SSHM Systems for Dams: 12 Years’ Experience in Cahora Bassa Dam. Equipment, Software, and Main Results

The 170 m-high Cahora Bassa dam, in operation since 1974, Mozambique, is one of the most important dams in Africa. Aiming to control its dynamic behavior over time, the dam was instrumented with a continuous vibrations monitoring system in 2010, consisting of force-balance accelerometers and data acquisition units, and of customized software for data management and analysis. This paper is dedicated to the experience acquired over the past 12 years for the case of Cahora Bassa dam, with emphasis on the instrumentation challenges faced on site and the adopted solutions, as well as on the developed software. The latest results on the dynamic behavior monitoring of the dam are presented, namely (a) the analysis of the evolution of the natural frequencies over time and of the corresponding mode shapes, and (b) a study on the measured seismic response. The comparison is made with numerical results, obtained using a calibrated finite element model of the Cahora Bassa dam-reservoir-foundation system.