Tesi: "Clays" – Grafiati

1

Hamer, Julian C. E. "Organo-iron compounds on clays and pillared clays". Thesis, Sheffield Hallam University, 1998. http://shura.shu.ac.uk/19748/.

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(Ferrocenylmethyl)dimethylammonium chloride has been synthesised and the cation intercalated into the montmorillonite Westone-L. Variable temperature Mossbauer spectroscopy indicated that the molecule had a similar Debye temperature in each environment (144 +/- 5 K and 140 +/- 5 K respectively). The intercalated Mossbauer spectra revealed a Karayagin effect above 80 K. The cation occupies 80 % of the total exchange capacity of the clay, most likely orientated with the cyclopentadienyl rings perpendicular to the silicate layers. Thermal decomposition of the intercalate involved the volatilisation of iron containing fragments below 350°C. Variable-temperature XRD showed the intercalated sample had a d[001]-spacing of 1.55 nm at room temperature, which decreased at 200°C to give a d[001]-spacing of 1.3 nm. An iron oxide probably remains within the interlayer after the inserted molecule has decomposed. 2,2''-bis [(dimethylamino)methyl]biferrocene has been synthesised and intercalated into acid exchanged Westone-L. Variable temperature Mossbauer spectroscopy revealed a Debye temperature of 172 +/- 5 K which dropped to 150 +/- 5 K on intercalation. The molecule was shown to occupy 75 % of the total CEC of the clay and most likely resides with the cyclopentadienyl rings perpendicular to the silicate sheet. Thermal decomposition of the biferrocene intercalate indicated the loss of iron containing fragments below 430°C. Variable-temperature XRD indicated a d[001]-spacing of 1.65 nm at room temperature which collapsed to 1.41 nm at 250°C, after which it slowly decreased to 1.29 nm at 400°C. An iron oxide was probably left within the interlayer after the intercalated molecule had decomposed. Contact of the biferrocene with the acid Westone-L for 3 and 48 hours resulted in 2 and 11 % oxidation to biferrocenium respectively. Contact of iodine with a suspension of the intercalated biferrocene resulted in ca. 16 % oxidation to biferrocene. The biferrocenium intercalate exhibited "domain" type valence electron de-trapping above 200 K until by 250 K only a single charge averaged doublet was observed. The molecule N,N-dimethylaminomethylferrocene was successfully intercalated into aluminium pillared Westone-L, occupying 30 % of the total CEC of the original clay. The inserted molecule was found to have a Debye temperature of 113 +/- 5 K as determined by variable temperature Mossbauer spectroscopy. Decomposition of the inserted molecule involved the loss of iron containing fragments below 350°C. When heated in air the inserted molecule gave rise to high spin iron(IH) in a distorted octahedral environment. Heating the sample in nitrogen and hydrogen resulted in a species characteristic of high spin octahedrally co-ordinated iron(II). At the higher temperatures, the sample heated in hydrogen exhibited a further high spin octahedrally co-ordinated iron(K) species, with a less symmetric co-ordination sphere than the first.

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2

Taha, Ahmed M. "Interface Shear Behavior of Sensitive Marine Clays --Leda Clay". Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28768.

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Leda clay, which is a type of sensitive marine clay in Canada, is a hazardous soil that could undergo sudden collapse and flow upon wetting and remolding. This type of soil causes many landslide disasters and foundation damage. The existence of Leda clay at or near the proximities of developed cities makes it challenging for infrastructure expansion, and therefore, challenging for geotechnical engineers. At the location where this sensitive marine clay exists, many foundation designers have adopted the use of deep foundations, such as pile foundations to support heavy structures. The shear behavior and strength parameters at the interface between the (friction) pile and soil are key design parameters. A sufficient knowledge of these interface shear behaviors and strength parameters is also essential for the safe and cost-effective design of several other geotechnical structures (e.g., retaining walls, reinforced soils, and buried structures). However, no studies have yet been implemented on the interface shear behavior between Leda clay and structural material. There is therefore, a need to generate more knowledge about the interface shear behavior of Leda clay. This thesis deals with an experimental study of the shear behavior at the interface between Leda clay and structural material, such as steel and concrete. The effects of several factors, such as surface roughness of the construction material, Leda clay's overconsolidation ratio (OCR), saturation degree, density, and salt content on interface shear behavior are also investigated. Laboratory tests have been carried out by using an automatic direct shear machine connected to a linear variable differential transformer (LVDT), loading cell and a data logging system. The results of the interface shear tests show that under consolidated drained (CD) and saturated conditions, the interface friction angle increases with an increase in the clay's OCR. The results also indicate that increasing the salinity of Leda clay's pore water enhances its frictional resistance at the interface. Furthermore, the results reveal that Leda clay with a higher dry density shows higher interface shear resistance. On the other hand, the results also show that the interface shear resistance decreases as the degree of saturation of the Leda clay increases.

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3

Nader, Athir. "Engineering Characteristics of Sensitive Marine Clays - Examples of Clays in Eastern Canada". Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30670.

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Sensitive marine clay in Ottawa is a challenging soil for geotechnical engineers. This type of clay behaves differently than other soils in Canada or other parts of the world. They also have different engineering characteristic values in comparison to other clays. Cone penetration testing in sensitive marine clays is also different from that carried out in other soils. The misestimation of engineering characteristics from cone penetration testing can result. Temperature effects have been suspected as the reason for negative readings and erroneous estimations of engineering characteristics from cone penetration testing. Furthermore, the applicability of correlations between cone penetration test (CPT) results and engineering characteristics is ambiguous. Moreover, it is important that geotechnical engineers who need to work with these clays have background information on their engineering characteristics. This thesis provides comprehensive information on the engineering characteristics and behaviour of sensitive marine clays in Ottawa. This information will give key information to geotechnical engineers who are working with these clays on their behaviour. For the purpose of this research, fifteen sites in the Ottawa area are taken into consideration. These sites included alternative technical data from cone and standard penetration tests, undisturbed samples, field vanes, and shear wave velocity measurements. Laboratory testing carried out for these sites has resulted in acquiring engineering parameters of the marine clay, such as preconsolidation pressure, overconsolidation ratio, compression and recompression indexes, secondary compression index, coefficient of consolidation, hydraulic conductivity, clay fraction, porewater chemistry, specific gravity, plasticity, moisture content, unit weight, void ratio, and porosity. This thesis also discusses other characteristics of sensitive marine clays in Ottawa, such as their activity, sensitivity, structure, interface shear behaviour, and origin and sedimentation. Furthermore, for the purpose of increasing local experience with the use of cone and ball penetrometers in sensitive marine clays in Ottawa, three types of penetrometer tips are used in the Canadian Geotechnical Research Site No. 1 located in south-west Ottawa: 36 mm cone tip, and 40 mm and 113 mm ball tips. The differences in their response in sensitive marine clays will be discussed. The temperature effects on the penetrometer equipment are also studied. The differences in the effect of temperature on these tips are discussed. Correlations between the penetrometer results and engineering characteristics of Ottawa's clays are verified. The applicability of correlations between the testing results and engineering characteristics of sensitive marine clays in Ottawa is also presented in this thesis. Two correlations from the Canadian Foundation Engineering Manual are examined. One of these correlations is between the N60 values from standard penetration testing and undrained shear strength. The other correlation is between the shear wave velocity measurement and site class. Temperature corrections are suggested and discussed for penetrometer equipment according to laboratory calibrations. The significance of the effects due to radical temperature changes in Canada and Ottawa is discussed. Some of the main findings from this research are as follows. • The Canadian Foundation Engineering Manual presents a correlation between standard penetration tests (SPTs) and the undrained shear strength of soils. This relationship may not be applicable to sensitive marine clays in Ottawa. • Another correlation between the site class, shear wave velocity, and undrained shear strength is presented by this same manual which may not be applicable to sensitive marine clays in Ottawa. • The rotation rate for field vane testing as recommended by ASTM D2573 is slow for sensitive marine clays in Ottawa. • Correction factors applied to undrained shear strength from laboratory vane tests may not result in comparable values with the undrained shear strength obtained by using field vane tests. • Loading schemes in consolidation or oedometer testing may affect the quality of the targeted results. • Temperature corrections should be applied to penetrometer recordings to compensate for the drift in the results of these recordings due to temperature changes. • The secondary compression index to compression index ratio presented in the literature may not be the value obtained from this research.

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4

Gonzalez‐Blanco, Laura. "Gas migration in deep argillaceous formations : Boom clay and indurated clays". Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/406355.

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Deep geological disposal remains the preferred option at present for the management of long-living and heat-emitting radioactive waste, which consists of confining the waste during a very long period (several hundreds of thousands of years) by placing them in a deep geological formation. Therefore, the understanding of the long-term behaviour of formations is becoming a key issue to ensure the feasibility of the geological disposal facilities, particularly regarding the generation and migration of gases. The present PhD work aims at better understanding the complex hydro-mechanical response of different argillaceous formations to gas migration process. To this end, gas flow through Boom Clay (one of the potential candidate plastic Paleogene clay formations to host nuclear waste in Belgium) has been deeply investigated on the basis of laboratory experiments at different scales and their numerical modelling. This main study has been complemented by presenting tests on two indurated and deeper claystone Mesozoicformations, considered as candidate host rocks in the Swiss programme for deep geological disposal, namely Opalinus Clay and ‘Brauner Dogger’. The different materials have been firstly characterised to evaluate mechanical (compressibility on loading) and two phase flow properties (water retention and permeability). Gas injection tests under oedometer and isotropic conditions have been performed following different testing protocols, in which boundary conditions have been carefully controlled. Major relevance has been given to restore the in situ stress state and to ensure full saturation conditions before the gas tests. Special emphasis has been placed in measuring sample deformation along the gas injection and dissipation process. The anisotropy of Boom Clay has been studied by carrying out tests with bedding planes parallel and normal to flow. Air injections have been performed at three different controlled-volume rates. The dissipation stages after shut-off have been also analysed to study air intrinsic permeability changes. Microstructure of samples before and after air injection tests has been evaluated by different techniques: mercury intrusion porosimetry, field-emission scanning electron microscopy and micro-focus Xray computed tomography. Gas migration turned out to be a fully coupled hydro-mechanical process. Air injection at constant stress induced expansion of the samples during pressure front propagation and compression during air pressure dissipation. The deformational behaviour was dependent on the injection rate. At slower injection rates expansion occurred during the injection while at higher rates it was delayed in time. Air intrinsic permeability resulted higher than water permeability suggesting that air flow took place along preferential pathways. Evaluation of the microstructural changes induced by air migration revealed the opening of fissures and allowed quantifying their apertures and separation, as well as their volume and connectivity. Air intrinsic permeability was found to be dependent on the fissured volume. To complete and better understand the gas transport mechanisms, numerical simulations of the experimental results have been performed using a fully coupled hydro-mechanical finite element code, which incorporates an embedded fracture permeability model to account for the correct simulation of the gas flow along preferential pathways. Clay intrinsic permeability and its retention curve have been made depend on strains through fracture aperture changes. Numerical results not only accounted for the correct simulation of the recorded upstream pressures and outflow volumes and pressures, but also for the volume change behaviour. The experimental and numerical information provided a good insight into the mechanisms of gas transport in deep clay formations and highlighted the role played by the deformational response on the air transport properties of argillaceous rock formations.
El almacenamiento geológico profundo es la solución actualmente aceptada para la gestión de los residuos radioactivos de alta actividad, que consiste en confinar dichos residuos durante un período muy largo de tiempo (varios cientos de miles de años) depositándolos en una formación geológica profunda. De ahí que el entendimiento del comportamiento a largo plazo se esté convirtiendo en una cuestión clave para asegurar la viabilidad de las instalaciones de almacenamiento de residuos, particularmente en lo que respecta a la generación y migración de gases. Este trabajo de doctorado tiene como objetivo mejorar la comprensión en lo que se refiere a la compleja respuesta hidro-mecánica de diferentes formaciones arcillosas frente a procesos de migración de gas. Con este objetivo, el flujo de gas a través de la arcilla Boom Clay (arcilla plástica del paleógeno candidata a alojar los residuos nucleares en Bélgica) se ha investigado en profundidad mediante experimentos de laboratorio a diferentes escalas y su modelación numérica. Este estudio principal se ha complementado con ensayos experimentales en dos formaciones arcillosas del mesozoico (más profundas y endurecidas),posibles candidatas a roca huésped en el programa suizo para el almacenamiento geológico profundo, llamadas Opalinus Clay y 'Brauner Dogger'. Inicialmente, los diferentes materiales han sido caracterizados para evaluar sus propiedades mecánicas (compresibilidad en carga) e hidráulicas (retención de agua y permeabilidad). Los ensayos de inyección de gas, bajo condiciones edométricas e isótropas, se han realizado siguiendo diferentes protocolos de ensayo controlando cuidadosamente las condiciones de contorno, así como, dando prioridad al hecho de restaurar el estado tensional in situ y las condiciones de saturación antes de los ensayos de gas. Además, se ha hecho especial hincapié en la medición de la deformación de las muestras a lo largo de los procesos de inyección y disipación de gas. La anisotropía de la Boom Clay se ha tenido en cuenta realizando ensayos con los planos de estratificación dispuestos en paralelo y perpendicular al flujo. Las inyecciones de aire se han realizado a tres velocidades volumétricas diferentes. Las etapas de disipación se han analizado para evaluar los cambios en la permeabilidad intrínseca al aire. La microestructura de las muestras se ha evaluado antes y después de los ensayos de inyección de aire mediante tres técnicas diferentes: porosimetría de intrusión de mercurio, microscopía electrónica de barrido de emisión de campo y micro-tomografía computarizada La migración de gases en estas rocas arcillosas saturadas resultó ser un proceso hidro-mecánico totalmente acoplado. La inyección de aire a tensión constante produjo expansión de las muestras durante la propagación del frente de presión y compresión durante la disipación de la presión de aire. El comportamiento deformacional dependió de la velocidad de inyección. A velocidades de inyección más lentas, la expansión se produjo durante la inyección, mientras que, a velocidades más altas, ésta se retrasó en el tiempo. La permeabilidad intrínseca al aire resultó ser más alta que la permeabilidad al agua medida, lo que sugiere que el flujo de aire tuvo lugar a lo largo de vías preferenciales. La evaluación de los cambios microestructurales inducidos por la migración de aire reveló la apertura de fisuras, cuantificando sus aperturas y separación, así como su volumen y conectividad, lo que permitió encontrar una relación de dependencia entre la permeabilidad intrínseca al aire y el volumen fisurado. Para completar la información experimental y comprender mejor los mecanismos de transporte de gas, se realizaron simulaciones numéricas de los resultados experimentales utilizando un código de elementos finitos acoplado, que incorpora un modelo de permeabilidad con fracturas embebidas para explicar el flujo de gas a lo largo de vías preferenciales. La permeabilidad intrínseca de la arcilla y su curva de retención dependen de la deformación a través de cambios en la apertura de la fractura. Los resultados numéricos no sólo reprodujeron de forma correcta las presiones registradas y los volúmenes de salida, sino también el comportamiento deformacional. Esta información experimental y numérica proporcionó una buena visión de los mecanismos de transporte de gas en formaciones arcillosas profundas y en los que destacó el papel desempeñado por la respuesta deformacional sobre las propiedades de transporte de aire.

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5

Lawrence, Monique A. M. "The adsorption of phenolic and organotin compounds by clays and cation exchanged clays". Thesis, Aston University, 1996. http://publications.aston.ac.uk/9677/.

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Quaternary ammonium exchanged laponites (Quat-laponites) show selectivity in the adsorption of phenols and chlorinated phenols. Strong adsorbate-adsorbent interactions are indicated by adsorption isotherms. Adsorption of phenols and chlorinated phenols by Quat-smectites is greater than that by the Bi Quat-Smectites prepared in this study. It is thought that the quaternary ammonium exchanged smectite components of the Bi Quat-smectites interact with each other (adsorbent-adsorbent interactions) reducing the number of sites available for adsorbate-adsorbent interactions. Solidification/stabilisation studies of 2-chlorophenol show that a blend of ground granulated blast furnace slag and ordinary Portland cement attenuates 2-chlorophenol more effectively than ordinary Portland cement alone. Tetramethyl ammonium- (TMA-) and tetramethyl phosphonium- (TMP-) montmorillonites were exposed to solutions of phenol or chlorinated phenols. TMP- montmorillonite was the better adsorbent and preferentially adsorbed 4-chlorophenol over phenol. Hydration of the interlayer cations occurs to a greater extent in the TMA-montmorillonite than the TMP-montmorillonite restricting interlayer adsorption. Contrary to that observed for phenols and chlorinated phenols, the Quat-smectites were ineffective as adsorbents for triphenyltin hydroxide and bis(tributyltin) oxide at room temperature. Under microwave conditions, only bis(tributyltin) oxide was adsorbed by the quaternary ammonium exchanged smectites. Bis(tributyltin) oxide was adsorbed from ethanol on the surface of the smectite clays at room temperature and under microwave conditions. The adsorbate-adsorbent interactions were weak. Adsorption is accompanied by conversion of bis(tributyltin) oxide to a different tin(IV) species and the release of sodium cations from the montmorillonite interlayer region. Attempts to introduce conditions suitable for charge transfer interactions between synthesised quaternary ammonium compounds and 2,4,6-trichlorophenol are documented. Transition metal complex exchanged clays adsorb 2,4,6-trichlorophenol and phenol. Strong adsorbate-adsorbent interactions (Type I isotherms) occur when the adsorbate is 2,4,6-trichlorophenol and when the adsorbent is [Fe(bipy)3]2+ exchanged montmorillonite or [Co(bipy)3]3+ exchanged montmorillonite. The 2,2'-bipyridyl ligands of the adsorbents are electron rich and the 2,4,6-trichlorophenol is electron deficient. This may have enhanced adsorbate-adsorbent interactions.

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6

Agaiby, Shehab Sherif Wissa. "Fracture characterization of clays and clay-like materials using flattened Brazilian Test". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85819.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 243-251).
Fracture mechanics has been used for many years to study the mechanical behavior of brittle and quasi-brittle materials like concrete, rock, wood, and ceramics. To date, the application of fracture mechanics to soils has been limited to dry and partially saturated soils where soil consistency changes due to suction and tends to be harder exhibiting a quasi-brittle behavior. Of late, studying fracture propagation in clays and mudrocks has become of interest as it provides a means to extract oil from oil bearing strata. While crack initiation in soils can be analyzed using basic soil mechanics theories, development and propagation of a crack is energy driven and requires application of fracture mechanics principles. An essential parameter in Linear Elastic Fracture Mechanics (LEFM), the main analytical tool in studying fracture in rock, is the critical stress intensity factor that defines stress concentration near a crack tip beyond which a fracture would propagate. The basic mode of crack loading can be obtained by applying a normal stress that has a corresponding opening mode of crack surface displacement, called mode-I (tensile mode), with a critical stress intensity factor termed fracture toughness, denoted by KIC. In this experimental research, KIC is measured indirectly using a modified Brazilian Test configuration where load is applied normally on flattened Brazilian disk specimens without the need to introduce a flaw into the specimen. Intact natural specimens from four different deposits; Boston Blue clay, San Francisco Bay Mud, Presumpscot Maine clay, and Gulf of Mexico clay; are tested in oven-dried state under atmospheric conditions. In addition, two Clay-like materials; molded Gypsum and Plaster of Paris; have been investigated. Based on the analysis of the test data, the relation between mode I fracture toughness and tensile strength for the six tested materials agrees to a great extent with reported trends in the literature even for different fracture toughness and tensile strength testing techniques and for wider tested range of soils, rocks, geomaterials, clay-like, and rock-like materials. However, no clear relation between mode I fracture toughness and elastic modulus or any other physical parameter was determined.
by Shehab Sherif Wissa Agaiby.
S.M.

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7

Brandes, Ian Marcus Civil &amp Environmental Engineering Faculty of Engineering UNSW. "The negative chargeability of clays". Awarded by:University of New South Wales. School of Civil & Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/21847.

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Coastal clay deposits are an increasingly important focus of environmental and geotechnical studies, and to date, geophysical techniques for mapping them have almost exclusively relied on bulk conductivity measurements. However, direct correlation of bulk conductivity data is difficult, as it is a non-unique parameter. A potential alternative geophysical mapping tool is the complex conductivity technique, where both in-phase and out-of-phase conductivity are measured concurrently. Using similar principles, the induced polarisation field technique measures the charge polarisation parameter chargeability. Studies that utilise these techniques have almost exclusively concentrated on the charge polarisation properties of sediments with low clay contents, and these sediments have intuitively credible positive chargeability values. However, the few studies that include high-clay-content sediments ??? like those encountered in coastal clay deposits ??? have often reported negative chargeabilities. No mechanism has been presented that accounts for this effect. Similar negative chargeability effects have been noted in other sciences, but often remain unexplained. Negative chargeability is shown here to be a non-linear property of clay gels ??? unique to sediments with bulk membrane properties and a potential new clay mapping parameter. A new clay polarisation model is presented which accounts for negative chargeability. Clay sediments are considered as a clay gel membrane, as opposed to traditional models ??? of clay zones within a solid substrate. In the revised model, non-linear ionic gradients occur within the sample, due to the bulk membrane properties of clay gels. Charge dispersion is described in terms of anomalous diffusion Warburg impedances, which create currents in the opposite sense to the applied potential. Negative chargeability is then a unique feature of sediments with bulk membrane properties. Laboratory electrical impedance spectroscopy (EIS) data are presented. The experimental data covers a variety of clay types at a variety of water contents. For pure clay samples, negative chargeability is shown to occur when the clay???s water content is such that it is in a gel state. The threshold water content is shown to be a function of the clay???s liquid limit. This trend is more complicated for natural clays. Field measurements of negative chargeability are presented. The Conductivity Cone Penetrometer (CCPT) is utilised as a chargeability-logging tool at a field site at Hexham, New South Wales. In the first study of its kind, negative chargeability CCPT logging is shown to be effective in mapping a coastal clay deposit.

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8

Halayko, Krista Sophia Gelmich. "Gas flow in compacted clays". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0014/MQ32123.pdf.

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9

Berry, A. J. "The dynamic penetration of clays". Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235369.

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10

Velazquez, Tzayhri Gallardo. "A study on pillared clays". Thesis, University of Salford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252970.

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11

Akl, Sherif Adel. "Wellbore instability mechanisms in clays". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/64569.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, February 2011.
"February 2011." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 331-341).
This dissertation investigates the stability of wellbores drilled in Ko-consolidated clays using non-linear finite element method (FEM) and effective stress soil models to characterize the behavior of clay and unconsolidated shale formations. Two constitutive models are used: Modified Cam Clay (MCC; Roscoe and Burland, 1968), and MIT-E3 (Whittle and Kavvadas, 1994). These soil models are incorporated in the commercial finite element program ABAQUS TM through user material subroutines (Hashash, 1992). The wellbores are modeled by a quasi-3D finite element model to approximate the far field stresses and plane strain boundary conditions. The constitutive models are calibrated to the behavior of Resedimented Boston Blue Clay (RBBC), an analog shale material which is Ko-consolidated to stress levels ranging from 0.15MPa to 10.0 MPa. The thesis comprises three major parts. Part one analyzes the short-term wellbore instability during drilling in low permeability formations. The part focuses on the relationship between the mud pressure inside the wellbore and the undrained shear deformations within the formations. The analyses predict critical mud pressure values necessary to maintain wellbore stability at different deviation angles and stress histories. The MIT-E3 model predicted higher deformations at reference mud pressure and estimated higher values of mud pressures than the underbalanced limit to prevent failure in highly deviated wellbores in NC clays. The second part validates the numerical analyses by comparing model predictions to results of an extensive program of model borehole tests. The lab experiments are performed on high pressure Thick- Walled Cylinder (TWC devices) using RBBC as analog testing material (Abdulhadi, 2009). The MIT-E3 predictions demonstrated a very good match with results from the experiments. The results from the analyses illustrated the effect of the device boundary conditions on specimen behavior and validated approximate analytical methods for interpreting TWC results. Part three studies the effects of consolidation on long-term wellbore stability. Non-linear coupled consolidation analyses are performed to simulate the post-drilling, time-dependent deformations and pore pressures around the wellbore. The analyses consider two different boundary conditions on seepage at the cavity. The analyses show that consolidation generates extensive volumetric strains around the wellbore and cavity deformations can aggravate stability conditions in highly deviated wellbores.
by Sherif Adel Akl.
Ph.D.

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12

Breakwell, I. K. "Chemical modification of smectite clays". Thesis, Aston University, 1992. http://publications.aston.ac.uk/9790/.

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Today, speciality use organoclays are being developed for an increasingly large number of specific applications. Many of these, including use in cosmetics, polishes, greases and paints, require that the material be free from abrasive impurities so that the product retains a smooth `feel'. The traditional `wet' method preparation of organoclays inherently removes abrasives naturally present in the parent mineral clay, but it is time-consuming and expensive. The primary objective of this thesis was to explore the alternative `dry' method (which is both quicker and cheaper but which provides no refining of the parent clay) as a process, and to examine the nature of the organoclays produced, for the production of a wide range of commercially usable organophilic clays in a facile way. Natural Wyoming bentonite contains two quite different types of silicate surface (that of the clay mineral montmorillonite and that of a quartz impurity) that may interact with the cationic surfactant added in the `dry' process production of organoclays. However, it is oil shale, and not the quartz, that is chiefly responsible for the abrasive nature of the material, although air refinement in combination with the controlled milling of the bentonite as a pretreatment may offer a route to its removal. Ion exchange of Wyoming bentonite with a long chain quaternary ammonium salt using the `dry' process affords a partially exchanged, 69-78%, organoclay, with a monolayer formation of ammonium ions in the interlayer. Excess ion pairs are sorbed on the silicate surfaces of both the clay mineral and the quartz impurity phases. Such surface sorption is enhanced by the presence of very finely divided, super paramagnetic, Fe2O3 or Fe(O)(OH) contaminating the surfaces of the major mineral components. The sorbed material is labile to washing, and induces a measurable shielding of the 29Si nuclei in both clay and quartz phases in the MAS NMR experiment, due to an anisotropic magnetic susceptibility effect. XRD data for humidified samples reveal the interlamellar regions to be strongly hydrophobic, with the by-product sodium chloride being expelled to the external surfaces. Many organic cations will exchange onto a clay. The tetracationic cyclophane, and multipurpose receptor, cyclobis(paraquat-p-phenylene) undergoes ion exchange onto Wyoming bentonite to form a pillared clay with a very regular gallery height. The major plane of the cyclophane is normal to the silicate surfaces, thus allowing the cavity to remain available for complexation. A series of group VI substituted o-dimethoxybenzenes were introduced, and shown to participate in host/guest interactions with the cyclophane. Evidence is given which suggests that the binding of the host structure to a clay substrate offers advantages, not only of transportability and usability but of stability, to the charge-transfer complex which may prove useful in a variety of commercial applications.

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13

Bond, Stephen P. "Interlamellar modification of smectite clays". Thesis, Aston University, 1991. http://publications.aston.ac.uk/9741/.

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Clay minerals, both natural and synthetic, have a wide range of applications. Smectite clays are not true insulators, their slight conductivity has been utilized by the paper industry in the development of mildly conducting paper. In particular, the synthetic hectorite clay, laponite, is employed to produce paper which is used in automated drawing offices where electro graphic printing is common. The primary objective of this thesis was to modify smectite clays, particularly laponite, to achieve enhanced conductivity. The primary objective was more readily achieved if the subsidiary objective of understanding the mechanism of conductivity was defined. The cyclic voltammograms of some cobalt complexes were studied in free solution and as clay modified electrodes to investigate the origin of electroactivity in clay modified electrodes. The electroactivity of clay modified electrodes prepared using our method can be attributed to ion pairs sorbed to the surface of the electrode, in excess of the cationic exchange capacity. However, some new observations were made concerning the co-ordination chemistry of the tri-2-pyridylamine complexes used which needed clarification. The a.c. conductivity of pressed discs of laponite RD was studied over the frequency range 12Hz- 100kHz using three electrode systems namely silver-loaded epoxy resin (paste), stainless-steel and aluminium. The a. c. conductivity of laponite consists of two components, reactive (minor) and ionic (major) which can be observed almost independently by utilizing the different electrode systems. When the temperature is increased the conductivity of laponite increases and the activation energy for conductivity can be calculated. Measurement of the conductivity of thin films of laponite RD in two crystal planes shows a degree of anisotropy in the a.c. conductivity. Powder X-ray diffraction and 119Sn Mossbauer spectroscopy studies have shown that attempts to intercalate some phenyltin compounds into laponite RD under ambient conditions result in the formation of tin(IV) oxide pillars. 119Sn Mossbauer data indicate that the order of effectiveness of conversion to pillars is in the order: Ph3SnCl > (Ph3Sn)2O, Ph2SnCl2 The organic product of the pillaring process was identified by 13C m.a.s.n.m.r. spectroscopy as trapped in the pillared lattice. This pillaring reaction is much more rapid when carried out in Teflon containers in a simple domestic microwave oven. These pillared clays are novel materials since the pillaring is achieved via neutral precursors rather than sacrificial reaction of the exchangeable cation. The pillaring reaction depends on electrophilic attack on the aryl tin bond by Brønsted acid sites within the clay. Two methods of interlamellar modification were identified which lead to enhanced conductivity of laponite, namely ion exchange and tin(IV) oxide pillaring. A monoionic potassium exchanged laponite shows a four fold increase in a.c. conductivity compared to sodium exchanged laponite RD. The increased conductivity is due to the appearence of an ionic component. The conductivity is independent of relative humidity and increases with temperature. Tin(IV) oxide pillared laponite RD samples show a significant increase in conductivity. Samples prepared from Ph2SnCl2 show an increase in excess of an order of magnitude. The conductivity of tin(IV) oxide pillared laponite samples is dominated by an ionic component.

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14

Patwary, Md Zillur R. "Clay Fluid Interactions in Montmorillonite Swelling Clays: A Molecular Dynamics and Experimental Study". Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26757.

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Swelling clays cause tremendous amounts of damage to infrastructure. For the effective prevention of detrimental effects of these clays, and to optimize the beneficial properties for industrial applications it is necessary to clearly understand the fundamental mechanisms of swelling of clays. In this study, we studied the effect of fluid polarity on swelling and flow properties of swelling clays using molecular modeling and experimental technique for bridging the molecular level phenomenon of these clays with microstructure change, particle breakdown and macro scale swelling and flow properties. A wide range of fluids (Dielectric Constant 110 to 2.4) were used, those are also commonly present in landfill leachates. We were able to tie the properties of swelling clays at different length scales. Then, we simulated the solvation of clay sheets, studied the effect of discrete charge distribution, contribution of edge charges on swelling clays and discussed some fundamental assumptions associated with double layer theories.
Department of Civil Engineering, North Dakota State University

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15

Naldrett, Dana L. "Glacigenic clays of the Ottawa Valley". Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/5275.

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16

Middleton, Glenn W. "Electrofluorescence studies of clays and DNA". Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305049.

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17

Williams, S. "Swelling behaviour of unsaturated expansive clays". Thesis, University of South Wales, 1988. https://pure.southwales.ac.uk/en/studentthesis/swelling-behaviour-of-unsaturated-expansive-clays(0b4f591f-9c33-404f-9aac-422fe5d17abe).html.

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Abstract (sommario):

This thesis examines two available approaches for predicting the swelling behaviour of unsaturated expansive clays: (i)simplified empirical relationships for rapidly identifying swelling soils and (ii)a more accurate prediction method suitable for design purposes and based upon experimentally measured swell moduli. The work was prompted by the absence of a universally accepted procedure for use with these soils. The initial (and shorter) phase of the work uses published swell data to assess available empirical swell prediction methods and also determine the relative significance of soil parameters used for this purpose. The work suggests that potentially expansive soils can be identified and classified, and the national or regional soil classification systems may be easily amended to allow for this. The results indicated: (i)the swell prediction methods are suitable for indicating the degree of swell behaviour only, and methods for actually quantifying volume change are usually limited to localised application (ii)in situ suction correlated closely with swell for available data, therefore it is suggested that the suction-swell relationship be derived for numerous soils in order to assess the possibility of using it as a stand-alone indicator. The second and most significant phase of the work involved an assessment of Fredlund's constitutive model approach for unsaturated soils when applied to the swell prediction of expansive clays. This required considerable equipment development for measuring volume changes and controlling the stresses of the soil, air and water phases. In addition, two conventional consolidometers (oedometers) were linked to a chart recorder to facilitate continuous data acquisition. An experimental programme of three test series was then instigated to provide data by which Fredlund's theory could be assessed; these included Null tests to assess the validity of the chosen stress state variables, Volume change (uniqueness tests)to evaluate Fredlund's constitutive equations and finally, Consolidometer swell tests to further evaluate the constitutive equations and assess an established soils laboratory test for swell prediction purposes. The results showed : (i)in general, Fredlund’s constitutive model approach is suitable for predicting volume changes in unsaturated expansive clays of a liquid limit range typically found in the field (up to 142%). (ii)despite equipment limitations, equal changes of the stress components (cr, Ua and Uw) produced negligible volume changes, thereby confirming the stress state variables. (iii)both the stress control and consolidometer tests indicated reasonable agreement between measured and predicted swell values, thus confirming the suitability of Fredlund’s constitutive model approach to expansive unsaturated clays. (iv)the theory makes no provision for (a) discontinuous phases in soils found at saturation levels below 25% and above 80-85% and (b) the non elastic behaviour of unsaturated soils following a reversal in stress change. Fredlund’s theory should therefore be further studied for soils composed of discontinuous phases and the effects of stress reversals upon volume change. The development of a full triaxial testing system is recommended.

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18

Lien, Bon-Hsiang. "Pressuremeter testing in miocene stiff clays". Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/39730.

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Abstract (sommario):

In geotechnical engineering, it has proven difficult to obtain reliable soil parameters for stiff clays. Laboratory testing results are often scattering due to the fissures and slickensides in these soils. Alternatively, in situ techniques offer a means to test the soils in place. This study focuses on in situ testing in Miocene stiff clays using an advanced nine strain arm self-boring pressuremeter (SBPM). This device was used to test the soils in both a self-boring and a simpler, non-boring mode (pre-bored or PBPM tests). The Miocene stiff clay was unique in that was sensitive and lacked of fissures and slickensides. The pressuremeter results could be compared to a range of other tests previously performed at the site. It is concluded that the SBPM provides accurate values of modulus and strength. Minor soil disturbance was found to have little effect when it could be anticipated. The simpler PBPM tests were not successful because of disturbance caused by borehole preparation.
Ph. D.

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19

Caton, Charlotte(Charlotte Elizabeth). "The sticky property of Ypresian clays". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123218.

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Abstract (sommario):

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 58-60).
Construction sites may encounter many problems with the underlying soil, and excavating in soft soils is one of them. One major issue when managing soft soils is clogging, which occurs because cohesive soils tend to adhere to the cutting head of tunnel boring machines or to the cutting wheel of hydromills. This thesis focuses on Ypresian clays, which are highly adhesive. The adhesive properties of Ypresian clays can slow down excavation processes, causing economic loss to the construction companies. Studying the different mechanisms behind the clogging phenomenon and ways to qualitatively and quantitatively assess it makes it possible to evaluate the clogging potential of Ypresian clay and compare it to that of the Boom clay, a similar formation which is shown to be less sticky. The high plasticity index of Ypresian clays is proved to be an indicator of its high stickiness, and the cone pull-out test gives a value for adherence that quantifies the clogging potential. Ypresian clays also support the hypothesis that the Casagrande chart's U-line could be used as an evaluation method for clogging. In these ways, evaluating clogging potential is possible, but a standardized method has yet to be agreed on. The physics behind the evaluation methods, however, is not well understood. That is why this thesis discusses using a microscopic approach to study the origin of Ypresian clay's stickiness. Research still needs to be done to see if inter-scaling is possible between micro-, meso-, and macroscopic scales and to find out if the particles' interactions at microscopic scale can be interpreted at the macroscopic scale.
by Charlotte Caton.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering

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20

Duong, Loc V. "The morphology and structure of intercalated and pillared clays". Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/17707/1/Loc_Van_Duong_Thesis.pdf.

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This thesis is submitted in a format of published papers by the candidate. Advanced methods of electron microscopy and X-ray spectroscopy have been used to study the relationship between the pillars and the silicate structure ranging from Al13 and Ga13 complexes to the final products Al- and Ga-pillared clays. The Al13 and Ga13 pillared montmorillonites have been prepared by conventional and ultrasonic methods. The ultrasonic method has been proven to be effective and showed very good catalytically activity. Transmission electron microscopy combined with elemental mapping by EDS showed the distribution of the Ga and Al pillars in the clay structure. The use of gallium allowed the independent observation of the Ga pillar distribution from the Al distribution in the clay structure. XPS spectra of the Ga13 pillared montmorillonites showed that the pillars has been changed from the original Keggin structure with a 7+ charge to something more stable with a lower charge upon intercalation. No direct evidence of the inverted silicon tetrahedron structure bonding to the pillar structure, as suggested by Plee in his original thesis, was observed. For comparative reasons the major aluminium hydroxide minerals in bauxite (gibbsite, bayerite and (pseudo-) boehmite) were studied. Detailed information about the Al13 structure was obtained by studying the basic sulphate and nitrate salts with XPS. The XPS results of a set of starting clays in comparison to the pillared clays indicated that small changes in the binding energy could explain the changes in the pillar structure and the formation of chemical bonds to the clay tetrahedral sheets during the calcination leading to the final products.

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21

Duong, Loc V. "The morphology and structure of intercalated and pillared clays". Queensland University of Technology, 2008. http://eprints.qut.edu.au/17707/.

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Abstract (sommario):

This thesis is submitted in a format of published papers by the candidate. Advanced methods of electron microscopy and X-ray spectroscopy have been used to study the relationship between the pillars and the silicate structure ranging from Al13 and Ga13 complexes to the final products Al- and Ga-pillared clays. The Al13 and Ga13 pillared montmorillonites have been prepared by conventional and ultrasonic methods. The ultrasonic method has been proven to be effective and showed very good catalytically activity. Transmission electron microscopy combined with elemental mapping by EDS showed the distribution of the Ga and Al pillars in the clay structure. The use of gallium allowed the independent observation of the Ga pillar distribution from the Al distribution in the clay structure. XPS spectra of the Ga13 pillared montmorillonites showed that the pillars has been changed from the original Keggin structure with a 7+ charge to something more stable with a lower charge upon intercalation. No direct evidence of the inverted silicon tetrahedron structure bonding to the pillar structure, as suggested by Plee in his original thesis, was observed. For comparative reasons the major aluminium hydroxide minerals in bauxite (gibbsite, bayerite and (pseudo-) boehmite) were studied. Detailed information about the Al13 structure was obtained by studying the basic sulphate and nitrate salts with XPS. The XPS results of a set of starting clays in comparison to the pillared clays indicated that small changes in the binding energy could explain the changes in the pillar structure and the formation of chemical bonds to the clay tetrahedral sheets during the calcination leading to the final products.

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22

Bond, Andrew John. "Behaviour of displacement piles in overconsolidated clays". Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/7781.

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23

Engin, Guleda. "Development of anionic clays for water treatment". Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342253.

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24

Gale, Julian David. "Computer simulation of zeolites and pillared clays". Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307093.

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25

Nocon, Melody Schwartz. "Inorganic Sorption in Polymer Modified Bentonite Clays". Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3850.

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Abstract (sommario):

In 1986, geosynthetic clay liners (GCLs) were invented and successfully used as a replacement for the soil layer in composite lining systems. In some applications an additive (polymer) is mixed with the bentonite to increase performance, especially in those that have low concentrations of sodium bentonite (EPA 2001).Studies showing significant increases in hydraulic conductivity values for bentonite in the presence of high salt concentrations are frequently documented and there is a risk of early breakthrough due to performance failure of the GCL clay component. (Ashmawy et al, 2002). It has also been stated that sodium, potassium, calcium, and magnesium have such a high affinity for the clay's surface other chemical species have little chance of attenuation (EPA 2001). For these reasons, researching sorption in the presence of major salt cations and polymers gains great importance.Distribution coefficients were extrapolated from Linear, Freundlich and Langmuir sorption isotherms for sodium and calcium cations modeled from data collected from batch tests of sodium bentonite and various manufactured and custom mixed polymer modified bentonites. Surface characterization before and after calcium or sodium solution exposure of all tested media was accomplished by use of scanning electron microscopy and energy dispersive x-ray analysis.

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26

Sharma, Radhey Shyam. "Mechanical behaviour of unsaturated highly expansive clays". Thesis, University of Oxford, 1998. http://ora.ox.ac.uk/objects/uuid:6ee59b08-357a-4d2d-96f1-c5987465f437.

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This thesis concerns the mechanical behaviour of unsaturated highly expansive clays. Given the high cost of damage to buildings, structures and roads caused by unexpected ground movements associated with unsaturated highly expansive clays and the increasing use of compacted expansive clays for engineered barriers for environmental protection and other purposes, it was considered important to investigate the behaviour of these materials. Previous researchers had reported the occurrence of substantial irreversible components of either wetting-induced swelling or drying-induced shrinkage during cycles of wetting and drying performed on unsaturated highly expansive clays containing active clay mineral such as montmorillonite. This form of irreversible behaviour cannot be represented by existing elasto-plastic models for unsaturated non-expansive clays. It had therefore been suggested that the behaviour of unsaturated highly expansive clays was fundamentally different to that of unsaturated non-expansive clays, and that the constitutive models developed for unsaturated non-expansive clays were inappropriate. The behaviour of an unsaturated highly expansive compacted bentonite/kaolin mix under isotropic stress states has been studied in a programme of controlled-suction tests incorporating isotropic loading and unloading at constant suction and cycles of wetting and drying (variation of suction) performed either under constant load or at constant volume. A smaller series of tests was also performed on unsaturated compacted samples of non-expansive pure kaolin. Either net shrinkage or net swelling occurred over a wetting/drying cycle for samples of the same soil, depending upon the compaction pressure. Irreversible shrinkage or swelling occurred during subsequent wetting/drying cycles, not just during the first cycle. Net shrinkage during a wetting/drying cycle was sometimes accompanied by a distinct change of stiffness (a yield point) during the appropriate drying path, but at other times was not. Yield points were never observed during both drying and wetting stages of a cycle. Net shrinkage or swelling during a wetting/drying cycle was always accompanied by a substantial net change of degree of saturation Sr during the cycle (termed hydraulic hysteresis). Experimental evidence showed that there is no fundamental difference between the mechanical behaviours of unsaturated highly expansive soils and unsaturated non-expansive soils. The experimental results suggested that unified modelling for both unsaturated highly expansive soils and unsaturated non-expansive soils is desirable. A new constitutive modelling framework is therefore proposed. In the modelling framework new forms of stress variables, with conjugate strain increment parameters, are used for the first time. Results from theoretical analysis of the influence of suction on inter-particle forces are used in developing the modelling framework. The influence of hydraulic hysteresis on stress strain behaviour is included in the framework, which has been developed in such a way that the otherwise difficult, transition between saturated and unsaturated conditions can be modelled in a relatively straightforward fashion. In the new modelling framework, both net shrinkage and net swelling during wetting/drying cycles, can be explained.

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27

Hazelwood, Adam Charles. "Synthesis and characterisation of novel pillared clays". Thesis, University of Exeter, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248171.

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28

Elmes, D. R. "Creep and viscosity in two kaolin clays". Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372627.

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29

Chin, Chung-Tien. "Open-ended pile penetration in saturated clays". Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/15176.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1986.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 245-248.
by Chung-Tien Chin.
Ph.D.

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30

Rafalovich, Alexander. "The mechanics of plate penetration in clays". Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13398.

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31

Bordallo, Heloisa N., Laurence P. Aldridge, G. Jock Churchman, Will P. Gates, Arnaud Desmedt e Mark T. F. Telling. "Understanding water diffusion in concrete and clays". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193924.

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32

Karami, Azzam Omar 1962. "Consolidation of clays using the triaxial apparatus". Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276842.

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Abstract (sommario):

The calculation of a consolidation settlement is an important problem encountered in the foundation of buildings. Due to need for simplicity engineers are mainly using the one dimensional theory of Terzaghi for calculations of consolidation settlements with time. Consolidation tests are still performed in most laboratories with the traditional oedometer cell. Although the results of the oedometer can provide relatively reliable results, they are not equally effective for the calculation of the rate of consolidation. This primarily because of the inability of the oedometer cell to obtain full saturation of the sample. To ensure full saturation, back pressure must be applied which is not possible for conventional oedometer cell. The alternative use of the triaxial cell to examine the consolidation behavior of soils is discussed here.

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33

Simoes, Ana M. "Natural attenuation of landfill leachate by clays". Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/79337/.

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34

Bordallo, Heloisa N., Laurence P. Aldridge, G. Jock Churchman, Will P. Gates, Arnaud Desmedt e Mark T. F. Telling. "Understanding water diffusion in concrete and clays". Diffusion fundamentals 6 (2007) 56, S. 1-2, 2007. https://ul.qucosa.de/id/qucosa%3A14235.

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35

Stark, Timothy D. "Mechanisms of strength loss in stiff clays". Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/74771.

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On September 14, 1981 a major slide was discovered in the upstream slope of San Luis Darn, located about 100 miles southeast of San Francisco, California. The slide occurred at the end of a period of rapid drawdown of the reservoir. Although this was the longest and fastest drawdown in the life of the dam, 180 feet in 120 days, there had been seven previous cycles of drawdown, some nearly as severe as the one that preceded the slide. Field measurements showed the slide was caused by the clayey slopewash material left in the foundation of the dam during construction. Although the slopewash was dry and extremely strong when the embankment was built, it apparently was weakened considerably when submerged beneath the reservoir and its strength was further degraded by cyclic loading effects as the reservoir level was raised and lowered during the 14 years preceding the slide. The objective of this research was to gain a better understanding of the mechanisms of strength loss in the slopewash that resulted in the 1981 slide at San Luis Dam. This was accomplished using laboratory tests on undisturbed samples of slopewash, analyses of seepage through the embankment and foundation, finite element analyses of stresses in the dam during construction and operation of the reservoir, and conventional equilibrium slope stability analyses. The laboratory tests showed that the shear strength of the slopewash decreases very quickly when the desiccated material is wetted. Wetting causes immediate reduction in shear strength to the fully softened value, and there is no lasting effect of consolidation by drying. After wetting the highly desiccated slopewash has the same strength as in the remolded, normally consolidated condition. Tests that simulated cyclic changes in normal stress and shear stress like those during drawdown and refilling of the reservoir showed that further strength loss results from cyclic loading of the slopewash. Cyclic loading at stress levels below the fully softened peak strength result in continual shear displacement, and eventually, when the cumulative horizontal displacement reaches approximately ten inches, the shear strength is reduced to its residual value.
Ph. D.

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36

Ghahremannejad, Behrooz. "Thermo-Mechanical Behaviour of Two Reconstituted Clays". Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/492.

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Abstract (sommario):

The effect of temperature on soil behaviour has been the subject of many studies in recent years due to an increasing number of projects related to the application of high temperature to soil. One example is the construction of facilities for the disposal of hot high level nuclear waste canisters (150-200C) several hundred meters underground in the clay formations. Despite this, the effects and mechanism by which temperature affects the soil properties and behaviour are not fully known. A limited amount of reliable experimental data, technological difficulties and experimental methods employed by different researchers could have contributed to the uncertainties surrounding the soil behaviour at elevated temperature. Also several thermo-mechanical models have been developed for soil behaviour, but their validity needs to be examined by reliable experimental data. In this research, efforts have been made to improve the experimental techniques. Direct displacement measuring devices have been successfully used for the first time to measure axial and lateral displacements of clay samples during tests at various temperatures. The thermo mechanical behaviour of two reconstituted clays has been investigated by performing triaxial and permeability tests at elevated temperature. Undrained and drained triaxial tests were carried out on normally consolidated and over consolidated samples of M44 clay and Kaolin C1C under different effective stresses, and at temperatures between 22C and 100C. Permeability tests were carried out on samples of M44 clay at temperatures between 22C and 50C. The effects of temperature on permeability, volume change, pore pressure development, shear strength and stiffness, stress strain response and critical state parameters for different consolidation histories have been investigated by comparing the results at various temperatures. The results are also compared with the predictions of two models. It has been found that at elevated temperature the shear strength, friction angle and initial small strain stiffness reduce whereas permeability increases. The slope of the swelling line in the v-p� plane has been found to reduce with temperature. The slope of the isotropic normal consolidation line (INCL) and critical state line (CSL) in the v-p� plane have been observed to be independent of temperature, but both the INCL and the CSL shift downwards to lower locations as temperature increases. The deformations during drained cooling and re heating cycles have been found to be elastic and to simply reflect the expansivity of the soils solid particles. The thermal volume changes during undrained heating have been observed to be direct results of the thermal expansion of water and clay particles. The internal displacement measuring devices have been found to produce reliable data for the variation of strains at elevated temperature.

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37

Ghahremannejad, Behrooz. "Thermo-Mechanical Behaviour of Two Reconstituted Clays". University of Sydney. Civil Engineering, 2003. http://hdl.handle.net/2123/492.

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Abstract (sommario):

The effect of temperature on soil behaviour has been the subject of many studies in recent years due to an increasing number of projects related to the application of high temperature to soil. One example is the construction of facilities for the disposal of hot high level nuclear waste canisters (150-200C) several hundred meters underground in the clay formations. Despite this, the effects and mechanism by which temperature affects the soil properties and behaviour are not fully known. A limited amount of reliable experimental data, technological difficulties and experimental methods employed by different researchers could have contributed to the uncertainties surrounding the soil behaviour at elevated temperature. Also several thermo-mechanical models have been developed for soil behaviour, but their validity needs to be examined by reliable experimental data. In this research, efforts have been made to improve the experimental techniques. Direct displacement measuring devices have been successfully used for the first time to measure axial and lateral displacements of clay samples during tests at various temperatures. The thermo mechanical behaviour of two reconstituted clays has been investigated by performing triaxial and permeability tests at elevated temperature. Undrained and drained triaxial tests were carried out on normally consolidated and over consolidated samples of M44 clay and Kaolin C1C under different effective stresses, and at temperatures between 22C and 100C. Permeability tests were carried out on samples of M44 clay at temperatures between 22C and 50C. The effects of temperature on permeability, volume change, pore pressure development, shear strength and stiffness, stress strain response and critical state parameters for different consolidation histories have been investigated by comparing the results at various temperatures. The results are also compared with the predictions of two models. It has been found that at elevated temperature the shear strength, friction angle and initial small strain stiffness reduce whereas permeability increases. The slope of the swelling line in the v-p� plane has been found to reduce with temperature. The slope of the isotropic normal consolidation line (INCL) and critical state line (CSL) in the v-p� plane have been observed to be independent of temperature, but both the INCL and the CSL shift downwards to lower locations as temperature increases. The deformations during drained cooling and re heating cycles have been found to be elastic and to simply reflect the expansivity of the soils solid particles. The thermal volume changes during undrained heating have been observed to be direct results of the thermal expansion of water and clay particles. The internal displacement measuring devices have been found to produce reliable data for the variation of strains at elevated temperature.

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38

Silva, Adriana Almeida. "Contribuição ao estudo das bentonitas do município de Boa Vista Estado da Paraíba". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-29062011-133500/.

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Abstract (sommario):

As argilas são rochas constituídas por argilominerais e por minerais acessórios, cuja estrutura cristalina permite a adsorção de cátions e ânions conferindo-lhes propriedades físico-químicas particulares. Quimicamente os argilomineriais são formados essencialmente por silicatos hidratados de alumínio, ferro e magnésio. As bentonitas apresentam mais de 140 usos industriais, com variações particulares, seja devido ao emprego tecnológico desta argila, seja devido à origem geológica ou à composição mineralógica desta, por isso, sendo consideradas tipos especiais de argilas industriais. O termo bentonita é usado para designar uma argila com alto teor de argila esmectítica. O maior produtor mundial de bentonita são os Estados Unidos representando cerca de um terço do total da produção mundial. No Brasil, os mais importantes jazimentos de bentonitas encontram-se na Paraíba, nos municípios de Boa Vista, Cubati e Pedra Lavrada. A bentonita bruta da Paraíba é lavrada por empresas mineradoras e comercializada em grandes quantidades no próprio Estado, sendo estas destinadas a empresas que as beneficiam, ativam e posteriormente vendem para os demais mercados nacionais. Os preços da bentonita variam em função da qualidade do produto, da pureza, da função ou aplicação, e do tipo do beneficiamento e ativação a que foi submetido o minério. Considerando a expectativa de crescimento desse setor para os próximos anos, este estudo tem como objetivo complementar e atualizar dados tecnológicos existentes na literatura sobre as bentonitas do Estado da Paraíba, contribuindo com estudos tecnológicos das bentonitas da Paraíba realizados em 1976 pelo professor Dr. Pérsio de Souza Santos. Pretende-se evidenciar como estão as propriedades e os usos de 5 argilas da mina Lages após 35 anos de estudos. Para o desenvolvimento deste trabalho utilizaram-se 5 tipos diferentes de bentonitas cedidas pela empresa BENTONISA - Bentonita do Nordeste S.A. Para estas foram realizadas as caracterizações físico-químicas e mineralógicas. Através da análise dos resultados obtidos foi possível realizar algumas indicações para os usos potenciais destes materiais.
The clays are composed of clay minerals and accessory minerals, whose crystal structure allows the adsorption of cations giving them particular physical and chemical properties. Chemically, the argilomineriais are formed mainly of hydrated silicates of aluminum, iron and magnesium. The bentonites are special types of industrial clays because submitting more than 140 industrial uses, with particular variations, whether due to technological employment of clay, is due to the geological origin and the mineralogy of this clay. The term bentonite is used to designate a high clay content of montmorillonite. The world\'s largest producer of bentonite is the United States represents about one-third of total world production. In Brazil, the most important bentonite clay bentonite deposits are found in Paraiba, in the municipalities of Boa Vista, Cubati and Pedra Lavrada. The crude bentonite Paraíba is wrought by mining companies and sold in large quantities within the State, which are aimed at companies that benefit, activate and subsequently sold to other markets. Prices vary depending on the bentonite product quality, purity, function or application, and the type of processing and activation in the ore that was submitted. Considering the expected growth of this sector in the coming years, this study aims to complement existing technology and update data in the literature on bentonite clays of Paraíba State, contributing to technological studies of bentonites from Paraíba conducted in 1976 by Professor Dr. Pérsio de Souza Santos. It is intended to highlight are the properties and uses of these materials after 35 years of studies. To develop this work, we used five types of bentonite clays supplied by the company BENTONISA-Bentonita do Nordeste S.A., For these were the physical and mineralogical characterization. By analyzing the results we achieve some indication for the potential uses of these materials.

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39

Stoddart, Christopher Paul. "Powder diffraction studies of solid solution effects in minerals". Thesis, Staffordshire University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385193.

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40

Wang, Liangcheng. "Reactions of leuco dyes on acid activated clays". Thesis, University of Central Lancashire, 1993. http://clok.uclan.ac.uk/20276/.

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The colour formers used in carbonless copying paper consist of admixtures of primary and secondary dyes. Work was carried out in this programme both on retarding the photofading of the primary dyes and on improving the reactivity of the clay minerals towards the development of the secondary dye. The photolytic fading behaviour of S primary dyes were examined both in solution and on solid clay surfaces, and the intermediacy of singlet oxygen in the fading processes of the dyes examined by the DPBF trapping method. The retardation of dye fading was accomplished using bis(dithiocarbamato)nickel(II) complexes and it was found that some hydroxy-possessing species conferred improved photo-stability upon the developed dyes, especially towards fluorans, and to a lesser degree towards phthalides. The dark development of carbazolyl blue was examined on a series of cation exchanged and acid activated clays. There appeared to be two main mechanisms governing S-RB development in the dark; the first was catalysis by co-ordination to the Lewis acid sites on the clay edges, whilst the second was a redox process probably associated with the Fe 3 cations present in the clays. Several treatments were applied to modify common commercial days. It was found that introducing Fe 3 and Cu2 into the clay profoundly improved the reactivity of the day to the secondary leuco dye. Cation exchange of clay with some transition metal ions such as CO 2 and Ni2 also showed a beneficial effect on the colour formation. The Langmuir isotherm type plots were used to examine cation adsorption behaviour for 9 types of montmorillonite clays. It was found that cation exchange of clay occurs at at least two different sites; the tetrahedral silica layer sites and the intact montmorillonite interlayer cation exchange sites. It was also found that the silica layer sites are the predominant ones responsible for S-RB development, with interlayer sites providing a much lesser contribution. Adsorption of aquated metal salts makes virtually no further contributions to the leuco dye reaction.

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41

Duquette, Martin. "Surface charge evaluation of soils, clays and oxides". Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39270.

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Two objectives are achieved in this thesis: (1) to develop a new method to measure the pH-dependent net surface charge of soils and (2) to determine if, by a combination of the surface charge evaluated by potentiometric titration and ion adsorption, we can separate the permanent charge, generated by the isomorphous substitution, from the variable charge. First, a laboratory procedure, using backtitration, was developed for the measurement of the pH-dependent net surface charge. This method was tested on ten soil horizons from Gleysols and Podzols. It appears that the pH-dependent net surface charge, measured by this technique, shows good agreement with that measured by ion adsorption. It is also possible, with this method, to identify some plateaus and inflection points in the backtitration curve associated with protonation/deprotonation reactions of specific soil components. Secondly, it was demonstrated that it is possible to increase the surface charge of montmorillonite with Al-oxide coatings under specific conditions.

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42

Baudet, Beatrice Anne. "Modelling effects of structure in soft natural clays". Thesis, City University London, 2001. http://openaccess.city.ac.uk/8394/.

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Geological processes give natural clays a different structure to that of clays that are reconstituted in the laboratory. In soft clays, this structure often breaks down under loading; this is called destructuration. This project aimed to develop a model to predict destructuration in soft natural clays. An understanding of the main characteristics of the behaviour of these clays detained was from data reported in the literature. Existing frameworks that describe the behaviour of these clays were reviewed, and basic concepts proposed to model structured soils. The Sensitivity framework (Cotecchia & Chandler, 2000) uses sensitivity as a parameter that can represent structure in both volumetric and stress space before significant destructuration takes place. Study of the behaviour of three soft clays with low to medium sensitivities; Sibari, Bothkennar and Pisa clays, demonstrated that sensitivity changes in parallel with destructuration during both volumetric compression and undrained shearing such that there is a single expression that directly relates change in normalised sensitivity to change in damage strain, where the increment of damage strain is the magnitude of the vector of plastic strain increment. This destructuration law was used to extend an existing model, the Three-surface kinematic hardening (3-SKH) model which was developed by Stallebrass & Taylor (1997) for reconstituted clays. The new model requires only three new parameters to represent structure and its degradation that can each be derived from data from a single isotropic compression test. They are: the initial sensitivity, which represents the initial degree of structure in the natural clay; the ultimate sensitivity, which represents the stable elements of structure in the clay; and the parameter k, which controls the rate of destructuration with plastic strains. The other parameters used are the same as in the 3-SKH model and are derived from data from tests on the corresponding reconstituted clay. The model was evaluated against data from tests on Bothkennar and Pisa clay. Qualitatively, the model could predict the important features of behaviour observed in these clays. Quantitatively, results of analyses showed that determining initial sensitivity in a consistent way by using the Sensitivity framework leads to predicted values of undrained shear strength within 10 to 20% of the experimental values. Typically destructuration was correctly predicted in analyses simulating volumetric compression, but it was over-predicted by about 15 to 25% in analyses simulating undrained tests. This could be improved in some cases by using an ultimate sensitivity greater than unity in analyses simulating tests on specimens that are likely to have stable elements of structure arising from fabric. Structural anisotropy seemed to influence the behaviour of Pisa clay, and a model including structural anisotropy may improve predictions on such soils. The main limitation of the current research is the difficulty in determining the initial stress state and sensitivity to be used in the analyses; improvement of this should be the prime aim of further work.

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43

Saffarzadeh, Morteza. "Engineering behaviour and microfabrics of clays and silts". Thesis, University of East Anglia, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386038.

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44

Warburton, C. I. "Preparation and characterisation of zirconium pillared interlayered clays". Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356081.

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45

Charles, Kate Elizabeth. "Synthesis, chemical tailoring and characterisation of smectite clays". Thesis, University of Exeter, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263146.

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46

Rummey, Jacqueline Michelle. "EXAFS studies of polyoxometallates and chromium pillared clays". Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305565.

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47

Wilson, Justin Benedict. "Shrink/swell potential of some British Mesozoic clays". Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266907.

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48

Kantartzi, Christina. "Ground movements during diaphragm wall installation in clays". Thesis, Queen Mary, University of London, 1993. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1532.

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Diaphragm walls are being used increasingly in connection with building basements and road improvement schemes, particularly in urban areas. Many of these walls retain overconsolidated clay, and the magnitude of the lateral stresses which will act on the wall under service conditions is uncertain. One of the reasons for this is that, although the initial in situ lateral effective earth pressures in an overconsolidated clay deposit will be high, they will be affected to some extent by the process of installation of the wall. Stress relief which occurs during installation should be taken into account, since it will influence the starting point for analysis of the post-construction behaviour. Ground movements which occur during installation are important in their own right, and might for a diaphragmtype retaining wall be more significant than those which occur during and after excavation in front of the wall. The investigation of this problem using a centrifuge modelling technique is the principal aim of the current research. An extensive literature review has been carried out to collate field data concerning the stress history and in situ lateral stresses of overconsolidated clay deposits. These were used to confirm that the proposed centrifuge modelling technique would achieve realistic stress states and changes in stress. A series of centrifuge tests has been carried out at the London Geotechnical Centrifuge Centre (operated jointly by Queen Mary & Westfield College and City University), on samples of overconsolidated speswhite kaolin, simulating the effects of excavation under a slurry trench and concreting the diaphragm wall. The background to the tests, and the geometry and design of the model are discussed. The influence of the groundwater level and panel width on ground movements and changes in pore water pressures during diaphragm wall installation have been investigated, and the results are presented. The centrifuge test results are compared with field data from various sites. The development of a simplified analytical method is presented, which may be used to estimate the installation effects of diaphragm walls in clay. The results of this analysis are compared with the centrifuge test results and field data. Finally, some areas of continuing uncertainty are highlighted and some suggestions for further research are made.

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49

MARTINS, THAIS KLEIN FORNAZELLI. "INTRINSIC COMPRESSIBILITY CHARACTERISTICS OF TWO COASTAL BRAZILIAN CLAYS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36620@1.

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Abstract (sommario):

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Um grande movimento de massa ocorrido em 28 de Março de 2013 no Porto de Santana, na região da foz do Rio Amazonas, no Amapá, motivou o estudo das características de compressibilidade de argilas moles a partir do material reconstituído. Os solos naturais diferem dos solos reconstituídos devido à influência da micro e macroestrutura. O conceito de linha de compressão intrínseca (ICL) proposto por Burland (1990) permite uma avaliação quantitativa da diferença no comportamento de compressão do solo nestas duas condições. Neste estudo, são analisados dois depósitos de solo mole da costa brasileira (Tijucas, SC e Porto de Santana, AP) e uma mistura artificial obtida em laboratório com caulim e bentonita na proporção de 98:2 em peso. Um total de 8 amostras são reconstituídas com teor de umidade igual a 1,25 vezes o limite de liquidez e submetidas a ensaios convencionais de adensamento (SIC - standard incremental consolidation tests). As curvas de adensamento das amostras reconstituídas apresentam boa concordância com a ICL proposta por Burland (1990), principalmente no intervalo de tensões de 100 a 1.000kPa. As análises evidenciam a presença de estrutura do solo natural, sendo encontrada uma maior influência nas argilas do Porto de Santana, as quais apresentam índice de vazios normalizado (Iv) de até 1,85. As correlações empíricas para obtenção dos parâmetros intrínsecos de compressibilidade e100 e Cc propostas por Burland (1990) não apresentaram bons ajustes para os resultados experimentais aqui reportados.
A large mass movement occurred on March 28, 2013 at the Port of Santana, in the region of the mouth of the Amazon River in Amapá, motivated the study of compressibility characteristics of soft clays from the reconstituted material. Natural soils differ from reconstituted soils due to the influence of micro and macrostructure. The concept of the intrinsic compression line (ICL) proposed by Burland (1990) allows a quantitative evaluation of the difference in soil compression behavior in these two conditions. In this study, two soft clay deposits of the Brazilian coast (Tijucas, SC and Porto de Santana, AP) were analyzed and an artificial mixture made in the laboratory with kaolin and bentonite in the proportion of 98: 2 by weight. A total of 8 samples are reconstituted with moisture content equal to 1.25 times the liquid limit and subjected to conventional consolidation tests (SIC - standard incremental consolidation tests). The consolidation curves of the reconstituted samples show good agreement with the ICL proposed by Burland (1990), especially in the stress range of 100 to 1,000 kPa. The analyzes show the presence of natural soil structure, with a higher influence in the Santana Port clays which have a normalized void index (Iv) up to 1.85. The empirical correlations to obtain the intrinsic parameters of compressibility e 100 and Cc proposed by Burland (1990) did not present good adjustments for the experimental results here reported.

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50

Pestana-Nascimento, Juan Manuel. "A unified constitutive model for clays and sands". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11724.

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