Stability analysis of gravity dams for the maximum design earthquake

• Autor(a) principal: Varagilal, Igor Acoob
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/40906
• topic: gravity dam; rock mass foundation; numerical modelling; hydrodynamic behavior; shear sliding; Rayleigh damping; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Civil

This thesis presents a two-dimensional hydrodynamic stability analysis of gravity dams for the maximum design earthquake. The coupled mechanical and hydraulic behavior of the dam’s rock mass foundation is taken into account. The main aspects concerning gravity dams are presented along with their main failure causes. The safety rules currently in use and approved by the International Commission on Large Dams (ICOLD) Seismic Committee are presented. The fundamental elements of seismic application relevant for the models used in this work are also presented, such as the dynamic interaction between the reservoir and the upstream face of the dam, adequate boundary conditions for an explicit method and different damping hypotheses. Two dams of different height are numerically analysed. Both dams have rock mass foundations with identical geometry, with horizontal and vertical discontinuities, and the grout and drainage curtains are simulated. Analysis is carried out with a discontinuum model, Parmac2D-FFlow. The displacements at the base of the dam, both on the dam’s heel and the dam’s toe, are compared for the Rayleigh damping hypothesis and the mass proportional term damping. In every case studied two different situations regarding the dam foundation behavior are considered: i) non-linear behavior of the dam/foundation interface and elastic behavior of the fractured rock mass area and ii) non-linear behavior of both the dam/foundation interface and the joints in the fractured rock mass area. The results presented allow the analysis of the effect of the peak ground acceleration to be carried out. Conclusions are drawn regarding the effect of joint normal stiffness on the behavior of gravity dams due to seismic loads.