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Fiberoptische Messinstrumente Instruments de mesures par fibre optique Daniele Inaudi, SMARTEC SA Advantages of Fiber Optic Sensors for Dams Monitoring Galvanic isolation EMI immunity Intrinsically safe Passive: no need for electrical power Possibility of remote, multiplexed operation Small size and lightweight Integrated telemetry: fiber itself is a data link High sensitivity Long measurement range Cost-effective Types of Fiber Optic Sensors Single-point sensor Fiber Sensing element Multiplexed (quasi-distributed) sensor Multiple sensing points Distributed sensor Continuous sensing element Components Learn more at instruments exhibit Point-sensing applications o Replacing conventional sensors in difficult environments: lightning, long cables, large T changes… o Long-gauge sensors (SOFO system) • Concrete deformations • Rock extensometer • Crack/joint monitoring o Fiber Bragg Gratings • Temperature monitoring • Strain sensors o Fabry-Perot sensors • Piezometers • Displacement sensors Point sensors Localized events and damage ? ? ? ? ? Distributed sensing Sensing “everywhere” Distributed Sensing Applications Pipeline Distributed sensing technology Reading Unit Distributed 0m Sensor 100m T1 5km T2 Temp. [°C] 1m T1 1km T2 Position [m] Distributed Fiber Optic sensing o Sensing everywhere • Temperature distribution: seepage, concrete setting… • Strain and deformation: settlements, cracks, landslides, sinkholes… o Detect and localize anomalies in dams • • • • • Abnormal seepage Internal erosion Abnormal temperature gradient Cracks Settlements o Continuous and automated system • Seamless integration with traditional sensors • Remote monitoring with alert triggering Application Examples Val de la Mare Dam Evaluate deformations due to Alkali Silica Reaction (ASR) Strain monitoring for penstocks Local Strain monitoring on penstock Distributed strain sensing inside penstock Luzzone Dam Temperature evolution during concrete setting Luzzone Dam – data analysis Koudiat Acerdoune Dam, Algeria Temperature monitoring and leak detection KA Dam – March 2009 Koudiat Acerdoune Dam Water reservoir Upstream face Downstream face – Leak detected Dike Monitoring iLevee Project, New Orleans, USA Strain monitoring for joints and settlements, leakage detection 1000m of dike monitored in Slovenia (leak detection) Conclusions o Fiber Optic sensors are a novel, but well proven technology useful for structural and geotechnical monitoring and instrumentation o Many Fiber Optic Sensor technology exist and have different types of applications: point and distributed sensing systems o Many successful application examples worldwide demonstrate the maturity of FOS technology o Some unique features of FOS, e.g. multiplexing or distributed sensing, open new application possibilities o Advantages of FOS include reliability, stability, ease of use, flexibility and (sometimes) lower system cost.