Continuous dynamic monitoring of large arch dams and vibration-based damage detection

The study described shows the potential of seismic and structural health monitoring systems for large concrete dams and the value of the combined use of experimental vibrations data and numerical results. The paper presents the dynamic behaviour of two large concrete arch dams, the 132 m-high Cabril dam in Portugal and the 170 m-high Cahora Bassa dam in Mozambique. Application studies were performed based on continuous dynamic monitoring data, collected in normal operating conditions, and on numerical results from finite element simulations. Evolution of the identified natural frequencies was analysed over time, and compared with computed frequencies for both dams. This led to an evaluation of the influence of reservoir water level variations in the dynamic properties of the global dam-reservoir-foundation system, and investigation of the structural health assessment systems to control evolutive deterioration phenomena, using a vibration and finite element-based damage detection methodology.