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1
Hatami, Kianoosh. "Effect of reservoir boundaries on the seismic response of gravity dams". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq30090.pdf.
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Amirkolai, Mohsen Ghaemian. "Dam-reservoir interaction effect on the seismic response of concrete gravity dams /". *McMaster only, 1997.
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3
Fouhy, David y Bayona Francisco Ríos. "Reliability-Based Analysis of Concrete Dams". Thesis, KTH, Jord- och bergmekanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176867.
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Dams are designed and assessed based on traditional factor of safety methodology. Several drawbacks of this approach exist; for example varying failure probability for structures where the factor of safety is the same. This traditional factor of safety methodology imposes conservative assumptions in terms of both design and analysis. A probability-based analysis has been suggested to account for the omission of uncertainties and provide a less conservative analysis (Westberg & Johansson, 2014). Through the stability analyses of three existing dam structures, a minimum level of reliability or maximum failure probability may be calculated with the ultimate goal of defining a target safety index (β-target) for buttress and gravity dams. These analyses shall in turn contribute to the formulation of a probability-based guideline for the design and assessment of Swedish concrete dams. This probability-based guideline shall be known as the ‘Probabilistic Model Code for Concrete Dams.’ The calculations carried out in this study adhere to the methodologies and specifications set out in the preliminary draft of the Probabilistic Model Code for Concrete Dams. These methodologies encompass analyses within two dominating failure modes for concrete dams; sliding stability and overturning stability. Various load combinations have been modelled for each dam structure to account for the probabilistic failure of each dam under commonly occurring circumstances. A parametric study has been carried out in order to provide insight into the contribution that existing rock bolts provide to the stability of each dam. Furthermore, a study has been carried out into the existence of a persistent rock joint or failure plane in the rock foundation and the effects its presence would have on the sliding stability of a dam. Finally a discussion had been carried out in order to provide suggestions into the formulation of a target safety index through the data envisaged by our analyses for the design and assessment of Swedish concrete dams.
4
Wishart, Jeremy Scott. "Overtopping Breaching of Rock-Avalanche Dams". Thesis, University of Canterbury. Civil Engineering, 2007. http://hdl.handle.net/10092/1193.
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River blockages formed by rock avalanches appear to pose a higher hazard potential than other landslide dams, given the extreme run-out distances and volumes of rock avalanche deposits. Recent research has identified rock avalanche deposits to have internal sedimentology consisting of a coarse surficial material (carapace) and a finer fragmented interior (body) potentially of critical importance to rock-avalanche dam stability. Physical scale modelling of overtopping failure and breach development in rock avalanche dams was used to quantify the influence of this sedimentology on critical breach parameters, and their prediction using existing embankment dam breach technologies. Results from this study indicate that the time to failure for rock avalanche dams is approximately twice that observed for homogeneous dams due to the armouring properties of the carapace; and that peak discharge is not significantly affected by sedimentology. While application of empirical, parametric, dimensional and physically based models indicated that uncertainty associated with predicted dam break discharges could range from ±19% to ±107%, no modelling technique was able to simulate the armouring phenomenon adequately. Comparison of actual and simulated breach evolution shows linear assumptions of breach depth and width development (as observed in homogeneous dams) to be incorrect. In the context of hazard management, the results suggest that empirical regression relationships should be used for rapid assessment of potential dam break flood magnitude.
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Chandrashaker, Rajagopalan Carleton University Dissertation Engineering Civil. "Seismic analysis of gravity dam-reservoir-foundation system using an effective hybrid technique". Ottawa, 1992.
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6
Nilsson, Isak y Leonard Sandström. "Behavior prediction of concrete dams". Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289385.
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As many dams were built around 1950, the expected life span of these dams are about tobe reached. With this, the need for monitoring and increased understanding of the damsstructural integrity increases. In order to prevent failures, two warning signals are defined;alert and alarm. The main difference being that the first indicates an unexpected changein behavior that needs to be addressed and evaluated in the near future, while the otherrequires that immediate action must be taken to ensure the safety of the dam.This report aims to evaluate the applicability of different models for designing alert values.In order to achieve this goal, two case studies have been performed. The first being onSchlegeis, an arch dam in Austria, and the second Storfinnforsen, a concrete buttress damin Sweden. The methods used are finite element modelling as well as data-based models.Data-based models work on the presumption that the dam behaviour is governed by variationsin environmental conditions such as temperature and water level. The report hasevaluated two commonly used data-based models, hydrostatic thermal time (HTT) and hydrostaticseasonal time (HST), as well as two machine learning based models artificial neuralnetworks (ANN) and boosted regression trees (BRT).The programs used in this report are BRIGADE plus for finite element method and MATLABfor the multi-linear regression analyses HTT and HST, as well as boosted regressiontrees. The neural networks were constructed in Python using TensorFlow and Keras API.The result from the case studies is that the commonly used data-based models HST andHTT perform well enough for creating predictions and alert levels when given a sufficientamount of historical data, approximately 3-5 years. Machine learning such as artificial neuralnetworks while comparable in prediction quality does not further increase the understandingof the dam behaviour and can due to the complexity of designing an appropriate networkstructure be less suited for this type of analysis. Finite element models can also capturethe behavior of the dam rather well. It is however not as accurate as data-based modelswhen sufficient data is available. An FE-model should be used for definition of alert valueswhen insufficient data exists after the dam conditions have been significantly altered, orwhen newly constructed. The main advantage that machine learning provides is that theyperform better for non-linear behavior than multi-linear regression.
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Durieux, Johan Hendrik. "Development of a practical methodology for the analysis of gravity dams using the non-linear finite element method". Diss., Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-06232009-152815/.
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Xu, Yao. "Analysis of dam failures and diagnosis of distresses for dam rehabilitation /". View abstract or full-text, 2010. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202010%20XU.
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Cai, Qingbo. "Finite element modelling of cracking in concrete gravity dams". Thesis, Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-01302008-160623.
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Wu, Xiuyuan Carleton University Dissertation Engineering Civil. "Seismic behaviour of clay embankment dams". Ottawa, 1992.
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11
Kitapcigil, Sulen Nur. "A Study On The Reliability-based Safety Analysis Of Hardfill Dams". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612802/index.pdf.
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Dams are important large structures providing vital benefits to human life. These
strategic structures are necessary in order to supply water and energy and to control
floods. Moreover, dams have important roles in regional development and national
economy. Thus, the design of dams deserves rigorous studies. Deterministic
approach may be acceptable for design of dams and may satisfy safety requirements
if large safety factors are used. However, such an approach will not be cost-effective
in economic terms. High safety factors utilized in deterministic approaches
necessitates large dimensions. One remedy for this overestimation is integrating
statistical information and techniques, such as Monte-Carlo simulations into the
analysis and design of dams. Probabilistic approaches may result in more
economical and reasonable designs. CADAM is a software program which allows
the user to analyze dams using Monte-Carlo simulation technique. Uncertainties
associated with tensile strength, peak cohesion, peak friction coefficient, normal
upstream reservoir elevation, drain efficiency and horizontal peak ground
acceleration are incorporated into stability and stress analysis using Monte-Carlo
simulations. In this thesis, utilization of CADAM software is demonstrated on a case
study. Cindere dam is evaluated in terms of structural safety
12
Reynolds, Sonel. "Evaluating the decision criteria for the prioritisation of South African dams for rehabilitation in terms of risk to human lives". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80288.
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Thesis (MScEng)--Stellenbosch University, 2013.ENGLISH ABSTRACT: In South Africa a large number of dams owned by the Department of Water Affairs (DWA) need to be rehabilitated. This study investigated the decision process involved in the prioritisation of dams for rehabilitation. DWA developed a risk analysis methodology for defining the risks associated with dam safety, expressed as the combination of the probability and consequences of dam failure. These risks are evaluated usingmultiple acceptability criteria to assess risk to human life and the economic, social, socio-economic and environmental impacts of dam failure. In this study, the criteria used in the decision process to evaluate the acceptability of life safety risks were evaluated by comparing to international best practice methods, where the acceptability of risk to human life is commonly assessed as the expected number of fatalities against life safety criteria presented as FN-criteria on an FN-diagram. Damrehabilitation should reduce the probability of dam failure, thereby reducing the risk to society in terms of the expected lives lost. However, the rehabilitation works come at a cost and the level of these investments are usually large. In addition, the rehabilitation of South African government owned dams are financed by society and these financial resources are limited. Thus investments into dam rehabilitation works should be worthwhile for society. Society’s Willingness to Pay (SWTP) for safety was applied to South African dam safety to determine the acceptable level of expenditure into life safety that is required by society. Investments into improved safety levels are not always dictated by society, but could also be driven by the decision maker or owner requiring an economically optimal solution for the rehabilitation. Economic optimisation accounts for considerations additional to life safety, including economic motivations, damage costs of dam failure as well as compensation costs for lives lost. Often economic optimisation would govern the decision problem. Also, the DWA current evaluation does not take the cost of rehabilitation into account in any way. Thus, FN-criteria that primarily evaluates life safety, but also incorporates a measure of economic efficiency, were suggested in this study.
AFRIKAANSE OPSOMMING: In Suid-Afrika moet ’n groot aantal dammewat deur dieDepartement vanWaterwese (DWA) besit word gerehabiliteer word. Hierdie studie het die besluitnemingsproses ondersoekwat toegepasword om damme te prioritiseer vir rehabilitasiewerke. DWA het ’n bestaande metodologie wat gebaseer is op risiko-analise. Die risikos wat verband hou met damveiligheid word deur die metode bepaal en word uitgedruk as die kombinasie van waarskynlikheid en die beraamde gevolge van damfaling. Hierdie risikosword geëvalueer teenoor verskeie kriteriawat die aanvaarbaarheid van risikos teenoor menselewens en die ekonomiese, sosiale, sosio-ekonomiese en omgewingsimpakte van damfalings assesseer. In hierdie studie word die kriteria wat gebruik word in die besluitnemingsproses om die aanvaarbaarheid van risikos teenoor menselewens te bepaal geëvalueer deur die kriteria te vergelyk met metodes wat internasionaal as beste praktyk beskou word. Internasionaal word die aanvaarbaarheid van risikos teenoor menselewens oor die algemeen as die verwagte aantal sterftes teenoor lewensveiligheidskriteria FN-kriteria op ’n FN-diagram geassesseer. Dam rehabilitasiewerke behoort die waarskynlikheid van damfaling te verminder, sodoende verminder die risiko teenoor die samelewing in terme van verwagte sterftes. Die rehabilitasiewerke vereis finansiële beleggings, en hierdie beleggings is gewoonlik groot. Verder word die rehabilitasie van Suid-Afrikaanse damme wat deur DWA besit word deur samelewing gefinansier en hierdie finasiële hulpbronne is beperk. Dus moet hierdie beleggings die moeite werd wees vir die samelewing. Die samelewing se bereidwilligheidomte betaal ("SWTP") vir veiligheid word toegepas in Suid- Afrikaanse damveiligheidomdie aanvaarbare vlak van beleggings vir ’n verbeterde veiligheid teenoor menselewens wat deur die samelewing vereis word te bepaal. Beleggings in verbeterde damveiligheidsvlakke word egter nie altyd bepaal deur die samelewing nie,maar kan ook gedryf word deur die besluitnemer of eienaar wat ’n ekonomies optimale oplossing vir die rehabilitatiesewerke vereis. Ekonomiese optimering neem oorwegings addisioneel tot lewensveiligheid in ag, insluitend ekonomiese motiverings, skade kostes as die dam faal, sowel as vergoedingskostes vir die verwagte sterftes. Ekonomiese optimering beheer dikwels die besluitnemingsprobleem. Verder neem die huidige DWA besluitnemingssproses in geen manier die kostes van rehabilitasie in ag nie. Dus word FN-kriteria wat hoofsaaklik veiligheid teenoor menselewens evalueer,maar wat ook ’n mate van ekonomiese doeltreffendheid insluit, voorgestel in hierdie studie.
13
Al, Maqbali Nasser. "Risk assessment of dams". Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09ENS/09ensa316.pdf.
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Bibliography: leaves 101-104. Explores risk assessment of dams, a fundamental approach for dam safety measurement, providing a base on which all safety assessment and any appropriate regulation should be developed. Includes an overview of the relevant literature; an example of the application of this method by the South Australia Water Corporation; and it is also applied to the Wadi Al Jizzi Recharge Dam in the Sultanate of Oman. Conclusions and recommendations are presented on the applicability of risk assessment of dams method in the Sultanate of Oman.
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Hellgren, Rikard. "Condition assessment of concrete dams in cold climate". Licentiate thesis, KTH, Betongbyggnad, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259719.
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Dams in many countries are approaching their expected service life. Proper assessment of the aging dams structural health increase the knowledge of the current safety, and allow for better planning of renovation and rebuilding investments. The behavior of concrete dams is, to a great extent, governed by the ambient variation in temperature and water level. In cold regions, the ice sheet formed in the reservoir may subject a pressure load on the dams. Theoretically, this load has a significant impact on the structural behavior of dams. Despite this, the maximum magnitude, as well as the seasonal variation of the ice load, constitute the most considerable uncertainty in the safety assessment of dams. This thesis presents research that examines how to model the expected behavior of dams in cold climate. The underlying problem is to predict the response of dams due to variation in the external conditions. Since the ice load is such a vital part of the external conditions in cold climate, the understanding and modeling of ice loads have been given extra attention. Models suitable to predict the long-term behavior of dams can be divided between theoretical, data-based, and hybrid. Prediction accuracy is essential to set alert thresholds, and in that regard, the data-based models are generally superior. The major contribution of this thesis is the design and installation of a prototype ice load panel with direct measurement of the ice pressure acting on a dam. The panel is attached on the upstream face of the dam and is large enough so that the whole thickness of the ice sheet is in contact with the panel. The predicted ice load from the best available model that includes loads from both thermal events and water level changes did not correspond to the measured ice loads. As there are no validated models or measurement methods for ice load on the dam, continued research is necessary, both through further measurements to increase knowledge and development of models.I många länder närmar sig vattenkraftsdammarna deras förväntade tekniska livslängd. Korrekt utvärdering av dammens strukturella status ökar kunskapen om det nuvarande säkerhetsläget och möjliggör för bättre planering av renoveringar och ombyggnadsinvesteringar. Betongdammarnas beteende styrs till stor del av variationen i omgivande temperaturer och vattennivå. I kalla regioner kan is som bildas i magasinet utsätta dammen för en tryckande last. Teoretiskt har denna belastning en betydande inverkan på dammarsstrukturella beteende. Trots detta är den maximala storleken såväl som säsongsvariationen för islasten en av de mest betydande osäkerheterna vidsäkerhetsbedömningen av dammar. Denna uppsats presenterar forskning som undersöker hur förväntat beteendehos dammar i kallt klimat kan modelleras. Den underliggande frågeställningen är att förutsäga en damms respons orsakad av variation i de yttre förhållandena. Extra fokus har lagts på förståelsen och modelleringen av islasten då den är en viktig del av de yttre förhållandena för dammar i kalla klimat. Modeller som är lämpliga för att förutsäga dammars beteende kan delas upp i teoretiska, databaserad, och hybridmodeller. Förutsägbarhetsnoggrannhet är avgörande för att ställa in varningsnivåer, och i det avseendet är de databaserade modellerna i allmänhet överlägsna. Det huvudsakliga bidraget från detta projekt är utvecklandet och installationen av en prototyp av en islast panel, fäst på en damms uppströmssida. Panelen mäter istrycket direkt mot dammen och är tillräckligt stor så att helaisens tjocklek förblir i kontakt med panelen. Panelen bidrar till ökad kunskap om säsongsvariationen i istryck och mekanismen för islaster orsakad av variation i vattennivån. Den predikterade islaten från den bästa tillgängliga islastmodellen som inkluderar termiska islaster och islaster från vattennivåförändringar överensstämmer inte med de uppmätta islastpanelen som uppmätts med panelen. Då det saknas validerade modeller eller mätmetoder för islast är det viktigt med fortsatt forskning, dels genom ytterligare mätningar för att öka kunskapen men även fortsatt modellutveckling.
QC 20190926
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Ersayın, Deniz Tayfur Gökmen. "Studying Seepage In A Body Of Earth-Fill Dam By (Artifical Neural Networks) Anns/". [s.l.]: [s.n.], 2006. http://library.iyte.edu.tr/tezler/master/insaatmuh/T000350.pdf.
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Durve, C. "Flow through tailings dams". Thesis, Open University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375642.
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This thesis deals with the study of flow through tailings dams. Examination of the current practices led to the construction of a valid experimental model. A unique system of instrumentation was developed, which was employed successfully to measure pore water pressures accurately and thus provide the necessary information to locate the position of the phreatic surface. Using the developed technique, models of tailings dams were constructed and monitored and it was discovered that a major deviation in the expected position of the phreatic surface occurred in a tailings dam. Further investigation by the construction of various types of dams led to the redefining of the phreatic surface and thus the flow regime. A computer programme based on the use of the finite difference technique was applied to water retention dams and found to locate the position of the phreatic surface accurately.
17
Mirghasemi, Seyedeh Soudeh. "Agriculture, Dams, and Weather". Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/579110.
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The first chapter investigates whether construction of the Bureau of Reclamation dams in the early twentieth century raise farm values and increase agricultural output? I construct a new county level panel data set from 1890 to 1920 with information on geography, climate, politics, agriculture, and major dams and then evaluate the effect of the Bureau of Reclamation dams on the value of farms and on crop productivity. Using fixed effect panel estimation, I find that new federal dam construction increased the average value of farm land by approximately 6.4 percent. When I apply an instrument to control for potential endogeneity, the effect of Bureau dams on the farm land value increases in size, although the estimate is no longer statistically significant. When examining the crop output, the only crop for which the dams had effects was alfalfa. In the second chapter I investigate the effect of the geographic, economic and political factors on dam construction at the beginning of the Bureau of Reclamation's operation in the American West. Applying county level data which has been linked from various data sources for the time period of 1900 to 1910, I show that the percentage of votes for Republicans in presidential elections has a significant and positive effect on major dam construction. The last chapter investigates the effect of climate change on US agriculture using county-level data from 1997 to 2007. Compared to previous contributions, we pay particular attention to the spatial heterogeneity across the climate zones and include the presence of extreme weather events. The lack of consideration for both effects may have led previous works to generate biased estimates and incorrect impact forecasts. While current approaches use projected climate variables derived from coarse resolution Global Climate Models (GCMs), we use data at a much finer resolution by relying on dynamically downscaled simulation data. Further, we pay particular attention to the spatial heterogeneity in the impact of climate among the climate zones. Chow-Wald tests indicate the presence of significant heterogeneity across zones in the effects of climate on land values.
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Piton, Guillaume. "Sediment transport control by check dams and open check dams in Alpine torrents". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU041/document.
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Barrages de corrections torrentielles et plages de dépôts jouent un rôle clés dans la protection contre les crues des torrents. Leurs gestionnaires ont pour mission de réduire les risques d'inondations, mais doivent désormais aussi minimiser les impacts environnementaux liés aux ouvrages de protection. Ceci nécessite une meilleure compréhension des effets des barrages de corrections torrentielles et des plages de dépôts sur le transport sédimentaire des torrents. Cette thèse s'inscrit dans cet objectif et se décompose en deux parties. Sa section sur l'état de l'art présente: i) les différents effets des barrages de correction torrentielle sur la production et le transfert sédimentaire; ii) des descriptions des processus hydrauliques et de sédimentation ayant lieu dans les plages de dépôts; et iii) les processus liés à la production et au transfert de bois d'embâcle. Une nouvelle méthode de quantification de la production sédimentaire des torrents complète cet état de l’art.La seconde partie de cette thèse présente le travail réalisé en banc d’essai expérimental. Une première série d’expérience a permis de mettre en évidence un transport par charriage plus régulier lorsque des barrages de correction torrentielle sont ajoutés à un bief alluvial. Une seconde série d’essais a été réalisée sur un modèle générique de plage de dépôt dans l’objectif d’en caractériser les écoulements. Pour cela, une nouvelle procédure de mesure et de reconstruction par approche inverse a été développée. Il en résulte une description des caractéristiques d’un écoulement proche du régime critique, ainsi que des mécanismes de rétrocontrôle entre morphologie et hydraulique pendant la phase de dépôtCheck dams and open check dams are key structures in torrent hazard protection. Their managers must mitigate flood hazards, but now must also minimize the environmental impacts of these protection structures. This requires to improve the knowledge on the effects of check dams and open check dams on the sediment transport, and this thesis forms a contribution towards this end.The section on the current state of research reviews i) the diverse effects of check dams on sediment production and transfer; ii) descriptions of the hydraulics and sedimentation processes occurring in open check dams; and iii) woody debris production and trapping processes. This state of the art is completed with proposition of new bedload transport estimation methods, specifically developed for paved streams experiencing external supply or armour breaking.Experimental results are then provided. Firstly, flume experiments highlight the emergence of a more regular bedload transport when check dams are built in alluvial reaches. In a second stage, experiments were performed on a generic Froude scale model of an open check dam basin in order to capture the features of laterally-unconstrained, highly mobile flows. A new flow measurement and inverse-reconstruction procedure has been developed. A preliminary analysis of the results describes flows that tend toward a critical regime and the occurrence of feedback mechanisms between geomorphology and hydraulics during massive bedload deposition
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Hsieh, Jen-Chi. "Free vibrations of inflatable dams". Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53533.
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This work deals with the linear two-dimensional free vibrations of an inflated cylindrical membrane. An air-inflated membrane is considered first. Vibration frequencies and modes are determined for various cases. The lowest mode shape is anti-symmetric. In the rest of the work, the membrane is inflated with water. In some cases there is a reservoir of water on one side of the membrane. The membrane equation of motion is solved using a finite difference method, and the hydrodynamic pressures on the membrane, caused by the motion of the internal and external water domains, are treated by the boundary element method. The effects of the membrane parameters, internal and external water head, and density of the membrane on the lowest four frequencies are illustrated. For the membrane without the outside water, the first two natural frequencies agree well with experimental values. The existence of the upstream head has a significant influence on the frequencies, and the mode shapes are shown to be tilted toward the downstream side of the membrane.Ph. D.
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Atallah, Tony A. "A review on dams and breach parameters estimation". Master's thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/37120.
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Nowadays, especially after the appearance of the global warming effects, water is becoming less and less available. Here appears the role of water resources engineering. That is; finding the mean through which we can collect water. One alternative for doing so is the storing of water behind dams. This is why this report will focus on damsâ issues. This report is divided in two sections. The first section deals with the most common types of dams, the forces applied on them, the modes of failure of these structures, the environmental effects on the stream, the decommissioning and other technical matters. The second part focuses on the different methods used in order to estimate or predict the breach of the dams especially for the embankment type. These methods are applied to the case of the Timberlake Dam in Lynchburg, VA that failed in 1995 and was rebuilt in 2000.Master of Science
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Bliss, Michael A. "Procedures to Perform Dam Rehabilitation Analysis in Aging Dams". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33157.
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There are hundreds of existing dams within the State of Virginia, and even thousands more specifically within the United States. A large portion of these dams do not meet the current safety standard of passing the Probable Maximum Flood. Likewise, many of the dams have reached or surpassed the original design lives, and are in need of rehabilitation. A standard protocol will assist dam owners in completing a dam rehabilitation analysis. The protocol provides the methods to complete the hydrologic, hydraulic, and economic analysis. Additionally, alternative augmentation techniques are discussed including the integration of GIS applications and linear programming optimization techniques. The standard protocol and alternative techniques are applied to a case study. The case study includes a set of flood control dams located in the headwaters of the South River watershed in Augusta County, VA. The downstream impacts of the flood control dams on the city of Waynesboro are demonstrated through the hydrologic and hydraulic analysis.Master of Science
22
Lau, Tak Chi. "Fully-coupled earthquake response analysis of earth dam including anisotropic effect /". View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202008%20LAU.
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Wortmann, Heid. "Sedimentation and desiccation of gold mines". Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-11052007-152710.
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Liu, Xiaochen. "Reliability – based analysis of embankment dams". Thesis, KTH, Jord- och bergmekanik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-257872.
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Embankment dams are widely used as water-retaining structures through the world. Two principal structural failure modes of embankment dams are internal erosion and slope instability. The objective of this thesis is to investigate the feasibility of applying probabilistic methods in embankment dam assessment. Compared to deterministic methods, probabilistic methods considers the variability in material properties and the results are more assessable. Meanwhile, the derived sensitivity factors of the variables can be used to find the most influential one.Through a literature review, it is found that the difficulties in defining a limit state function for the full process of internal erosion for embankment dams hold back the application of reliability-based methods. However, reliability-based methods have been recognized as suitable for slope stability assessment.In this thesis, both deterministic and probabilistic calculations have been performed for a homogenous embankment dam. The deterministic calculation is carried out in Slope/W to first find out the most critical slip surface. The failure probability of this slip surface is estimated by both Monte Carlo simulations in Slope/W and FORM analysis in Comrel. Then, the 34 most critical slip surfaces from Slope/W are chosen to calculate the system reliability with simple bounds and applied integration. The results from the deterministic and probabilistic calculations showed that the studied dam has a higher risk of failure than allowed. In the system reliability calculation, simple bounds gives a wide range, especially the upper bounds. It was found that classification of different slip surfaces into different groups with respect to geometry and material was useful to simplify the calculations. Not much improvement in accuracy of the system probability of failure is found when increasing the numbers (from 1 to 5) of the most critical slip surfaces from each group. Even the combination of 1 slip surface from each group only gives an error of 6.5%. Categorizing slip surfaces before performing a system reliability analysis is a good way for simplification of the calculations. Due to this, the criteria used for categorization of the slip surfaces are of interest. In this work, it was found that the slip geometry in combination with the materials included in the slip surface constitute a possible way forward to do this.
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Johansson, Sam. "Seepage monitoring in embankment dams". Doctoral thesis, KTH, Civil and Environmental Engineering, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2477.
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Internal erosion, which is one of the major reasons forembankment dam failure, causes an increased seepage flow due toloss of fines. A seepage measuring system is therefore a vitalpart of an embankment dams monitoring system. Manyexisting seepage monitoring systems are not however sensitiveenough to detect small changes in the seepage flow. Temperatureand resistivity measurements represent two methods for seepagemonitoring in embankment dams. They are able to detect effectscaused by time dependent processes such as internal erosion,where the relative accuracy is more important than the absoluteaccuracy. Temperature can normally be easily measured inexisting standpipes. Resistivity measurements are morecomplicated; they require a computer-based monitoring systemand minor technical installations on the dam.
The temperature in an embankment dam depends mainly on thetemperature in the air and the water temperature in theupstream reservoir. These two temperatures vary seasonally andcreate temperature waves propagating through the dam. Theseepage rate, and its change with time, can be evaluated frommeasurements repeated at regular intervals. The sensitivity ofthe method depends mainly on the distance between the dam crestand the measurement point, the size of the dam, the location ofthe standpipes, and the temperature variation in the reservoirat the inflow level. The seepage detection level of the methodis about 1 ml/sm2 for a typical Swedish dam with a height ofabout 30 m. The detection level depends linearly on the damheight. Results from field measurements show that the methodgives reasonable information concerning the condition of thedam. Zones with anomalous seepage rates have been located andseepage flow rates have been quantified. Changes in the seepageflow rate as well as the seepage pathway have also beenobserved.
The resistivity of the ground depends mainly on theporosity, saturation and clay content. When reservoir waterseeps through a dam, the properties of the water in thereservoir will also affect the resistivity in the dam. Theresistivity of the reservoir water is temperature dependent,but it is also a function of the total dissolved solids. Boththese parameters vary seasonally and this causes variations inthe dam. The seepage flow can be evaluated from the resistivitydata using methods similar to those employed for seepageevaluation from temperature data. The sensitivity is similar tothat of the temperature method but the resolution and accuracyis lower. Zones with anomalous leakage can be located. Groundpenetrating radar and borehole radar methods are based on themeasurement of material dependent properties. These are lesssensitive to seepage changes than flow dependent parameters.The relatively high accuracy obtained by borehole radarmeasurements compensates however for their lower sensitivity toporosity changes. Borehole radar based on tomographic analysiscan be a valuable method for mapping areas with increased andanomalous porosity formed as a consequence of increased seepageand internal erosion.
Key words:embankment dams, internal erosion, seepagemonitoring, temperature, resistivity, ground penetratingradar
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Kassa, Negede Abate. "Probabilistic safety analysis of dams". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-60843.
Texto completoResumen
Successful dam design endeavor involves generating technical solutions that can meet intended functional objectives and choosing the best one among the alternative technical solutions. The process of choosing the best among the alternative technical solutions depends on evaluation of design conformance with technical specifications and reliability standards (such as capacity, environmental, safety, social, political etc pecifications). The process also involves evaluation on whether an optimal balance is set between safety and economy. The process of evaluating alternative design solutions requires generating a quantitative expression for lifetime performance and safety. An objective and numerical evaluation of lifetime performance and safety of dams is an essential but complex undertaking. Its domain involves much uncertainty (uncertainty in loads, hazards, strength parameters, boundary conditions, models and dam failure consequences) all of which should be characterized. Arguably uncertainty models and risk analysis provide the most complete characterization of dam performance and safety issues. Risk is a combined measure of the probability and severity of an adverse effect (functional and/or structural failure), and is often estimated by the product of the probability of the adverse event occurring and the expected consequences. Thus, risk analysis requires (1) determination of failure probabilities. (2) probabilistic estimation of consequences. Nonetheless, there is no adequately demonstrated, satisfactorily comprehensive and precise method for explicit treatment and integration of all uncertainties in variables of dam design and risk analysis. Therefore, there is a need for evaluating existing uncertainty models for their applicability, to see knowledge and realization gaps, to drive or adopt new approaches and tools and to adequately demonstrate their practicability by using real life case studies. This is required not only for hopefully improving the performance and safety evaluation process accuracy but also for getting better acceptance of the probabilistic approaches by those who took deterministic design based research and engineering practices as their life time career. These problems have motivated the initiation of this research.
In this research the following have been accomplished:
(1) Identified various ways of analyzing and representing uncertainty in dam design parameters pertinent to three dominant dam failure causes (sliding, overtopping and seepage), and tested a suite of stochastic models capable of capturing design parameters uncertainty to better facilitate evaluation of failure probabilities;
(2) Studied three classical stochastic models: Monte Carlo Simulation Method (MCSM), First Order Second Moment (FOSM) and Second Order Second Moment (SOSM), and applied them for modeling dam performance and for evaluating failure probabilities in line with the above mentioned dominant dam failure causes;
(3) Presented an exact new for the purpose analytical method of transforming design parameters distributions to a distribution representing dam performance (Analytical Solution for finding Derived Distributions (ASDD) method). Laid out proves of its basic principles, prepared a generic implementation architecture and demonstrated its applicability for the three failure modes using a real life case study data;
(4) Presented a multitude of tailor-made reliability equations and solution procedures that will enable the implementations of the above stochastic and analytical methods for failure probability evaluation;
(5) Implemented the stochastic and analytical methods using real life data pertinent to the three failure mechanisms from Tendaho Dam, Ethiopia. Compared the performance of the various stochastic and analytical methods with each other and with the classical deterministic design approach; and
(6) Provided solution procedures, implementation architectures, and Mathematica 5.2, Crystal Ball 7 and spreadsheet based tools for doing the above mentioned analysis.
The results indicate that:
(1) The proposed approaches provide a valid set of procedures, internally consistent logic and produce more realistic solutions. Using the approaches engineers could design dams to meet a quantified level of performance (volume of failure) and could set a balance between safety and economy;
(2) The research is assumed to bridge the gap between the available probability theories in one hand and the suffering distribution problems in dam safety evaluation on the other;
(3) Out of the suite of stochastic approaches studied the ASDD method out perform the classical methods (MCSM, FOSM and SOSM methods) by its theoretical foundation, accuracy and reproducibility. However, when compared with deterministic approach, each of the stochastic approaches provides valid set of procedures, consistent logic and they gave more realistic solution. Nonetheless, it is good practice to compare results from the proposed probabilistic approaches;
(4) The different tailor-made reliability equations and solution approaches followed are proved to work for stochastic safety evaluation of dams; and
(5) The research drawn from some important conclusions and lessons, in relation to stochastic safety analysis of dams against the three dominant failure mechanisms, are. The end result of the study should provide dam engineers and decision makers with perspectives, methodologies, techniques and tools that help them better understand dam safety related issues and enable them to conduct quantitative safety analysis and thus make intelligent dam design, upgrading and rehabilitation decisions.
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Dounias, George Theodoros. "Progressive failure in embankment dams". Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/8350.
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Li, Bingjun. "Flowthrough and overtopped rockfill dams". Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10420.
Texto completoResumen
The emphasis of this thesis is on the derivation of original results or improvement to the available results in order to obtain a practical design methodology for overtopped rockfill dams. The work comprised of experiments in a large hydraulic flume, and extensive theoretical development of design aspects. A non-linear finite element analysis for non-Darcy flow in dams has also been formulated. The important contributions of the thesis are listed as follows: I. Non-Darcy seepage flow. (1) Development of a general relationship between the Reynolds number and the friction coefficient for seepage in rockfill; (2) Development of a general relationship between the hydraulic gradient and the velocity of seepage flow in rockfill; (3) Investigation of the difference between all the available formulae for non-Darcy flow by the computer simulation with wide range of porosity and size of rockfill. Comparisons between the simulated results of available formulae and the available prototype data have also been undertaken. (4) Determination of the hydraulics mean radius of rockfill material by empirical relationship; (5) Estimation of the seepage discharge through a rockfill dam without numerical modelling. II. Numerical modelling of non-Darcy seepage flow. (1) Development of a high-accuracy finite element method to model the non-Darcy seepage field within a flowthrough and overtopped rockfill dam. III. Stability analysis and design methodology for flowthrough and overtopped rockfill dams. (1) Development of a formula for the design of the external layer comprising of large-size particles at the downstream slope of a flowthrough and overtopped flow rockfill dam; (2) Development of a formula for the design of mesh protection at the downstream slope of a flowthrough and overtopped rockfill dam; (3) Development of a formula for the design of steel bars protected at the downstream slope of a flowthrough and overtopped rockfill dam; (4) Development of a practical design methodology which applies to small flowthrough and overtopped rockfill dams. IV. Behaviour of forces acting on the downstream slope. (1) Investigation of the stochastic and statistical behaviour of the forces acting on the force panels installed at the downstream slope in a model flowthrough and overtopped rockfill dam. V. Theoretical solution of 1-D seepage flow in overtopped rockfill. (1) Development of a theoretical solution for the seepage flow at the transition zone in an overtopped rockfill dam.
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Irhouma, Abdulhamid Mohamed. "Rehabilitation of cracked concrete dams". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0026/NQ51639.pdf.
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Welch, Jonathan Paul. "Water flow through tailings dams". Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5523/.
Texto completoResumen
Water levels in tailings dams are generally lower than those of standard earth dams. Previously, other authors have shown that embankment geometry and variation in permeability can be responsible for a concave upwards steady state seepage line. These factors are investigated in greater detail using a finite element program to model flow in the saturated portion of the embankment. It is shown that the angle of the upstream slope only has an appreciable effect on the form of the seepage line if the pond is close to the downstream face of the dam. An increasing permeability in the direction of flow and seepage path length are responsible for reducing the height of the seepage line. This effect is demonstrated for both a continuous variation of permeability and a step jump in permeability between the tailings deposit and the dam. Anisotropy of tailings and dam permeability is also investigated. Transient analyses of saturated flow are performed for tailings dams constructed of dry compacted waste. For this case, the seepage line is straight for a constant pond level, and concave upwards for a rising pond and a low dam permeability. The simple computer model also predicts that for a constantly rising pond level, the seepage line advances at a constant rate dependent on the rate of pond rise, and the material properties of the dam. A fully automatic finite element program has been written, combining an adaptive mesh regeneration algorithm and a variable mesh technique. The program is shown to provide both an accurate and precise solution of the free surface problem. A method of automatically generating "square" flow nets by post-processing the finite element data is presented for the first time. Flow nets provide a visual proof of the correctness of the computer model and are a useful aid to other workers.
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Ding, Deping. "Consolidation analysis of embankment dams". Thesis, Swansea University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281063.
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Chernoloz, Oleksiy y Oleksiy Chernoloz. "Cataloging Tailings Dams in Arizona". Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/625329.
Texto completoResumen
Tailings storage facilities (TSFs) and conventional water retaining dams are the largest manmade structures on Earth. Statistics show that TSFs are more likely to fail than water retaining dams.Recent catastrophic failures of TSFs have led to the loss of lives (Germano mine, Brazil), environmental damage (Mount Polley, Canada), contamination of drinking water (Baia Mare, Romania), and the destruction of property (Kingston Fossil Plant, USA). As the scale of mining increases, TSFs increase in height and volume, therefore increasing the consequence of failure. To help mitigate risk associated with large TSFs mining companies empanel expert groups to review operations of TSFs and conduct regular visual inspections. In the US the Mine Safety and Health Administration has regulatory responsibility for the safety of TSFs. As population centers expand nearer to existing and proposed TSFs, the public requires assurance of the integrity of these structures. A pro-active approach to public safety is more desirable than a post-mortem analysis after a major failure.
We have examined both the regulatory practices, the industry practices, and public data on TSFs in Arizona. In this thesis paper we address inadequacies of the official government records on TSFs in the two largest publicly accessible databases of dams inthe US – the National Inventory of Dams (NID), and the National Performance of Dams Program (NPDP). Both databases contain numerous errors and omissions, including descriptions and geographic coordinates of TSFs that are inaccurate by many kilometers. Several large TSFs in Arizona are not included in either database.We address these shortcomings with a pilot project for Arizona that demonstrates recording accurate information in a database is neither expensive nor onerous, communicating best practices for operation can help alleviate community concerns, and continuous monitoring technology can resolve shortcomings with visual inspections.
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Park, Youngjin. "Investigation of the Ability of Filters to Stop Erosion through Cracks in Dams". Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11086.
Texto completoResumen
The ability of a filter to stop erosion through cracks in the core of a embankment dam requires that the filter be graded so that it will restrain movement of particles from the core, and that the filter be truly cohesionless, so that it will not crack even when subjected to the same types of deformations that cause cracks in the core.
To achieve resistance to cracking, most current filter criteria require that the filter should contain no more than 5% of material finer than the #200 sieve, and that this fine material should be non-plastic. This research study was conducted to investigate whether there specifications do, in fact, result in filters that can be relied upon to slump, fill cracks, and prevent interval erosion in embankment dams.
The research study involved filter erosion tests using a 4-inch diameter device and a 12-inch square device, and "sand castle" tests to investigate the tendency for candidate filters to slump when immersed in water. These tests showed that conventional filter criteria no more than 5% fines, and fines that are non-plastic, are conservative. The research study showed that even filters with 5% of highly plastic fines are able to slump, fill cracks, and prevent erosion.Ph. D.
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Economides, Thoukidides A. "Experimental investigation on the dynamics of inflatable dams". Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-172109/.
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Mysore, Guruprasad Jr. "Vibration Analysis of Single - Anchor Inflatable Dams". Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/36846.
Texto completoResumen
Inflatable dams are flexible, cylindrical structures anchored to a foundation. They are used for a variety of purposes, e.g. diverting water for irrigation or groundwater recharging, impounding water for recreational purposes, and raising the height of existing dams or spillways.
The vibration behavior of such dams is analyzed. Single-anchor inflatable dams with fins are considered. First, a static analysis is performed which yields the equilibrium shapes of the dam, both in the presence and absence of water. Then, a dynamic analysis is undertaken which analyzes the small vibrations of the inflatable dam about the equilibrium configuration, both in the presence of water (hydrostatic water as well as parallel flowing water) and absence of water.
The dam is modeled as an elastic shell. It is assumed to be air-inflated and resting on a rigid foundation. The cross-sectional perimeter, material thickness, modulus of elasticity, and Poisson's ratio are given. The analysis is performed for different values of internal pressure and external water heads.
Initially, the dam is assumed to lie flat. The internal pressure is then increased slowly until it reaches the desired value. Then the external water is applied and the equilibrium configuration is obtained. Small vibrations about this configuration are considered. The water is assumed to be inviscid and incompressible, and potential theory is used. The infinite-frequency limit is assumed on the free surface. A boundary element technique is utilized to determine the behavior of the water, and the finite element program ABAQUS is used to analyze the structural behavior. Both the cases of fluid at rest and flowing parallel to the dam are considered. The vibration frequencies and mode shapes are computed. The effect of the internal pressure of the dam is investigated, and the results are compared to those for the dam in the absence of external water.
Master of Science
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Boughoufalah, Mohamed. "Earthquake input mechanisms for dam-foundation interaction". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63932.
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Svensen, Daniel. "Numerical analyses of concrete buttress dams to design dam monitoring". Thesis, KTH, Betongbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-189250.
Texto completoResumen
Old concrete buttress dams are sensitive to cracking if exposed to large temperature variations. The cracks can make dams sensitive to failure, depending on the size and location of the cracks. These problems can be overcome by lowering the temperature variations and stabilizing the dams. Insulation walls can be built to lower the temperature variations, and the area inside the insulation wall can be climate controlled to ensure a constant temperature. Stabilizing measures could be installing tendons, anchoring monoliths to the foundation or to keep parts of the monolith together. However, the best way to make sure the dam is functioning as expected is to monitor the behavior of the dam through different sensors. The sensors should be connected to some kind of dam monitoring software, which can indicate whether the dam is going to fail in a near future. For this to work, some kind of alert and alarm values has to be determined. The main purpose for this project is to develop a finite element model that could be used to simulate the real behavior of a concrete buttress dam and predict the future behavior of the dam. This makes it possible to determine alert and alarm values for monitoring equipment installed on the dam. Some steps are necessary to be able to create a finite element model representing the real behavior and to predict the future behavior of a dam. A first step is calibration of the model against real measurements, and during the calibration process it is important to evaluate the predictions made. A second step is to determine the normal variation in the behavior of the dam. A last step is to define suitable alert and alarm values, where the alert values are based on the normal variation of the dam and the alarm values are based on failure analyses. The results show that it is possible to calibrate a finite element model with sufficient accuracy in order for it to be used for predictions of the dams behavior. The results show two failure modes of the concrete buttress dam which deviate from previous research, where post-tensioned tendons were not included. From the results, information is given about where to place sensors to be able to capture a failure, how well the finite element model is calibrated, and what the alarm values should be. Furthermore, the results show that the evaluation of predictions made in the calibration process is of utmost importance to achieve a model representing the real behavior.Gamla betonglamelldammar är känsliga för sprickbildning om de utsätts för stora temperaturvariationer. Sprickor kan göra dammarna känsliga för brott, beroende på storlek och placering av sprickorna. Dessa problem kan övervinnas genom att sänka temperaturvariationerna och stabilisera dammarna. Isoleringsväggar kan byggas för att sänka temperaturvariationerna, och området innanför isoleringsväggen kan klimatkontrolleras för att säkerställa en konstant temperatur. Stabiliserande åtgärder skulle kunna vara att installera spännkablar, förankring av monoliten till berggrunden eller att hålla ihop delar av monoliten. Emellertid är det bästa sättet att se till dammen fungerar som förväntat för att övervaka beteendet hos dammen genom olika sensorer. Givarna borde anslutas till någon form av programvara för dammövervakning, som kan indikera om dammen kommer att gå till brott inom en snar framtid. För att detta ska fungera måste någon form av mjuka och hårda larmvärden bestämmas. Huvudsyftet för detta projekt är att skapa en finit elementmodell som kan användas för att simulera det verkliga beteendet hos en betonglamelldamm och förutsäga framtida beteende av dammen för att kunna bestämma mjuka och hårda larmvärden för vald övervakningutrustning på dammen. Några steg är nödvändiga för att kunna skapa en finit elementmodell som representerar det verkliga beteendet och göra det möjligt att förutsäga det framtida beteendet av en damm. Ett första steg är kalibrering av modellen mot riktiga mätningar och under kalibreringsprocessen är det viktigt att utvärdera predikterade värden. Ett andra steg är att bestämma den normala variationen av dammens beteende. Ett sista steg är att definiera lämpliga värden för mjuka och hårda larmvärden, där de mjuka värdena baseras på dammens normala variation och de hårda larmvärdena på brottsanalyser. Resultaten visar att det är möjligt att kalibrera en finit elementmodell med tillräckligt god noggrannhet att den kan användas för prediktering av dammens beteende. Resultaten visar två brottmoder av betonglamelldammen som skiljer sig från tidigare studier där spännkablar inte hade inkluderats. Från resultaten ges information om var sensorer ska placeras för att kunna fånga ett brott, hur väl finita elementmodellen kalibrerats, och vilka de mjuka och hårda larmvärdena bör vara. Dessutom visar resultaten att utvärderingen av predikteringar som gjorts i kalibreringsprocessen är av yttersta vikt för att uppnå en modell som representerar det verkliga beteendet.
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McIntosh, Bruce John. "A SIMPLIFIED PROBABILITY APPROACH TO THE DESIGN AND ANALYSIS OF URANIUM TAILINGS IMPOUNDMENTS". Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276414.
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Leeuwrik, Maarten James. "Nonlinear vibration analysis of inflatable dams". Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45786.
Texto completoResumen
In recent years the use of inflatable dams has become more widespread throughout the world. Various people have done studies on the shape and membrane tension of these structures; however, only a few authors have considered dynamic behavior. Due to the nature of the applications and the material composition of these structures, a study considering the dynamic response of an inflatable dam is warranted.
In this study, the equation of motion for an air-inflated dam is derived, then solved using the
Galerkin approximation method. The solution is performed for a one-term approximation and
a two-term approximation, where both solutions use a sine function to approximate the deflected
shape of the dam. Frequencies and amplitudes are calculated and presented in tables
and plots for the first four modes, and three different values of the central angle of the dam.
Comparisons to the results of other studies are presented at the conclusion of this study.
Master of Science
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Vos, Adele. "Unsteady flow conditions at dam bottom outlet works due to air entrainment during gate closure : Berg River dam model". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71850.
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Thesis (MSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: A trial closure of the emergency gate of the Berg River Dam was undertaken by the Trans- Caledon Tunnel Authority (TCTA) on 12 June 2008. The air vent downstream of the emergency gate was designed to introduce air to mitigate the negative pressures that were expected in the conduit during emergency gate operations. The emergency gate has to close when the radial gate at the downstream end of the outlet conduit fails. Contrary to the theoretical design, the measured air vent velocities in the field indicated that, while the emergency gate was closing, very large volumes of air were apparently continuously being released from the air vent, commencing when the gate was about 30% closed (i.e. 70% open). This is in contrast to what the design intended, namely that air should have been drawn into the vent. This thesis is concerned with the testing of a 1:14.066 physical model representing the outlet works and air vent of the Berg River Dam as a means to determine the reasons for the release of large volumes of air from the air vent during the trial closure in 2008. It also seeks solutions to mitigate the excessive airflow from the air vent. It was concluded that the air velocity in the air vent was independent of the rate of closure of the emergency gate, but to increase with increasing water head. The problem at the Berg River Dam was determined to be one of air blowback. Modifications were made to the configuration of the model in order to determine whether the configuration of the outlet works caused air to be released from the air vent. It was determined that the downward sloping roof at the outlet of the conduit, used to accommodate the radial gate chamber, was the cause of the air blowback phenomenon. An additional air vent was fitted directly onto the conduit at the constriction was found to be ineffective in reducing the air blowback. It was concluded that there are no rational structural change that can prevent or inhibit a recurrence of the blowback phenomenon in the Berg River Dam outlet conduit. The recommendation follows that the outlet conduit should not be constricted by any structural or mechanism further downstream in the conduit.
AFRIKAANSE OPSOMMING: ʼn Toetssluiting van die noodsluis van die Bergrivierdam is op 12 Junie 2008 deur die TCTA (Trans-Caledon Tunnel Authority) uitgevoer. Die lugskag stroomaf van die noodsluis is ontwerp om lug in te voer om die verwagte negatiewe drukke tydens die noodsluissluiting te beperk. Die noodsluis moet sluit indien die radiaalsluis aan die einde van die uitlaatpyp sou faal. In teenstelling met die teoretiese ontwerp, het die gemete lugsnelhede in die lugskag in die veld aangedui dat groot volumes lug voortdurend uit die lugskag vrygelaat word wanneer die noodsluis ongeveer 30% toe is (dit wil sê 70% oop). Dit is in teenstelling met die ontwerp, want die lugskag is ontwerp vir die insuig van lug. Hierdie tesis het ten doel om die redes vir die vrylating van groot volumes lug uit die lugskag vas te stel met behulp van ʼn 1:14.066 fisiese skaalmodel van die uitlaatwerke en lugskag van die Bergrivierdam soos getoets tydens die inwydingstoetssluiting in 2008. Die toetse op die model het getoon dat die lugsnelheid in die lugskag onafhankik van die sluistoemaak tyd is, maar verhoog met die toename in die watervlak. Die Bergrivier dam probleem was bepaal as die van lug terugslag. Die model is gewysig ten einde te bepaal of die spesifieke samestelling van die uitlaatwerke die oorsaak van die vrystelling van lug uit die lugskag is. Die analises en verandering aan die uitleg toon aan dat die skuins afwaartse dak van die uitlaattonnel om die radiaalsluiskamer te huisves die rede was vir die vrylating van die lug uit die lugskag. ‘n Addisionele lugskag was gebou in die dak van die uitlaattonnel reg bo die sametrekking, maar was oneffektief om die terug vloei van lug te verminder. Die gevolgtrekking is dat daar geen rasionele strukturele verandering aangebring kan word aan die Bergrivier dam om die vrystelling van lug uit die lugskag te verhoed of te verminder nie. ’n Aanbeveling vir toekomstige ontwerpe is dus dat die uitlaattonnel nie beperkend by die uitlaatend moet wees nie.
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Yilmaz, Metin. "Control Of Groundwater By Underground Dams". Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1259621/index.pdf.
Texto completoResumen
In this study underground dams are briefly described and detailed information about the design and construction aspects is provided. Since the material, of which dam wall is composed, is the main variable influencing the groundwater behavior, various types of dam wall are discussed. The use and usefulness of the underground dams as a means of sustainable development, and their performance in the management of groundwater resources are analyzed with the help of two example studies. In the first example a hypothetical idealized aquifer is considered, while in the second one, a real aquifer is selected.
For the performance evaluation, and for the analysis of the impact of the underground dams on the groundwater behavior, numerical simulation is opted. For that purpose, a well-known computer code, MODFLOW, A Modular Three-Dimensional Finite Difference Groundwater Flow Model of U.S. Geological Survey, (McDonald and Harbaugh, 1988) is used.
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Boberg, Björn y David Holm. "FEM modeling of concrete gravity dams". Thesis, KTH, Vattendragsteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99351.
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Hansen, David. "The behaviour of flowthrough rockfill dams". Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7658.
Texto completoResumen
This thesis deals with the hydraulics and stability of "flowthrough" rockfill embankments. This thesis provides new information in the following seven areas: (1) A multi-disciplinary consideration of most of the available equations describing one-dimensional non-Darcy flow. Such flow is characterized by a non-linear dependence of velocity on the hydraulic gradient. New data is presented to assist in the evaluation of the effect of particle irregularity, as compared to perfect spheres. (2) A new computational method to estimate the quantity of flow moving through a rockfill embankment, as a function of the upstream water level, is presented. (3) If some minimum upstream water level is required, an impermeable element (in the form of a wall-like hydraulic barrier) will be needed. The hydraulics of an upstream impermeable facing (UIF) was studied in this research program. Some guidance is presented as to how to account for the effect of an elevated downstream water level on the stage-discharge rating curve of a flowthrough rockfill embankment. (4) Three distinct analytical methods for computing the position of the phreatic line are presented and evaluated. The validity of the Dupuit assumption, which is inherent in all three of the analytic methods, is also discussed. (5) A detailed computational framework is presented to make possible the prediction of the minimum elevation over which mesh protection is needed to prevent erosion of the downstream face of the dam. (6) The possibility of massive deep-seated failure was investigated in detail. As a first step to permit such evaluations, non-Darcy pore-pressure modelling was performed. An efficient method for executing such modelling on an electronic spreadsheet is presented. In an innovative series of experiments it was found that the measured bursting force at incipient failure was far closer to that theoretically predicted by the wedge method than that predicted by a classical rotational slip-circle method (Bishop's Simplified Method). (7) In another innovative series of experiments, this low-temperature behaviour was investigated using the Low Temperature Laboratory of the National Research Council of Canada. Based on this research a simple method for estimating the rate of growth of ice at the phreatic surface is presented. Ice was not observed to form in the voids within the body of the dam, except in one case in a small mixing zone (the base of Parkin's zone 3) below the lip of the UIF. A detailed theoretical framework for performing heat budget calculations is also presented, together with a short computer program to facilitate these calculations. It is quantitatively demonstrated that the viscous dissipation of hydraulic energy plays an important role in preventing ice formation in the voids. (Abstract shortened by UMI.)
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Maranha, J. R. M. "Analysis of embankment dams : computational aspects". Thesis, Swansea University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638000.
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Aspects of the numerical simulation of the static behaviour of embankment dams were investigated in this thesis. Different stress updated algorithms were compared and the implicit backward Euler scheme was found to be the most accurate and robust. Particular emphasis was given to the use of a tangent modulus matrix consistent with the backward Euler scheme in the context of the Newton-Raphson method of solution of the nonlinear finite element equations. This combination was found to provide a robust algorithm. A closed form solution and a numerical procedure to evaluate the consistent tangent modulus matrix were described. The implications of using 2D and 3D formulations of elasto-plastic models were analysed. In particular 3D version of Tresca, Mohr-Coulomb and the critical state model were compared to their respective 2D versions. A robust stress update algorithm for the Mohr-Coulomb model formulated in principal stresses was presented. The comparisons were made by means of numerical examples that included: a rigid smooth strip footing, a purely cohesive slope and the construction of a dam. A 3D analysis of a hypothetical dam located in a v shaped narrow valley was made in parallel with a plane strain analysis of the same dam and the arching effect evidenced. A framework for incorporating plastic anistropic behaviour into elasto-plastic constitutive laws for soils based on a second order tensor was described. A rotational anistropic extension of the 2D version Tresca model and a shear anisotropy extension of the 2D version of the critical state model were presented and aspects of their performance illustrated by means of numerical examples. An investigation of an algorithm to model collapse settlement of soils having a general constitutive law was conducted. A version of the algorithm particularly adequate for the displacement based finite element method was presented. A back analysis of an actual dam (Beliche dam) incorporating an elasto-plastic model (c.s.m.) and collapse settlement was performed.
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Schrader, Ernest K. "Roller compacted concrete (RCC) for dams". Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284794.
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CHUQUIMUNI, ROBERTH APOLINAR AGUILAR. "NUMERICAL ANALYSIS OF RAISING EARTH DAMS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8624@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROUma das atividades relacionadas à recuperação de barragens envolve o alteamento de barragens existentes, normalmente com o objetivo de aumentar a capacidade de armazenamento dos reservatórios, melhorar o fator de segurança dos taludes ou a proteção da estrutura contra possíveis cheias. O alteamento pode estar previsto no projeto original da barragem, mas na maioria dos casos trata-se de um novo estudo, com a barragem em operação, devendo-se verificar as novas condições de fluxo, efeitos na estabilidade de taludes e na resposta da barragem a carregamentos estáticos e sísmicos, estes principalmente em regiões de alta sismicidade, como no sul do Peru, onde se enontram a barragem de terra de Viña Blanca, aqui considerada. Nesta dissertação o método dos elementos finitos e o método de equilíbrio limite, isolada ou conjuntamente, são empregados para análise estática e dinâmica destas barragens de terra considerando diversas opções de alteamento, como a construção de muros parapeito, muros de gabião, solo compactado, solo reforçado com geotêxteis e solo reforçado com revestimento de concreto. De estudos de perigo sísmico efetuados no local das barragens, selecionou-se o valor de aceleração horizontal máximo para ser utilizado nos registros de aceleração ocorridos nos terremotos de Lima (1974) e de Moquegua (2001). As análises numéricas efetuadas mostram que as opções de alteamento consideradas não alteram significativamente as condições de segurança das barragens existentes, tanto do ponto de vista hidráulico como da estabilidade de taludes e resposta dinâmica durante a incidência de terremotos.
One of the activities related to dam constructions involves the raising of the existent structure, normally done with the objective of increasing the water storage capacity of the reservoirs, improving the safety factor of the embankment slopes or to ensure a better protection against possible water flooding. The raising of an earth dam can be predicted in the original dam plan, but in mostly situations consists of a new design, with the dam fully operational, where the effects of a new dam height and reservoir level should be assessed with respect to flow conditions, stability of the embankment soil slopes and the response of the revised structure under static and seismic loads, mainly in highly seismic regions, as in the South of Peru where the earth dam of Viña Blanca, herein studied, was constructed. In this dissertation, the finite element method and the limit equilibrium method were used for the static and dynamic analyses of these earth dams, in their original geometry as well after dam raising with reinforced soil, compacted soil and concrete or gabion structures, among other options. From studies of seismic risk analyses carried out at the dam sites, the value of maximum horizontal acceleration equal to 0.4g was chosen to be used as the peak acceleration in the Lima (1974) and Moquegua (2001) acceleration time histories. The numerical results indicate that all dam raising options investigated in this work do not affect the safety conditions of the dams significantly, either under the point of view of the hydraulic behavior as well as soil slope stabilities or the dynamic response of the earth dams to seismic loads.
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Al, Baghdady Shayma y Linnea Khan. "Designing Roller compacted concrete (RCC) dams". Thesis, KTH, Betongbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231473.
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Concrete is the most common building material in the world and it consists of aggregates,cement and water that harden over time, it is also known as a composite material. The use ofconcrete is very versatile due to its resistance to wind and water and its ability to withstandhigh temperature. These qualities make concrete a suitable building material for largestructures such as dams.A dam is a huge construction that needs massive amount of concrete to build it with and thatleads to high cost, so alternative methods should be considered to minimize the cost ofconstructing the dams. One method is building the dams with Roller Compacted Concrete(RCC), which by definition is a composite construction material with no-slump consistency inits unhardened state and it has achieved its name from the construction method. The definitionfor a no-slump consistency is a freshly mixed concrete with a slump less than 6 mm. TheRCC is placed with the help of paving equipment and then it is compacted by vibrating rollerequipment. The RCC ingredients are the same as for the conventional concrete but it hasdifferent ratios in the materials that are blended to produce the concrete. It differs when itcomes to aggregates because both similar aggregates used in conventional concrete oraggregates that do not fulfill the normal standards can be used in the RCC mixtures. Thismeans, for example that aggregates found on the construction site can be used for the RCC.Compared to when constructing a conventional concrete dam, which is usually built in largeblocks, the RCC dam are usually built in thin, horizontal lifts, which allows rapidconstruction. This reduces the amount of formwork, but also the demand for man-hours areless due to the usage of machines for spreading and compacting, ultimately making it acheaper method. Building with RCC has become very popular around the world because of itsadvantages and new methods have been developed over the past two decades, adapted to theexperience gained after each project. All RCC dams that has been built, usually faceschallenges both during and after construction, and it includes everything from temperaturevariations, cracks to leakage.The main purpose of this master thesis is to create a guideline for how to design and constructdams with RCC and the idea is to be able to use it as a basis for future dams. Therequirements of Eurocode 2 and RIDAS are the basis of the criteria that the dam must fulfilland information of what is expected of the RCC is presented in this thesis. Furthermore anexample for design of an existing embankment dam to an RCC dam has been presented in thisthesis. The embankment dam needs to be rebuilt in order to increase the safety of the dam andthe goal of the case study was to determine the dimensions of the new RCC dam.Betong är det vanligaste byggmaterialet i världen och det är ett material som består av ballast,cement och vatten som härdas över tiden, även känt som ett komposit material. Användningenav betong är mycket mångsidig tack vare dess motståndskraft mot vind och vatten och dessförmåga att motstå höga temperaturer. Dessa egenskaper gör betong ett lämpligt byggmaterialför stora strukturer som dammar.En dam är en enorm konstruktion som kräver massiva mängder av betong för att bygga denmed och det leder till höga kostnader, därför bör alternativa metoder övervägas för attminimera dessa. Ett förslag till en metod är att bygga dammar med Roller CompactedConcrete (RCC), som per definition är ett komposit material med ett sättmått på mindre än 6mm i sitt ohärdade tillstånd. RCC har erhållit sitt namn från sin byggmetod, då den sprids medhjälp av utrustning för att lägga vägar och sedan kompakteras den med en traktordrivenvibratorvält. Ingredienserna för RCC är samma som för konventionell betong, men den storaskillnaden utgörs av att det är olika mängd-förhållanden av de material som blandas för attproducera denna betong. Det skiljer sig också när det gäller ballasten, eftersom både liknandeballast som används i konventionell betong eller ballast som inte uppfyller de normalastandarder kan användas för RCC. Det betyder att exempelvis, ballast som man erhåller påbyggarbetsplatsen kan användas för att producera RCC.I jämförelse med när man bygger en traditionell betongdamm, som vanligen byggs i storablock, så bygger man oftast en RCC damm i horisontella lager vilket ger möjligheten försnabbt byggande. Detta reducerar behovet av att använda gjutformar, men även antaletmantimmar på grund av användningen av maskiner för spridning och kompaktion. De härfaktorerna gör det till en billigare metod. RCC dammar har blivit populärt att bygga runt om ivärlden på grund av dess fördelar och nya metoder har utvecklats under de senaste 20 årenanpassade efter erfarenheten man har erhållit efter varje projekt. Alla RCC dammar sombyggts stöter ofta på utmaningar både under och efter byggandet och det har med, allt fråntemperatur variationer, sprickor, och läckage, att göra.Huvudsyftet med det här examensarbetet är att skapa en guide för hur man designar ochbygger en RCC damm och tanken är att man ska kunna använda den som en grund förframtida dammbyggen. Kraven från Eurokod 2 och RIDAS är grunden för kriterierna somdammen ska uppfylla och information om vad som förväntas av RCC är presenterat. Enfallstudie har gjorts, där ett exempel på en design för en RCC damm som ska ersätta enbefintlig fyllningsdamm i Hylte är presenterad. Fyllningsdammen är i behov av ombyggnationför att höja säkerheten av dammen och målet med fallstudien är att avgöra dimensionerna förden nya RCC dammen som ska placeras där.
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Fekadu, Robel Tekeste y Sujata Kayastha. "Safety Assessment of Cracked Buttress Dams". Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284527.
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Most of the concrete buttress dams in Sweden were built from the 1950s till the1980s based on the traditional method of analyses. Those structures are reinforced and heavy in structure. Their height to thickness ratio being large makes them prone to crack during their lifespan. The presence of these cracks make the reinforcements used in the buttress dam susceptible to corrosion due to the water entering through the cracked areas. Therefore, studying the effect of cracks and corrosion regarding the safety of dams is important and should be carried out before the dams fail to function. However, only limited researches have been conducted to address these issues. The main goal of this project is to evaluate if the traditional method of analysis were sufficient to capture the failure modes of the dam before and after the occurrence of cracks and corrosion of the reinforcement. In the traditional method, the analytical stability calculations for the factor of safety of sliding and overturning are computed separately. However, in reality, those two failure modes do not occur separately but in combined mode. Therefore, to study this matter, two case studies were considered. In these studies, both finite element analysis (FEA) and analytical calculations were performed to investigate the failure modes. Moreover, this project assesses the influence of cracks and corrosion of reinforcements in the factor of safety. And, the software that was used to carry out the FE analyses were COMSOL and Abaqus. And alongside to FE software, MATLAB was used to carry out the analytical calculations. The results from the analyses showed that the combined failure modes in FE-analyses were the mode of failure of the buttress dams in all cases. Therefore, the analytical calculations were not sufficient to capture the failure modes. Furthermore, the reinforcements that were incorporated in the dam were observed to have a significant effect on the factor of safety depending on the patterns of the cracks. Similarly, the corrosion of the reinforcement had severe effects on the factor of safety based on the crack patterns. Based on the findings from the project, the combined failure mode from FE analysis the governing failure mode, and therefore, traditional analytical methods should be carried out to help evaluate those FE analyses but not to capture the actual failure modes. Besides, the incorporated reinforcements and their corrosion had notable influences on the safety factor of dams which should be investigated carefully.De flesta betonglamelldammar i Sverige byggdes under 1950 - 80-talet baserat påden traditionella analysmetoden. Dessa strukturer är armerade och tunga. Derashöjd-tjocklek förhållande är stor nog för att de ska vara benägna att spricka underderas livstid. Uppkomsten av dessa sprickor utsätter armeringen i lamelldammar förkorrosion på grund av att vattnet tränger in genom dessas sprickor. Därför är detytterst viktigt att studera effekter av sprickor och medföljande korrosion avseendedammsäkerhet och bör utföras innan dammarna är ur funktion. Trots vikten avdetta problem, har endast begränsade studier genmfört för att hantera dessa frågor.Huvudmålet med detta examensarbete är att utvärdera den traditionellaanalysmetodens kapacitet att fånga dammens brottillstånd före och efteruppkomsten av sprickor och armeringskorrosion. I den traditionella metoden utförsde analytiska stabilitetsberäkningar av säkerhetsfaktorn för glidning och stjälpningseparat. Men i verkligheten förekommer inte dessa två fenomen separat utan ikombinerat form. För att studera detta fenomen beaktades därför två fallstudier. Ibåda fallen utfördes finita element metod (FEM) och analytiska beräkningar föratt utvärdera brottillstånd. Dessutom utvärderas påverkan av sprickor ocharmeringskorrosion på säkerhetsfaktorn. Programvaran som användes för attutföra FE-analyserna var COMSOL och ABAQUS. Analytiska beräkningarutfördes i MATLAB.Resultaten från analyserna visade att ett kombinerat brottillstånd uppstod iFE-analyserna av lamelldammarna i samtliga studerade fall. Därmed är de utfördaanalytiska beräkningar inte tillräckliga för att fånga brottillståndet. Vidareobserverades att armeringar hade betydande inverkan på säkerhetsfaktornberoende på sprickmönstren. På liknande sätt hade armeringskorrosion signifikantinverkan på säkerhetsfaktorn beroende på sprickmönstren.Utifrån resultatet av FE-analyserna kan man konstatera att den kombineradebrottmoden var det avgörande brottillståndet, och därför bör traditionellaanalysmetoder utföras för att stödja utvärderingen av dessa FE-analyser men inteför att erhålla de faktiska brottillstånd. Dessutom, det kunde observeras attarmering och armeringskorrosion har betydande påverkan på säkerhetsfaktorn avdammar och bör undersökas noggrant.
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Bukenya, Patrick. "Ambient vibration testing of concrete dams". Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10178.
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In this thesis, seven techniques namely; rational fractional polynomial, complex exponential, frequency domain decomposition (FDD) based techniques which include; frequency domain decomposition (FDD), enhanced frequency domain decomposition (EFDD), curve fitting frequency domain decomposition (CFDD) and stochastic subspace identification (SSI) methods namely; unweighted principal component (UPC), principal component (PC) and canonical variant analysis (CVA)) have been applied to data from ambient vibration testing of two concrete dams namely; Roode Elsberg and Kouga dams.
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Morris, Mark William. "Breaching of earth embankments and dams". Thesis, Open University, 2011. http://oro.open.ac.uk/54530/.
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Despite 'modern' construction and management techniques, flood embankment and embankment dam failures occur almost routinely around the world. The need to understand, predict and prevent the breaching process remains a high priority for owners and flood risk managers alike. This research provides new understanding and improved methods for predicting breach initiation and growth through earth flood embankments or dams. The improvement of breach model accuracy has made slow progress over the past 20 years, with confusion around breaching processes arising from a lack of appreciation of soil mechanics interacting with hydraulics and structural behaviour. The prediction of different breach processes requires the integration of techniques from all three disciplines. This thesis makes advances from earlier work (Mohamed, 2002) to produce a predictive breach model intended for industry application. The research develops improved approaches for flow calculation, sediment erosion and structural response for predicting breach initiation and growth and uses field data, including video footage, from the EU IMP ACT project and large scale test and case study data from collaboration with the International Dam Safety Interest Group breach modelling project.