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Numerical evaluation and analysis of the occurrence of earth fissures in faulted sedimentary basinsHernandez-Marin, Martin 10 January 2010 (has links)
This dissertation describes the occurrence of pumping-induced earth fissures associated with quaternary faulting using numerical simulations. The Eglington Fault located in Las Vegas valley has been selected as the prototype fault described herein. The finite-element software program ABAQUS is used for the numerical simulations.
The Eglington fault area is chosen because it represents one of the best examples displaying the complex relationship between fissuring, faulting and pumping-induced stress. This fault is known to influence both the vertical and horizontal deformation patterns through the accumulation of stress in its vicinity. The result is that fissures are observed on both sides of the fault and in close proximity to the fault plane. In addition to the complex fault-fissure connection, a thick caliche-rich vadose zone with weak mechanical strength allows for the initiation and propagation of fissures.
The numerical analysis a) investigates the geometrical and hydromechanical features of the zone of influence surrounding the Eglington Fault; b) identifies the zones of accumulated stress on the surface and at depth that can lead to fissuring; and c) simulates the onset and propagation of tensile-induced fissures.
Three-dimensional numerical simulations of this fault indicate that a 100-meter wide fault-zone composed by sand-like material best reproduces the conditions of stress that may lead to fissuring in the vicinity of the fault. Additionally, two-dimensional models reveal that two main mechanisms promote the accumulation of stress in the vicinity of the fault zone: one is the counterclockwise rotation of the unsaturated portion of the fault zone; the other is the differential compaction caused by the difference in the accumulated thickness of compressible layers. Tensile stress is concentrated on the surface in the hanging wall, but maximum shear stress zones are simulated to occur on both sides of the fault at the contact between the saturated aquifer and the vadose zone. A final analysis of the initiation and propagation of tensile-induced fissures demonstrates that fissures commence and propagate only within the vadose zone, and that the propagation path is influenced by the mechanical properties of the medium and the location of the main load, which in this case is pumping. / Ph. D.
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Methods for Evaluating Aquifer-System Parameters from a Cumulative Compaction RecordVanhaitsma, Amanda Joy 12 August 2016 (has links)
Although many efforts and strategies have been implemented to reduce over-pumping of aquifer-systems, land subsidence is still a serious issue worldwide. Accurate aquifer characterization is critical to understand the response of an aquifer-system to prolonged pumping but is often difficult and expensive to conduct. The purpose of this thesis is to determine the validity of estimating aquifer-system parameters from a single cumulative compaction record and corresponding nested water-level data deconvolved into temporal components.
Over a decade of compaction and water-level data were collected from an extensometer and multi-level piezometer at the Lorenzi site in Las Vegas Valley and when graphed yearly, seasonal, and daily signals are observed. Each temporal signal reflects different characteristics of the aquifer-system, including the distinction between aquifer and aquitard parameters, as the three temporal stresses influence the compaction record uniquely. Maximum cross-correlation was used to determine the hydrodynamic lag between changing water-levels and subsidence within the seasonal signal while principal components analysis was used to statistically verify the presence of the three temporal signals.
Assumptions had to be made but nearly all estimated Lorenzi site aquifer-system parameters fell either within the reasonable range or were similar in magnitude to parameter values estimated in previous studies. Unfortunately, principal components analysis was unable to detect the three temporal signals. A cumulative compaction record may be difficult to obtain but analyzing the precision measurements of an extensometer results in precise aquifer-system parameters and as the precision of aquifer-system parameters increase so does the ability to sustainably manage groundwater. / Master of Science
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Using GPS to Quantify Three Dimensional Storage and Aquifer Deformation in the Virgin River Valley, NVWarner, Sandra McCarthy 11 February 2004 (has links)
The horizontal component of land subsidence is typically assumed to be negligible, although recently, theoretical simulations have shown that horizontal strain is significant. A field based investigation in Mesquite, NV, was undertaken from May to July, 2003, for the purpose of evaluating the significance of horizontal strain during an aquifer test. The hydraulic heads in the aquifer were monitored within a meter of the municipal pumping well used for the aquifer test and also at a distance of approximately 1,470 meters from the pumping well. Aquifer deformation in the horizontal and vertical directions were measured using GPS for the first 22 days of pumping in 10 different locations at radial distances from the well varying from 100 meters to 2500 meters. From 22 to 60 days of the aquifer test, the number of GPS stations monitoring deformation was reduced to five.
Radial displacement was measured at all monitoring stations during the aquifer test, indicating that the aquifer is moving closer to the pumping well. The greatest magnitude displacement measured 140 m from the well was approximately 10 mm at the land surface. A zone of radial compression occurred between the pumping well and the first monitoring station 140 m away from the pumping well. Vertical displacement was measured in decreasing magnitude with increasing distance from the well. Because GPS is not as precise a tool in the vertical direction as it is in the horizontal, the vertical signal of displacement is not as accurate.
Numerical simulations using the BIOT and IBS codes were performed to reproduce the aquifer test and land deformation. The model included six layers representing three hydrogeologic units: a bottom aquifer (four layers) in which pumping occurred , a top aquifer (one layer) in which the monitoring well was screened, and a semi-confining bed (one layer) between the two aquifers that represented an equivalent thickness of interbeds and clays layers. The Biot code was used to simulate radial and vertical movements in an axisymmetrical simulation, while the IBS code was used to simulate only vertical displacement but also provided for the simulation of elastic and inelastic storage and compression.
The vertical distribution of radial displacement was simulated using the BIOT code. At the onset of pumping, the greatest radial displacement occurred in the bottom aquifer in which pumping occurred. At a distance of 2,000 m from the well, the radial displacement was uniform over all depths indicating that the differences in hydraulic diffusivity are not as important a factor at distance from the well.
The change in porosity that occurred as a result of horizontal strain was greatest in the bottom aquifer. Using the strain calculated directly from the GPS measurements at the land surface, vertical strain comprised almost 99% of the volume strain at the land surface. However, when the strain was simulated over the entire aquifer system, the radial and hoop strain contributed more than vertical strain in the bottom aquifer at a radius of 100 m from the pumping well at the onset of pumping until the aquifer reached near equilibrium, at which time vertical strain again dominated. / Master of Science
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Subsidence Cracking of Concrete Over Steel Reinforcement Bar in Bridge DecksKyle, Nathan Lawrence 30 May 2001 (has links)
It is known that subsidence cracking may cause premature deterioration of concrete slab structures in salt laden environments. Chlorides from either deicing salts or marine environments may cause chloride-induced corrosion of the reinforcing steel resulting in spalling of the cover concrete. Concrete specimens with 16 mm (# 5) diameter bars were cast with various cover depths, bar spacing and two concrete mixture types to determine the influence that epoxy coated reinforcement, cement type and bar spacing may have on the probability of subsidence cracking in bridge deck slabs. It was determined that there is not a significant difference in the probability of cracking of concrete between concrete cast with epoxy coated reinforcing steel and bare reinforcing steel. Concrete subsidence cracking was found to be dependent upon the clear cover depth and cement type. / Master of Science
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Earth Observation Data-Driven Assessment of Local to Regional, Contemporary, and Emerging Coastal Environmental Security ChallengesOhenhen, Osadebamwen Leonard 25 September 2024 (has links)
Coastal zones are hotspots of global environmental changes. Worldwide, coastal environments face multiple, interactive stressors caused by both natural and anthropogenic impacts on climatic, oceanographic, ecological, and socio-economic processes such as sea level rise, storm surges, hurricanes, land subsidence, and population growth. The coastal U.S. is highly vulnerable to many of these climate and human-induced stressors. Over the past three decades, sea levels have risen by about 0.1 m along the U.S. coasts, with an additional projected increase of 0.2 to 0.3 m by 2050, and up to 2.0 m by the end of the century. The rise in sea levels will cause tides and storm surges to reach further inland, significantly altering flood regimes in coastal cities. By 2050, potentially damaging coastal flooding is expected to occur ten times as often compared to a baseline for the start of the 21st century. Moreover, these changes along the U.S. coastlines vary regionally and locally due to either positive or negative changes in land elevation over time (i.e., vertical land motion (VLM)). Lowering of land elevation (i.e., land subsidence) exacerbates sea level rise and the risk of inundation along coastal zones, presenting significant security challenges to coastal ecosystems, infrastructure, and populations. These dynamic and interacting stressors necessitate continuous monitoring to inform effective mitigation and adaptation strategies. Earth observation data allows for accurate, high-resolution, and continuous measurements of changing coastline. Despite the increasing availability of Earth observation data, current methods for monitoring VLM along coastlines lack the necessary spatial resolution and continuous coverage to accurately assess localized surface elevation changes. In this dissertation, I introduce a framework to jointly invert interferometric synthetic aperture radar (InSAR) and global navigation satellite systems (GNSS) data to provide semi-continuous measurement (50 m spatial resolution) of VLM for the contiguous U.S. coasts from 2007 – 2020. Combining the VLM dataset with projected sea level rise using different scenarios, I estimate flood hazards exposure for 32 major U.S. coastal cities by 2050, demonstrating that current measurements and frameworks underestimate flood vulnerability in several cities by not accounting for local and regional high-resolution VLM data. Next, I evaluate the possible drivers of land subsidence, exploring the relationship between spatio-temporal dynamic VLM and groundwater withdrawal from aquifers in major U.S. cities. Additionally, I assess the hazards and risks of land subsidence to infrastructure and wetlands along U.S. coasts. Finally, I extend this analysis beyond the U.S. coastline, investigating how land subsidence is linked to the incessant occurrence of building collapses in Lagos, Africa's most populous coastal city. / Doctor of Philosophy / Coastal areas worldwide are under significant stress from both natural and human-made changes, including rising sea levels, flooding, storms, hurricanes, land sinking, and population growth. The U.S. coasts are particularly affected by these issues. Sea levels have risen significantly over the past few years, with further increases expected in the near future. As sea levels rise, tides and storm patterns will change; thereby altering the flood frequency and magnitude in coastal cities. Land sinking exacerbates the impact of sea-level rise and flooding, affecting people, buildings, and the natural environment in coastal cities. These factors change over time, so they must be constantly monitored to develop effective strategies for adaptation and mitigation. Here, I used satellite-based tools to monitor land changes over time, identifying areas where the land is sinking. I combined this information of where land is sinking with sea-level rise data to estimate the areas that will be vulnerable to flooding by 2050 in 32 U.S. coastal cities, including Boston (MA), New York (NY), Virginia Beach (VA), Charleston (SC), Miami (FL), New Orleans (LA), Galveston (TX), and San Diego (CA). I also examined the causes of land sinking, particularly how groundwater extraction can lead to land sinking and the risks this poses to buildings and the natural environment along the U.S. coasts. This research highlights the impact of climate change and human activities on the U.S. coasts and the importance of continuous monitoring to enhance coastal resilience against current and future challenges.
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Mesure et suivi spatio-temporel des déplacements de surface dans le nord-ouest de la Turquie, par interférométrie radar à haute résolution : glissement asismique et subsidence / MONITORING OF SURFACE DEFORMATION IN NORTHWEST TURKEY FROM HIGH-RESOLUTION INSAR : FOCUS ON TECTONIC ASEISMIC SLIP AND SUBSIDENCEAslan, Gokhan 30 April 2019 (has links)
Le but de cette thèse est centré sur la détection et la surveillance de la déformation de surface dans le nord-ouest de la Turquie, induite par une variété de phénomènes naturels (telles que l'activité tectonique, les glissements de terrain lents, etc.) et anthropiques (extraction des eaux souterraines, activités de construction, etc.), et sur l’analyse des mécanismes de déformation associés et de leurs conséquences pour l’environnement. Ce travail est basé sur le calcul de séries temporelles de déplacement du sol par interférométrie radar à synthèse d’ouverture (InSAR) afin d'analyser l'évolution des déplacements du sol, pour trois cas d’études associés à différents phénomènes géophysiques et processus sous-jacents. L’objectif de cette thèse est double : (1) révéler et quantifier les caractéristiques spatio-temporelles du glissement asismique le long de la rupture du séisme d’Izmit du 17 août 1999, et discuter de leur relation potentielle avec les propriétés de la faille (lithologie, géologie); (2) étudier la subsidence du sol dans des zones urbaines ou des zones exploitées par l'homme, induite par divers facteurs, et discuter des rôles relatifs de la tectonique, de la lithologie et des activités anthropiques dans ce mouvement du sol.Dans la première étude de cas, j’ai combiné des mesures InSAR, à partir d’images radar TerraSAR-X (bande X) et Sentinel-1 AB (bande C) acquises sur la période 2011-2017, à des mesures GPS en champ proche, effectuées tous les six mois à partir de 2014 jusqu'en 2016, ainsi qu’à des mesures de creepmeter, pour analyser le champ de vitesse en surface autour de la NAF, après le tremblement de terre d'Izmit de 1999. Les champs de vitesse moyenne horizontale InSAR révèlent que le taux de fluage (« creep ») sur le segment central de la rupture d'Izmit continue de décroître, plus de 19 ans après le séisme, ce qui concorde globalement avec les modèles de décroissance logarithmique des glissements post-sismiques de type « afterslip ». Le long de la section de la faille rompue à une vitesse « supershear » lors du séisme d'Izmit, le fluage se poursuit à une vitesse pouvant atteindre 8 mm / an. Un événement transitoire significatif, avec un fluage en accélération, est également détecté en décembre 2016 sur la série temporelle Sentinel-1, en accord avec les mesures d’un creepmeter installé près de la zone où la vitesse de fluage est maximum. Il est associé à un déplacement de surface total de 10 mm accumulé en un mois seulement.La deuxième cas d’étude porte sur l'identification et la mesure de la déformation du sol long-terme à Istanbul à partir d'une série InSAR couvrant près de 25 ans d'observations radar par satellite (1992-2017). Cette série temporelle InSAR a été calculée à partir d'images radar de plusieurs satellites (ERS-1, ERS-2, Envisat, Sentinel-1 A, B) afin d'étudier l'étendue spatiale et le taux de subsidence du sol dans la mégapole d'Istanbul.Dans le troisième cas d’étude, une série InSAR est calculée pour quantifier la subsidence de la plaine de Bursa (sud de la région de Marmara en Turquie), auparavant interprétée comme d’origine tectonique. Dans cette étude, StaMPS est utilisé pour traiter des séries d'images radar Sentinel 1 A-B acquises entre 2014 et 2017 le long d’orbites ascendantes et descendantse. Le champ de vitesse verticale obtenu après décomposition des champs de vitesse en ligne de visée sur deux traces complémentaires révèle que la plaine de Bursa s'affaisse à des vitesses allant jusqu'à 25 mm / an. A l’est, le signal de subsidence le plus important dans le bassin forme une ellipse allongée est-ouest et est limité par une plaine alluviale Quaternaire subsidant à environ 10 mm / an. Ces observations indiquent que l'accélération récente de la subsidence est principalement due aux activités anthropiques plutôt qu'aux mouvements tectoniques régionaux. / The aim of this thesis is centered on the detection and monitoring of surface deformation in northwest Turkey induced by a variety of natural (such as tectonic activity, slow moving-landslides, etc.) and anthropogenic (ground water extraction, construction activities, etc.) hazards and on the analysis of the related deformation mechanisms and their environmental consequences. In this work, I computed Interferometric Synthetic Aperture Radar (InSAR) time series to examine ground deformation evolution for three different case studies associated to different geophysical phenomena and underlying processes. The focus of this thesis is two-fold : (1) to reveal and monitor the spatio-temporal characteristics of aseismic slip along the August 17, 1999 Mw 7.4 Izmit earthquake rupture, and discuss its potential relationship with lithology and geology (2) to investigate ground subsidence in urban or human-exploited areas induced by various factors, and discuss the relative roles of tectonics, lithology and anthropogenic activities in such ground motion.In the first case-study, I combined InSAR measurements, based on X-band TerraSAR-X and C-band Sentinel-1 A-B radar images acquired over the period 2011-2017, with near field GPS measurements, performed every 6 months from 2014 to 2016, as well as creep meter measurements to examine the surface velocity field around the NAF after the 1999 Izmit earthquake. In this study, the Stanford Method for Persistent Scatterers InSAR package (StaMPS) was employed to process series of Sentinel 1 A-B (acquired along ascending and descending orbits) and TerraSAR-X (ascending orbits) radar images. The InSAR horizontal mean velocity fields reveal that the creep rate on the central segment of the 1999 Izmit fault rupture continues to decay, more than 19 years after the earthquake, in overall agreement with models of postseismic afterslip rate decaying logarithmically with time. Along the fault section that experienced a supershear velocity rupture during the Izmit earthquake, creep continues with a rate up to ~ 8 mm/yr. A significant transient event with accelerating creep is detected in December 2016 on the Sentinel-1 time series, consistent with creepmeter measurements, near the maximum creep rate location. It is associated with a total surface slip of 10 mm released in one month only. The second case study deals with the identification and measurement of secular ground deformation in Istanbul from a long-term InSAR time-series spanning almost 25 years of satellite radar observations (1992-2017). This InSAR time series was computed from radar images of multiple satellites (ERS-1, ERS-2, Envisat, Sentinel-1 A, B) in order to investigate the spatial extent and rate of ground subsidence in the megacity of Istanbul.In the third case study, InSAR time-series analysis is calculated for quantifying the subsidence of the Bursa Plain (southern Marmara region of Turkey), which has been interpreted as resulting from tectonic motions in the region. In this study, the StaMPS is employed to process series of Sentinel 1 A-B radar images acquired between 2014 and 2017 along both ascending and descending orbits. The vertical velocity field obtained after decomposition of line-of-sight velocity fields on the two tracks reveals that the Bursa plain is subsiding at rates up to 25 mm/yr. The most prominent subsidence signal in the basin forms an east-west elongated ellipse of deformation in the east, and is bounded by a Quaternary alluvial plain undergoing average vertical subsidence at ~10 mm/yr. The InSAR time series within the observation period is well correlated with changes in the depth of the ground water. These observations indicate that the recent acceleration of subsidence is mainly due to anthropogenic activities rather than tectonic motion.
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Subsidence Quaternaire en Asie du Sud-Est : de la dynamique du manteau à la circulation atmosphérique - Modélisation géomorphologique, géodynamique et climatique / Quaternary subsidence in South-Est Asia : from mantle dynamics to atmospheric circulation - Geomorphologic, geodynamic and climate modelingSarr, Anta-Clarisse 19 December 2018 (has links)
En défléchissant la Terre, la topographie dynamique module l'extension des zones inondées dans les régions où l'altitude est proche du niveau marin. Ce phénomène contribue ainsi à modifier la paléogéographie à grande échelle et ont un impact sur les sphères externes (atmo-, hydro- et bio-sphère) en altérant notamment les circulations atmosphériques et océaniques. Ces travaux de thèse, qui s’appuient sur une approche interdisciplinaire, illustrent la chaîne de connections entre dynamique mantellique et climat à travers l'étude de l'évolution Quaternaire du Continent Maritime. Le caractère insulaire de la région et la présence de mers peu profondes comme la mer de Java, permettent des modifications rapides de la répartition terre-océan à grande échelle, et en font un cas idéal pour étudier les connections entre géodynamique et climat. D’autre part, la dynamique mantellique, excitée par les nombreuses subductions, y est très active et contribue à déformer la surface et la dynamique climatique régionale est étroitement associée à la géographie particulière de l’archipel Indonésien.Les changements paléogéographiques sont d'abord révélés par la cartographie des morphologies côtières. Celle-ci souligne la répartition contrastée de la déformation Quaternaire en soulignant le soulèvement général de la région centrale (Wallacea), alors que les deux plateformes continentales localisées à l'Ouest et au Sud-Est subsident. L'utilisation combinée des observations et de la modélisation de la croissance des récifs coralliens est utilisée afin de quantifier la vitesse verticale de déformation. Notre méthode est basée sur la comparaison entre la morphologie des récifs observés sur la plateforme de la Sonde, à l'ouest de l'Asie du Sud-Est, et les morphologies récifales issues des simulations numériques et permet une quantification inédite de la vitesse de subsidence de la plateforme. Les résultats suggèrent que la Sonde était émergée de manière permanente avant 400 000 ans, formant une masse continentale entre les îles de l'Ouest Indonésien et le continent asiatique. Les causes de ces changements paléogéographiques sont appréhendées à l'aide de la modélisation mécanique de la géodynamique. Un modèle numérique en trois dimensions d'une zone de subduction a été utilisé afin de d'explorer les causes dynamiques de la déformation. L'analyse des simulations permet de décrire l'évolution spatio-temporelle de la déformation à l'aplomb d'une zone de subduction, lors d'une perturbation provoquée par l'arrivée dans la fosse d'un bloc continental ou d'un plateau océanique, un cas simplifié similaire à l'Asie du Sud-Est. Les résultats montrent que lors d'un épisode de collision, l'initiation d'une déchirure dans la plaque en subduction générée par l'entrée dans la fosse de matériel peu dense entraîne une modification de l'écoulement mantellique. Cette modification provoque un épisode de subsidence dynamique qui fait suite à un épisode de surrection provoquée par la collision. Les vitesses de déformations calculées ont un ordre de grandeur comparable aux vitesses de déformations enregistrées et modélisées à l'échelle régionale. Les conséquences des changements paléogéographiques sont appréhendées à l'aide d'un modèle du climat IPSL-CM5A2. Les résultats montrent que la présence d'une plateforme de la Sonde émergée provoque une augmentation saisonnière des précipitations sur le Continent Maritime. Cette augmentation est engendrée par une intensification de la convergence à l'échelle régionale contrôlée par le chauffage radiatif des surfaces continentales exposées. L'exposition de la plateforme de la Sonde engendre également une modification du transport dans le détroit de Makassar avec un impact local sur la salinité et les températures de surface de l'océan. Nos analyses montrent par ailleurs que l'augmentation de la saisonnalité des précipitations est indépendante de la paramétrisation de la convection et des nuages dans le modèle. / Dynamic topography modulates the extension of inundated areas, at places where elevation is near sea level, by deflecting the surface of the Earth. This phenomenon produces large-scale paleogeography changes, which in turn modify external spheres (atmo-, hydro- and biosphere) by subsequent alteration of atmospheric and oceanic circulations and biodiversity. This inter-disciplinary work illustrates the connection string between Earth mantle dynamics and climate through the study of Quaternary evolution of South East Asia. The insularity of the region and the presence of low bathymetry seas, as the Java sea, enable fast and efficient modifications of land-sea mask and make it an ideal case for studying the connection between geodynamics and climate. Mantle flow, excited by the numerous subduction zones, is vigorously stirred and contributes to surface deformation. In this region, climate dynamics is also tightly related to the peculiar geography of the Indonesian archipelago. Paleogeographic changes are first revealed by coastal morphologies. They show the contrasted pattern of large-scale Quaternary deformation that underlines general uplift within the central-eastern part of the region, namely Wallacea, whereas the continental shelves, to the West and Southeast, are more likely subsiding. The combination of field observations with numerical modeling of coral reef growth is used to quantify vertical deformation. Our method is based on reef morphology (terrace number, depth, modern reef length) that we observed on the Sunda shelf (Western South East Asia) and reef morphologies obtained by numerical modeling, and enable an original quantification of subsidence rates of the platform. The results imply that Sundaland region was entirely and permanently emerged before 400 000 yr and formed at this time a unique continental mass between West Indonesian islands and continental Asia. The causes of paleogeographic changes are explored using modeling of regional geodynamics. A three-dimension subduction numerical model was devised to simulate the dynamical origin of deformation. This model analysis enables us to describe the spatio-temporal evolution of the deformation above a subduction zone in case of perturbation induced by the arrival at the trench of a continental block or oceanic plateau, a simplified case that is similar to SE Asia. Our results show that during a collisional episode, slab tearing generated by the arrival of light material unable to subduct is responsible for changes in mantle convection. Those changes are responsible for dynamic subsidence that followed an uplift event related to the first stages of collision. Inferred deformation rates have an range of magnitude similar to both measured and modeled rates at regional scale. The consequences of paleogeographic changes are studied using general circulation model simulations. Results show that the presence of an emerged Sunda shelf leads to a seasonal increase in precipitation over the Maritime Continent. This increase is related to seasonal increase in large-scale convergence induced by thermal heating of exposed land surfaces, a situation that, as we show, occurred before 400 ka. Sunda shelf exposure is also responsible for changes in horizontal water transport within the Makassar strait that modify sea surface salinities and temperatures at local scale. Our analysis further shows that increased precipitation seasonality is independent on model convection and cloud parameterization
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Development Of A Subsidence Model For Cayirhan Coal MineHaciosmanoglu, Esenay Meryem 01 October 2004 (has links) (PDF)
In this study, subsidence analyses were carried out for panels B14, B12, B10, B02, C12, C10, C08 of Ç / ayirhan Lignite Mine using in-situ subsidence measurements.
Using the measurements from stations, installed both parallel and perpendicular to panel-advance direction, subsidence profiles were plotted as a function of time and distance from panel center. Horizontal displacement and strain curves were also plotted and compared with subsidence profiles.
There are various methods used for subsidence prediction. In this study however, a subsidence model was developed based on empirical model obtained from nonlinear regression analysis. During the analyses SPSS (V.10.0) software was used and the unknown parameters associated with subsidence function were determined for the stations above B14 panel. Since it was too complicated to take all the affecting factors into consideration, only the parameters which could be estimated by statistical evaluation were taken into account during analyses.
One significant contribution of this study to subsidence subject was the comparison of the subsidence values measured during this investigation with the values predicted by some other empirical methods.
In this study, the structural damages to the pylons installed on ground surface above retreating longwall panels were also investigated by the use of previous studies. Slope as well as horizontal strain changes caused by ground movements
due to underground mining were determined.
Last but not least, it should be stated another significant contribution of this study to engineering was the collection of a significant database obtained from field measurements.
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Apport de l'interférométrie radar satellitaire pour le suivi des évolutions environnementales en Amazonie, Brésil / SAR interferometryanalysis based on orbital data over equatorial regions : a case study in Manaus, Amazonas, Brazil / Desenvolvimento de técnicas para processamento de dados orbitais de interferometria SAR em regiões equatoriais úmidas : estudo de caso em Manaus, Amazonas, BrasilLedo Gonçalves Ramos, Fernanda 27 September 2013 (has links)
Pendant ces dix dernières années, les lancements successifs de satellites pour l´observation de la Terre dotés de capteurs SAR (Synthetic Aperture Radar) ont permis de montrer son fort potentiel, car ces systèmes sont capables de couvrir de vastes régions avec une résolution élevée, ce qui représente un avantage pour le suivi terrain. Cette thèse propose d’élargir les applications conventionnelles, en s’occupant d´investiguer le potentiel et les limites de l’interférométrie SAR pour la mesure de la déformation du terrain dans la région amazonienne, qui n’a pas encore été étudiée dans ce cadre spécifique. L´application consiste à estimer le déplacement de la surface de la Terre sur la zone urbaine de Manaus, la plus grande ville de l'État d'Amazonas au Brésil, qui représente un site important pour l'exploration pétrolière et gazière et pour le transport. Ce site est entouré par des écosystèmes fragiles, qui le rendent très sensible à la présence de l'industrie pétrolière. Dans ce contexte, une compréhension de la dynamique temporelle et de la distribution spatiale des phénomènes de néotectonique est fondamentale pour la définition de bonnes pratiques de gestion de l'environnement. Au niveau méthodologique, afin de lever les principales difficultés rencontrées pour l’application de l’interférométrie différentielle sur une pile de données Radarsat-1, une stratégie multi-échelles et “model free”, basée sur l´information de déformation non-linéaire au cours du temps est adoptée avec succès. La caractéristique essentielle de cette procédure est la séparation du signal de phase en différentes échelles spatiales pour simplifier la séparation des trois composantes de phase (topographie, atmosphère et déplacement). Cela conduit à une plus grande robustesse et permet l'inversion de composantes de phase pour les petites piles d’images. Au niveau géophysique, l’application de l’interférométrie à l’étude du déplacement du terrain est réalisée pour la première fois sur le milieu de l´Amazonie, en complétant les études de géologie structurale antérieures basées sur les mesures issues de la corrélation des images optiques et les mesures de terrain. En complément des connaissances antérieures, la présente étude apporte une information précise sur l'hypothèse de mouvements de la croûte récents liés aux activités néotectoniques du bassin de l'Amazonie. Les résultats indiquent une zone de mouvement de la croûte adjacente à une structure de drainage circulaire dans la ville de Manaus. Les images Radarsat-1 et 2 acquises sur cette région apportent une meilleure compréhension des activités géologiques et du mouvement de la croûte dans le bassin de l'Amazonie. / During the past decade, successive satellites launches for Earth observation with SAR (Synthetic Aperture Radar) sensors onboard have shown its potential, once these systems are able to cover large areas with high resolution, which represents an advantage for surface monitoring. The mass of data generated has enabled the development of radar interferometry and its relevance to the study of small deformations in urban areas or in fault zones, showing that the technique was able to focus on different spatial scales of deformation, as well as temporal scales ranging from a few weeks to more than a decade. Usually, these types of applications have been limited to non-equatorial regions of the world due to the presence of atmospheric disturbances that affect the radar signal. Given the large size and the remote location of tropical basins such as the Amazon, satellite observations remain as a viable approach to validate existing geophysical models. In this context, this thesis proposes to extend conventional applications, taking care to investigate the potential and limitations of SAR interferometry for the measurement of ground deformation in the Amazon region, not yet studied in this specific context. The research aim is to estimate the displacement at the surface of the Earth on the urban area of Manaus, the largest city in the state of Amazonas in Brazil, which is an important site for oil and gas exploration and the transport. This site is surrounded by fragile ecosystems, which make it very sensitive to the presence of the oil industry. Considering this, an understanding of the temporal dynamics and spatial distribution of neotectonic phenomena is fundamental to the development of best practice environmental management. At the methodological level, to overcome the major challenges of the application of differential interferometry on the data stack Radarsat-1, a multi-scale and "model free" strategy, based on the information of a non-linear deformation over time is passed successfully. The essential feature of this process is the separation of the phase signal into small and large scale spatial contributions to simplify the separation of the three phase components (topography, atmosphere and movement). This leads to a more robust processing and allows the phase component inversion for small piles of images. In the geophysical level, the application of interferometry to investigate the ground movement is performed for the first time in the middle of the Amazon, complementing previous studies of structural geology based on measurements from the correlation of optical images and field measurements. In addition to prior knowledge, this study provides accurate information on the hypothesis of recent crustal movements associated with neotectonic activities of the Amazon basin. The results indicate a range of motion of the adjacent crust structure circular drainage in the city of Manaus. The Radarsat-1 and 2 acquired in this region provide a better understanding of geological activity and crustal movement in the Amazon basin.
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Investigation of mining subsidence prediction under tectonic influencesBabaryka, Aleksandra 26 January 2024 (has links)
This dissertation addresses the challenge of predicting human-induced subsidence in tectonic settings. The study focuses on the non-symmetric and shape-defying nature of subsidence troughs in tectonic regions, which deviates from conventional symmetric models. The aim of the dissertation is to improve the accuracy of subsidence prediction by incorporating horizontal stress effects into empirical methods. Through a combination of numerical investigations and empirical modelling, the research reveals stress-induced patterns in subsidence profiles. The developed model, based on various concepts, successfully incorporates asymmetry and shape deviation, resulting in significantly improved prediction accuracy. Application of the model to a real subsidence case in a salt cavern shows a 30% improvement in prediction (based on mean squared error comparison with classical solution). This new solution covers subsidence profile patterns not previously considered by empirical models.:Inhalt
1 Introduction
2 State of the art
2.1 Subsidence prediction methods
2.1.1 Empirical subsidence prediction method overview
2.1.2 Numerical methods for subsidence prediction
2.2 Subsidence monitoring methods
2.2.1 Observation methods
2.2.2 Interplay and evolution of techniques
2.3 Subsidence anomalies
2.4 In-situ-stress field
2.5 Subsidence prediction methods for anomalies
2.6 Conclusions
3 Goals and objectives
4 Foundations
4.1 Empirical subsidence prediction methods
4.1.1 Convergence
4.1.2 Transmission coefficient
4.1.2 Influence factor
4.2 Numerical models for subsidence case
4.2.1 Grid size for subsidence case
4.2.2 Boundary conditions
4.2.3 Constitutive models
4.3 Validation
4.3.1 Observation methods
4.3.2 Parameter estimation
4.3.3 Global parameter estimation
4.3.4 Local parameter estimation
4.3.5 Quality measures for result valuation and validation
5 Methodology
6 Numerical investigation
6.1 Preliminary investigation
6.1.1 Method
6.1.2 Choice of constitutive model
6.1.3 Model and input data
6.1.4 Preliminary investigation results
6.2 Design of the main experiment: non-uniform stress distribution
6.2.1 Constitutive model and input data
6.2.2 Model simplification
6.2.3 Output data
6.3 Contribution of asymmetrical stress distribution
6.3.1 Discussion of the basic distribution form
6.3.2 Discussion of maximum subsidence
6.3.3 Discussion of assymetry
6.3.4 Discussion of influence angle
6.4 Conclusions
7 Adaptation of an empirical model to the discovered features
7.1 Subsidence asymmetry
7.2 Subsidence shape flexibility
7.3 Unifying solution
7.4 Conclusion and outlook
8 Application to a full scale
8.1 General information for a salt cavern storage field
8.2 Estimation of the observed subsidence surface as reference
8.3 Model implementation
8.3.1 Parameter estimation results
8.4 Statistical validation of models
8.5 Conclusions
9 Conclusion
9.1 Limitations
9.2 Outlook
References
Appendix
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