In simulation of closely- or separately-joined rock masses, stability of rock blocks is of primary concern. However, there seems to be no approach that can handle general modes of simultaneous sliding and truly large rotation under general forces, including non-conservative forces such as water forces. General causes of failure for rock blocks, such as limit points, bifurcation points, and dynamic instability (divergence and flutter), have never been addressed. This research implements a formulation, called BS3D(an incremental-iterative algorithm introduced by Tonon), for analyzing general failure modes of rock blocks under conservative and non-conservative forces. Among the constitutive models for rock fractures developed over the years, Barton's empirical model has been widely used because it is easy to apply and includes several important factors associated with fracture characteristics. Although Barton's failure criterion predicts peak shear strength of rock fractures with acceptable precision, it has some weaknesses in estimating the peak shear displacement, post-peak shear strength, dilation, and surface degradation in unloading and reloading. In this dissertation, modifications are made to Barton's original model in order to address these weaknesses. The modified Barton’s model is validated by a series of direct shear tests on rock fractures and implemented in BS3D to consider the dilatant behavior of fractures. The mechanical behavior of a rock block formed in the roof of a tunnel is governed by its geometry, the mechanical characteristics and the deformability of the fractures forming the block, the deformability of the block and that of the surrounding rock mass, and the stresses within the rock. BS3D, after verification and validation, is used to investigate the effect of dilatancy on stability of rock blocks formed in the roof of a circular tunnel. High-velocity plunging jets, issuing from hydraulic artificial or natural structures, can result in scouring of the rock riverbed or the dam toe foundation. Assessment of the extent of scour is necessary to ensure the safety of the dam and to guarantee the stability of its abutments. BS3D is used to investigate effect of high-velocity jet impact on stability of rock blocks in plunge pools. / text

Fractures can increase the permeability and producability of reservoirs by acting as fluid and gas conduits to wells. Networks of fractures are most important in reservoirs where little to no matrix permeability exists such as tight gas sandstones. Two significant variables, fracture length and the abundance of fractures, are not readily measurable from subsurface observations such as those obtained from cores or well logs. Numerical models suggest natural fracture apertures and lengths follow systematic power-law (Marrett, 1996; Olson, 2007) and negative exponential distributions (Olson, 2004); fracture trace lengths are interrogated. This study tests those propositions through study of fractures in outcrop. Outcrops of the Cretaceous Frontier Formation at Oyster Ridge in southwest Wyoming and Oil Mountain near Casper, in central Wyoming provide evidence of reservoir scale fracture networks in sandstones. In the subsurface the Frontier Formation sandstones are reservoirs that produce gas and oil in several Wyoming basins. I mapped fracture patterns at twenty locations at Oyster Ridge and Oil Mountain and measured fracture trace length distributions and abundance (intensity). Fracture cumulative length distribution plots illustrate systematic length distributions. Trace length distributions of every fracture network follow negative exponential distributions regardless of the number of fractures (N = 39 to N = 394) or the size of the outcrop (1.3 to 710 m²). Results show that the fractures follow a negative exponential distribution over a range of lengths of a few centimeters to tens of meters. These trace length distributions are consistent with geomechanical model fracture pattern simulation results by Olson (2004) that suggests negative exponential trace length distribution result from fracture to fracture interaction during fracture formation. Length distributions from my field study are inconsistent with pattern simulation results by Marrett (1996) and Olson (2007) and others that produce power-law length distributions. This inconsistency suggests that the model assumptions of Olson (2004) best account for the patterns I observed. Two dimensional fracture intensity, defined as the total fracture trace length divided by the map area, was measured for each outcrop to determine how structural position affects fracture abundance patterns. Two-dimensional fracture intensity measurements collected at thirteen structural locations around Oil Mountain show higher values of fracture intensity near the fold-axial-trace compared to fold limbs. The difference is as much as 7.4 fractures per meter near fold hinges compared to 0.63 fractures per meter in fold limbs. Outcrops near small faults, with displacement of a few meters, show an increase in fracture intensity from background values around 4.8 fractures per meter to values nearly three times as high (13 fractures per meter) near faults. Values of fracture intensity that are more elevated near small tear faults imply that faulting has a greater influence on fracture intensity than folding. / text

Defects in bone are a constant and serious problem. They occur as a result of high energy trauma, congenital conditions or are created surgically to treat bone tumours or infection. Currently the treatment for these conditions is awkward for the patient, takes a long time and has a high complication rate. An elegant solution would be to mend the bone defect using the patient own cells; osteoblasts or mesenchymal stem cells seeded onto a supportive material scaffold. For successful regeneration of bone structures, a scaffold production technique has to be adopted that can precisely control porosity, internal pore architecture and fibre thickness, as well as maximising media diffusion and optimising scaffold mechanical properties so that the scaffold can withstand bone bearing pressures. It would also be beneficial if the scaffold uniformly distributed surface strain along the fibres throughout the entire scaffold as this would encourage more even cell proliferation/differentiation in the structure. This was addressed by performing a series of finite element analyses on the computer aided design model where the mechanical properties of the natural or synthetic polymer used have been incorporated to yield an accurate strain profile of the entire scaffold. The process used here to generate the scaffolds is a Rapid Prototyping method that creates a three-dimensional object through the repetitive deposition of fibres in layers via extrusion. Due to the high accuracy and versatility of the extruder, the diameter of the pores can be precisely controlled to an accuracy of 10μm, in the manufactured scaffolds the pore size ranges from 100 to 300μm as that is what is found in trabecular bone. Natural and synthetic polymers were plotted which altered the biodegradability properties of the scaffold and the degrees of cell adhesion, proliferation and differentiation in the structure. Scaffolds were manufactured that demonstrated compatibility with cell adhesion, proliferation and osteogenic differentiation. On completion of the scaffolds, the latter were seeded with osteoblasts or marrow stromal cells and put into a mechanically stimulating bioreactor machine to induce a small strain in the scaffold; this was performed to encourage cell proliferation/differentiation. The structure was left until the osteoblasts or marrow stromal cells modified the scaffold through bone deposition. In-vivo experiments were then undertaken. Preliminary data indicated an effect of mechanical stimulation of the cell/scaffold construct on the degree of mineralization of cell matrix generated by human osteogenic cells.

The West Elk Breccia has been studied since the late 1800’s with many interpretations regarding its origin. One unrecognized possibility is that parts of it are debris-avalanche deposits. This study has recognized evidence for this interpretation at three scales: volcano scale, outcrop scale, and intra-outcrop scale. At the volcano scale, a scarp in the old volcano reveals underlying Mesozoic bedrock, suggesting sector collapse. At the outcrop scale, megablocks of the original edifice, up to hundreds of meters in length, have atypical orientations and are surrounded by a gravel matrix. At the intra-outcrop scale, jigsaw-fit fracturing and rip-up clasts are common in distal deposits, which are documented in analogous debris-avalanche deposits. Similar to the debris-avalanche deposit at Mt. Shasta, medial-to-distal-matrix volcaniclast content decreases by 23%; Paleozoic and Mesozoic clasts increase by 5%; and the size of megablocks decreases. The geochemical and petrographic signatures reveal breccia blocks composed of pyroxene-andesite, a more silicic matrix facies, and the andesitic-to-dacitic East Elk Creek Tuff, all compositions that corroborate previous work on this northern extension of the San Juan volcanic field. Measured sections in the 100-km² study area allow for an estimation of total formation volume of approximately 8.5 km3.

Aufgrund der Tatsache, dass die Wahl der Therapie bei Wirbelfrakturen der Klasse A3 nach Magerl et al. (1994) weiterhin kontrovers diskutiert wird, wurden in dieser Arbeit die Patientenfälle der Abteilung Orthopädie und Unfallchirurgie der Universitätsmedizin Göttingen betrachtet, die im Zeitraum von 2008 bis 2013 eine Wirbelfraktur im Bereich der Brust- und Lendenwirbelsäule erlitten. Das gesamte Kollektiv umfasst 475 Patienten, von denen 266 männlich und 209 weiblich sind. Es wurden objektive Daten wie GDW, Kyphosewinkel und Wirbelkörperhöhenminderung zu fest definierten Zeitpunkten erhoben. Anhand dieser Daten konnte der Verlauf der Stabilität und sowohl der Korrekturgewinn durch die Therapie als auch der Korrekturverlust während der Nachsorge für die jeweiligen Therapiemethoden erfasst werden. Die Therapiemethoden, die hier verglichen werden, sind die konservative Therapie, die Kyphoplastie, die dorsale und die kombiniert dorsoventrale Stabilisierung. Die in der radiologischen Verlaufskontrolle erhobenen Parameter zeigen, dass bei Frakturen der Klassen A1 und A2, die als stabil gelten, die konservative Therapie zu einem guten Ergebnis führt. Bei A3- Frakturen, bei denen in der internationalen Literatur starke Unstimmigkeit darüber besteht, ob diese Frakturen als stabil oder instabil gelten und wie solche Frakturen im allgemeinen zu behandeln sind, bringt die operative Vorgehensweise klare Vorteile. Zudem können bei kombiniert dorsoventraler Operation noch stabilere Ergebnisse erzielt werden. Für die Rotationsfrakturen stellt sich heraus, dass nach der Entfernung des eingebrachten Osteosynthesematerials ein größerer Korrekturverlust eintritt. Abschließend lässt sich sagen, dass bei isolierten Berstungsfrakturen ohne Beteiligung des Bandapparates die Indikation für die kombiniert dorsoventrale Operation häufiger und frühzeitiger gestellt werden sollte. Außerdem sollte beachtet werden, dass bei instabilen Frakturen die Verlängerung der Tragezeit des Fixateurs einen positiven Einfluss auf den Korrekturerhalt hat.

Small mammals, namely those species larger than microfauna like rats and murids but smaller than medium, sheep-size fauna, are generally one of the less studied areas of zooarchaeology. While this may be partly influenced by modern cultural biases, it is more often because finding small, rabbit-sized, mammal remains in archaeological deposits presents a problem in accurately differentiating between those arising from natural, biological and anthropogenic agencies. This thesis tackles this subject using a synthesis of different methods, examining the exploitation and role of small, non-ungulate mammals in early Western European prehistory by combining existing ethnographic knowledge and archaeological research with actualistic experiments and bone assemblage analysis. It first presents a detailed summary of the various taphonomic effects on bone from natural, biological and human action, with particular reference to those of small mammals, using empirical evidence to describe the processes and likely resultant effects. Small mammal utilisation is then contextualised using archaeological and ethnographic evidence to examine past and present practices in Europe and other areas of the world. Different acquisition methods, such as hunting and trapping, are described, and using small mammals for dietary and non-dietary purposes is outlined, along with the rationale for such utilisation given their size. Also considered are other, more abstract ideological and symbolic roles they fulfilled within different cultures, whether physically using parts of the animal, or conceptually. To extend the existing methods available to zooarchaeologists, and improve identifying human exploitation of these species, the ‘chaîne opératoire’ of small game use is examined from an osteological perspective, starting with acquisition, through processing, cooking and consumption to discard, using a series of experiments and microscopic analysis to explore potential bone modification signatures and fracture patterns arising from such activities. Finally, it places these results into broader context by comparing the fracture patterns with bones from British and North American archaeological sites, to demonstrate that similar changes can be seen.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

This study focuses on numerical modeling of fluid flow and solute transport in rough-walled rock fractures and fracture-matrix systems, with the main aim to investigate the impacts of fracture surface roughness on flow and transport processes in rock fractures. Both 2D and 3D fracture models were built from laser-scanned surface tomography of a real granite rock sample, to consider realistic features of surface tomography and potential asperity contacts. The flow was simulated by directly solving the Navier-Stokes equations (NSE) and the transport was modeled by solving the advection-dispersion equation (ADE) in the entire domain of fracture-matrix system, including matrix diffusion process. Such direct simulations provided detailed flow and concentration fields for quantitatively analysis of flow and transport behavior. The detailed analysis of surface roughness decomposition, complex flow patterns (i.e., channeling, transverse and eddy flows), effective advective flow apertures, effective transmissivity, effective dispersivity, residence time, transport resistance and specific surface area demonstrated significant impacts of realistic fracture surface roughness on fluid flow and solute transport processes in rock fractures. The results show that the surface roughness and shear displacement caused asperity contacts significantly enhance nonlinearity and complexity of flow and transport processes in rough-walled fractures and fracture-matrix systems. The surface roughness also causes invasion flows in intersected fractures which enhance solute mixing at fracture intersections. Therefore, the fracture surface roughness is an important source of uncertainty in application of such simplified models like cubic law (CL) for fluid flow and analytical solutions for solute transport in rock fractures. The research conducted advances our understanding of realistic flow and transport processes in natural fractured rocks. The results are useful for model validation/extension, uncertainty analysis/quantification and laboratory experiments design in the context of various applications related to fracture flow and transport. / Denna studie fokuserar på numerisk modellering av vätskeflöde och transport av lösta ämnen i frakturer med ojämna väggar samt fraktur-matrissystem, med det huvudsakliga syftet att undersöka effekterna av frakturernas ytjämnhet på flödes- och transportprocesser i bergsfrakturer. Både 2D och 3D modeller skapades utifrån laser skannad tomografi av ett verkligt bergartsprov av granit, för att överväga de realistiska egenskaperna hos ytan och potentiell skrovlighet. Flödet simulerades genom att lösa Navier-Stokes ekvationer (NSE) och transporten modellerades genom att lösa advektion-dispersion ekvation (ADE) i hela domänen av fraktur-matrissystemet, inklusive diffusions process i matrisen. Sådana direkta simuleringar resulterade i detaljerade flödes- och koncentrationsfält för att kvantitativt kunna analysera flödet och transportbeteendet. En detaljerad analys av upplösningen av ytjämnhet, komplexa flödesmönster (dvs kanalisering, tvärgående och virvelströmmar), effektiv advektiv flödesöppning, effektiv transmissivitet, effektiv dispersivitet, uppehållstid, transport motstånd och specifik yta visade signifikanta effekter av realistiska ojämna frakturväggar på vätskeflöde och lösta transportprocesser i bergssprickor. Resultaten visar att ytjämnhet och skjuvningssystemsorsakade asperitetskontakter avsevärt förbättrar olinjäritet och komplexitet av flödes- och transportprocesser i frakturer med ojämna väggar samt fraktur-matrissystem. Ytråheten orsakar också intrång av flöde i tvärgående frakturer vilket ökar blandingen av lösta ämnen i korsningarna. Därför är ytjämnhet av frakturerna en viktig källa till osäkerhet i tillämpningen av sådana förenklade modeller som kubisk lag (CL) för vätskeflöde och analytiska lösningar för transport av lösta ämnen i bergsfrakturer. Studien har ökat förståelsen för realistiska flödes- och transportprocesser i naturligt sprucket berg. Resultaten är användbara för modellvalidering/förlängning, osäkerhetsanalys/kvantifiering och design av laboratorieexperiment i samband med olika tillämpningar av flöde och transport i bergsfrakturer. / <p>QC 20161010</p>

Due to the demographic development osteopoorosis is an increasing serious medical and economical problem today in developed industrial countries including Czech republic. Fractures of the proximal femur in the elderly are one of the manifestations of the illness. Within the context of the pharmacological prevention we must consider carefully its contribution in comparison with costs of the fracture treatment in the hospital. This graduation theses deals with evaluation of expenses on the surgical treatment of these fractures and expenses on the pharmacological prevention using Fosamax. This comparison is made in economic situation in Czech republic in the end of the first decade of 21. century

L'objectif de cette thèse est de démontrer comment faire une analyse théorique de fatigue et de mécanique de la rupture d'une structure éolienne à l'axe horizontal. La chaîne des calculs nécessaires pour atteindre cet objectif s'avère être particulièrement longue pour deux raisons : d'abord, la vitesse du vent varie aléatoirement avec le temps ; deuxièmement, l'amplitude de vibration du mât est amplifié en raison des ses fréquences naturelles de vibration. Un chapitre entier est consacré à la modélisation de la vitesse du vent dans l'espace et dans le temps. Ce même chapitre démontre comment synthétiser un signal aléatoire à partir d'une fonction de densité spectrale de puissance (DSP). La force axiale du rotor est le chargement le plus important sur une structure éolienne à l'axe horizontal. Cette force a un rapport non linéaire avec la vitesse du vent. Cela implique la nécessité de déterminer la DSP de la force axiale à partir de son signal, en se servant d'une technique d'estimation spectrale. La méthode Thomson Multitaper s'est avéré la plus satisfaisante pour cette application. La DSP des déplacements du mât est déterminée en associant la réceptance du système structurel avec la DSP de la force qui représente tous les chargements. Un signal de contrainte peut finalement être synthétisé à partir de sa DSP. La technique de comptage de cycles de chargement connue sous le nom de rainflow est abordée et appliquée. Le fait que le signal de contraintes a une amplitude variable implique la nécessité d'employer une technique plus avancée de simulation de propagation de fissures. La technique choisie pour cette thèse est connue sous le nom de strip-yield (bande d'écoulement). / The objective of this thesis is to demonstrate how to do theoretical analyses of fatigue and fracture mechanics in a structure for horizontal axis wind turbine. The chain of calculations required to reach this objective is particularly long for two reasons : firstly, the wind speed varies randomly with time , secondly, the vibration amplitude of the mast is amplified due to its natural frequencies of vibration. A whole chapter is dedicated to modeling the wind speed in space and time. The same chapter shows how to synthesize a random signal by employing a power spectral density function (PSD). The axial force of the rotor is the most important loading on a structure for horizontal axis wind turbine. This force has a non linear relation with the wind speed. This implies the need to determine the PSD of the axial force from its signal, by employing a spectral estimation method. The Thomson Multitaper method revealed to be the most satisfactory for this application. The PSD of displacement of the mast is determined by associating the receptance of the structural system and the PSD of the force representing all loadings. Finally, a signal of stress can be synthesized from its PSD. The fatigue cycle counting method known as rainflow is discussed and employed. The fact that the signal of stress has a variable amplitude implies the need of a more sophisticated method to simulate a crack propagation. The method chosen in this thesis is called strip-yield.