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 Sensing element Fiber 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”

Pipeline Distributed Sensing Applications

Distributed sensing technology T1T1 Reading Unit Distributed Sensor 0m 1m 100m 1km 5km T1T1 T2T2 T2T2 Position [m] Temp. [°C]

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

o Val de la Mare Dam on Jersey Island: Alkali Silica Reaction (ASR) o Strain monitoring on/in penstocks o Luzzone Dam: Temperature evolution during concrete setting o Koudiat Acerdoune RCC, Algeria: leakage detection o iLevee, New Orleans: integrity monitoring

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 KA Dam – March 2009 Temperature monitoring and leak detection

Koudiat Acerdoune Dam – Leak detected Downstream face Upstream face Water reservoir

Dike Monitoring 1000m of dike monitored in Slovenia (leak detection) iLevee Project, New Orleans, USA Strain monitoring for joints and settlements, leakage 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.