Multi-physical Simulation of Concrete Hydraulic Facilities Affected by Alkali-Aggregate Reaction: From Material to Structure

Abstract

AbstractThis work aims to fill the gap between experimentation on laboratory specimens and structural diagnosis of mass concrete hydraulic structures affected by alkali-aggregate reaction (AAR) by conducting numerical and experimental investigations on an existing hydroelectric facility affected by AAR.A large experimental program was performed to characterize the mechanical properties and the kinetics of the AAR chemical reaction for the original mass concrete used in the construction of the facility (maximum aggregate size of 76 mm). The importance of considering mechanical and chemical size effects is discussed, on the basis of the asymptotic fracture energy and the free AAR expansion curve.The developed phenomenological hygro-chemo-mechanical approach for AAR modelling in mass concrete hydraulic structures is presented. The efficient and yet simple approach is based on three analyzes: transient thermal analysis, transient hygral analysis, and final multi-physical analysis that includes mechanical loading. The modelling approach was validated with existing benchmarks from the literature and provided very promising results, despite the simplifications made and the assumptions for some uncertain input parameters.Application of the numerical modelling approach to the existing hydraulic facility demonstrated its feasibility in an industrial context. It also provided fairly similar damage pattern if compared to the existing cracking pattern and improved the understanding of the complex structural behaviour of the facility. Comparison of displacement model predictions and available monitoring data allowed to assess an important size effect between laboratory and in-situ expansions.KeywordsAlkali aggregate reactionConcrete hydroelectric facilityAssessmentSize effectsMulti-physical simulation