Analysis and interpretation of the structural behaviour of Bouçoais-Sonim dam during the first filling of the reservoir and the following 10 years of operation

Abstract

This paper presents the relevant monitoring data and the main results of the analysis and interpretation of the structural behaviour of Bouçoais-Sonim dam, a medium-size gravity concrete dam of 42.5 m high, during the first filling of the reservoir, in March 2005, and the subsequent 10 years of operation. As usual, the dam safety control is performed by considering the data provided by the monitoring system, which is analysed and interpreted with the support of numerical models. These activities are particularly relevant during the first filling of the reservoir, which is a real load testing, and during the first years of operation, when the dam’s body and its foundation adapt to the local serviceability conditions. A three-dimensional finite element model of the dam and of the rock mass foundation, considering the concrete viscoelastic behaviour and the variation of the reservoir water level and temperatures, allows simulating numerically the thermal and structural dam behaviour. The dam’s concrete delayed behaviour was represented by the Bažant and Panula’s basic creep function, evaluated from ordinary concrete laboratory tests. The monitoring results, namely the displacements measured through plumb-lines, exhibit a good agreement with those obtained by the structural analysis, showing that the observed response is coherent with the evolution of the main actions.