Seismic and Structural Health Monitoring of Cabril dam

Abstract

This paper is focused on the Portuguese experience regarding the development and operation of continuous vibrations monitoring systems in large concrete dams. The goal is to emphasize the importance of the combined use of monitoring data and numerical models for Seismic and Structural Health Monitoring (SSHM) of Dams. The case study is Cabril arch dam (132 m high), the highest dam in Portugal, in which a pioneer SSHM system has been in operation since 2008. This system, installed by LNEC, was designed for measuring accelerations in the dam body and near the base (dam-foundation interface), using 16 uniaxial and 3 triaxial accelerometers. Appropriate software has been developed to integrate and complement the monitoring system, aiming to automatically process and analyse the recorded data, including tools for simplified study of monitoring results and for automatic comparison with numerical results from 3DFE models. The main experimental results obtained for Cabril dam are presented, namely the evolution of natural frequencies over time, mode shapes and the measured seismic response to an earthquake event. A comparison with results from numerical modelling is presented, using a coupled 3DFE model based on a formulation in displacements and pressures, considering a state space approach to simulate the dynamic behaviour of the dam-reservoir-foundation system and the Newmark method to compute the seismic response.