ABSTRACT
The Pian Telessio dam, an 80 m high arch-gravity dam located in Northern Italy, is suffering from the effects of an alkali-aggregate reaction (AAR) since the second half of the 70s. The concrete expansion due to the AAR causes an upstream drift that reached approximately 60 mm in 2008. In 2008 rehabilitation works by means of vertical slot cuttings in the upper half of the dam were performed to reduce the effects of the concrete expansion. The rehabilitation works allowed a minor recovery of the upstream drift in the order of 5-10 mm, lower than expected.
The structural safety of the dam has been re-evaluated by means of a 3D numerical model, including the effect of the AAR expansion. The implemented AAR model, specifically developed for this analysis, accounts for several aspects affecting the swelling reaction: reaction kinetics, state of stress and temperature. The results of the calibration were remarkably satisfactory showing an agreement with several field measurements: displacements, joints opening, crack pattern and state of stress.
