Riesgo sísmico y análisis dinámico de presas arco-gravedad

Résumé

This thesis analyses the seismic hazard on the site where the Rules Dam is located (Granada province, in Southern Spain). The performance of the dam body is considered as well as its structural elements. First, the seismic hazard analysis is carried out by using Deterministic Seismic Hazard Assessment (DSHA) and Probabilistic Seismic Hazard Assessment (PSHA), which estimate the Safety Evaluation Earthquake (SEE) and the Operating Basis Earthquake (OBE), respectively. The recent seismogenic zone in Spain (2015) is used, which provides important data to carry out the analysis, such as the geologic and seismic characteristics. Then, the fluid-structure-foundation-sediments interaction has been carried out. To consider it, 2D and 3D mathematical models have been developed via finite elements, gravity methods, numerical analyses and step-by-step integration. Concrete arch gravity dams need to be modelled in 2D and 3D in accordance to classic theoretical method and current codes, in order to calculate the vibration periods, hydrodynamic pressures, and the maximal stresses. Finally, an analysis to define the non-linear displacements of the arch-dam blocks has been carried out. The plastic-degradation theory could define the reduction of the elasto-plastic modulus during the hysteretic cycles. The consequences of a dam failure and damage have been estimated. A good calibration between the observations and modelling output has been obtained, as well as a comparison among the seismic hazard spectra, several real accelerograms and Spanish elastic spectra. In the Spanish code the Peak Ground Acceleration (PGA) for this area is 0.17 g, however in the current analysis the greatest soil acceleration registered is 0.35 g, which is about twice the value. Seismic input from the Safety Evaluation Earthquake has shown that maximum accelerations are three times higher than the Spanish code value. Consequently, the stress has exceeded the maximum allowed tension, creating many plastic hinges. A dam, as it is well known, is an extremely strategic construction, which needs to be carefully designed to avoid environmental damage to water reservoirs and nearby facilities and for human safety. Given that the recent sources of hazard in Spain are from 2015, it would be advisable to reassess the seismic hazard particularly related to existing dams in areas of high seismicity, such as where the Rules Dam is located.