Numerical prediction of swelling in concrete arch dams affected by alkali-aggregate reaction

A chemo-damage model is presented for anisotropic swelling analysis of concrete arch dams affected by alkali-aggregate reaction (AAR). The model combines the AAR kinetics and the plastic-damage model, and the chemical and mechanical phases are coupled. A redistributing weight function, determined by the applied stresses in the concrete, is introduced to control the AAR-induced anisotropic expansion of the concrete. Creep strain is also included in the approach using the Kelvin–Voigt model. Accelerated tests, in which the specimens are confined with steel rings and subjected to axial loads, are first analyzed using the proposed model. The computed strains of the specimens are in good agreement with the experimental measured strains. The application to the AAR-affected Kariba dam is then carried out. The radial and vertical displacements of the dam due to AAR are reproduced with sufficient accuracy. The stresses within the dam are significantly redistributed during the AAR process. Severe cracking and damage appear to occur in the dam heel and the downstream face on both sides of the dam-foundation interface. It demonstrates Kariba dam is facing an increased risk of collapse associated with the increasing compressive stresses within the dam and developing cracks on both sides of the downstream face during the development of AAR.