MONKOPS: Monitoring of water dam KOPS using fiber optic sensors

Water power plants are an important source of sustainable energy. In Austria, more than 50% of the power production is based on water power plants. Within the last 70 years, more than twenty large concrete dams were erected in alpine areas. Most of these dams are gravity or arch dams and are traditionally operated as storage power stations. Due to legal regulations, these structures have to be monitored in regular intervals. IGMS developed a permanent structural monitoring system for the continuous measurement of concrete joints of water dams in pump-storage operation. The features of the developed system are

• the possibility of continuous measurements,
• an accuracy of better than 0.01mm and
• a total amount of 16 sensors connected by a minimal number of measurement chains.

The developed monitoring system is based on fiber bragg gratings (FBG) sensors. The advantages of FBG sensors compared to conventional electric sensors are their electromagnetic immunity and the possibility to place several sensors along one single cable which reduces the installation effort enormously. To achieve the required accuracy of better than 0.01mm, every sensor was calibrated with IGMS intern calibration device. The monitoring system was installed in September 2013 and long term measurements started right after the installation. It could be demonstrated that the impact of small water level changes which typically occur in pump-storage operation can be depicted reliably. A water level change of 1m results in length changes of the expansion joints of up to 4μm. Temperature induced deformations can also be measured due to the system's high precision of 0.4μm. Daily temperature variations result in cyclic expansion joints movements with amplitudes of up to 4.5μm. The developed monitoring system is the basis for modern structural monitoring of concrete dams with pump-storage operation. The high measurement resolution gives new insights into the structural behaviour of dams and can potentially improve the design of new dams. Watch a demonstration video below or download the video directly!