Diagnosis of Dams Affected by Swelling Reactions: Lessons Learned from 150 Monitored Concrete Dams in France

摘要

EDF operates and monitors a large number of concrete dams, of which at least 207a are affected by swelling reactions, the first cause of their pathology. These expansions can be complex and varied, but the phenomena of ACR (Alkali-Carbonate Reaction) and ASR (Alkali-Silica Reaction) are the most common causes. Based on a range of 150 monitored concrete dams operated by EDF, this study provides useful insights into improving diagnostic techniques and better comprehension of the behaviour caused by swelling reactions. Analysis of the monitoring data has allowed identification of the different parameters affecting the chemical reactions (quality of cement and aggregates depending on construction periods and local geology). In this regard, it is interesting to analyze the kinetics of swelling measured at different dams using various devices. The results are compared with kinetics theory provided from a laboratory. Even though it is difficult to generalize the results of this swelling phenomenon (e.g. due to the diversity in their intensity and location inside the dam), specialized maintenance could be adopted depending on the measured behaviours. The complex mechanisms involved in concrete swelling generate macroscopic effects on dams, which generally could be monitored using adequate devices. The resulting displacement and strain depend on the morphology and geometry of the structure (e.g. strength of seals, slits, openings in the orientation of the displacement of gravity dams, particularities of cylindrical versus double curvature arch dams, etc.). Therefore, the global vision of this large range of monitored concrete dams is to objectify the diagnostic strategy for each dam by inter-comparison and use of physico-statistical criteria.