Utilization of fiber optics for determining flow velocities
DOI:
https://doi.org/10.24849/j.geot.2020.149.02Keywords:
Optical fiber, lab model, seepage analysisAbstract
Infiltration through hydraulic and earth structures poses a substantial risk of damage, including dam failure due to regressive internal erosion. Therefore, it is essential to monitor the flow of water in the dam structure, being the optical fiber one of the tools to perform this monitoring. The use of fiber optic cables extended along the structure allows for comprehensive monitoring of the area covered by this control instrument, not limited to spot checks. Given the unprecedentedness of this tool and the importance it represents for landfills, the subject has been the subject of a Research and Development Project. The proposal included the installation of more than 6 km of optical fiber in a 500 m stretch, installed on the vertical filter horizontal draining mat of the left bank dam and the Colíder Hydroelectric Power Plant, located in the state of Mato Grosso, midwest region of Brazil. Based on laboratory tests performed in a pressure cell, the present work seeks to recognize fiber optics as an option for monitoring flow variations. The use of fiber optic cables, unlike the conventional monitoring system, is placed as a new type of sensor allowing, besides the evaluation, the distributed quantification of the internal water flow in the massif of an earth dam. The evaluation of the significance of the meaning of the read variations in the field temperature was performed from the development of functions that relate temperature variation with flow velocity variation.
Downloads
References
Aufleger, M.; Conrad, M; Strobl, T.; Malkawi, A.I.H; Duan, Y. (2003). Distributed Fibre Optic Temperature Measurements in RCC-Dams in Jordan and China. Simpósio Internacional de Barragem de Concreto Compactado com Rolo, p. 401-407, Madrid.
Aufleger, M.; Conrad, M.; Perzlmaier, S.; Porras, P.; Strobl,T. (2005). Distributed Fibre Optics Temperature Measurement on it way to become an ordinary tool in Dam Monitoring. Hydro Review Worldwide, v. 13, HCI Publications, Kansas City, USA.
Aufleger, M.; Conrad, M.; Goltz, M. (2007). Distributed fiber optic temperature measurements – a competitive alternative for temperature monitoring in large RCC dams. In: Proceedings of the 5th International Symposium on RCC Dams, Guiyang, China, November 2-4.
Aufleger, M.; Goltz, M.; Perzlmaier, S.; Dornstädter, J. (2008). Integral Seepage Monitoring on Embankment Dams by the DFOT Heat Pulse Method. First International Conference on Long Time Effects and Seepage Behavior of Dams.
Fand, R. M.; Varahasamy, M.; Greer, L. S. (1993). Empirical correlation equation for heat transfer by forced convection from cylinders embedded in porous media that accounts for wall effects and dispersion. Int. J. Heat and Mass Transfer, Vol. 36, pp. 4407-4418.
Glisic, B.; Inaudi, D.; Kronenberg, P.; Vurpillot, S. (1999). Dam Monitoring Using Long SOFO Sensor. In Proceedings of the Hydropower into Next Century, Gmunden, Austria; pp. 1–9.
Goltz, M.; Aufleger, M. (2009). Distributed fiber optics temperature measurements using the heat-up method – laboratory tests to determine progression of the wet front. Relatório apresentado no encontro entre a Universidade de Innsbruck e LACTEC.
Goltz, M. (2012). Contribution to monitoring of embankment dams by means of distributed fiber optic measurements. Universität Innsbruck: Forum Umwelttechnik und Wasserbau, Innsbruck University Press.
Incropera, F.P.; Dewitt, D.P.; Bergman, T.L.; Lavine, A.S. (2008). Fundamentos de transferência de calor e de massa. Rio de Janeiro, RJ: LTC, 643p, 6ª Edição.
Koga, H.; Katahira, H.; Kawano, H. (2003). Thermal measurement and analysis of large roller compacted concrete dams. Simpósio Internacional de Barragem de Concreto Compactado com Rolo, p. 1139-1148, Madrid.
Perzlmaier S.; Aufleger, M.; Conrad, M. (2004). Distributed fiber optic temperature measurements in hydraulic engineering - prospects of the heat-up method proceedings, 72 Annual Meeting of the International Commission on Large Dams (ICOLD), Seoul, Korea, 16.-22.
Perzlmaier S.; Aufleger, M.; Conrad, M. (2006). Integral seepage monitoring on open channel embankment dams by the DFOT heat pulse method. XXII Congress of the International Commission on Large Dams, Barcelona.
Perzlmaier, S. (2007). Verteilte filtergeschwindigkeitsmessung in staudämmen. lehrstuhl und versuchsanstalt für wasserbau und wasserwirtschaft, Technische Universität München, Bericht.
Pettres, R.; Rocha, R. P. O.; Lacerda, L. A. (2012). Metodologia para a determinação de nível de água com monitoramento através de fibras ópticas. VIII Simpósio sobre Pequenas e Médias Centrais Hidrelétricas, Porto Alegre.
Pirolli, C. (2017). Medidas Distribuídas de Fibra Óptica para o Monitoramento de Vazões em Barragens de Terra – Estudo Laboratorial aplicado ao Caso da UHE Colíder. Dissertação de Mestrado. Universidade Federal do Paraná. Curso de Pós-Graduação em Construção Civil. Curitiba.
Rocha, R. P. O. (2011). Instrumentação geotécnica com fibra ótica: monitoramento de frente de umedecimento e análise da variação do grau de saturação em solos arenosos. Dissertação de Mestrado. Universidade Federal do Paraná. Curso de Pós-Graduação em Construção Civil.
Watley, D.; Johansson, S. (2005). Optical allusions. International Water Power and Dam Construction, p. 22-25.
