Very intense pulse in the groundwater flow in fissurized-porous stratum

An asymptotic solution is obtained corresponding to a very intense pulse: a sudden strong increase and fast subsequent decrease of the water level at the boundary of semi-infinite fissurized-porous stratum. This flow is of practical interest: it gives a model of a groundwater flow after a high water period or after a failure of a dam around a collector of liquid waste. It is demonstrated that the fissures have a dramatic influence on the groundwater flow, increasing the penetration depth and speed of fluid penetration into the stratum. A characteristic property of the flow in fissurized-porous stratum is the rapid breakthrough of the fluid at the first stage deeply into the stratum via a system of cracks, feeding of porous blocks by the fluid in cracks, and at a later stage feeding of advancing fluid flow in fissures by the fluid, accumulated in porous blocks.

Seismic behavior of a masonry chimney with severe cracking condition: preliminary study

This paper presents a structural analysis of a masonry chimney built in the 1940s, which is currently being cataloged as local interest heritage. This structure has not served any industrial purpose for the last thirty years. The chimney is located in the town of Agost (Alicante - Spain) and directly exposed to the prevailing winds from the sea, as it is approximately 12 km away from the waterfront and there are not any significant barriers, which could protect the structure against the wind. There are longitudinal cracks and fissures all along the shaft because of the chimney’s geometrical characteristics, the effect of the masonry creep and especially the lack of maintenance. Moreover, there is also a permanent bending deformation in the upper 1/3 of the height due to the wind pressure. A numerical analysis for the static behavior against gravity and wind loads was performed using the structure’s current conditions after a detailed report of its geometry, its construction system and the cracking pattern. Afterwards, the dynamic behavior was studied, i.e. a seismic analysis using both response spectra and accelerograms in order to examine the structural stability. This work shows the pre-monitoring analysis before any experimental testing. Using the current results the future test conditions will be determined (e.g. number of sensors and monitoring point location, excitation systems, etc) prior to a possible structural reinforcement by applying composite material (fiber reinforced polymers).

Restoration of religious temples: intervention in the church “Nuestra Señora de Belén” in Crevillente (Alicante)

Heritage conservation has raised historical problems usually centered in defects resulting from water leaks. Thus, any intervention is presented as a difficult task, both due to building techniques to be used and the lack of economic resources in many cases. In relation to the temples existing in Alicante (Spain), water drainage is solved with pitched roofs on slope formation (in vaulted naves) or directly supported on the vaulted elements (in the domes). Since those construction systems are composed by brick and plaster, the presence of moisture is problematic, and represents a risk of losing the strength capacity and therefore the stability of the dome. An example of this problem is the dome of the church “Nuestra Señora de Belén” in Crevillente, built with solid bricks, it has the highest diameter of the province (18th century). This historic building has been restored on several occasions in the recent years due to moisture, cracks or fissures. The study of these works give an idea of the difficulties of maintenance, conservation and proper restoration of such kind of buildings as unique and valued constructions in our heritage.

Termografía infrarroja aplicada en cúpulas históricas: identificación y análisis de sistemas constructivos

El uso específico de la termografía infrarroja como técnica no destructiva permite el estudio de sistemas constructivos en edificios históricos (caracterización de materiales, disposición constructiva o identificación de elementos originales). Así, se muestra una aplicación práctica en templos en la provincia de Alicante construidos entre finales del siglo XVII y principios del xix, donde se analiza la complementariedad de las imágenes termográficas de 140 cúpulas (junto con datos recopilados in situ, dibujos originales y levantamiento de planos) como herramienta de estudio en fases de análisis previas a una restauración. En conclusión, la investigación detalla una aplicación termográfica al estudio de distintos aspectos como el reconocimiento de materiales empleados (90,71 % ladrillo macizo, 6,43 % ladrillo hueco y 2,86 % piedra), variaciones de espesor interior y exterior (75,71 % perfil apuntado, 17,86 % perfil semiesférico y 6,43 % perfil rebajado), caracterización de grietas/fisuras (estado de conservación) e identificación de cúpulas originales (96,43 %) o restauradas (3,57 %).

Imaging Land Subsidence Induced by Groundwater Extraction in Beijing (China) Using Satellite Radar Interferometry

Beijing is one of the most water-stressed cities in the world. Due to over-exploitation of groundwater, the Beijing region has been suffering from land subsidence since 1935. In this study, the Small Baseline InSAR technique has been employed to process Envisat ASAR images acquired between 2003 and 2010 and TerraSAR-X stripmap images collected from 2010 to 2011 to investigate land subsidence in the Beijing region. The maximum subsidence is seen in the eastern part of Beijing with a rate greater than 100 mm/year. Comparisons between InSAR and GPS derived subsidence rates show an RMS difference of 2.94 mm/year with a mean of 2.41 ± 1.84 mm/year. In addition, a high correlation was observed between InSAR subsidence rate maps derived from two different datasets (i.e., Envisat and TerraSAR-X). These demonstrate once again that InSAR is a powerful tool for monitoring land subsidence. InSAR derived subsidence rate maps have allowed for a comprehensive spatio-temporal analysis to identify the main triggering factors of land subsidence. Some interesting relationships in terms of land subsidence were found with groundwater level, active faults, accumulated soft soil thickness and different aquifer types. Furthermore, a relationship with the distances to pumping wells was also recognized in this work.

Split Ends

Thesis (Master's)--University of Washington, 2016-06

NMR imaging of the diffusion of water at 310 K into semi-IPNs of PEM and Poly(HEMA-co-THFMA)

Magnetic resonance imaging has been used to monitor the diffusion of water at 310 K into a series of semi-IPNs of poly(ethyl methacrylate), PEM, and copolymers of 2-hydroxyethyl methacrylate, HEMA, and tetrahydrofurfuryl methacrylate, THFMA. The diffusion was found to be well described by a Fickian kinetic model in the early stages of the water sorption process, and the diffusion coefficients were found to be slightly smaller than those for the copolymers of HEMA and THFMA, P(HEMA-co-THFMA), containing the same mole fraction of HEMA in the matrix. A second stage sorption process was identified in the later stage of water sorption by the PEM/PTHFMA semi-IPN and for the systems containing a P(HEMA-co-THFMA) component with a mole fraction HEMA of 0.6 or less. This was characterized by the presence of Water near the surface of the cylinders with a longer NMR T-2 relaxation time, which would be characteristic of mobile water, such as water present in large pores or surface fissures. The presence of the drug chlorhexidine in the polymer matrixes at a concentration of 5.625 wt % was found not to modify the properties significantly, but the diffusion coefficients for the water sorption were systematically smaller when the drug was present.

Petrology of weathered lower lias clays

In weak argillaceous rocks the unweathered strength may be barely sufficient to meet civil engineering reguirements and any reductjon due to weathering will be critical. This study investigates the weathering of the Lower Lias clays with particular reference to their petrography and engineering properties. Investigations revealed the Midland Basin of deposition to contain reasonable thicknesses of clay, relatively uniform in nature with a well developed weathered zone, From the available exposures, the weathering zone of the Blockley Clay pit was selected and sampled for laboratory investigations of; Structure, Mineralogy and Chemistry and Engineering Properties. The nature and orientation of the fissures in the unweathered clay were analysed. A close relationship was found to exist between the major joint set and the ground surface, with stress release due to excavation being almost negligible. Thin sections of the clay, examined for structural data, suggested that there exist layers or areas that have been disturbed as a result of density differences. Shear planes were found in both the unweathered and weathered clay, in the latter case often associated with remoulding of the material. A direct measure of remoulding was obtained from the birefringence ratio. The fabric was examined in closer detail using the scanning electron microscope. Mineralogy, as revealed by X-ray and optical techniques indicated illite as the dominant clay mineral, with kaolinite subsidiary; quartz, calcite, pyrite, chlorite/vermiculite are present as accessory minerals. Weathering changes this relationship, calcite and pyrite being removed early in the process, with illite being degraded. The cementing action of calcite and iron oxides was investigated however, this was shown to be negligible. Quantitative measurements of both fixed (with minerals) and free (oxide coatings) iron were obtained by atomic absorption, with the Fe 3+/ Fe2+ ratio obtained by Mossbauer spectroscopy, Evidence indicates that free iron oxide coatings only become important as a result of weathering with the maximum concentration in the very highly weathered material. Engineering index properties and shear strength values were taken throughout the profile, Relationships between moisture content and strength, liquid limit and iron (Fe) were obtained and a correlation between the weathering zomes and the shear strength/depth curve has been established.

Topographic studies of scalp potentials evoked by pattern presentation

The waveform and scalp distribution of the visual evoked potentials elicited by stimuli in the foveal and parafoveal regions have been investigated in a group of normal humans using a 16-channel `brain mapping' system. The waveform and topography of the responses to pattern onset and pattern reversal stimulation were investigated, using 4 x 4o full field and 4 x 2o lateral and altitudinal half-field stimuli. The responses were composed of several successive peaks which are in some respects consistent with those demonstrated by other workers using larger field sizes. The differences in the behaviour of these components with respect to the position of the stimulus in the visual field were suggestive of origins in different areas of the visual cortex and/or different visual mechanism. Of particular interest were the major early positive components `P90' and `P95' of the responses to pattern onset and pattern reversal stimulation respectively. More detailed exploration of the behaviour of these major early positive components was carried out using `M-scaled' stimuli selected to activate one square centimetre patches of striate cortex and associated extrastriate re-projections, positioned at different points in the foveal and parafoveal area of the visual field. The inter- and intra-subject variability in amplitude and localisation of the signals elicited by these targets was considered to be a reflection of the individual variations in relationship of visual field projections with the pattern of gyri and fissures on the proximal surface of the occipital lobe. The behaviour of component P90 of the onset response is consistent with a lateral origin in extrastriate visual cortex; that of P95 of the pattern reversal response is consistent in some respects with a striate cortical origin, but in others with a partial origin in extrastriate cortex.

War Worlds: Violence, Sociality, and the Forms of Twentieth-Century Transatlantic Literature

“War Worlds” reads twentieth-century British and Anglophone literature to examine the social practices of marginal groups (pacifists, strangers, traitors, anticolonial rebels, queer soldiers) during the world wars. This dissertation shows that these diverse “enemies within” England and its colonies—those often deemed expendable for, but nonetheless threatening to, British state and imperial projects—provided writers with alternative visions of collective life in periods of escalated violence and social control. By focusing on the social and political activities of those who were not loyal citizens or productive laborers within the British Empire, “War Worlds” foregrounds the small group, a form of collectivity frequently portrayed in the literature of the war years but typically overlooked in literary critical studies. I argue that this shift of focus from grand politics to small groups not only illuminates surprising social fissures within England and its colonies but provides a new vantage from which to view twentieth-century experiments in literary form.

We Are the Ones We Have Been Waiting for: Pan-African Consciousness Raising and Organizing in the United States and Venezuela

We Are the Ones We Have Been Waiting for: Pan-African Consciousness Raising and Organizing in the United States and Venezuela, draws on fifteen months of field research accompanying organizers, participating in protests, planning/strategy meetings, state-run programs, academic conferences and everyday life in these two countries. Through comparative examination of the processes by which African Diaspora youth become radically politicized, this work deconstructs tendencies to deify political s/heroes of eras past by historicizing their ascent to political acclaim and centering the narratives of present youth leading movements for Black/African liberation across the Diaspora. I employ Manuel Callahan’s description of “encuentros”, “the disruption of despotic democracy and related white middle-class hegemony through the reconstruction of the collective subject”; “dialogue, insurgent learning, and convivial research that allows for a collective analysis and vision to emerge while affirming local struggles” to theorize the moments of encounter, specifically, the moments (in which) Black/African youth find themselves becoming politically radicalized and by what. I examine the ways in which Black/African youth organizing differs when responding to their perpetual victimization by neoliberal, genocidal state-politics in the US, and a Venezuelan state that has charged itself with the responsibility of radically improving the quality of life of all its citizens. Through comparative analysis, I suggest the vertical structures of “representative democracy” dominating the U.S. political climate remain unyielding to critical analyses of social stratification based on race, gender, and class as articulated by Black youth. Conversely, I contend that present Venezuelan attempts to construct and fortify more horizontal structures of “popular democracy” under what Hugo Chavez termed 21st Century Socialism, have resulted in social fissures, allowing for a more dynamic and hopeful negation between Afro-Venezuelan youth and the state.

Modélisation du comportement des bétons fibrés à ultra-hautes performances par la micromécanique : Effet de l'orientation des fibres à l'échelle de la structure

Cette thèse s’inscrit dans le contexte d’une optimisation industrielle et économique des éléments de structure en BFUP permettant d’en garantir la ductilité au niveau structural, tout en ajustant la quantité de fibres et en optimisant le mode de fabrication. Le modèle développé décrit explicitement la participation du renfort fibré en traction au niveau local, en enchaînant une phase de comportement écrouissante suivie d’une phase adoucissante. La loi de comportement est fonction de la densité, de l’orientation des fibres vis-à-vis des directions principales de traction, de leur élancement et d’autres paramètres matériaux usuels liés aux fibres, à la matrice cimentaire et à leur interaction. L’orientation des fibres est prise en compte à partir d’une loi de probabilité normale à une ou deux variables permettant de reproduire n’importe quelle orientation obtenue à partir d’un calcul représentatif de la mise en oeuvre du BFUP frais ou renseignée par analyse expérimentale sur prototype. Enfin, le modèle reproduit la fissuration des BFUP sur le principe des modèles de fissures diffuses et tournantes. La loi de comportement est intégrée au sein d’un logiciel de calcul de structure par éléments finis, permettant de l’utiliser comme un outil prédictif de la fiabilité et de la ductilité globale d’éléments en BFUP. Deux campagnes expérimentales ont été effectuées, une à l’Université Laval de Québec et l’autre à l’Ifsttar, Marne-la-Vallée. La première permet de valider la capacité du modèle reproduire le comportement global sous des sollicitations typiques de traction et de flexion dans des éléments structurels simples pour lesquels l’orientation préférentielle des fibres a été renseignée par tomographie. La seconde campagne expérimentale démontre les capacités du modèle dans une démarche d’optimisation, pour la fabrication de plaques nervurées relativement complexes et présentant un intérêt industriel potentiel pour lesquels différentes modalités de fabrication et des BFUP plus ou moins fibrés ont été envisagés. Le contrôle de la répartition et de l’orientation des fibres a été réalisé à partir d’essais mécaniques sur prélèvements. Les prévisions du modèle ont été confrontées au comportement structurel global et à la ductilité mis en évidence expérimentalement. Le modèle a ainsi pu être qualifié vis-à-vis des méthodes analytiques usuelles de l’ingénierie, en prenant en compte la variabilité statistique. Des pistes d’amélioration et de complément de développement ont été identifiées.

Age an origin of the "Mexican Onyx" at San Antonio Texcala (Puebla, Mexico)

A great variety of color banded CaC03 is known as „Mexican Onyx“, and is extensively used for ornamental purposes. Within the San Antonio Texcala mining district an area of about 24.000 m2 is covered by a thick travertine crust with a calculated volume of at least 2,8 x 1061. It originates from warm waters that emerge on young fissures and faults. It seems to be likely that the travertine formation is related to the hydrothermal activity of the Transmexican Volcanic Belt and to the seismicity of this zone. The deposit is built up by different travertine varieties. The main lithotypes are: (1) dense crystalline laminated travertine; (2) ray crystal travertine; (3) shrub layer travertine; (4) irregular porous travertine; (5) travertine breccia. Textural variation seems to be related to water temperature/distance from the emergence point, rapid or slow degassing of CO, and bacterial influence. At the moment, a light green banded variety (native sulfur impurities) is mined. It is the facture fill of a morphological prominent fissure-ridge travertine. U/Th data indicate, that the travertine has been deposited since at least 52 + 5 ka.

Étude du comportement des piles de pont confinées de PRFC par écoute acoustique

Une structure en béton armé est sujette à différents types de sollicitations. Les tremblements de terre font partie des événements exceptionnels qui induisent des sollicitations extrêmes aux ouvrages. Pour faire face à cette problématique, les codes de calcul des ponts routiers font appel à une approche basée sur des niveaux de performance qui sont rattachés à des états limites. Actuellement, les états limites d'une pile de ponts en béton armé (BA) confinée à l'aide de polymères renforcés de fibres de carbone (PRFC) proposés dans la littérature ne prennent pas en compte le confinement lié au chemisage de PRFC en combinaison avec celui des spirales d'acier. Ce projet de recherche était la suite du volet de contrôle non destructif d'une étude réalisée en 2012 qui comprenait un volet expérimental [Carvalho, 2012] et un volet numérique [Jean, 2012]. L'objectif principal était de compléter l'étude du comportement des poteaux en BA renforcés de PRFC soumis à un chargement cyclique avec les données acoustiques recueillies par St-Martin [2014]. Plus précisément, les objectifs spécifiques étaient de déterminer les états limites reliés aux niveaux de performance et de caractériser la signature acoustique de chaque état limite (p. ex. fissuration du béton, plastification de l'acier et rupture du PRFC). Une méthodologie d'analyse acoustique basée sur l'état de l'art de Behnia et al. [2014] a été utilisée pour quantifier la gravité, localiser et caractériser le type de dommages. Dans un premier temps, les données acoustiques provenant de poutres de 550 mm x 150 mm x 150 mm ont permis de caractériser la signature acoustique des états limites. Puis, des cinq spécimens d'essai construits en 2012, les données acoustiques de trois spécimens, soient des poteaux circulaires d'un diamètre de 305 mm et d'une hauteur de 2000 mm ont été utilisée pour déterminer les états limites. Lors de ces essais, les données acoustiques ont été recueillies avec 14 capteurs de résonances qui étaient reliés à un système multicanal et au logiciel AEwin SAMOS 5.23 de Physical Acoustics Corporation (PAC) [PAC, 2005] par St-Martin [2014]. Une analyse de la distribution des paramètres acoustiques (nbr. de comptes et énergie absolue) combiné à la localisation des événements et le regroupement statistique, communément appelé clustering, ont permis de déterminer les états limites et même, des signes précurseurs à l'atteinte de ces états limites (p. ex. l'initiation et la propagation des fissures, l'éclatement de l'enrobage, la fissuration parallèle aux fibres et l'éclatement du PRFC) qui sont rattachés aux niveaux de performances des poteaux conventionnels et confinés de PRFC. Cette étude a permis de caractériser la séquence d'endommagement d'un poteau en BA renforcé de PRFC tout en démontrant l'utilité de l'écoute acoustique pour évaluer l'endommagement interne des poteaux en temps réel. Ainsi, une meilleure connaissance des états limites est primordiale pour intégrer les PRFC dans la conception et la réhabilitation des ouvrages.

La inobservancia a las normas sociales: hendiduras a la ontología de la realidad social

El presente estudio ofrece una interpretación de naturaleza ontológica a uno de los fenómenos más divulgados recientemente por los medios informativos de comunicación: la displicencia de los sujetos al seguimiento de normas sociales. El trabajo se centra, especialmente, en los casos en los que se asume que la indiferencia a las normas tiene como causa la condición del privilegiado social. Argumenta que la inobservancia a las normas, más que ser un asunto de desigualdad social, es la sintomatología de importantes hendiduras en la ontología de la realidad social. Así, tres partes conforman este trabajo. En la primera se describen algunos casos que, desde los medios de comunicación, se presentan como representativos en la inobservancia a las normas sociales, especialmente, aquellos que son interpretados como un asunto de abuso de privilegio social. En la segunda parte, a partir de algunos trabajos de John Austin, Ulises Moulines y Gottlob Frege, se presenta una concepción de normas sociales, y su valor para la construcción de la ontología social. En la tercera parte, desde la propuesta del filósofo John Searle, se describen algunos rasgos esenciales de la ontología de la realidad social. Se concluye que el no seguimiento de las normas sociales socava los modos de existencia de la realidad social, y que los casos interpretados por los medios de comunicación como asunto de desigualdad social, requieren una interpretación que tenga en cuenta la estructura de la realidad social.