. The results agree well with the previous research and laboratory observations. The simulations indicate that the proposed methodology can be applied in the HMC analysis of the reactive transportation in fractured rock masses and promise a wider application in a more comprehensive analysis in the future. INTRODUCTION Understanding the reactive transportation of fluid in fractured stratum has been of interest over the last decades in many engineering disciplines for different kinds of applications, including underground radioactive waste repositories, over-pumping and contamination from industry and agriculture, and other energy engineering projects. With increasing attention being paid to the sustainable development of underground space, more advanced tools and methodologies are required for design, operation, and safety assessments of these human activities to mitigate environmental damage (Molson, Aubertin, & Bussiere, 2012). The reactive transportation in rock mass is a typical multi-field coupling process. Besides moving with the fluid flow in fractured geological materials by convection, the reactive solute or particle in the groundwater system can also be retarded by other physical or chemical mechanisms, such as sorption on fracture surfaces, diffusion in and out of the rock matrix, in-situ stresses, and chemical reactions between the solute and the rock matrix or the fracture walls (Zhao, Jing, Neretnieks, & Moreno, 2011). For instance, the acid mine drainage produces one of the most sever ground water contamination, characterized by low pH and high dissolved concentration of rock minerals, which can erode rock mass and exert significant long-term impact on underground environment. This chemical solution will migrate through different flow paths, including shallow permeable subsurface pathways (for example a porous aquifer), or deeper through bedrock which is usually controlled by flow through fractures. Meanwhile, it is well known that the in-situ stresses must be taken into consideration in underground engineering, especially in the analysis of fractured rock mass. The field stress changes fracture apertures by causing normal closure, opening, or shear dilation, and consequently varies the seepage field (the flow rate and water head in a specific fracture). Combining with the influence of dissolution or precipitation at fracture surface in chemical reaction, makes the reactive transportation in fractured stratum a complicated Hydro-Mechanical-Chemo (HMC) issue.
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Cottrell, Mark, Alfred Lacazette, Bill Chmela, Saman Karimi, and B. D. Marsh. "Evaluating the Geothermal Potential of Hot Sedimentary Aquifers Using a Hybrid Approach." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0422.
Анотація:
ABSTRACT Flow through geothermal reservoirs is highly complex, and often includes contributions from both fracture networks and the porous rock matrix. Discrete Fracture Network (DFN) models are proven, effective tools for the characterization of rock masses especially where fracture dominated fluid flow is encountered; whereas more conventional tools, such as Finite Volume (FV) methods, are more numerically favorable for simulating problems where detailed multiphysics is required. This paper presents a workflow that combines discrete and continuum descriptions that captures the salient features of the geological materials whilst also remaining numerically tractable. DFN models of fractured rock masses are typically developed using statistical distributions to generate realistic three-dimensional (3D) descriptions of the natural fracture network. Superimposed with this fracture description, is a matrix-orientated description based on an intact rock property model. Integration of these two descriptions into a single continuum rock mass description is achieved through a novel discrete-continuum upscaling process which combines fractures and intact properties into a unified form, providing effective mass permeability and geomechanical descriptions. The composite rock mass description is then carried forward into a numerically efficient multiphysics solver that provides effective simulation of both temperature and flow in a fully coupled manner to evaluate the performance potential of geothermal reservoir units. In addition, it will be demonstrated how the presented work can naturally embed within the stochastic framework of DFN and permit a probabilistic based evaluation. This paper presents application of the hybrid DFN-FV workflow for a hot sedimentary aquifer. The application is presented in terms of the characterization steps and a description of the input used, which is then supplemented with the dual fracture and matrix description. The demonstration will also touch on the efficient gridding of geological domains and provide example simulation results of multi-well injector and producer fluid flow and heat transfer. The work in this paper shows how the DFN-FV approach can be systematically employed to help with the success of geothermal well placement and completion studies in hot sedimentary aquifers.
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Manko, A. V., and E. A. Muraveva. "Fracture mechanics of fractured rock masses and verification of rheological calculation models." In CONSTRUCTION: THE FORMATION OF LIVING ENVIRONMENT: FORM-2022. AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0144320.
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Ifrene, Ghoulem E. H., Sven Egenhoff, Prasad Pothana, Neal Nagel, and Bo Li. "High-Resolution Fluid Flow Simulation in X-Crossing Rough Fractures." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0333.
Анотація:
ABSTRACT Modeling of fluid flow in rock fractures is a key issue in answering numerous geoengineering problems in the fields of geophysics, reservoir engineering, rock mechanics, to geothermal processes. Although fluid flow in single fractures has been extensively studied in the last 7 decades, fractures commonly seen in fractured reservoir systems intersect each other forming complex geometric structures. Such fracture networks likely affect fluid flow behavior and solute transport. To investigate the impact of geometric characteristics of connected rough-walled fractures with an X junction shape on linear and nonlinear fluid flow behaviors, a sensitivity analysis was carried out by conducting a series of numerical fluid flow simulations on X shape fractures, generated by scanning real rock fractures with distinct roughness (low, medium, and high), intersecting angles, and apertures. The fluid flow through these fractures at different flow rates was simulated by solving Naiver-Stokes equations. The results show that tortures paths and the formation of eddies are more accentuated on the rough fracture than the smoother ones, and the tortuosity of the streamlines is related to the roughness and the geometric characteristics of the intersection. Simulation results of the different models were compared, which show that the intersection significantly impacts the relationship between the hydraulic gradient and the flow. Therefore, the pressure gradient increases with the decrease of the intersection angle especially for low aperture and rough cases. INTRODUCTION Understanding fluid flow through a fractured rock mass has great importance to numerous underground industrial activities, such as geothermal extraction (Zhao, 2016), CO2 storage (Catherine Noiriel et al., 2013), oil and gas exploration (Bo Li et al., 2016), underground oil storage (Qiao et al., 2017; Wang et al., 2015), and hydraulic fracturing (Blanton TL,1982). It is important to measure the impact of roughness to improve the performance of large-scale models since most existing large-scale models still rely heavily on simplified smooth parallel-plate models and related models for natural rock fractures with rough walls (Zimmerman et al., 1992; Zimmerman and Bodvarsson, 1996; Ge 1997; Bodin et al., 2007; Zhao et al., 2013; Wang et al., 2015).
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Li, Bingxie, Yongcun Feng, Chengyun Ma, Sishuai Li, Chenxi Lai, Shuai Zhang, and Feiyu Su. "Particle Size Optimization of Lost Circulation Materials: A Comprehensive Experimental Study." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0359.
Анотація:
ABSTRACT Severe lost circulation in fractured formations is one of the most common and challenging problems in oil and gas drilling engineering. The lack of theoretical guidance on the selection of lost circulation materials (LCMs) for millimeter-level fractures results in unstable fracture bridging, which is prone to repeat failure. In this paper, a comprehensive laboratory experimental study was conducted with modified PPA equipment for millimeter-level fractures. The effectiveness of the LCMs is evaluated by fluid loss amount, pressure-bearing capacity, and the LCMs bridge location and integrity. Experimental results show that a single LCM size distribution cannot effectively seal millimeter-level fractures, while an optimized combination of bridging and filling particles can achieve successful sealing. It is recommended that the mass ratio of bridging particles to filling particles be 2:1. The D50 and D90 of the bridging particles should be 35-40% and 70-80% of the fracture entrance width, respectively. The D90 of the supplementary flaky materials, e.g., mica, should be slightly less than the fracture entrance width. The results of this laboratory study can provide guidance for selecting LCM size for effective fracture sealing and improved wellbore strengthening performance. INTRODUCTION During the drilling process, lost circulation happens when a lot of drilling fluid leaks into the formation. Lost circulation can result in the drilling fluid's depletion and prolong the drilling cycle. Improper management of lost circulation may also lead to complex situations, such as wellbore instability, blowouts, and stuck pipes, ultimately resulting in catastrophic engineering accidents. The lost circulation rate is estimated to account for approximately 20% to 25% of the total number of drilled wells. The annual cost of well plugging can reach $4 billion USD. In North America (the United States and Canada), the percentage of drilled wells that experience severe lost circulation in carbonate oil and gas reservoirs, shale oil and gas reservoirs, and other formations amounts to about 40% of the total. In the Middle East, the wells that experience severe lost circulation during the drilling of carbonate-fractured oil reservoirs account for more than 30% of the total, with the time loss due to lost circulation exceeding 50%.
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Yu, Jiayi, Jiehao Wang, Yan Li, Amr El-Fayoumi, Ruiting Wu, Xiaolong Liu, Peggy Rijken, Andrew P. Rathbun, and Derek Elsworth. "Permeability-Friction Relationships for Propped Fractures in Shale." In 56th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2022. http://dx.doi.org/10.56952/arma-2022-2242.
Анотація:
ABSTRACT: We investigate controls on fluid transfer into massive hydraulic fractures due to reactivation of, and proppant penetration into, oblique fractures transecting the main fracture face during long-term reservoir depletion through tightly constrained laboratory experiments. Permeability evolution of fracture-contained proppant permeability/conductivity is highly sensitive to both normal stress and proppant loading concentration and less sensitive to shear displacement rate. By experimentally examining the shale and steel fractures – as an analog to end-member manifestations of soft/weak and hard/strong fracture surfaces – and calibrating using granular mechanics models (DEM), we conclude that the evolution of friction-permeability relationship of a propped shale fracture is largely controlled by the rock friction/rigidity. To be specific, propped hard/strong fractures show a continuous permeability decay at near-constant rate throughout a shear deformation. Conversely, permeability of soft/weak fractures declines rapidly during pre-steady-state-friction then declines more slowly after transitioning to steady-state-friction. We posit that weak fracture walls accommodate shear deformation via the combined effects of distributed deformation across the interior of the proppant pack and from sliding at the fracture-proppant interface. However, strong rocks accommodate shear deformation primarily through distributed deformation within the proppant pack. 1. INTRODUCTION Recent advances in methods of recovery – horizontal drilling and massive hydraulic fracturing – enable oil and gas recovery from deep, ultralow-permeability shale reservoirs. This new resource has dramatically changed energy supply in the United States and worldwide over the past two decades. However, the deployment of massive hydraulic fracturing is accompanied by controversy. Large scale fluid injection into the subsurface potentially generates overpressure and may result in the reactivation of faults and fractures (Warpinski and Teufei, 1987; Maxwell et al., 2002; Zhou et al., 2008; Taleghani and Olson, 2011; Zhou and Xue, 2011; Taleghani et al., 2016). In addition, the intersection of natural fractures by the driven hydraulic fracture results in complex fracture networks with the architecture controlled by constraints on the crossing of these fractures (Olson and Taleghani, 2009; Cheng et al., 2015; Zhang et al., 2017). Oblique fractures intersecting the main hydraulic fracture may reactivate in shear as the effective stress state is modified by the passing hydraulic fracture (Wang et al., 2018). Other plausible causes for fracture slip include stress reorientation and poroelastic effects due to nonuniform pressure depletion in heterogeneous permeability fields (Segall and Fitzgerald, 1998; Rousssel and Sharma, 2012; Zhang et al., 2017), undesired fluid leakage into pre-existing hydraulic fractures (Guindon 2015), fluid reinjection (Dohmen et al., 2017) and the enhanced interactions between the natural fractures and hydraulic fractures during fracture propagation (Weng, 2015; Fang et al., 2017a). Some in situ observations suggest that the induced shear deformations can also influence the fluid transport characteristics of the reservoir formation (Guglielmi et al., 2015). Thus, concurrent observations of shear deformation and fluid transport are important in understanding the evolution of fracture permeability in response to fracture reactivation, especially during long-term reservoir depletion.
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Baidoo, Mark, Marie-Hélène Fillion, Alexander Hutchison, and Claudia González. "Controlled Lab-Scale Evaluation of the Secondary Permeability Represented in a 3D Printed Discrete Fracture Network (DFN) Model." In 3rd International Discrete Fracture Network Engineering Conference. ARMA, 2022. http://dx.doi.org/10.56952/arma-dfne-22-0010.
Анотація:
Abstract The evaluation of fluid flow through fractured media is essential for many applications. In hard rocks, fluid flow depends on fracture aperture and connectivity, as fractures are the preferential flow paths within the rock mass. Previous research studied fluid flow, using Discrete Fracture Networks (DFN) and numerical modelling methods, with fewer lab-scale experiments. Advancements in 3D printing technology allows for generating valuable lab-scale physical models representing fractured media. In this work, a DFN model is built using the DFN software MoFrac and a 3D physical model is generated with a 3D printer. The 3D printed DFN model is fixed in an experimental set-up, which functions as a differential pressure meter by restricting airflow through a transition duct. The objectives of the experiment are to establish the behavior of the changing pressure to fluid flow through fractures. This laboratory experiment is part of an ongoing research project investigating the constructability of a Natural Heat Exchange Engineering Technology system. This system uses natural means to provide economically significant thermal regeneration capacity through a volume of rocks for ventilating mine workings. The major contribution of the lab-scale experiment is to verify whether the secondary permeability of a rockmass can admit sufficient flow.
Звіти організацій з теми "Fractured rock massif":
1
Peter, J. M., and M. G. Gadd. Introduction to the volcanic- and sediment-hosted base-metal ore systems synthesis volume, with a summary of findings. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328015.
Анотація:
This volume presents results of research conducted during phase 5 of the Volcanic- and Sedimentary-hosted Base Metals Ore Systems project of the Geological Survey of Canada's Targeted Geoscience Initiative (TGI) program. The papers in this volume include syntheses and primary scientific reports. We present here a synopsis of the findings during this TGI project. Research activities have addressed several mineral deposit types hosted in sedimentary rocks: polymetallic hyper-enriched black shale, sedimentary exhalative Pb-Zn, carbonate-hosted Pb-Zn (Mississippi Valley-type; MVT), and fracture-controlled replacement Zn-Pb. Other carbonate-hosted deposits studied include a magnesite deposit at Mount Brussilof and a rare-earth element-F-Ba deposit at Rock Canyon Creek, both of which lack base metals but are spatially associated with the MVT deposits in the southern Rocky Mountains. Volcanogenic massive-sulfide deposits hosted in volcanic and mixed volcanic-sedimentary host rock settings were also examined. Through field geology, geochemical (lithogeochemistry, stable and radiogenic isotopes, fluid inclusions, and mineral chemistry), and geophysical (rock properties, magnetotelluric, and seismic) tools, the TGI research contributions have advanced genetic and exploration models for volcanic- and sedimentary-hosted base-metal deposits and developed new laboratory, geophysical, and field techniques to support exploration.
2
Fatehi Marji, Mohammad, Arash Pashapour, and Mohsen Masihi. Effect of fracture dip angle on the aperture and fluid flow under in-situ stresses in deep fractured rock masses. Cogeo@oeaw-giscience, September 2011. http://dx.doi.org/10.5242/iamg.2011.0190.
3
Ahn, Joonhong. Mass transfer and transport of radionuclides in fractured porous rock. Office of Scientific and Technical Information (OSTI), April 1988. http://dx.doi.org/10.2172/7132953.
4
Klavetter, E. A., and R. R. Peters. Estimation of hydrologic properties of an unsaturated, fractured rock mass. Office of Scientific and Technical Information (OSTI), July 1986. http://dx.doi.org/10.2172/59907.
5
Wang, H. F. Poroelasticity of fractured rock masses. Final report, August 1, 1991--October 31, 1997. Office of Scientific and Technical Information (OSTI), February 1998. http://dx.doi.org/10.2172/615657.
6
Bower, Kathleen Marie. A numerical model of hydro-thermo-mechanical coupling in a fractured rock mass. Office of Scientific and Technical Information (OSTI), June 1996. http://dx.doi.org/10.2172/285475.
7
Drozhko, E. G., Yu G. Mokrov, Yu V. Glagolenko, and L. M. Samsonova. Determination of Hydrologic Parameters of Fractured Rock Mass Based on Regional Groundwater Level Data in the Lake Karachai Area. Office of Scientific and Technical Information (OSTI), September 1996. http://dx.doi.org/10.2172/760314.
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Lacerda Silva, P., G. R. Chalmers, A. M. M. Bustin, and R. M. Bustin. Gas geochemistry and the origins of H2S in the Montney Formation. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329794.
Анотація:
The geology of the Montney Formation and the geochemistry of its produced fluids, including nonhydrocarbon gases such as hydrogen sulfide were investigated for both Alberta and BC play areas. Key parameters for understanding a complex petroleum system like the Montney play include changes in thickness, depth of burial, mass balance calculations, timing and magnitudes of paleotemperature exposure, as well as kerogen concentration and types to determine the distribution of hydrocarbon composition, H2S concentrations and CO2 concentrations. Results show that there is first-, second- and third- order variations in the maturation patterns that impact the hydrocarbon composition. Isomer ratio calculations for butane and propane, in combination with excess methane estimation from produced fluids, are powerful tools to highlight effects of migration in the hydrocarbon distribution. The present-day distribution of hydrocarbons is a result of fluid mixing between hydrocarbons generated in-situ with shorter-chained hydrocarbons (i.e., methane) migrated from deeper, more mature areas proximal to the deformation front, along structural elements like the Fort St. John Graben, as well as through areas of lithology with higher permeability. The BC Montney play appears to have hydrocarbon composition that reflects a larger contribution from in-situ generation, while the Montney play in Alberta has a higher proportion of its hydrocarbon volumes from migrated hydrocarbons. Hydrogen sulphide is observed to be laterally discontinuous and found in discrete zones or pockets. The locations of higher concentrations of hydrogen sulphide do not align with the sulphate-rich facies of the Charlie Lake Formation but can be seen to underlie areas of higher sulphate ion concentrations in the formation water. There is some alignment between CO2 and H2S, particularly south of Dawson Creek; however, the cross-plot of CO2 and H2S illustrates some deviation away from any correlation and there must be other processes at play (i.e., decomposition of kerogen or carbonate dissolution). The sources of sulphur in the produced H2S were investigated through isotopic analyses coupled with scanning electron microscopy, energy dispersive spectroscopy, and mineralogy by X-ray diffraction. The Montney Formation in BC can contain small discrete amounts of sulphur in the form of anhydrite as shown by XRD and SEM-EDX results. Sulphur isotopic analyses indicate that the most likely source of sulphur is from Triassic rocks, in particular, the Charlie Lake Formation, due to its close proximity, its high concentration of anhydrite (18-42%), and the evidence that dissolved sulphate ions migrated within the groundwater in fractures and transported anhydrite into the Halfway Formation and into the Montney Formation. The isotopic signature shows the sulphur isotopic ratio of the anhydrite in the Montney Formation is in the same range as the sulphur within the H2S gas and is a lighter ratio than what is found in Devonian anhydrite and H2S gas. This integrated study contributes to a better understanding of the hydrocarbon system for enhancing the efficiency of and optimizing the planning of drilling and production operations. Operators in BC should include mapping of the Charlie Lake evaporites and structural elements, three-dimensional seismic and sulphate ion concentrations in the connate water, when planning wells, in order to reduce the risk of encountering unexpected souring.