Dynamic interaction of concrete dam-reservoir-foundation: Analytical and numerical solutions

The majority of concrete dams worldwide have behaved relatively well during seismic events. However, there are several cases where global failure or substantial damages have occurred. The need for new dam construction and retrofitting of existing dams necessitates the use of advanced design approaches that can take realistically into account the potential dam-reservoir-foundation interaction. Seismic design of concrete dams is associated with difficulties to estimate the dynamic distress of the dam as well as the response of the dam-reservoir-foundation system and to assess the impact of the various parameters involved. In this chapter, after an extensive literature review on the dynamic interaction of concrete dams with retained water and underlying soil, results from numerical simulations are presented. Initially, analytical closed-form solutions that have been widely used for the calculation of dam distress are outlined. Subsequently, the numerical methods based on the finite element method (FEM) which is unavoidably used for complicated geometries of the reservoir and/or the dam, are reviewed. Emphasis is given on FEM-based procedures and the boundary conditions and interactions involved. Numerical results are presented to illustrate the impact of various key parameters on the distress and response of concrete dams considering dam-foundation interaction phenomena. It is shown that in general the water level and the thickness of the soil layer have a substantial impact on the dynamic characteristics of the dam-reservoir-foundation system in terms of its eigenfrequencies and damping. Moreover, simplified equivalent soil springs are calculated for the assessment of the additional dam dynamic distress due to the presence of the reservoir.