Дисертації з теми "Soil and Fractured Rocks"
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1
Felton, David Scott. "Theoretical dissolution coefficient for rock fractures." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/21505.
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2
Depner, Joseph Scott. "Estimation of the three-dimensional anisotropic spatial covariance of log permeability using single-hole and cross-hole packer test data from fractured granites." Thesis, The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_407_sip1_w.pdf&type=application/pdf.
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3
Jarsjö, Jerker. "Hydraulic conductivity relations in soil and fractured rock : fluid component and phase interaction effects /." Stockholm : Tekniska högsk, 1998. http://www.lib.kth.se/abs98/jars0527.pdf.
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4
Blake, Oshaine Omar. "Seismic transport properties of fractured rocks." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569902.
Повний текст джерелаАнотація:
Fracture in rock is a major factor that affects the rock's physical properties and it also provides the route for the passage of fluids that can transport potentially hazardous substances and hydrothermal fluids. Assessment of the degree of fracture in rocks is important as they play an essential role in many geomechanical issues (stability of boreholes, stimulation of oil and geothermal reservoirs, the design of civil structures, tunnels and hazardous waste disposals), and in understanding a number of processes in the Earth's crust such as magmatic intrusions, plate tectonics, fault mechanics and sedimentary basins. The fundamental understanding of how seismic waves are altered when they pass through fractured rock are currently poorly understood, hence a comprehensive study is timely. An improved understanding of how fractures affect the physical properties (such as seismic velocity and attenuation) would significantly enhance our ability to predict the fracture state of rock at depth remotely. The main focus of this thesis is to characterize P and S wave velocity, their ratio, shear wave splitting and attenuation and their dependence on the fracture density of the rock. Laboratory experiments were carried out in uniaxial compressive condition to increase microfracture density and hydrostatic confining condition to close microfractures. Experiments were performed on a single rock type (Westerly granite) to keep the mineralogy, chemical composition, and grain size constant. The condition of the microfractures was dry to remove the complexity of saturation and fluid type. Through transmission technique was used to measure P and S wave velocities and spectral ratio technique was used to measure attenuation. P and S wave velocities were measured at 1.5MHz. Attenuation measurements were made in the frequency range of O.8MHz to 1.7MHz. Elastic properties can be measured statically where strain data are recorded and related to stress during slow loading of a specimen, or dynamically, where the elasticity can be calculated from the velocity of P and S waves. In order to understand the elastic properties of the crust at depth using seismology, the relationship between the static and dynamic properties must be known. Increasing-amplitude, uniaxial cyclic loading experiments were carried out to investigate and quantify the effect of microcracking on the elastic properties, and to establish a relationship between static and dynamic measurements. There is a linear relationship between static and dynamic Young's moduli, and a significant discrepancy between the static and dynamic Poisson's ratio. We attribute the differences in the static and dynamic elastic properties to the size distribution of the crack population relative to the amplitude and frequency of the applied stress, frictional sliding on closed cracks during loading/unloading, and the assumption of isotropic elasticity in the sample. Strong stress-dependency exists in the uniaxial compressive and hydrostatic confining conditions due to closure of microcracks. This resulted in: an increase in the P and S wave velocities, their ratio, static and dynamic Young's modulus, and static and dynamic Poisson's ratio; and a decrease in the P and S wave attenuation. The increase of fracture density caused: a decrease in the P and S wave velocities and static and dynamic Young's modulus; a small increase in the dynamic Poisson's ratio and VpNs; and a large increase in the static Poisson's ratio, and P and S wave attenuation. Seismic wave attenuation is more sensitive than seismic wave velocity to closure of microcracks and Increase of microfracture density. The effect of varying crack density on the P and S wave velocities and elastic properties under confining pressure (depth) were quantified. The elastic wave velocities and Young's modulus of samples that have a greater amount of microcrack damage required higher confining pressure to be equal to those of samples with no induced microcrack damage. We found that fractures are completely closed at ~5km (~130MPa) in crystalline rocks. At shallow depth (less than 5km), fracture density affects seismic wave velocities. We observed an overall 6% and 4% reduction in P and S wave velocities respectively due to an increase in the fracture density. The overall reduction in the P and S wave decreased to 2% and 1 % at ~2km. Consequently, assessing the degree of fracture between 2km and 5km using seismic wave velocities may be difficult
5
Noorian-Bidgoli, Majid. "Strength and deformability of fractured rocks." Doctoral thesis, KTH, Mark- och vattenteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-155719.
Повний текст джерелаАнотація:
This thesis presents a systematic numerical modeling framework to simulate the stress-deformation and coupled stress-deformation-flow processes by performing uniaxial and biaxial compressive tests on fractured rock models with considering the effects of different loading conditions, different loading directions (anisotropy), and coupled hydro-mechanical processes for evaluating strength and deformability behavior of fractured rocks. By using code UDEC of discrete element method (DEM), a series of numerical experiments were conducted on discrete fracture network models (DFN) at an established representative elementary volume (REV), based on realistic geometrical and mechanical data of fracture systems from field mapping at Sellafield, UK. The results were used to estimate the equivalent Young’s modulus and Poisson’s ratio and to fit the Mohr-Coulomb and Hoek-Brown failure criteria, represented by equivalent material properties defining these two criteria. The results demonstrate that strength and deformation parameters of fractured rocks are dependent on confining pressures, loading directions, water pressure, and mechanical and hydraulic boundary conditions. Fractured rocks behave nonlinearly, represented by their elasto-plastic behavior with a strain hardening trend. Fluid flow analysis in fractured rocks under hydro-mechanical loading conditions show an important impact of water pressure on the strength and deformability parameters of fractured rocks, due to the effective stress phenomenon, but the values of stress and strength reduction may or may not equal to the magnitude of water pressure, due to the influence of fracture system complexity. Stochastic analysis indicates that the strength and deformation properties of fractured rocks have ranges of values instead of fixed values, hence such analyses should be considered especially in cases where there is significant scatter in the rock and fracture parameters. These scientific achievements can improve our understanding of fractured rocks’ hydro-mechanical behavior and are useful for the design of large-scale in-situ experiments with large volumes of fractured rocks, considering coupled stress-deformation-flow processes in engineering practice.QC 20141111
6
Dong, Chengli. "Acidizing of naturally-fractured carbonate formations." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3031042.
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Zhao, Zhihong. "Stress Effects on Solute Transport in Fractured rocks." Doctoral thesis, KTH, Teknisk geologi och geofysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-42361.
Повний текст джерелаАнотація:
The effect of in-situ or redistributed stress on solute transport in fractured rocks is one of the major concerns for many subsurface engineering problems. However, it remains poorly understood due to the difficulties in experiments and numerical modeling. The main aim of this thesis is to systematically investigate the influences of stress on solute transport in fractured rocks, at scales of single fractures and fracture networks, respectively. For a single fracture embedded in a porous rock matrix, a closed-form solution was derived for modeling the coupled stress-flow-transport processes without considering damage on the fracture surfaces. Afterwards, a retardation coefficient model was developed to consider the influences of damage of the fracture surfaces during shear processes on the solute sorption. Integrated with particle mechanics models, a numerical procedure was proposed to investigate the effects of gouge generation and microcrack development in the damaged zones of fracture on the solute retardation in single fractures. The results show that fracture aperture changes have a significant influence on the solute concentration distribution and residence time. Under compression, the decreasing matrix porosity can slightly increase the solute concentration. The shear process can increase the solute retardation coefficient by offering more sorption surfaces in the fracture due to gouge generation, microcracking and gouge crushing. To study the stress effects on solute transport in fracture systems, a hybrid approach combing the discrete element method for stress-flow simulations and a particle tracking algorithm for solute transport was developed for two-dimensional irregular discrete fracture network models. Advection, hydrodynamic dispersion and matrix diffusion in single fractures were considered. The particle migration paths were tracked first by following the flowing fluid (advection), and then the hydrodynamic dispersion and matrix diffusion were considered using statistic methods. The numerical results show an important impact of stress on the solute transport, by changing the solute residence time, distribution and travel paths. The equivalent dispersion coefficient is scale dependent in an asymptotic or exponential form without stress applied or under isotropic compression conditions. Matrix diffusion plays a dominant role in solute transport when the hydraulic gradient is small. Outstanding issues and main scientific achievements are also discussed.QC 20111011
8
Bennett, Richard Antony. "Impact fragmentation of boulders confined in soil." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323184.
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Khoshboresh, Amir Rahim. "A study on deformation of tunnels excavated in fractured rocks." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/29831/29831.pdf.
Повний текст джерелаАнотація:
La déformation due au fluage d'un massif rocheux autour d'un tunnel a été rencontrée fréquemment. Ce phénomène est évident où il y a des tunnels creusés dans la roche tendre, des masses rocheuses faible et fortement cisaillées, ou des massifs rocheux soumis à des contraintes in-situ élevées. La déformation due au fluage se produit fréquemment au moment d’excavation des tunnels longs où il y a des failles et des zones fracturées et cisaillées. Ce phénomène peut causer différents dommages sur des systèmes de soutènement en raison de la déformation excessive et des effondrements. La déformation excessive impose une ré-excavation de la section du tunnel, qui monte le coût supplémentaire, la durée de la réalisation du projet et le risque de la sécurité sur le projet. En plus, comme la stabilité de terrain est dans un état critique durant la ré-excavation, une petite négligence peut conduire à une grande caverne. Bien que la déformation de fluage est commune dans un massif rocheux à une faible résistance dans un tunnel très profond, mais ce phénomène a été observé dans des tunnels peu profonds.
Une bonne compréhension des déformations causées par une excavation souterraine requiert la connaissance de l'interaction roche-support et l'interprétation des données de terrain. Auparavant, l’objet principal de la surveillance effectuée durant la construction du tunnel était des mesures de la pression au terrain imposé sur le revêtement du tunnel. Mais aujourd’hui, les méthodes modernes de construction de tunnel se concentrent sur la surveillance des déplacements pendant et après la construction.
Afin de déterminer des déformations dans les tunnels, Panet et Sulem ont supposé que "Le tunnel a une section transversale circulaire et le milieu est homogène et isotrope, aussi le tunnel est suffisamment profond pour considérer que la distribution des contraintes est homogène". Mais dans le cas quasi réel, la distribution de la contrainte autour du tunnel est hétérogène et anisotrope. Dans cette étude, pour la modification des équations Panet et Sulem, certaines équations sont proposées en cas de matériau hétérogène et anisotrope pour généraliser le problème.
La galerie de force motrice Seymareh a été considérée comme l’étude de cas. Celle-ci est une partie du conduit d’eau dans le projet de centrale électrique du barrage Seymareh. Ce projet est situé à l'ouest de l'Iran. Les données de surveillance de la galerie de force motrice sont collectées au moment de l’excavation du tunnel, et sont comparées avec les résultats de la modélisation numérique et de la solution analytique. Cette comparaison montre que les résultats des données expérimentales obtenues par la surveillance sont très proches des résultats de la solution analytique, mais il y a une différence entre les deux et la modélisation numérique. Il était prévisible, car l’effet d’autres activités comme l’excavation des tunnels verticaux n’est pas prise en compte dans l’analyse numérique et aussi dans la solution analytique. Il est évident que les autres activités comme l’excavation des tunnels verticaux et l'excavation du tunnel principal vers deux directions opposées, peuvent affecter sur les résultats de la surveillance. D'autre part, les données initiales utilisées dans l'analyse numérique et la solution analytique ne sont pas tout à fait exactes, car elles sont obtenues en tant que représentatives du massif rocheux de la région, mais pas pour une section particulière. Toutefois, le but de cette étude est le développement d'une solution analytique de la déformation dans les tunnels sur les conditions générales et la poursuite de cette étude pourra être plus développée.The creep deformation of a rock mass around a tunnel has been encountered frequently. It is particularly common in tunnels excavated in soft rock, heavily sheared weak rock masses or rock masses subjected to high in-situ stresses. Creep deformation in fault and shear fractured zones are one of the frequently encountered difficulties in long tunnel construction, which tend to cause failure of supporting systems due to excessive deformation and cavern. Excessive deformation would necessitate re-mining of the tunnel cross section, thus imposing impacts such as extra cost, extended time schedule and safety risk on the project. Furthermore, as the ground stability is in critical condition during re-mining, the slightest negligence would lead to major cavern. Although creep deformation is common to extremely poor rock mass under high overburden in a tunnel alignment, but however this phenomenon is not limited to tunnels with high overburden. A good understanding of the deformations caused by an underground excavation requires simultaneously knowledge of the rock-support interaction and interpretation of field data. Formerly, the main purpose of the monitoring carried out during tunnel construction was to measure the ground pressures acting on the tunnel lining. Modern tunneling practice emphasizes the monitoring of the displacements occurring during and after the construction. Panet and Sulem for determining of deformations in tunnels have assumed that "The tunnel has a circular cross section and around the tunnel, the rock is homogeneous and isotropic and also the tunnel is deep enough to consider that the stress distribution is homogenous". But in almost real cases, the stresses distribution around the tunnel is not homogeneous and isotropic. In this study, for modification of the Panet and Sulem equations, some equations are proposed in case of nonhomogeneous and anisotropic for generalizing of the problem. Seymareh power tunnel which is considered as a case study is a part of the powerhouse waterways system of the Seymareh dam and hydroelectric power plant project. The project is located in west of Iran. The monitoring data of power tunnel which are collected during excavation of tunnel is compared with the results of numerical modelling and analytical solution results as well as. The results obtained from comparison show although the field data, which are collected through the monitoring, are very close to the analytical solution results (approximately), but there is a significant difference between both of them and numerical modelling results. It was predictable; because the influence of the other activities such as excavation of shaft and surge tank in the numerical analysis and also analytical solution are not considered. It is obvious that other activities such as excavation of shaft and surge tank and also excavation of mean tunnel from other direction which were under operation at the same time can effect on the results of monitoring. On the other hand, the initial data which are used in numerical analysis and analytical solution are not quite accurate; because they are extracted as a representative of the rock mass of region, not for a particular section. However the goal of this study is development of analytical solution of deformation in tunnels on general conditions and pursuit of the study could be leaded to more development in this field.
10
Hyun, Yunjung. "Multiscale anaylses of permeability in porous and fractured media." Diss., The University of Arizona, 2002. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2002_321_sip1_w.pdf&type=application/pdf.
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11
Schaffer, Andrew 1952. "PERMEABILITY TESTING AND GROUTING OF FRACTURED ROCK." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275420.
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12
Amalokwu, Kelvin J. "Saturation effects on frequency-dependent seismic anisotropy in fractured porous rocks." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/391107/.
Повний текст джерелаАнотація:
The response of Earth materials to seismic wave propagation is the most commonly used geophysical method for studying the Earth’s crust. Rocks making up the Earth’s crust are porous, with fluids occupying the pore space. The saturation of the pore space can be multiphase, for example, in gas reservoirs and gas bearing oil reservoirs where gas and liquid occupy the pore space. Additional voids such as aligned fractures are common in the Earth’s crust and are known to cause seismic anisotropy. Knowledge of the effects of pore fluids and of aligned fractures on seismic wave propagation is needed for the interpretation of seismic data in terms of these physical properties. This information is particularly useful for the hydrocarbon industry as the presence of either natural or artificially induced fractures can play a major role in the safe and efficient exploration and production of hydrocarbons. Therefore, it is important to be able to remotely characterise fractures in fluid-filled reservoir rocks. Theoretical models are used to relate seismic measurements to the physical properties of rocks such as porosity, saturation, and fracture properties. Previous studies have either focused on multiphase saturation effects in non-fractured isotropic rocks or on single fluid phase saturation effects in fractured anisotropic rocks. Therefore, the combined effect of multiphase saturation and aligned fractures is still poorly understood. This thesis focuses on improving the understanding of the effect of saturation on fracture-induced seismic anisotropy.
13
Tillotson, Philip Robert. "A laboratory investigation of frequency-dependent seismic anisotropy in fractured rocks." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/412144/.
Повний текст джерелаАнотація:
Equivalent medium theories can be used to interpret seismic anisotropy in field seismic data to infer the properties of subsurface fractures. These theories analyse the seismic response of the rock in the long wavelength limit and relate the degree of anisotropy measured to the fracture properties. They have particular use in the hydrocarbon industry where extraction can be determined by both naturally and induced fractures. Validation is required to use these theories with more confidence in the commercial setting. One method for validation is through controlled laboratory seismic experiments. For the idealised fracture distributions found in these equivalent medium theories the laboratory experiments require rocks that can be built with a controlled fracture geometry. I present ultrasonic laboratory data from three different experiments of synthetic porous rocks containing controlled fracture geometries. I then analyse the data using suitable theory where possible. Despite the ultrasonic experiments violating equivalent medium criteria strong relationships between data and theory were found. The relationship between shear-wave splitting and fracture density was found to be highly robust. The dependence of shear-wave splitting on fluid saturation at 45° to the fracture normal was quantified for variations of fluid viscosity and bulk modulus and has direct implications for oil/water discrimination in fractured reservoirs. Based on a single fitting parameter from the water saturated data it was possible to accurately predict Thomsen’s anisotropy parameters, e and d for air and glycerin saturation. Predictions of g are independent of fluid saturation and model fitting and show strong agreement with the laboratory data.
14
Wang, Mingyu. "Discrete fracture fluid flow modeling and field applications in fractured rocks." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284182.
Повний текст джерелаАнотація:
Fluid flow modeling in fractured rocks is a complicated and important research and application topic in many fields such as geological, hydrogeological, environmental and petroleum engineering. Commonly used methods based on equivalent continuum assumption for fluid flow modeling can generally be applied directly to the porous geological media, but have limited applicability when the geological medium is dominated by fractures. It often happens that only limited time, cost, hydrogeological data and computer resources are available in solving a practical problem of the fluid flow modeling in fractured rocks. Therefore, it is a challenge, but necessary, to investigate the hydraulic behaviors and propose new approaches, procedures, and methodologies to build a reliable fluid flow model for fractured rocks with limited available related data. The general concepts on fluid flow modeling in fractured rocks are introduced firstly and the different ways to treat major and minor fractures in 2-D and 3-D discrete fracture fluid flow modeling are propounded. The author has investigated the relations between the hydraulic behaviors and fracture geometry parameters and found out the effect of fracture parameters on the Representative Elementary Volume (REV) for the fracture systems with statistically distributed fracture geometry parameters including the size, orientation and location. Further, a systemic procedure for fluid flow modeling in fractured rocks in two-dimensional domain is suggested and demonstrated through a 2-D case study for groundwater resources evaluation. Six 3-D conceptual linear pipe discrete fracture fluid flow models which focus on the utilization of fracture information are proposed to simulate packer or pumping tests conducted in fractured rock masses. These models can reflect channel flow in fractures, simplify and minimize the complexity of fluid flow in fractures, save computer resources and increase the possibility to solve a field problem at large scales, and implement a discrete fracture fluid flow model easily. Finally, the author has developed a practicable systemic approach to determine the REV for hydraulic properties and then the hydraulic conductivity tensor for the REV in fractured rocks using single well packer test results. These procedures are illustrated through a 3-D case study by implementing the proposed fluid flow models.
15
Sidborn, Magnus. "Modelling long-term redox processes and oxygen scavenging in fractured crystalline rocks." Doctoral thesis, Stockholm : Kemiteknik, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4491.
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Woloshun, Colleen Loeven 1953. "Temperature as an indicator of flow in fractured rocks near Oracle, Arizona." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/192014.
Повний текст джерелаАнотація:
Knowledge of flow patterns in fractured rocks is important in understanding hydrology and contaminant transport. Methods of locating flow zones based on geophysical measurements are unreliable because of a lack of correlation between fracture density and hydraulic conductivity. In this work, analysis of data from natural temperature profiles, longterm heating tests, and three-hole recirculation thermal tracer experiments in saturated fractured granite indicates that temperature measurements can be used to identify local flow paths and flow directions in fractured systems. However, adequate controls on background noise and sufficient supplementary information must be incorporated into the testing procedure. Although thermal tracer tests at the Oracle site were inconclusive due to insufficient heat input, the use of heat as a tracer to define larger-scale flow patterns is found to be potentially useful in situations where ample supplies of warmer or cooler water are available.
17
Li, Wei Ph D. Massachusetts Institute of Technology Department of Civil and Environmental Engineering. "Numerical and analytical modeling of heat transfer between fluid and fractured rocks." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90059.
Повний текст джерелаАнотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 111-114).
Modeling of heat transfer between fluid and fractured rocks is of particular importance for energy extraction analysis in EGS, and therefore represents a critical component of EGS design and performance evaluation. In conventional fracture dominated geothermal systems with reinjection, this modeling process is also helpful for understanding how the thermal front migrates and for optimizing of reservoir management strategies. Both numerical and analytical approaches are used to help us get a better understanding of the heat transfer process between the fluid and the fractured rocks in a geothermal reservoir. In the numerical approach, a stochastic discrete fracture network model, GEOFRAC, is used to generate a fracture network. GEOFRAC-FLOW, is used to calculate the flow path in the fracture network and flow rate in each fracture. On the basis of the two, a heat transfer model, GEOFRAC-THERMAL, is developed. Parametric studies with the three models are conducted to analyze the sensitivity of the parameters. A case study with the three models on the Fenton Hill project is conducted to demonstrate the capability of the three models in modeling the heat and mass transfer in the geothermal reservoir. In the analytical approach, a conceptual geothermal reservoir model is introduced. The heat transfer process in the fluid and the fractured rock is formulated based on energy conservation. With the assumption of uniform rock temperature, the 0-D solution is obtained. Parametric studies and case study on the Fenton Hill project are conducted with the 0-D solution. With the assumption of heat conduction happening only in the transverse direction of the rock, the 1-D solution is obtained. Parametric studies are conducted with the 1 -D solution and useful conclusions are obtained. A simply configured heat transfer problem is used to compare the results of the finite element analysis and the 1-D solution. The effect of the simplification in the 1 -D solution is analyzed based on the comparison.
by Wei Li.
S.M.
18
DeCesar, Richard T. "Natural gradient tracer tests in a highly fractured soil /." Full text open access at:, 1987. http://content.ohsu.edu/u?/etd,143.
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Fauziah, Miftahul. "Behaviour of stiff clayey soils using fracture mechanics approach." Thesis, Curtin University, 2009. http://hdl.handle.net/20.500.11937/964.
Повний текст джерелаАнотація:
Most of the conventional elastic plastic models of soils are based on continuum mechanics, however, for stiff, hard soils and soft rocks discontinuities develop under load, and since the models assume continuity, they would cease to apply. These discontinuities had not been accounted for in the continuum-based elastic plastic models. On the other hand, fracture mechanical theory may be used to advantage to replicate their behaviour. The behaviour of soil commonly is interpreted from conventional triaxial apparatus, whereas, testing of soil using the plane strain device would be more useful information, as more geotechnical field problems are basically occur in these situations.The present study has dealt with the investigation on the behaviour of saturated over consolidated clay as well as partially saturated clay, which represent the stiff and hard brittle clay by the use of a new biaxial device modified from conventional triaxial apparatus. In general, the apparatus was able to produce data which are in a good accordance with known soil behaviour of stiff clay. Shear band localization occurred in all test specimens of over consolidated clay. Specimen initiated to be discontinuous upon reaching the peak stresses. It is evident that specimen of partially saturated containing fissures had weaker shear strength as well as compressive strength.From point of view of the discontinuities that take places in the stiff clay, a model based on the unified model (Lo et al, 1996) and the elasto-plastic shear fracture model (Lo, et al, 2005) was used in this study. The problem may be dealth with one of brittle fracture of a three-phase specimen, where the matric suction is disrupted by tensile or shear loading. As a result the fracture toughness of the specimen would vary according to matric suction changes. A problem of plane strain compression testing was carried out to implement the model. The crack propagation simulation was resulted the same pattern with the experimental results on partially saturated kaolin clay.
20
Lang, Philipp. "Multi-scale modelling of coupled thermo-hydro-mechanical-chemical processes in fractured rocks." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/45644.
Повний текст джерелаАнотація:
A first-principle modelling framework for thermo-hydro-mechanical-chemical processes in fractured rock is developed. The key characteristics of such rocks are incorporated by direct representation: the power law nature of fracture size distribution, the fractal nature of rock surfaces, the scale dependence of discrete contact between these, and the mechanically induced fluid-flow anisotropy. It is shown that hydro-mechanical modelling in fractured rock can be reduced to a single free parameter, the friction coefficient. Properties of fractured rock, such as transmissivity, stiffness and permeability, emerge as direct results of physical processes, and need not be complemented by empirical relationships or distribution functions. Results reproduce the field observation that critically-oriented fractures are likely hydraulic conduits; while the established reasoning of shear activation and associated fracture dilation for this fact is confirmed, it is also shown, for the first time, that chemically-mediated processes have the potential to contribute to this effect. Compaction mechanisms of pressure solution and precipitation act preferably on fractures with stress ratios far from Coulomb failure, which increases the relative contribution of near-critical fractures. New insights also emerge as to the likely orientation of the maximum permeability of a fractured rock mass. Due to shear-induced anisotropy of fracture transmissivity, the preferential flow direction tends to be aligned with the orientation of the intermediate stress. The capability to accurately determine the upscaled permeability tensor is facilitated by a novel algorithm that is independent of geometry and reference system, and accounts for locally anisotropic matrix permeability and fracture transmissivity. The developed framework presents a path forward in fractured rock modelling. It accounts for state of the art knowledge of the internal processes of fractured rock across multiple scales, and perhaps aids to overcome the necessity for using isotropic effective properties that is prevalent in many applications.
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Tsoflias, Georgios Padelis. "Hydrogeologic characterization of fractured carbonate aquifers employing ground-penetrating radar /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Watanabe, Norihiro. "Finite element method for coupled thermo-hydro-mechanical processes in discretely fractured and non-fractured porous media." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-104411.
Повний текст джерелаАнотація:
Numerical analysis of multi-field problems in porous and fractured media is an important subject for various geotechnical engineering tasks such as the management of geo-resources (e.g. engineering of geothermal, oil and gas reservoirs) as well as waste management. For practical usage, e.g. for geothermal, simulation tools are required which take into account both coupled thermo-hydro-mechanical (THM) processes and the uncertainty of geological data, i.e. the model parametrization. For modeling fractured rocks, equivalent porous medium or multiple continuum model approaches are often only the way currently due to difficulty to handle geomechanical discontinuities. However, they are not applicable for prediction of flow and transport in subsurface systems where a few fractures dominates the system behavior. Thus modeling coupled problems in discretely fractured porous media is desirable for more precise analysis.
The subject of this work is developing a framework of the finite element method (FEM) for modeling coupled THM problems in discretely fractured and non-fractured porous media including thermal water flow, advective-diffusive heat transport, and thermoporoelasticity. Pre-existing fractures are considered. Systems of discretely fractured porous media can be considered as a problem of interacted multiple domains, i.e. porous medium domain and discrete fracture domain, for hydraulic and transport processes, and a discontinuous problem for mechanical processes. The FEM is required to take into account both kinds of the problems. In addition, this work includes developing a methodology for the data uncertainty using the FEM model and investigating the uncertainty impacts on evaluating coupled THM processes. All the necessary code developments in this work has been carried out with a scientific open source project OpenGeoSys (OGS).
In this work, fluid flow and heat transport problems in interactive multiple domains are solved assuming continuity of filed variables (pressure and temperature) over the two domains. The assumption is reasonable if there are no infill materials in fractures. The method has been successfully applied for several numerical examples, e.g. modeling three-dimensional coupled flow and heat transport processes in discretely fractured porous media at the Gross Schoenebck geothermal site (Germany), and three-dimensional coupled THM processes in porous media at the Urach Spa geothermal site (Germany).
To solve the mechanically discontinuous problems, lower-dimensional interface elements (LIEs) with local enrichments have been developed for coupled problems in a domain including pre-existing fractures. The method permits the possibility of using existing flow simulators and having an identical mesh for both processes. It enables us to formulate the coupled problems in monolithic scheme for robust computation. Moreover, it gives an advantage in practice that one can use existing standard FEM codes for groundwater flow and easily make a coupling computation between mechanical and hydraulic processes. Example of a 2D fluid injection problem into a single fracture demonstrated that the proposed method can produce results in strong agreement with semi-analytical solutions.
An uncertainty analysis of THM coupled processes has been studied for a typical geothermal reservoir in crystalline rock based on the Monte-Carlo method. Fracture and matrix are treated conceptually as an equivalent porous medium, and the model is applied to available data from the Urach Spa and Falkenberg sites (Germany). Reservoir parameters are considered as spatially random variables and their realizations are generated using conditional Gaussian simulation. Two reservoir modes (undisturbed and stimulated) are considered to construct a stochastic model for permeability distribution. We found that the most significant factors in the analysis are permeability and heat capacity. The study demonstrates the importance of taking parameter uncertainties into account for geothermal reservoir evaluation in order to assess the viability of numerical modeling.
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Gentry, William Miles. "Evaluation of Spring Discharge for Characterization of Groundwater Flow in Fractured Rock Aquifers: A Case Study from the Blue Ridge Province, VA." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/30965.
Повний текст джерелаАнотація:
Recent models of groundwater flow in the Blue Ridge Province suggest multiple aquifers and flow paths may be responsible for springs and seeps appearing throughout the region. Deep confined aquifers and shallow variably confined aquifers may contribute water to spring outlets, resulting in vastly different water quality and suitability for potable water supplies and stock watering. A new Low Flow Recording System (LoFRS) was developed to measure the discharge of these springs that are so ubiquitous throughout the Blue Ridge Province.
Analysis of spring discharge, combined with electrical resistivity surveying, aquifer tests, and water chemistry data reveal mixed shallow and deep aquifer sources for some springs, while other springs and artesian wells are sourced only in the deep aquifer. The technique is suitable for rapid characterization of flow paths leading to spring outlets. Rapid characterization is important for evaluation of potential water quality problems arising from contamination of shallow and deep aquifers, and for evaluation of water resource susceptibility to drought. The spring discharge technique is also suitable for use in other locations where fractured rock and crystalline rock aquifers are common.Master of Science
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Mahmoudzadeh, Batoul. "Solute transport through fractured rocks : the influence of geological heterogeneities and stagnant water zones." Doctoral thesis, KTH, Kemisk apparatteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183592.
Повний текст джерелаАнотація:
To describe reactive solute transport and retardation through fractured rocks, three models are developed in the study with different focuses on the physical processes involved and different simplifications of the basic building block of the heterogeneous rock domain. The first model evaluates the effects of the heterogeneity of the rock matrix and the stagnant water zones in part of the fracture plane. The second and the third models are dedicated to different simplifications of the flow channels. Both account for radioactive decay chain, but consider either a rectangular channel with linear matrix diffusion or a cylindrical channel with radial matrix diffusion. Not only an arbitrary-length decay chain, but also as many rock matrix layers with different geological properties as observed in the field experiments can be handled. The analytical solutions thus obtained from these three models for the Laplace-transformed concentration in the flow channel can all be conveniently transformed back to the time domain by use of e.g. de Hoog algorithm. This allows one to readily include the results into a fracture network model or a channel network model to predict nuclide transport through flow channels in heterogeneous fractured media consisting of an arbitrary number of rock units with piecewise constant properties. The relative impacts and contributions of different processes in retarding solute transport in fractured rocks can easily be evaluated by simulating several cases of varying complexity. Additionally, a model is developed to study the evolution of fracture aperture in crystalline rocks mediated by pressure dissolution and precipitation. It accounts for not only advective flow that can carry in or away dissolved minerals but also the fact that dissolved minerals in the fracture plane, in both the flow channel and the stagnant water zone, can diffuse into the adjacent porous rocks. The analytical solution obtained in the Laplace space is then used to evaluate the evolution of the fracture aperture under combined influence of stress and flow, in a pseudo-steady-state procedure. The simulation results give insights into the most important processes and mechanisms that dominate the fracture closure or opening under different circumstances.QC 20160318
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Mahmoudzadeh, Batoul. "Modeling Solute Transport in Fractured Rocks-Role of Heterogeneity, Stagnant Water Zone and Decay Chain." Licentiate thesis, KTH, Kemisk apparatteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141778.
Повний текст джерелаАнотація:
A model is developed to describe solute transport and retention in fractured rocks. It accounts for the fact that solutes not only can diffuse directly from the flowing channel into the adjacent rock matrix composed of different geological layers but can also at first diffuse into the stagnant water zone occupied in part of the fracture and then from there into the rock matrix adjacent to it. Moreover, the effect of radioactive decay-chain has also been studied in the presence of matrix comprising different geological layers. In spite of the complexities of the system, the analytical solution obtained for the Laplace-transformed concentration at the outlet of the flowing channel can conveniently be transformed back to the time domainby use of e.g. De Hoog algorithm. This allows one to readily include it into a fracture network modelorachannelnetwork model to predictnuclide transport through channels in heterogeneous fracturedmedia consisting of an arbitrary number of rock units withpiecewise constant properties. Simulations made in this study indicate that, in addition to the intact wall rock adjacent to the flowing channel, the stagnant water zone and the rock matrix adjacent to it may also lead to a considerable retardation of solute in cases with a narrow channel. The results further suggest that it is necessary to account for decay-chain and also rock matrix comprising at least two different geological layers in safety and performance assessment of the repositories for spent nuclear fuel. The altered zone may cause a great decrease of the nuclide concentration at the outlet of the flowing channel. The radionuclide decay, when accounted for, will drastically decrease the concentration of nuclides, while neglecting radioactive ingrowth would underestimate the concentration of daughter nuclides.QC 20140224
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Zhang, Xiaoxian. "Simulating water flow in variably saturated soils containing fractures and soil pipes." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285396.
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Wong, Kan-hok Ken. "Review of Menard pressuremeter test in weak rocks." Click to view the E-thesis via HKUTO, 2003. http://sunzi.lib.hku.hk/hkuto/record/B4257724X.
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Wong, Kan-hok Ken, and 王勤學. "Review of Menard pressuremeter test in weak rocks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B4257724X.
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Teimoori, Sangani Ahmad Petroleum Engineering Faculty of Engineering UNSW. "Calculation of the effective permeability and simulation of fluid flow in naturally fractured reservoirs." Awarded by:University of New South Wales. School of Petroleum Engineering, 2005. http://handle.unsw.edu.au/1959.4/22408.
Повний текст джерелаАнотація:
This thesis is aimed to calculate the effective permeability tensor and to simulate the fluid flow in naturally fractured reservoirs. This requires an understanding of the mechanisms of fluid flow in naturally fractured reservoirs and the detailed properties of individual fractures and matrix porous media. This study has been carried out to address the issues and difficulties faced by previous methods; to establish possible answers to minimise the difficulties; and hence, to improve the efficiency of reservoir simulation through the use of properties of individual fractures. The methodology used in this study combines several mathematical and numerical techniques like the boundary element method, periodic boundary conditions, and the control volume mixed finite element method. This study has contributed to knowledge in the calculation of the effective permeability and simulation of fluid flow in naturally fractured reservoirs through the development of two algorithms. The first algorithm calculates the effective permeability tensor by use of properties of arbitrary oriented fractures (location, size and orientation). It includes all multi-scaled fractures and considers the appropriate method of analysis for each type of fracture (short, medium and long). In this study a characterisation module which provides the detail information for individual fractures is incorporated. The effective permeability algorithm accounts for fluid flows in the matrix, between the matrix and the fracture and disconnected fractures on effective permeability. It also accounts for the properties of individual fractures in calculation of the effective permeability tensor. The second algorithm simulates flow of single-phase fluid in naturally fractured reservoirs by use of the effective permeability tensor. This algorithm takes full advantage of the control volume discretisation technique and the mixed finite element method in calculation of pressure and fluid flow velocity in each grid block. It accounts for the continuity of flux between the neighbouring blocks and has the advantage of calculation of fluid velocity and pressure, directly from a system of first order equations (Darcy???s law and conservation of mass???s law). The application of the effective permeability tensor in the second algorithm allows us the simulation of fluid flow in naturally fractured reservoirs with large number of multi-scale fractures. The fluid pressure and velocity distributions obtained from this study are important and can considered for further studies in hydraulic fracturing and production optimization of NFRs.
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Brenne, Sebastian [Verfasser], Michael [Gutachter] Alber, and Jörg [Gutachter] Renner. "Hydraulic fracturing and flow experiments on anisotropic and pre-fractured rocks / Sebastian Brenne. Gutachter: Michael Alber ; Jörg Renner." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1109051220/34.
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Deeds, Neil Edward. "Development and evaluation of partitioning interwell tracer test technology for detection of non-aqueous phase liquids in fractured media /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Stander, McLachlan Du Toit. "An investigation into the influence of soil pattern on preferential flow and groundwater recharge in fractured bedrock and cover sand aquifers." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18089.
Повний текст джерелаАнотація:
Thesis (MScAgric)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Increased pressure on groundwater sources due to increased population size and threats of climate change is driving research to better understand the process of aquifer recharge. Soil pattern is of interest as it serves to partition rainwater into different flowpaths destined for surface runoff, evapotranspiration and deep percolation. The challenges inherent to studying these flowpaths are almost universal as uncertainties concerning spatial and temporal heterogeneity in catchments make the upscaling of models complex. This research addresses these challenges as it aims to improve the catchment scale hydrological models of two aquifer systems: One a fractured bedrock system at the Kogelberg Nature Reserve, Kleinmond, and the other a cover sand system in Riverlands Nature Reserve, Malmesbury. This study focussed on strengthening the link between what is known about a given soil form and the hydrological assumptions that can be drawn from that classification, and formulating the results so that they may ultimately be used to calibrate the recharge prediction models for the respective catchments. The research was done in two parts: The first phase was to conduct soil surveys in both reserves during which soils were classified according to South African Soil Classification. Samples were collected at representative observation points which provided textural data for use in pedotransfer functions (PTFs). These PTFs were used to estimate plant available water (PAW) and hydraulic conductivity (K) for the observed profiles. Infiltration experiments were subsequently done to investigate the infiltration patterns of distinctly different soil forms at two sites from each reserve. The experiments included double ring and mini disc infiltration, volumetric water content determination and flow path visualisation using a staining dye. A statistical comparison between the hydrological properties (K and PAW) of the different soil forms suggest that hydraulic properties differed between the deep sandy soil forms (Fernwood, Pinegrove and Witfontein in Kogelberg and Witfontein, Concordia and Lamotte in Riverlands) and the shallow rocky soil forms (Cartref and Glenrosa in Kogelberg). Thus grouping of hydrological similar units (HSUs) could be done on the basis of the soil forms present within the given catchments. The infiltration study showed that shallow, rocky soils that grade into bedrock would have infiltration rates far greater than those estimated using PTFs in Kogelberg. This is due to the prevalence of continuous preferential flow (PF) of water between coarse fragments in these profiles. Recharge estimates would thus be inaccurate in such soils and calibration using locally derived data is recommended. On the contrary, PTFs produced accurate infiltration estimates relative to measured infiltration rates in deep sandy soils in Kogelberg and Riverlands. The Lamotte soil form is an example of such a soil form. It should however be noted that an increase in PF in these soils had subsequently higher K values than estimated, thus illustrating the link between PF and accelerated infiltration rates. These results confirm that using soil survey information, in the form of a soil map, and calibrated hydrological properties, one can delineate HSUs that encompass a large degree of heterogeneity in a given catchment.
AFRIKAANSE OPSOMMING: Verhoogde druk op grondwaterhulpbronne weens die groeiende bevolking en klimaatsverandering dryf tans navorsing om akwifeer hervulling beter te verstaan. Die grondlaag is van belang sienend dat dit reënwater verdeel in oppervlak afloop, evapotranspirasie en diep dreinering. Die uitdagings in hidrologiese navorsing is universeel as gevolg van onsekerhede oor ruimtelike en tydelike variasie wat lei tot komplekse grondwatermodelle. Diè navorsing mik om die tekortkominge in akwifeer hervulling aan te vul deur groundwatermodelle van twee akwifeersisteme te verbeter: Die een is 'n gebroke rots sisteem in die Kogelberg Natuur Reservaat, Kleinmond, en die ander is 'n sand-bedekde sisteem in Riverlands Natuur Reservaat, Malmesbury. Die navorsing streef om die verhouding tussen 'n spesifieke grondvorm en sy hidroliese vloeipaaie te bestudeer en om die gevolgtrekkings so te formuleer dat dit kan gebruik word om die onderskeie grondwatermodelle te kalibreer. Die eerste fase van die navorsing was om 'n grondopname van die onderskeie reservate te doen waartydens die gronde geklassifiseer was volgens die Suid Afrikaanse Grondklassifikasie Sisteem. Grondmonsters is by verteenwoordigende observasiepunte geneem en geanaliseer om tekstuurdata vir pedo-oordraagbare-funksies (PTFs) te kry. Die PTFs was gebruik om plant beskikbare water (PBW) en hidrouliese geleiding (K) te voorspel vir die verskeie observasiepunte. Infiltrasie eksperimente was daarna gedoen om die infiltrasie patroon van twee verskillende grondvorms van elke reservaat te bestudeer. Die eksperimente sluit dubbel- en minidisk-infiltrasie, volumetriese waterinhoud bepaling en vloeipad visualisering met die gebruik van 'n kleurstof in. Die statistiese vergelyking van die hidrouliese eienskappe (K en PBW) en grondvorm dui aan dat die hidrouliese eienskappe verskil tussen die diep, grondvorms met 'n oorwegende sand tekstuur (Fernwood, Pinegrove en Witfontein in Kogelberg en Witfontein, Concordia en Lamotte in Riverlands) en die vlakker, klipperige grondvorms (Cartref en Glenrosa in Kogelberg). Groepering van hidrologies soortgelyke eenhede (HSE's) kan dus op die basis van die teenwoordige grondvorms in 'n opvangsgebied gedoen word. Die infiltrasie studie het bewys dat vlak, klipperige gronde wat tot die rotsbodem gradueer 'n baie hoër infiltratsie tempo sal hê as die PTF voorspelde waardes. Dit is as gevolg van die voorkoms van aaneenlopende voorkeurvloei (VV) van water tussen die growwe materiaal in die profiele, veral die gebroke rots ondergorond. Voorspellings van akwifeer hervulling sal dus onakkuraat wees en kalibrasie met plaaslike data word dus aanbeveel. In teendeel met die begenoemde, het die PTFs akkurate voorspellings gemaak relatief tot die gemete infiltrasie tempo's in die diep sanderige grondvorms in Kogelberg en Riverlands. Dit was duidelik met metings dat 'n toename in aaneenlopende VV hoër gemete K waardes getoon as die voorspelde waardes. Die verband tussen VV en verhoogde infiltrasie tempo word dus hiermee geillustreer. Die resultate bevestig dus dat grondopname data, in die vorm van 'n grondkaart en gekalibreerde hidrouliese eienskappe gebruik kan word om hidrologies soortgelyke eenhede uiteen te sit wat die meerderheid van die variasie in 'n gegewe opvangsgebied insluit. Die HSE's kan gebruik word om grondwatermodelle meer akkuraat te laat funksioneer en dus beter voorspellings te genereer.
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Frank, Sascha [Verfasser], Stefan [Gutachter] Wohnlich, and Jürgen [Gutachter] Schreuer. "Transport processes and heat transfer in single fractured reservoir rocks / Sascha Frank ; Gutachter: Stefan Wohnlich, Jürgen Schreuer ; Fakultät für Geowissenschaften." Bochum : Ruhr-Universität Bochum, 2021. http://d-nb.info/1236814142/34.
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Lee, In-Keun. "Mechanical behaviour of compacted decomposed granite soil." Thesis, Online version, 1991. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.292710.
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Chen, Tao Verfasser], Christoph [Akademischer Betreuer] [Clauser, Olaf [Akademischer Betreuer] Kolditz, and Gabriele [Akademischer Betreuer] Marquart. "Upscaling permeability for fractured porous rocks and modeling anisotropic flow and heat transport / Tao Chen ; Christoph Clauser, Olaf Kolditz, Gabriele Marquart." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1180733703/34.
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Dawson, James W. "Determination of fractured aquifer characteristics from evaluation of pump tests of wells in the crystalline rocks of the Blue Ridge allocthon." Thesis, Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/50075.
Повний текст джерелаАнотація:
The Precambrian age rocks of the Blue Ridge thrust sheet near Roanoke, Virginia, comprise an igneous and metamorphic assemblage with the predominance of porosity and permeability of the formations attributed to secondary factors. Aquifer characteristics of transmissivity, storage coefficient, hydraulic conductivity and fracture NL) permeability are determined from evaluation of pump tests conducted on ground water supply wells developed in this fractured aquifer. Evaluation of pump test data indicates that aquifer response is similar to a double porosity medium in some instances. Comparison of pump tests at locations close to, and further removed from, the leading edge of the Blue Ridge Thrust Fault indicate little variability in fracture permeability. The data suggest that deep circulation of ground water in the Blue Ridge allochthon may be more likely than previously thought.Master of Science
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Chen, Tao [Verfasser], Christoph [Akademischer Betreuer] Clauser, Olaf [Akademischer Betreuer] Kolditz, and Gabriele [Akademischer Betreuer] Marquart. "Upscaling permeability for fractured porous rocks and modeling anisotropic flow and heat transport / Tao Chen ; Christoph Clauser, Olaf Kolditz, Gabriele Marquart." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1180733703/34.
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Zhai, Yang. "Fundamental shear behavior of saturated loose fills of completely decomposed rocks /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22050371.
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Jeanne, Pierre. "Architectural, petrophysical and hydromechanical properties of fault zones in fractured-porous rocks : compared studies of a moderate and a mature fault zones (France)." Nice, 2012. http://www.theses.fr/2012NICE4016.
Повний текст джерелаАнотація:
Bien que les zones de failles représentent un très petit volume de la croute terrestre, elles influencent grandement ses propriétés hydromécaniques. Ce travail compare des analyses multidisciplinaires, de hautes précisions, de deux zones de failles aux propriétés contrastées : l’une est une zone de failles mature de plusieurs kilomètres de long, l’autre s’étend seulement sur quelques centaines de mètres. Leurs propriétés architecturales, hydromécaniques et de résistance mécanique ont été caractérisées dans le but d’améliorer la compréhension des couplages entre l’évolution de leurs propriétés hydromécaniques et leur potentiel de réactivation. Un protocole de caractérisation in-situ des propriétés hydrauliques et mécaniques a été mis au point. Il intègre des analyses microstructurales, des descriptions détaillées des propriétés pétrophysiques à plusieurs échelles. Les deux zones de failles étudiées montrent toutes deux des relations entre leurs histoires diagénétiques, les propriétés initiales des formations sédimentaires et leurs propriétés actuelles hydromécaniques. Il a été mis en évidence que le paramètre le plus important gouvernant le comportement hydromécanique des zones de failles est la continuité de sa zone d’endommagement. Une zone de failles mature aura une zone d’endommagement relativement continue alors qu’une zone de failles non-mature aura une zone d’endommagement hétérogène caractérisée par une alternance de niveaux fracturés et non-fracturés. Ces contrastes architecturaux dépendent des propriétés initiales de la roche intacte. Au sein de la série sédimentaire, les variations de la résistance à la compression (σc) de la roche intacte induisent différents mécanismes d’accommodations des déformations. Il en résulte une architecture de zone de failles présentant de fortes variations d’épaisseur, caractérisée par une alternance de niveaux très perméables et très déformables avec des niveaux imperméables et peu déformablesAlthough fault zones represent a very small volume of the crust, they highly influence the crust’s mechanical and fluid flows properties. This work compares high definition trans-disciplinary analyses of two fault zones with highly contrasted properties. One is a mature fault zone of plurikilometer length, and the other is a small fault zone of a few hundred meters length. We have characterized the architectural, hydromechanical and strength properties of these faults to improve the understanding of the coupling between fault zones hydromechanical properties and their potential activation. A protocol to characterize in the field (on outcropping segments) the faults hydraulic and mechanical properties has been conducted through the coupling of micro-structural analyses, detailed rock physical descriptions at the rock mass several scales. The two studied fault zones despite their different sizes display some similarities. Both show a strong coupling between the fault zone diagenetic history, the initial properties of the sedimentary layers and the fault zone current hydraulic and mechanical properties. We show that the most important parameter governing the hydromechanical behaviors of fault zones is the continuity of the damage zones. A mature fault zone will have a relatively continuous damage zone while a small fault zone will contain a more heterogeneous damage zone characterized by an alternation of fractured and un-fractured layers. These architectural contrasts of damage zones also depend on the initial intact rock properties of the sedimentary series. Contrasted initial intact rock strengths (σc) induce contrasted strain accommodation mechanisms in the fault zone compartments, and an associated fault zone architecture that displays large thickness variations, characterized by alternate high-permeable-low-stiff and low-permeable-high-stiff layers in the damage zone
40
Zhai, Yang, and 翟陽. "Fundamental shear behavior of saturated loose fills of completely decomposed rocks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B3040910X.
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Shamsabadi, Pegah Jarast. "Numerical and Physical Modeling of Cone Penetration in Unsaturated Soils and Numerical Simulation of Fracture Propagation in Shale Rock during Brazilian Test." Thesis, University of New Hampshire, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10622976.
Повний текст джерелаАнотація:
Partially water saturated condition in soils may change the cone penetration resistance comparing with that of dry or saturated conditions. This effect was investigated in this study using numerical finite element modeling and experimental centrifuge testing. The results showed suction in unsaturated soil significantly influenced the soil resistance to cone penetration. Two approaches were implemented to numerically consider the partially saturated soil condition; i.e. modifying simple constitutive models using an apparent cohesion strategy and implementing Barcelona Basic Model for unsaturated soils. Both successfully captured the cone resistance profiles inside a calibration chamber and also in free field. In addition, details of developing a miniature cone setup capable of for cone penetration inside geotechnical centrifuge was explained. Further, the use of Linear Softening Cohesive Model (LCFM) to predict the fracture growth in shale rocks during Brazilian Test was examined. The application and importance of considering two different compressive and tensile elastic modulus and soil anisotropy during the fracture modeling of shales were demonstrated.
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Fabbri, Heber Agnelo Antonel. "Modeling the effects of natural fractures on the permeability of reservoir rocks /." Bauru, 2019. http://hdl.handle.net/11449/190698.
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Orientador: Osvaldo Luís ManzoliAbstract: This work presents a numerical method based on Discrete Fracture Model (DFM) and the Finite Element Method (FEM), where the fractures are approximated by a reduced model. The flow along and across the fracture is described by a simplified set of equations considering both conductive fractures and barriers. The coupled hydromechanical model is composed of a linear poroelastic Biot medium and a nonlinear model based on damage mechanics for the fractures, which captures the nonlinear normal deformation and shear dilation according to the Barton-Bandis model. Both flow and geomechanical models are approximated using the finite element model. Fractures are explicitly represented by three-node standard finite elements with high aspect ratio (i.e. ratio between the largest and the smallest element dimensions) and appropriate constitutive laws. These interface high aspect ratio elements represent a regularization method which continuously approximate the discontinuous pressure and displacement fields on a narrow material band around the fracture. The complete mathematical formulation is presented together with the algorithm suggested for its numerical implementation. The efficiency of the proposed method is demonstrated through numerical examples, as well as the effects of fractures in the hydraulic properties of porous rocks and its dependency of the stress state.
Resumo: Este trabalho apresenta um método numérico baseado no Modelo de Fratura Discreta (MFD) e no Método dos Elementos Finitos (MEF), onde as fraturas são aproximadas por um modelo reduzido. O fluxo ao longo e através da fratura é descrito por um conjunto simplificado de equações, considerando tanto fraturas condutoras quanto barreiras. O modelo hidromecânico acoplado é composto por um meio poroelástico linear e um modelo não linear para fraturas, baseado na mecânica do dano e que captura a deformação normal não linear e a dilatância ao cisalhamento de acordo com o modelo de Barton-Bandis. Os modelos de fluxo e geomecânico são aproximados usando o método dos elementos finitos. As fraturas são explicitamente representadas por elementos finitos triangulares de três nós com elevada razão de aspecto (isto é, a razão entre a maior e a menor dimensão do elemento) e leis constitutivas apropriadas. Esses elementos de elevada razão de aspecto representam um método de regularização que aproxima de forma contínua os campos de pressão e deslocamento descontínuos em uma estreita faixa material ao redor da fratura. A formulação matemática completa é apresentada juntamente com o algoritmo sugerido para sua implementação numérica. A eficiência do método proposto é demonstrada através de exemplos numéricos, bem como os efeitos de fraturas nas propriedades hidráulicas de rochas porosas e sua dependência do estado de tensão.
Mestre
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Ahrens, Benedikt [Verfasser], Jörg [Gutachter] Renner, Holger [Gutachter] Steeb, and Carsten [Gutachter] Jürgens. "Experimental analysis of the frequency dependence of elastic and hydraulic properties of fractured rocks / Benedikt Ahrens ; Gutachter: Jörg Renner, Holger Steeb, Carsten Jürgens ; Fakultät für Geowissenschaften." Bochum : Ruhr-Universität Bochum, 2020. http://d-nb.info/1205975764/34.
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Klepikova, Maria. "Imaging of fractured rock properties from flow and heat transport : field experiments and inverse modelling." Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00865302.
Повний текст джерелаАнотація:
La caracterisation de l'agencement spatial des proprietes hydrauliques est essentielle pour predire les ecoulements et le transport des solutes dans les milieux heterogenes. Les methodes de tomographie hydraulique, principalement developpees pour estimer les proprietes des milieux poreux, n'ont qu'une faible r'esolution spatiale qui ne reflete pas la vraie heterogeneite des distributions de fractures des milieux fractures. Le principal objectif de cette these est de developper une nouvelle methode d'inversion specifique pour imager les proprietés hydrauliques et de transport des milieux fractures a l'echelle du site. Pour atteindre ces objectifs, des experiences in situ ainsi qu'une nouvelle approche de modelisation inverse sont proposees, notamment en utilisant la temperature comme marqueur des ecoulements. Nous proposons tout d'abord la tomographie d'ecoulement bas'ee sur des tests s'equentiels de debimetrie entre puits, comme une nouvelle approche pour caracteriser la connectivit'e des fractures ainsi que leur transmissivite. A partir de simulations numeriques reproduisant des cas d'etudes synth'etiques, nous montrons que l'approche par tomographie r'eduit significativement l'incertitude sur les parametres estimes, et fournit une caracterisation detaillee du reseau de fracture sans requerir a l'utilisation d'obturateurs hydrauliques. Nous montrons ensuite comment les mesures de temperature peuvent etre utilisees pour quantifier les ecoulements dans les milieux fractur'es. Le grand int'erˆet d'utiliser la temperature est d'obtenir facilement et de facon continue en puits des profils de temp'erature. En utilisant un mod'ele numerique d'ecoulement et de transfert de chaleur a l'echelle du puits, une methode d'inversion pour estimer les vitesses d'ecoulement dans le puits 'a partir des donnes de temperature est proposee. Nous couplons ensuite les deux approches presentees precedemment dans une nouvelle approche experimentale consistant en des enregistrements sequentiels de temperature dans un puits dans des conditions de pompage entre puits. L'application de cette approche de tomographie en temperature sur le site de Stanger Brune montre des resultats encourageants pour l'identification du reseau global de connectivite et des zones d'ecoulement principales. Enfin, nous discutons de l'interet d'utiliser la chaleur comme traceur par rapport 'a l'utilisation de traceurs classiques. Nous montrons que realiser des tests de tracage thermiques en milieu fracture fournit des contraintes supplementaires importantes sur les propri'et'es de transport du milieu.
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Lin, Lixiang. "Hydraulic Properties of the Table Mountain Group (TMG) Aquifers." Thesis, University of Western Cape, 2008. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5115_1262826953.
Повний текст джерелаАнотація:
Research findings in current study provide a new insight into the fractured rock aquifers in the TMG area. Some of the results will have wide implications on the groundwater management and forms a solid basis the further study of the TMG aquifers.
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Jeanpert, Julie. "Structure et fonctionnement hydrogéologiques des massifs de péridotites de Nouvelle-Calédonie." Thesis, La Réunion, 2017. http://www.theses.fr/2017LARE0047/document.
Повний текст джерелаАнотація:
Le fonctionnement et la structure hydrogéologiques des aquifères de socle des granites et des gneiss sont aujourd'hui relativement bien compris. En revanche, dans cet ensemble, les aquifères dans les péridotites sont très peu étudiés et mal compris. Dans ce contexte, les massifs obductés de Nouvelle-Calédonie présentent un laboratoire naturel exceptionnel pour améliorer la connaissance de cet hydrosystème original en contexte tropical. Ainsi l'objectif du présent travail de thèse est d'approfondir la connaissance de la structure et du fonctionnement hydrogéologiques de ces massifs. L'analyse porte d’abord sur le manteau d'altération constitué de la cuirasse, des latérites, des saprolites grossières et du saprock. Plus de 60 essais hydrauliques sont menés sur les massifs de péridotites et les résultats sont compilés aux données existantes. La conductivité hydraulique moyenne des latérites est évaluée à 1.10-7 m/s et celle des saprolites grossières et du saprock à 8.10-7 m/s. L'hétérogénéité de cet horizon altéré est marquée par une gamme de variation de la conductivité hydraulique sur six ordres de grandeur et l'analyse piézométrique met en évidence des connexions hydrauliques avec le substratum fracturé profond. Le substratum est ensuite considéré. L'étude de la fracturation est réalisée à partir de mesures structurales sur affleurement et de la description de près de 1000 m de carottes de forages. L'analyse de la fracturation met en évidence l'importance du réseau serpentineux par sa densité d’une part, et par son lien avec l'altération supergène d'autre part. De plus, il est vérifié que la conductivité hydraulique du substratum diminue avec la profondeur. Cette variation est liée à la diminution de la densité de fractures altérées. Ainsi, à l'issue de ces analyses, la structure des massifs de péridotites est définie. Un réseau primaire de fractures d’espacement décimétrique lié au réseau serpentineux préstructure les péridotites. Sur ce réseau se surimpose un réseau de fractures dont l'espacement est décamétrique et caractérisé par une altération supergène. Les fractures altérées présentent localement de fortes conductivités hydrauliques, de l'ordre de 10-5 m/s. En profondeur l'espacement des fractures est hectométrique et les fractures sont majoritairement fermées, scellées par les minéraux néoformés ou par l'effet de la pression lithostatique. Les réseaux de fractures déca et hectométriques, visibles également sur l'effet d’échelle de la conductivité hydraulique, sont majoritairement verticaux, développés par instabilité de dissolution lors des processus d’altération. Cependant, des structures à faible pendage existent également et permettent la percolation du réseau. Enfin, à partir de ces nouveaux résultats et de l’intégration de l'ensemble des données acquises sur les différents massifs, un modèle de structure et de fonctionnement hydrogéologiques est proposé à l'échelle du massif. Ce modèle comprend l'horizon des latérites qui constitue un aquitard homogène sous lequel se développe l'aquifère dont l'épaisseur est de l'ordre de cinquante mètres. Le substratum est discrétisé en trois couches dont la conductivité hydraulique décroît de 2.10-7 à 2.10-8 m/s entre 50 m et 250 m environ sous le mur de l'aquifère. Les modèles numériques construits permettent de valider le modèle conceptuel unitaire et montrent que l'état de saturation des massifs est contraint par leur géomorphologie. Au terme de ce travail, plusieurs aspects doivent encore être approfondis. Le rôle hydrogéologique de la cuirasse doit être précisé et considéré dans le modèle hydrogéologique. Enfin, compte tenu du développement possible de structures très perméables, voire pseudo-karstiques, la connaissance de la distribution des structures drainantes doit être améliorée. Les résultats appliqués de ce travail de recherche sont exposés dans un rapport final et un guide méthodologique livrés dans le cadre du projet CNRT « HYPERK »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
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Morris, Lesley. "Combining Environmental History and Soil Phytolith Analysis at the City of Rocks National Reserve: Developing New Methods in Historical Ecology." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/35.
Повний текст джерелаАнотація:
Historical ecology is an emerging and interdisciplinary field that seeks to explain the changes in ecosystems over time through a synthesis of information derived from human records and biological data. The methods in historical ecology cover a wide range of temporal and spatial scales. However, methods for the more recent past (about 200 years) are largely limited to the human archive and dendrochronological evidence which can be subject to human bias, limited in spatial extent or not appropriate for non-forested systems. There is a need to explore new methods by which biological data can be used to understand historic vegetation and disturbance regimes over the recent past especially in arid ecosystem types. Soil phytolith analysis has the potential to provide much needed information regarding historical conditions in both areas. Phytoliths are structures formed in plants through deposition and accumulation of silica within and around cell walls that are released from plants and preserved in sediments long after death and decay of plant material. The City of Rocks National Reserve in southern Idaho was an excellent place to develop new methods in historical ecology because the human records of historic environmental conditions were so rich. There were two overarching and interconnected objectives for this dissertation research. The first was to reconstruct an ecological history of the City of Rocks National Reserve from the period of overland emigration to present. The second objective was to explore the utility of soil phytolith analysis for inferring vegetation and disturbance regime change over the recent past by testing its sensitivity to record known changes. I employed modern analogue studies, a multi-core approach and detailed core analysis to test for known changes through analysis of extraction weights, relative abundance of phytolith assemblages, microscopic charcoal and burned (darkened) phytoliths. My results showed that this combination of history and soil phytolith analysis would be a useful approach for inferring vegetation changes (e.g. increases in introduced grasses) and disturbances (e.g. fire) in ecological histories.
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Ferreira, Gabriela Ribeiro de Sena. "Arsenic Mobilization from Silicic Volcanic Rocks in the Southern Willamette Valley." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/2752.
Повний текст джерелаАнотація:
Volcanic tuffs and tuffaceous sediments are frequently associated with elevated As groundwater concentrations even though their bulk As contents (~ 5 mg kg-1; Savoie, 2013) are only marginally greater than the average crustal abundance of 4.8 mg g-1 (Rudnick & Gao, 2003). Thus, As mobilization must be facilitated by conditions particular to these rocks. Alkaline desorption, anionic competition, reactive glass dissolution, and reductive dissolution of iron oxides are proposed processes of As release from volcanic rocks. Geogenic As contamination of groundwater in the southern Willamette Valley in western Oregon has been well-documented since the early 1960s, and previous studies have identified the Little Butte Volcanics Series and Fisher and Eugene Formations as the source of As contamination.
This study examines 19 samples from 10 units of ash flow tuffs and tuffaceous sediments within the Fisher Formation and Little Butte Volcanics Series, representing a range of weathering and devitrification, to determine conditions of mobilization and mineralogical constraints that control As release into solution. Leachate studies were conducted over a range of pH from 7 to 11, phosphate concentrations from 10 μM to 100 mM, and in time series from 4 to 196 hours. Results demonstrate that silicic volcanic tuffs are capable of mobilizing As in concentrations above regulatory limits at pH conditions produced naturally by the tuffs (pH 8-9) or with moderate concentrations of P (10-100 μM). Alteration products, e.g. zeolites and clays, appear to be the primary host phases for mobile As. Samples that do not contain these alteration products tend to produce concentrations of As well below regulatory limits and often below the instrument detection limits of this study. The type of alteration may influence As mobilization: tuffs containing more clays tend to mobilize As through surficial desorption, and tuffs containing more zeolites tend to mobilize As by dissolution or formation of colloids. Additionally, one volcaniclastic sample demonstrates that extremely elevated concentrations of As, up to 1000 μg/L are possible as a result of oxidative dissolution of As-bearing sulfide phases.
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Schleicher, Anja. "Clay mineral formation and fluid-rock interaction in fractured crystalline rocks of the Rhine rift system case studies from the Soultz-sous-Forêts granite (France) and the Schauenburg Fault (Germany) /." [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975238027.
Повний текст джерела
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Acaba, Joseph Michael. "Primary Sediment Production from Granitic Rocks in Southeastern Arizona." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/231212.
Повний текст джерелаАнотація:
Isolated granitic rock bodies (granites, granodiorites, quartz monzonites) in the vicinity of Benson in southeastern Arizona were studied to trace the behavior of rock weathering. Thin sections of fresh granites were examined to characterize the original mineralogy which consisted mainly of quartz, feldspars, and micas. The weathering products show up on the granites as grus and soil profiles as well as down slope in the basin deposits. X -ray diffraction studies of the < 2 micrometers fraction of the weathering products proved illite, smectite, illite-smectite mixed layer, and kaolinite to be the dominant clays; quartz and feldspar also persisted into this size fraction. Silt sized material produced similar results. The quartz monzonite of Texas Canyon afforded a special study of the initial weathering stages of feldspars and micas. In the < 2 micrometers fraction obtained from granitic material placed in an ultra sonic bath, the feldspars weathered to a Na-montmorillinite while biotite weathered to vermiculite.