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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Geotechnical Investigations of Wind Turbine Foundations Using Multichannel Analysis of Surface Waves (MASW)

Hicks, Malcolm Andrew January 2011 (has links)
The geophysical technique known as Multichannel Analysis of Surface Waves, or MASW (Park et al., 1999) is a relatively new seismic characterisation method which utilises Rayleigh waves propagation. With MASW, the frequency dependent, planar travelling Rayleigh waves are created by a seismic source and then measured by an array of geophone receivers. The recorded data is used to image characteristics of the subsurface. This thesis explains how MASW was used as a geotechnical investigation tool on windfarms in the lower North Island, New Zealand, to determine the stiffness of the subsurface at each wind turbine site. Shear‐wave velocity (VS) profiles at each site were determined through the processing of the MASW data, which were then used to determine physical properties of the underlying, weathered greywacke. The primary research site, the Te Rere Hau Windfarm in the Tararua Ranges of the North Island, is situated within the Esk Head Belt of Torlesse greywacke (Lee & Begg, 2002). Due to the high level of tectonic activity in the area, along with the high rates of weathering, the greywacke material onsite is highly fractured and weathering grades vary significantly, both vertically and laterally. MASW was performed to characterise the physical properties at each turbine site through the weathering profile. The final dataset included 1‐dimensional MASW shear‐wave evaluations from 100 turbine sites. In addition, Poisson’s ratio and density values were characterised through the weathering profile for the weathered greywacke. During the geotechnical foundation design at the Te Rere Hau Windfarm site, a method of converting shear wave velocity profiles was utilised. MASW surveying was used to determine VS profiles with depth, which were converted to elastic modulus profiles, with the input parameters of Poisson’s ratio and density. This study focuses on refining and improving the current method used for calculating elastic modulus values from shear‐wave velocities, primarily by improving the accuracy of the input parameters used in the calculation. Through the analysis of both geotechnical and geophysical data, the significant influence of overburden pressure, or depth, on the shear wave velocity was identified. Through each of the weathering grades, there was a non‐linear increase in shear wave velocity with depth. This highlights the need for overburden pressure conditions to be considered before assigning characteristic shear wave velocity values to different lithologies. Further to the dataset analysis of geotechnical and geophysical information, a multiple variant non‐linear regression analysis was performed on the three variables of shear wave velocity, depth and weathering grade. This produced a predictive equation for determining shear wave velocity within the Esk Head belt ‘greywacke’ when depth and weathering data are known. If the insitu geological conditions are not comparable to that of the windfarm sites in this study, a set of guidelines have been developed, detailing the most efficient and cost effective method of using MASW surveying to calculate the elastic modulus through the depth profile of an investigation site.
2

Depositional Mechanism of Greywackes, Clorindorme Formation (Middle Ordovician), Gaspé, Quebec

Parkash, Barham 05 1900 (has links)
<p> Sedimentary structures, textures and fabric were studied in detail in eight turbidite greywacke beds from the Cloridorme Formation (Middle Ordovician), Gaspe, Quebec. The beds are exposed on the wave-cut platform near Grande Vallee and were traced for about two miles along the strike (276 degrees), which is parallel to the average current direction (274 degrees) as indicated by sole mark directions. </p> <p> The beds under study show the following systematic downcurrent changes along the strike from east to west: (i) Sole mark types show the following changes: (1) tool marks such as grooves, prod marks and isolated flute marks, to (2) longitudinal ridges, longitudinal ridges with overlapping flute, closely spaced flutes, to (3) poorly developed, shallow longitudinal ridges with occasional cuspate crossing bars, to (4) smooth bottom with occasional grooves. (ii) There is an increase in variance of sole mark directions without a large change in the mean direction in most beds, but the sole mark direction changes by nearly 90° as one of the beds is traced from east to west along the strike. (iii) Most of the beds are massive and are divided into two parts by a bedding joint. However, in the proximal region, if a bed is unusually thin, the bedding joint is absent and the bed shows slightly wavy, plane-laminated structure at places. (iv) Grain orientations are generally statistically non-significant in the upper massive part of the bed in the proximal region and significant in the rest of the bed. Significant grain orientations and graptolite orientations show large deviations from the sole in the distal region. Deviations increase towards the top of the bed. (v) The beds show a change from good grading to poor grading or slight reverse grading from the proximal to distal region. It is considered that the beds were deposited by low concentration, highly turbulent currents. Deposition of the beds took place in two distinct phases. First a 'quick' bed separated from the current was sheared extensively by the overflowing current and on consolidation formed the lower part of the bed. Later deposition in the proximal region from the upper part of the current and the part close to the tail was by settling of individual particles from the suspension. Separation and consolidation of another 'quick' bed in some cases formed the upper part of the beds in the distal region. </p> <p> The depositing currents produced a good vertical and lateral grain size grading in the proximal region, but poor vertical grading in the distal region due to the loss of coarse grains and possibly increased concentration of flocculated clay. Also, the turbidity currents tended to "meander" greatly on slowing down in the distal region. </p> / Thesis / Doctor of Philosophy (PhD)
3

Petrology And Geochemistry of The 1308 Lake Sill, Beechey Lake Area, District of Mackenzie, Northwest Territories / Petrology of The 1308 Lake Sill, Beechey Lake Area, N.W.T.

Collver, Timothy 04 1900 (has links)
<p> A gabbroic intrusion within the Goulburn group of sediments near the west margin of Bathurst trench was studied and mapped using a TV-1 scintillometer. Petrographic examination of the sill was carried out and geochemical whole rock and trace element data were obtained using X.R.F. methods. </p> <p> The 1308 Lake sill was injected conformably between the Western River (argillite/greywacke) and Burnside River (pink quartzite) units of the Goulburn group of sediments. The sill subsequently underwent minor fractional crystallization and differentiation. Generally the sill exhibits poor phase layering, but can be divided into six basic units. </p> 1) Upper Chilled Margin Gabbro 2) Leuco-Micro-Syenite Lens 3) Diabasic Gabbro 4) Pyroxene Granophyre 5) Diabasic Gabbro 6) Basal Sheared Chilled Margin Gabbro These units are evident in this section and are distinguishable both modally and texturally. In most cases, variations in the chemistry and norms reflect the units mapped in the field. Comparisons have been drawn and theories incorporated from other gabbroic intrusions to help explain some features of the 1308 Lake sill. </p> / Thesis / Bachelor of Arts (BA)
4

Les scarabées inscrits et autres amulettes de cœur de l’Égypte ancienne (présentation, corpus, critères de datation, caractéristiques, collections) / Inscribed Scarabs and other Heart Amulets in Ancient Egypt (Presentation, Corpus, Dating criteria, Characteristics, Collections)

Laroche, Claude 06 December 2014 (has links)
Le seul ouvrage dédié exclusivement à ce qu’il est convenu d’appeler « les scarabées de cœur » est signé du Professeur Michel Malaise et date de 1978. Ce livre est depuis cette date la référence en la matière mais, en l’absence d’un corpus, les critères de datation proposés n’y peuvent être ni exhaustifs ni très précis. L’objectif de cette étude était de remédier à ces lacunes.Les scarabées de cœur étaient des amulettes disposées dans la région du cœur de la momie d’un individu, juste après son décès, afin de le protéger contre la trahison possible de son propre cœur. En effet, le défunt devait subir l’épreuve de la pesée du cœur devant un tribunal de dieux présidé par Osiris, mais c’est son cœur qui était interrogé pour savoir quelle avait été la conduite de son propriétaire lors de son passage sur la terre. Les réponses à ces questions conditionnaient l’avenir du défunt dans l’au-delà : la vie éternelle ou l’anéantissement. Pour se concilier les bonnes grâces du cœur, d’autant plus que celui-ci pouvait mentir, les amulettes étaient inscrites d’une prière choisie dans un des chapitres 26 à 30 B du Livre des Morts, suppliant le cœur d’avoir des réponses favorables devant le tribunal.La présente étude a pris huit années pour rassembler un corpus de 1400 scarabées de cœur et autres amulettes ayant la même fonction rituelle, soit probablement plus de 85% de ceux qui sont conservés dans les musées, qui sont désignés ici sous le nom générique d’« amulettes de cœur ». Ce corpus a donné lieu à l’établissement d’une typologie permettant de déterminer des séries d’amulettes présentant des caractèristiques plastiques et épigraphiques semblables qui, croisées avec celles des amulettes de date connue, qui sont soit celles dont les propriétaires sont des personnages historiques soit celles provenant de fouilles bien datées, ont conduit à la détermination de critères de datation objectifs. L’étude présente aussi les clichés de plus de 1200 amulettes avec description, une traduction des textes inscrits et une proposition de datation. / The only book dealing specifically with the so-called “ Heart Scarabs” was written by Professor Michel Malaise and published in 1978. It has remained since the reference on the subject but, due to the unavailibility of a corpus, the datation criteria could not be exhaustive nor accurate. The target of this dissertation was to fill these gaps. The heart scarabs were amulets to be laid on (or in) the mummy of a person just after his death in the heart area, in order to protect him from the possible treachery of his own heart. In effect, the Dead was to be put to the test of the weighing of his heart, in front of a court of gods presided by Osiris, but it was his hesart which was interrrogated in order to know whether its owner had behaved well during his life. The answers to these questions would determine whether he would be granted an eternal life or the nothingness. In order fo gain the heart’s goodwill, especially when it might lie, the amulets were inscribed with a prayer chosen in one of the chapters 26 to 30B of The Book of the Dead. This prayer was begging his heart to make favorable answers to the court.It took eight years to gather a corpus of 1400 heart amulets and others amulets with the same ritual function, called “heart amulets” in this dissertation, a number representing likely more than 85% of the total in existence. The gathering of these amulets made possible an adapted typology to be built, which lead to the determination of series of amulets with similar shape or epigraphic characteristics to be compared with the characteristics of amulets with a known date, which are the ones the owners of which are historical persons or those originating from well dated excavations. This comparison allowed for the determination of objective datation criteria. This memoire finally presents photos of more than 1200 amulets with a description, a translation of the texts and an estimated datation.
5

Rock mass strength and deformability of unweathered closely jointed New Zealand greywacke

Stewart, Scott William January 2007 (has links)
Closely jointed greywacke rock masses are widespread throughout both the North and South Islands of New Zealand and much of New Zealand's infrastructure is constructed upon greywacke rock masses. This thesis deals with determining the rock mass strength of unweathered closely jointed New Zealand greywacke rock masses. Currently, the estimation of rock mass strength and deformability is reasonably well predicted through the use of such empirical failure criteria as the Hoek-Brown failure criterion and empirical expressions to predict deformability. However, previous studies upon predicting the strength and deformability of unweathered closely jointed New Zealand greywacke rock masses has shown that existing empirical methods of determining strength and deformability are unsatisfactory. The problem with predicting rock mass strength and deformability moduli of New Zealand greywacke and the lack of adequate data to calibrate a failure criterion was the starting point for this work. The objective of this thesis was to increase the knowledge of intact and defect properties of closely jointed greywacke, develop reliable rock mass data with which to calibrate a failure criterion and improve the ability to estimate the rock mass strength of greywacke rock masses. A review of existing failure criteria for rock masses was conducted and of these criteria, the Hoek-Brown rock mass failure criteria was selected to calibrate to both the intact rock and rock mass failure data, because of its broad acceptance in the rock mechanics community. A database of greywacke properties was developed based on previous studies upon unweathered greywacke around New Zealand and is attached to the thesis as an Appendix. The database included descriptions of greywacke defect properties and mechanical properties of the intact rock and joints. From this database, inputs could be justified for numerical modelling and later analyses of failure criteria. Records from the construction archives of the Benmore and Aviemore hydroelectric power projects in the South Island of New Zealand were reviewed to obtain information and results from a series of shear tests carried out on unweathered closely jointed greywacke in the 1960s. Data on rock mass strength at failure and rock mass deformability were extracted from these records to assess the predictability of the failure criterion and deformability expressions. Problems experienced during the shear tests at the Aviemore dam site created doubt as to the actual rock mass strengths achieved at failure. The behaviour of these tests was studied using the finite difference code FLAC. The work was aimed at investigating the potential for transfer of shear force between the two concrete blocks sheared in each test and the impact shear force transfer had upon the likely normal stresses beneath each block at failure. The numerical modelling results indicated that a combination of preferential failure occurring in one direction, and doubt in the actual normal load applied to the concrete blocks during testing lead to premature failure in the blocks sheared upstream. The blocks sheared in the opposite direction failed at normal stresses that are reflective of the strength of an unweathered greywacke rock mass, but these results could be explained by failure occurring along defects therefore not satisfying the assumptions of homogeneity typically required of a rock mass failure criterion. The Hoek-Brown failure criterion for intact rock was investigated by fitting it to the largest intact greywacke datasets. For a full set of test data (i.e. including tensile data), the Mostyn & Douglas (2000) variant of the Hoek-Brown failure criterion gave the best fit for a full set of rock mass data. A multiple regression method was developed which improved the fitted curve to intact data in the tensile region and gave the best estimate of tensile strength if no existing lab results for tensile strength were available. These results suggest that the Hoek-Brown failure criterion is significantly limited in its applicability to intact NZ greywacke rock. Hoek-Brown input parameters different to those suggested by Hoek et al (2002) are recommended for using the Hoek-Brown failure criterion for intact NZ greywacke. For closely jointed NZ greywacke rock masses, the results from the shear tests at Aviemore and Benmore were separated into different GSI classes and Hoek-Brown envelopes fitted to the datasets by multiple regression. Revised expressions were proposed for each Hoek-Brown input parameter (mb, s, ab) as a function of the GSI. The resulting revised Hoek-Brown failure envelopes for NZ greywacke offer a significant improvement on the existing criterion used to predict the strength of NZ greywacke intact rock and rock masses. The differences in the behaviour of the reaction blocks that failed before the test blocks and the reduction in rock strength due to sliding along defects from that predicted could be reasoned from recorded observations and the behaviour of the concrete blocks during the shear tests. This study has clearly illustrated the need for continued research in this area. This includes (1) a means of assessing the role of defects upon the shear strength of closely jointed greywacke rock mass into a failure criterion, (2) further modelling of the in-situ shear tests by a discrete element procedure to expressly determine the role of the defect on failure, (3) more testing on rock masses to obtain more data to calibrate a rock mass failure criterion, and (4) more studies on predicting the strength of extremely disturbed rock masses.
6

Deformace, metamorfóza a metasomatóza v gemersko-veporské kontaktní zóně v Západních Karpatech a možné vazby na Greywacke Zone ve Východních Alpách / Deformation, metamorphism and metasomatism in the Gemer-Vepor Contact Zone in the Western Carpathians and the possible links to the Greywacke Zone in the Eastern Alps

Novotná, Nikol January 2019 (has links)
The studied area extends from the Ochtiná Unit in Western Carpathians to the Veitsch Nappe Eastern Alps. The thesis represents a complex multidisciplinary work that combines the structural analysis, petrology and geochronology. The three main objectives of this thesis: reevaluation of the structure, deformation and metamorphic records, and original position of the Ochtiná Unit, understanding the distinct metasomatic processes recorded along the contact of two major units of the Central Western Carpathians - in the Gemer-Vepor Contact Zone - and their relation to distinct tectono-metamorphic events, testing the possible links between the Ochtiná Unit in the Gemer-Vepor Contact Zone of the Western Carpathians and the Veitsch Nappe in the Greywacke Zone of the Easten Alps, both well known for the Lower Carboniferous shale/schist sequence accompanied by the abundant presence of magnesite ore bodies. Keywords: Central Western Carpathians, Greywacke Zone, Ochtiná Unit, Veitsch Nappe, U-Pb zircon dating, Phase equilibrium modelling

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