Le concept de facteur de securite dans l'evaluation de la stabilite structurale des barrages-poids lors des crues

New criteria for design and the aging process jeopardize the structural safety of existing concrete gravity dams subjected to floods. The traditional performance criteria used for the evaluation of safety is usually conservative.;First, different methods of analysis are described. The main advantages and limitations are established for each method. Parametric studies are carried out on typical dam ranging from 21 m to 90 m in height.;Secondly, the uplift pressures are studied. Different modelling techniques to represent internal uplift pressure using finite elements are described. These are specified internal pore pressures for elements, or the use of equivalent forces at the nodes.;Thirdly, some analysis methodologies to take uncertainty into account, are described.;A parametric study is realised. From the results, the semi-probabilistic approach is applied using the partial derivation method to get the mean and the standard deviation of the sliding safety factor. The influence of the parameters is obtained to compare the methods or the parameters one to each other.;The linear finite element analysis under-estimates the performance criteria compared to the other analysis methods. The globally nonlinear analysis are more severe because the propagation of the crack is based on principal stress instead of the other methods that are based on normal stress. The results obtained by the gravity method and the locally non linear are between the one of the linear analysis and the globally non linear analysis. The results show that the performance criteria should be established in relation with the method used for analysis. (Abstract shortened by UMI.)...