MODELING OF CONCRETE DAM MOVEMENTS CAUSED BY EXPANSIVE PHENOMENA

Expansive chemical reactions as Internal Sulphate Attack and Alkali-Silica Reaction are degradation phenomena that, under specific conditions, develop inside concrete structures. Concrete dams have been frequently diagnosed with such issues. Expansive reactions proceed for long time and eventually lead to different forms of deterioration and damage. Amongst the latter ones, movements of points of the dam have been attributed to the development of the reactions. The main goal of this master thesis is to model the movements that are detected in concrete dams. The movements captured by auscultation systems, placed on the dams since an adequate number of years, are valuable hints of what happens inside the concrete. Points of the dams sometimes showed non negligible displacements, together with other deterioration mechanisms. First the movements, in the vertical and horizontal direction, are obtained and analysed. These data, belonging to four Spanish dams (Graus, Tavascan, Paso Nuevo, Toràn), are then modelled with a mathematical exponential law, characterized by parameters that proved to be related to physical characteristics of the dams and to the physical-chemical nature of the reactions involved. Robustness analysis was carried out, with the objective to find out whether the mathematical law that fitted the data is robust. The movements showed similar patterns among the different dams, that are composed of three characteristic phases: initiation, development and passivation. Fitting a specific portion of the pattern, and the whole dataset sometimes lead to similar results. In the last stage parameters of the modelling of the movements are related, conceptually, to the physical and chemical aspects involved. Mathematical parameters of the model turned out to have a correlation with specific aspects of the anomalous dam behaviour, i.e. entity of the movements and their rates of development.