No description available.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-11-06T00:47:32Z No. of bitstreams: 1 JOÃO AUGUSTO BARBOSA SOUSA - DISSERTAÇÃO PPGECA 1991..pdf: 20226382 bytes, checksum: eba1c136d21ab9224bc5d71dd5640c90 (MD5) / Made available in DSpace on 2018-11-06T00:47:32Z (GMT). No. of bitstreams: 1 JOÃO AUGUSTO BARBOSA SOUSA - DISSERTAÇÃO PPGECA 1991..pdf: 20226382 bytes, checksum: eba1c136d21ab9224bc5d71dd5640c90 (MD5) Previous issue date: 1991-03-06 / Este trabalho consiste no desenvolvimento e apresentação de uma sistemática de cálculos que, utilizando elementos finitos e microcomputadores, permite dimensionar e posicionar fenômenos hidráulicos no interior dos sistemas, maciços, fundações e dispositivos de proteção das barragens de terra e rock-fill, quando esses se encontrarem em regime permanente e submetidos a variações de fluxo, nas fases de construção, operação e manutenção. Buscando-se atingir ao objetivo pretendido, elaborou-se um sistema de programas e arquivos que, integrados, possibilita a utilização do Programa FPM500 de modo prático. O FPM500 trata dos escoamentos nos meios porosos, confinados e não confinados, nos sistemas bidimensional e/ou tridimensional com simetria de revolução. Entretanto, apesar de flexível, para o seu emprego, era grande a quantidade de dados de entrada a serem informados, diretamente, pelos usuários e, por ser acoplado a um gerador de malhas, aumentava o número de informações, levando esse, na versão original, a ser processado somente em computadores de grande porte. Na sistemática apresentada, inicia-se com um arquivo contendo informações relativas aos blocos estruturais. Um programa acoplado a um renumerador processa essas e renumera todos os nós da malha de elementos, assim reduzindo as bandas das matrizes de fluxo e otimizando memórias em microcomputadores. Este recurso possibilita substancial ganho em velocidade, em busca das soluções dos sistemas com múltiplas equações lineares simultâneas. Os dados resultantes deste processamento permitem a confecção de malhas integradas por elementos triangulares e/ou quadrilaterais lineares, no sistema bidimensional simultâneas. Os dados resultantes deste processamento permitem a confecção de malhas integradas por elementos triangulares e/ou quadrilaterais lineares, no sistema bidimensional / This dissertation deals with the development and the presentation as well of a systematics of calculus that, by making use of finite elements and microcomputers alike, enables both to settle the dimension and the position of hydraulic phenomena in the interior of systems, massifs, foundations and protection organs for earth and rock-fill dams, when the latter are to be found at everlasting rate and suodued to flood variations in the construction, operation and maintenance phases. In the search for an intended purpose, a program and files system was carried out which, once integrated, makes feasible the utilization of Program FPM500 in a practical way. Such a program (viz., FPM500) is related to flows in porous enviroments, restrained or no restrained, in bidimensional and/or tridimensional systems with revolution symmetry. However, despite being flexible for its usage, the quantity of input data to be directly informed by users is huge and, on account of its being coupled to a network generator, it increased the number of informations so that it, at the long run, finished being processed only mainframe computers. In the presented systematics, one begins with a file encompassing informations related to structural blocks. A program coupled to a renumerator processes them and numbers again ali nodes of the elements network by so reducing the flow matrix bandwidth therefore de creasing storage requirements in the computer. Such resource enabls a substantial gain in speed in the systems with mutiple linear simultaneous equations. The data arising from that processing enable the making of integrated networks by triangular and/or four-sided linear elements in the bidimensional system. In another program, the data necessary to the studies of different hydric systems are completed. Therein the outputs of GETOP Program are resettled, the refomations dealing with the boundary conditions and with structural blocks. Such data are kept in files, appropriately shaped in a given format in order to feed Program FPM500. Program FPM500 processes ali elaborated informations as it calculates loads, pressures and flows by providing a report with informations likely to interest studies of hydraulic stability of earth and rock-fill dams. The presented methodology has the advantage to exclude the great amount of blunders committed on input data, in the usage of finite elements thrregh conventional processes. There is also the possibility of a future implementation of graphic programs for drawing element networks thrugh plotter or video. Thus, one is afforded to state that such a systematic, beyond facilitating the calculi, presents confidence and speed as it can be used in different practical equations, the aim of which is likely to be the previous knowledge of the conditions of hydraulic stability in those structures.

MESMEG / Department of Mining and Environmental Geology / See the attached abstract below

This thesis examines the evaluation of the economic, environmental and social effects of dams, and lessons learned from previous dams. It then focuses on cost benefit analysis as a decision-making tool pre-project for evaluating the potential gains and losses of building a dam; and as a framework for evaluating dams in operation. It reviews the basic assumptions required for a legitimate cost benefit analysis, and the inherent limitations of this method. It uses the Sardar Sarovar dam as a case study for the use and abuse of cost benefit analysis in decision-making, interstate politics, propaganda and activism. It also illustrates the difficulties in dividing costs and benefits in an equitable manner at national, state, and grassroots levels.

This study is an evaluation on the seismic behavior of the Nahrain Dam, which is located in Khorasan province in the central part of Iran. The finite element method is used for the dynamic analysis of the dam. Using a slope stability computer program, the critical slip surface near the crest of the dam and the yield acceleration corresponding to this slip surface are determined. Static analysis was completed by using the finite element computer program SAP90 and SAP2000 in order to determine the stress conditions within the body of the dam prior to earthquake. The stresses obtained from this analysis were used in the assessment of the dynamic material properties of the dam. Two near by actual earthquakes were modified and used as input motions of different magnitudes. At the next step, the harvested data was used as input data for the program TELDYN to perform dynamic analysis. Permanent displacements under the scenario base motions were calculated by using the Newmark&rsquo / s method.

M.Sc. / The Merriespruit Tailings dam disaster killed seventeen (17) people and covered a part of Virginia with approximately 2.5 million cubic metres of tailings, causing such an emotional uproar that all resources were focused on repairing the dam and addressing some of the social issues. Little attention was given to the environment. The identified need in this study was therefore to investigate the consequences of the disaster on the environment, a need which derives from the uniqueness of this particular disaster and its consequences. The Department of Minerals and Energy require the submission of an Environmental Management Program Report (EMPR) on all prospecting and mining operations. It is clear that, in the compilation of such an EMPR, Harmony Gold Mine neglected to establish a Management Plan to regulate the physical impact of the disaster on the environment, mainly because no attention was given to disasters in the Aide-Memoir. A Management Plan was established by adapting existing formats of management plans to the uniqueness of this disaster. By following the procedure stipulated in the Management Plan it can be ensured that Environmental Management requirements will be effectively integrated into either the project management actions and contracts or operational systems and processes for the following issues: • Water management • Storm water control • Waste management • Dust • Aesthetics and socio-economic implications • Rehabilitation of the area. The investigation showed that the disaster exerted a definite negative influence on the environment, which can be managed by taking preventative measures stipulated in the Management Plan. However, one of the main issues identified in this study is that storm water management has been problematic for a period of time. It is therefore noted that some attention should be given to establishing a wetland system to contain the storm water runoff. Although this study does not focus on the socio-economic impacts in detail, it is recommended that these impacts are considered as it is evidently problematic. The primary aim of this study was to compile an EMP in order to manage, and possibly mitigate, the physical impact of the disaster on the immediate environment, an aim which clearly was accomplished. Harmony Gold Mine can benefit from the compilation of this EMT, as management goals were set and feasible means of achieving them were specified.

In respect of autogenous and drying shrinkage and the effects of relaxation creep during the hydration cycle, roller compacted concrete in dams has to date been universally assumed to behave in the same manner as conventional mass concrete, despite notional evidence to the contrary on prototype dam structures, particularly in respect of high-paste RCC. While the results of laboratory materials testing and associated early behaviour analyses for RCC have been published, no conclusive example exists in the public domain whereby predicted behaviour is confirmed through measured behaviour on a comprehensively-instrumented prototype dam structure. In his PhD thesis, Quentin Shaw presents evidence to indicate that the early behaviour of RCC, and particularly high quality, high-paste RCC in dams, is quite different to that of CVC. Referring to instrumentation records from Wolwedans and Knellpoort dams in South Africa, Çine Dam in Turkey, Wadi Dayqah Dam in Oman and Changuinola 1 Dam in Panama, indications of less than expected shrinkage and stress relaxation creep during the hydration cycle in the constituent RCC are documented. Taking the comprehensively-instrumented and monitored Wolwedans Dam, the actual materials behaviour of the constituent RCC is evaluated through the replication of the prototype behaviour on a finite element model. Through this analysis, it is clearly demonstrated that the level of shrinkage and stress relaxation creep that would be traditionally assumed in RCC simply did not occur. In fact, the analyses suggested that no shrinkage, or creep was apparent. The reasons for the different behaviour of high-paste RCC compared to CVC are subsequently explored. With Wadi Dayqah Dam as the only example evaluated where some drying shrinkage and/or stress relaxation creep was obviously apparent, the evident susceptibility of this lean RCC mix, with a high w/c ratio, a high content of non-cementitious fines, natural gravel aggregates, a high aggregate water absorption and placement in a very dry environment, is noted. However, it is considered to be the combination of a strong aggregate skeletal structure developed through roller compaction and a low w/c ratio that results in a particularly resilience in high-paste RCC to early shrinkage and creep. It is also recognised that temperature and gravity effects in an arch dam structure will tend to limit, or even eliminate containment stresses in the critical load-carrying upper section and that this will reduce the risk and impact of stress relaxation creep. Consequently, a new understanding of the early behaviour of RCC in large dams is presented, suggesting that a high quality RCC mix in an arch dam can be designed for a cumulative shrinkage and stress relaxation creep under the hydration cycle of approximately 20 microstrain, compared with a more traditionally accepted value of between 125 and 200 microstrain. The implications of these findings on the design of large RCC dams are demonstrated to be significant, particularly in respect of RCC arch dams. In addition, suggestions are made for the requirements in respect of RCC mix design for negligible shrinkage and creep, while an approach to combine the use of field measurement with structural modelling to predict and demonstrate actual RCC behaviour is briefly discussed. / Thesis (PhD)--University of Pretoria, 2011. / Civil Engineering / unrestricted

MEnv.Sc / Department of Geography and Geo-Information Sciences

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. / <p>QC 20190926</p>

The purpose of this thesis is to evaluate the contribution of grouted rock bolts on the stability of concrete dams. The load capacity of the grouted rock bolts are assessed considering eventual deteriorating processes. An additional objective was to compare the resulting load capacity with the prevailing regulations in RIDAS (the power companies’ guidelines on dam safety) and possibly suggest new guideline values. The literature study consists of two parts; concrete dams and grouted rock bolts. In the first part concrete dams are discussed and especially the inherent forces and aspects when controlling their stability. The second part treats grouted rock bolts and the theoretical focus is on their function and possible failure modes as well as on the degrading processes (primarily corrosion) that are affecting the rock bolts.  Subsequently, the theory was applied on the Swedish concrete buttress dam Storfinnforsen, which is the largest concrete dam in Sweden. The dam was selected for this study mainly because its shape is archetypical for buttress dams. In addition, a digitalized model of the dam was obtainable from previous research projects.  A numerical analysis with the finite element analysis software ABAQUS was performed in order to evaluate the stability of the dam and to support the analytical analysis. The load capacity of the grouted rock bolts was analytically evaluated with consideration to eventual degradation. Assuming a corrosion rate of 60 μm/year, the grouted rock bolts in Storfinnforsen could after 100 years be trusted with a load capacity of approximately 180 MPa. That load capacity is due to shear failure, which constitutes the most plausible failure mode for rock bolts in buttress dams. The value 180 MPa is to be seen in contrast to the current limitation of 140 MPa that is defined in RIDAS (2011). The conclusion of this thesis is accordingly, that the maximum allowed load capacity that can be assigned the grouted rock bolts in the stability calculations of concrete dams can be increased from todays 140 MPa. This conclusion is substantiated by the analytical analyses with the numerical calculations as support.