Continuous Dynamic Monitoring System of Foz Tua Arch Dam: Installation and First Results

Abstract

The Foz Tua hydroelectric development is located in the north of Portugal at the mouth of the Tua river, a tributary of the Douro river, and is equipped with 270 MW of power capacity, making it a very important asset in the country’s energy production capacity. Its reservoir is accomplished through a 108 m high concrete arch dam whose construction was concluded in 2017. The arch dam has been equipped with a vibration-based structural health moni-toring system, which is composed by a set of accelerometers that were radially disposed over the two upper visit galleries. The accelerometers are connected to a set of digitizers distributed in the dam, being the synchronization of the data assured by GPS. This paper describes the addressed monitoring system, as well as the results ob-tained during the first months of operation, such as the characterization of ac-celerations (maximum and effective values) and the automatic identification of the dam modal properties. Additionally, the influence of operational conditions on modal properties is preliminarily studied, namely the effect of reservoir wa-ter level variation on the tracked natural frequencies.