A Review on Thermo-mechanical Modelling of Arch Dams During Construction and Operation: Effect of the Reference Temperat
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ORIGINAL PAPER
A Review on Thermo‑mechanical Modelling of Arch Dams During Construction and Operation: Effect of the Reference Temperature on the Stress Field Fernando Salazar1 · David J. Vicente1 · Joaquín Irazábal1 · Ignasi de‑Pouplana1 · Javier San Mauro1 Received: 30 March 2020 / Accepted: 29 April 2020 © CIMNE, Barcelona, Spain 2020
Abstract Double-curvature dams are unique structures for several reasons. Their behaviour changes significantly after joint grouting, when they turn from a set of independent cantilevers into a monolithic structure with arch effect. The construction process has a relevant influence on the stress state, due to the way in which self-weight loads are transmitted, and to the effect on the dissipation of the hydration heat. Temperature variations in the dam body with respect to those existing at joint grouting generate thermal stresses that may be important in the stress state of the structure. It is thus essential to have a realistic estimate of this thermal field, also called reference or closing temperature. In this work, the factors involved in the calculation of the reference temperature of double-curvature arch dams are analysed: material properties, boundary conditions and numerical aspects. First, a critical review of the state of the art is made with respect to the criteria used by various authors for decision-making in the construction of the model. Next, specific analyses are made on the effect of some important elements: the time step, the size of the domain of analysis and the methodology used for the calculation of the reference temperature. The results show the relevance of a correct calculation of the closing temperature to adequately determine the stress state of the structure.
1 Introduction Thermal effects are highly relevant in the performance of concrete dams, both during construction and operation. At early stages, concrete cracking can occur due to the hydration heat generated by the exothermic reactions that take place during concrete curing. In structural elements with large thickness, where certain areas are far from the environment, the dissipation of such heat is difficult, therefore * Fernando Salazar [email protected] David J. Vicente [email protected] Joaquín Irazábal [email protected] Ignasi de‑Pouplana [email protected] Javier San Mauro [email protected] 1
CIMNE – Centre Internacional de Metodes Numerics en Enginyeria, Barcelona, Spain
the risk of cracking increases. This effect is well known in concrete dam engineering, where the placing temperature of the concrete is frequently controlled with cooling pipes or similar devices [67]. Gravity and arch dams are typically built in separated vertical blocks of around 15 m width. Its construction is planned with different raising velocities to favour heat dissipation as the area in contact with the surrounding air is increased. By contrast, in roller-compacted-concrete (RCC) dams, the construction process requires that the whole dam body is built at the same pace (typica
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