Análisis numérico de presas de hormigón bajo acciones expansivas
- Autores: André Campos de Moura
- Directores de la Tesis: Carlos María López Garello (dir. tes.), Antonio Aguado de Cea (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2012
- Idioma: español
- Tribunal Calificador de la Tesis: Joaquín Díez-Cascón Sagrado (presid.), Sergio Horacio Oller Martínez (secret.), Pere Prat Catalan (voc.), María Pilar Alaejos Gutiérrez (voc.), Gilberto Carbonari (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
The main objective of this thesis is to study the mechanical behavior of a dam concrete under internal expansive phenomena in both the macro-structural and the meso-structural level. An important contribution of this work is the diffusion-reaction model proposed for the internal sulfate attack (ISA), which simulates the oxygen diffusion into the concrete and its consumption in the iron sulfides oxidation in the aggregates. This model allows obtaining the volume increments over time caused by the chemical reactions involved in the process. The mechanical analysis was conducted in the macro-structural and the meso-structural levels. The latter takes into account the expansions due to delayed ettringite formation in conventional concrete considering the explicit representation of the first level internal structure or meso-structure. The numerical results obtained were validated with experimental data from the literature. Then, the effects of the ISA in conventional concrete and in a dam concrete were analyzed, yielding a prediction of the young modulus and the tensile strength degradation depending on the degree of expansion of concrete. Furthermore, this dissertation shows the evolution of cracking and fracture energy dissipation, both of which were correlated with the degree of expansion and the variation of mechanical parameters. The results obtained illustrate the potential of the meso-structural model for analyzing different expansive processes in concrete. In the macro-structural level, real cases of dams affected by expansive problems were analyzed. The dams studied were Mequinenza, Paso Nuevo and Graus. The case of Mequinenza focused on the behavior of block 13-14 that presented pronounced non-recoverable displacements. A 2D model was used, including horizontal joints with non-linear behavior located where cracks had been observed. The numerical results show how the formation, evolution and opening of a series of horizontal cracks cause much of the displacements measured, thus realistically explaining the behavior of the dam. For the case of Paso Nuevo (an arch gravity dam affected by internal expansive problems), a 3D model was used to adjust the calculated displacement with the measured one. A hyperbolic strength criterion was used to assess the global behavior of the dam. Then, the left abutment zone was analyzed using a continuum non-linear damage model. Finally, the case of Graus was studied with linear models (2D and 3D). Then the analysis of block 5 was performed using a 2D model that included non-linear joints located where cracks and casting joints were present. The results obtained throughout this study reproduce satisfactorily the evolution of the expansive process in the macro-structural and meso-structural levels. They explain with good accuracy the anomalous behavior observed in the real cases studied and show the potential of the tools and methodology used in this work.
