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Thermal cracking of a thin concrete arch dam Optionally Subtitle of the Full Paper

pubblicazioni - Memoria

Thermal cracking of a thin concrete arch dam Optionally Subtitle of the Full Paper

La memoria descrive la modellazione numerica effettuata per analizzare lo stato di fessurazione di una sottile diga di calcestruzzo che subisce forti variazioni termiche stagionali.

This paper describes the numerical modelling carried out to analyze the cracking pattern of a thin concrete arch dam which undergoes strong seasonal temperature variations. Two geometric models have been used to discretize the dam, the spillway and a portion of the rock foundation. In the refined mesh the finite elements are smaller towards the zones of the geometric model where the thermal gradients are higher. Only in the refined mesh the steel reinforcement layers on both the upstream and downstream surfaces have been modelled, and an interface between the dam/spillway and the rock foundation has been included. Considering a reference temperature of 4°C, a transient heat transfer analysis, covering a period of three years, has been carried out to attain a thermal steady state condition. A convective heat transfer with a sinusoidal variation of the mean values of the ambient air and water temperatures has been taken into account. Starting from the thermal steady state condition attained at the end of the third year, four quasi-static coupled temperature-displacement analyses have been carried out applying the gravity load of the structure, the hydrostatic pressure and a sinusoidal variation of the ambient air and water temperatures. The thermo-mechanical analyses have the goal to calculate both the risk of cracking and the possible extent of cracking in the dam body. An elasto-plastic damage constitutive law has been used to simulate the non-linear behavior of the dam; a Coulomb friction model describes the foundation joint behavior. In the paper the convergence and stability issues occurred during the non-linear thermos-mechanical analyses will be outlined, underlining how they could affect the final results in terms of damage and displacement conditions.

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