Vattenkraft står idag för ungefär fyrtiofem procent av Sveriges samlade elproduktion. Det är landets enskilt största förnybara energikällan och den möjliggörs tack vare välbyggda dammar i svenska älvar och vattendrag. Dammar är således en viktig del av den svenska infrastrukturen vilket ställer höga krav på dammsäkerheten i både drift och projektering.   Syftet med följande rapport är att:   redovisa allmän teori kring olika dammars utformning, funktion och statiska verkningssätt studera gällande standard rörande dammsäkerhet, RIDAS utarbeta beräkningsprogram för: lamelldammar massivdammar utskov kombinerad dammonolit redovisa kontrollberäkningar mot befintliga dammkonstruktioner   Resultaten från de utförda kontrollberäkningarna visar att beräkningsprogrammens svar erhålls på den säkra sidan, anledningarna till detta analyseras och diskuteras i slutet av rapporten. För de program där kontrollberäkning ej möjliggjorts har diskussion och handberäkningar visat att dokumenten fungerar som de ska och går att använda. / Hydropower accounts for approximately forty-five percent of Sweden’s overall energy production. It’s the country’s single largest source of renewable energy and is made possible through well built and maintained dams in the countless rivers and streams throughout Sweden. Dams are thus an important part of the Swedish infrastructure which therefore creates a demand for high standards on dam safety.   The purpose of this following report is:   present general theoretical knowledge about different types of dams, their applications and static systems study current safety standard on dams, RIDAS compose calculations programs regarding: buttress dams concrete gravity dams spillways combined dam monolith present control calculations for existing dams   The results from the performed control calculations show that our programs obtained answers on the safer side. The reasons for this are analyzed and discussed in the end of this report. For some of the programs control calculations were not made possible, through discussion and handmade calculations we’ve concluded that these programs are functioning properly.

The safety of a concrete dam is ensured by designing according to failure criteria, for all combinations of loads using safety factors. Today in Sweden, RIDAS, the Swedish power companies’ guidelines for dam safety, is used for the design of dams and is based on BKR, the National Board of Housing, Building and Planning. Swedish dams are designed to resist two global failure modes; sliding and overturning. Combination of failure modes, that should be considered in the design of concrete dams, is however fairly unknown. Since 2009 the Eurocodes was adopted and came into force 2011. The Eurocodes have replaced BKR in the design of most structures in Sweden where the partial factor method is used to ensure safety in the design. The objective of this report was to examine if the design criteria for concrete dams in today’s condition are enough to describe real failure modes. The other objective was to analyse if Eurocode is comparable to RIDAS in dam design. The stated questions were answered by performing a literature study of known dam failures and analytical calculations for different types of concrete gravity dams, with varying geometry and loading conditions. The programs CADAM and BRIGADE were also used as calculation tools to further analyse if failure occurred as expected. The results from the analytical calculations together with the performed FE analysis indicate that limit turning does occur and often generate lower safety factors compared to overturning. Limit turning is similar to overturning failure although it accounts for material failure in the rock. This design criterion is therefore, highly dependent on the quality of the rock and requires investigations of the foundation to be a good estimation of the real behaviour of the dam body. From the compilation of reported failures the conclusion was that the current design criteria are adequate. However, the real challenge lies in ensuring that the construction of dams is correctly performed to fulfil the stated criteria. A transition to Eurocode appears to be reasonable for the stability criterion. A modification of the partial factors is nevertheless necessary to obtain result corresponding to RIDAS, especially for the overturning criteria. / För att uppnå säkra dammkonstruktioner, för alla lastkombinationer, dimensioneras dammar enligt bestämda brottvillkor som ska uppfylla en viss säkerhetsfaktor. Idag används RIDAS, för dimensionering av dammar i Sverige. RIDAS Kraftföretagens riktlinjer för dammsäkerhet, är baserat på BKR, Boverkets konstruktionsregler. I Sverige dimensioneras dammar för att motstå de två globala brottmoderna glidning och stjälpning. Frågan som behöver besvaras är om det finns eller kan finnas några kombinationer av brottmoder som borde beaktas vid dimensionering av dammar. 2009 antogs Eurokoderna och trädde i kraft 2011. Eurokoderna har ersatt BKR vid dimensionering av de flesta konstruktioner i Sverige. I Eurokod används partialkoefficienter för att garantera säkra konstruktioner. Syftet med denna rapport var att undersöka om dagens brottkriterium är tillräckliga för att beskriva hur dammar går till brott. Rapporten behandlar även möjligheten att övergå från att dimensionera dammar enligt RIDAS till att dimensionera enligt Eurokod. För att besvara detta genomfördes en litteraturstudie av rapporterade dammbrott. Dessutom genomfördes analytiska beräkningar för flera olika typer av dammar med varierande geometri och lastfall. Programmen CADAM och BRIGADE användes som ytterligare verktyg för att analysera brottmoderna. Enligt resultat från de analytiska beräkningarna tillsammans med FE-beräkningarna ansågs limit turning inträffa och genererade i högre grad en lägre säkerhetsfaktorer i jämförelse med stjälpning. Limit turning kan förklars som delvis stjälpande och inkluderar brott av bergmassan. Brottmodet är dock beroende av kvalitéten hos berget och det krävs undersökningar av grunden för att kunna göra en god uppskattning av dammens verkliga beteende. Sammanställningen av tidigare brott visade att nu gällande brottkriterier är lämpliga och troligtvis tillräckliga. Utmaningen är istället att säkerställa att konstruktionerna är korrekt utförda och därmed uppfyller dessa brottkriterier. En övergång till Eurokod tycks vara möjlig för de globala brottmoderna, dock är det väsentligt att partialkoefficienterna justeras för att uppnå resultat som överensstämmer med RIDAS, särskilt för stjälpning.

Made available in DSpace on 2014-12-17T14:52:52Z (GMT). No. of bitstreams: 1 CarlosCGD.pdf: 1489111 bytes, checksum: 001f763e52671d83a36d43eff64141cc (MD5) Previous issue date: 2006-05-19 / The objective of this study was to investigate the environmental perception of: People with common-sense knowledge on the desertification process in RN. People with scientific knowledge on the desertification process in RN. Focal points in the combat at desertification of the RN and public ministery representant with actions in interinstitutional articulations promoter (and/or relative actions) at the desertification process in the RN. The research was carried in the city of Natal-RN and in two small cities of the Serid? region (RN): Caic? and Currais Novos. The research carried, is classified as exploratory and 22 people were interviewed. The research includes: The propension/intensity of the desertification in the RN and in the Serid? region; Evaluation of the knowledge of those interviewed, concerning the subject desertification ; Problems in order to combat desertification; Causes of desertification; The profile of the interviewed. The results of this present study indicate that the a desertification process is more agressive in the Serid? region than in the state of RN, being the two following: the absence of preocupation of the affected population with the process and the escarcity of governamental recurses, indicates how problems greather in the combat to the phenomen. Decreasing of produtivity in the agriculture and increasing of the migration to the urbans centers have been the main consequences of the process, that have at water scarcity, deforestation and extraction of argil (being this, regional factor), relevant variables in the influence to the surgiment of the desertification process of the RN / O objetivo deste trabalho foi investigar a percep??o ambiental de: Detentores de conhecimento popular acerca do processo de desertifica??o no RN. Detentores de conhecimento cient?fico acerca do processo de desertifica??o no RN. Pontos focais no combate ? desertifica??o do RN e representante do minist?rio p?blico que atuasse na promo??o de articula??o interinstitucional (e/ou a??es relacionadas) ao processo de desertifica??o no RN. A pesquisa foi realizada em Natal-RN e em dois munic?pios da regi?o do Serid? (RN): Caic? e Currais Novos. A pesquisa realizada, que ? enquadrada como explorat?ria, contou com 22 pesquisados e abordou: A propens?o/intensidade da desertifica??o no RN e no Serid?; Avalia??o do conhecimento do pesquisado, acerca do assunto desertifica??o ; Problemas no combate ? desertifica??o; Causas da desertifica??o; Perfil dos pesquisados. Os resultados obtidos apontam que a desertifica??o ? mais grave na regi?o do Serid? que no Estado como um todo, sendo a falta de preocupa??o da popula??o afetada pelo processo e a escassez de recursos governamentais, indicadas como principais problemas no combate ao fen?meno. Perda de produtividade agr?cola e eleva??o da migra??o para os centros urbanos evidenciaram-se como as principais conseq??ncias do processo, que tem na escassez de ?gua, no desmatamento e na retirada de argila (sendo esse ?ltimo, fator regional), vari?veis de destacada import?ncia na influ?ncia ao surgimento do processo de desertifica??o do RN

Uplift pressure is one of the most dominant forces on a dam structure. Difference in head water and tail water creates a hydraulic gradient resulting an upward oriented pressure called uplift pressure, which reduces the dam safety against sliding. However, there are great uncertainties determining the actual magnitude and distribution of the uplift pressure. Therefore, finite element methods were used in order to study the pore pressure in greater extent to increase the knowledge about the field measurements.    In this MSc report, the pore pressure in the rock foundation at monolith M42 in Storfinnforsen hydropower dam has been investigated. The aim of the project is to study the realistic pore pressure distributions and its magnitude underneath the dam. The aim is also to compare and find correlation between the numerical results and field measurements as well as the analytical results based on guidelines for dam safety.    Pore pressure in rock foundations can be influenced by many factors such as, the presence of drainage, grout curtain and rock fractures. Therefore, several numerical models have been developed containing different combinations based on these factors. Numerical results were then compared to both field measurements and analytical results. Furthermore, the uplift pressure from the best calibrated model and models representing critical states of the dam are used to calculate stability safety factor against sliding. The finite element program Abaqus is used to perform all the numerical pore pressure analyses. Field measurements is obtained from two pore pressure sensors installed underneath the dam and analytical results are calculated based on guidelines for dam safety. Based on the results from the case study, comparison of the numerical pore pressure with the field measurements showed that the drains have the largest impact on the pore pressure compared to the parameters. Models without drains have showed significantly larger pore pressure than the field measurements. When drains are in operation, considering empty drains underestimate the pore pressure while water filled drains slightly overestimated the pore pressure.    The influence of grout curtain varies if the effect of drains are included or not. Considering fractured rock foundation, the grout curtain showed large reduction of the pore pressure in the analyses without drains. If drains are in operation, this reduction becomes quite small. Moreover, all the numerical analyses showed that the uplift pressure in the rock fracture are lower than what is defined in the design guideline (RIDAS, 2020).

AbstractThe overall safety of dams depend on several stipulations. One of them is global stability of the dam, which is addressed with approaches like that in (RIDAS, 2017) (the Swedish power companies’ guidelines for dam safety). When designing a new dam, two global failure modes; sliding and overturning should be considered according to RIDAS. However, this is a simplification and other failure modes may exist, such as the combination of sliding and overturning failure. In this combined mode, the dam typically starts to overturn slightly, then as it looses its contact in the upstream area of the footprint, the dam starts to slide. This combined failure mode is yet to be fully addressed in design codes.One additional failure mode that may occur is an internal failure which is caused by material failure of the dam or where existing cracks govern the failure mode. Reinforced concrete structures are expected to crack and hence it likely that such failure mode may occur. The objective of this report is to understand the behavior of a pre-cracked buttress dam under typical loading conditions, and to analyze potential internal failure modes caused by these cracks. Moreover, the validity of using RIDAS design criteria for evaluating the safety of cracked concrete buttress dams will be examined. Finally, this report will study the influence of various possible cracks to study if these are critical and influence the overall dam safety.The stated objectives were investigated by performing analytical calculations and FE-analyses for three different geometries, where each geometry was analyzed with and without pre-existing cracks. The analytical calculations were carried out using MATLAB, to study the two global failure modes suggested by RIDAS: sliding and overturning for the selected geometries. FE-analyses were performed using BRIGADE Plus 6.2 software, where all geometries were studied for all potential global failure modes, including a combination of sliding and overturning failure modes. When comparing results of uncracked and cracked sections, whether it was obtained analytically or by FE-analyses, the influence of cracks in reducing the overall safety of the structure could be clearly highlighted. Moreover, the results comparing analytical solution using RIDAS and FE-analysis did not follow a uniform pattern, therefore, no concrete results could be concluded and further studies to develop more detailed analytical calculation methods were suggested. Finally, the cracks develop between the inspection gangway and the front-plate was proven to have larger influence on the residual mass of the dam, and thus, the overall safety of the dam.