Numerical Modeling of Early-age Effects on the Mechanical Behavior of Concrete Gravity Dams

Abstract

The control of thermal cracks induced by the effect of early age are the main concerns in concrete dam during the construction stage. Despite its importance, detailed thermal analysis of concrete gravity dams during the construction period is relatively rarely in the literature, eventually because prediction the behavior of concrete gravity dam on early stage requires taking into account the several phenomena and interaction, demands a considerable computational effort. To overcome this drawback, the present paper proposes a numerical modeling strategy to predict the thermo-mechanical behavior of concrete gravity dams during construction periods considering the effect of early age and the construction schedule. The proposed strategy is also used to study the effect of pre-cooling methods on the thermal-mechanical fields on concrete gravity dam during construction process. For this purpose, a Chemo-Thermo-Mechanical model is developed for predicting the behavior of a gravity dam at early stages. Firstly, temperature field model was established and verified with the results reported in the literature. Furthermore, the thermo-mechanical behavior of a concrete gravity dam is performed for two configurations: Early age state with pre-cooling and early age without pre-cooling. Thermal stress analysis was also conducted and results showed that the greatest tensile stresses after construction are developed at the heel of dams and resumption of concreting interface due to the internal restraint imposed by the concrete. The numerical results showed that the pre-cooling methods is an effective way to reduce both the hydration temperature and tensile stress induced by the effect of early age.