Numerical model for the analysis of the dynamic response of the soria dam including soil-structure interaction

Abstract

Soria arch dam and reservoir is the largest infrastructure of this type that exists in the Canary Islands both in capacity (32 hm3 ) and height (120 m). It is located in the south of the Island of Gran Canaria, between the municipalities of Mogán and San Bartolomé de Tirajana.

The goal of this paper is the development of a numerical model for the analysis of the dynamic and seismic behavior of this arch dam. The model includes both the concrete arch dam and the surrounding area, so that soil-structure interaction phenomena can be taken into account as accurately as possible. On the contrary, the water-soil-structure interaction effects are not included in the model. The model is used to evaluate the magnitude of soil-structure interaction and also the influence of the accuracy of the geometrical representation of the surrounding topography on such soil-structure interaction effects.

To do so, two different numerical models are built. On the one hand, a Finite Element Model of the actual geometry of the concrete dam wall is developed and used to perform a modal analysis of the fixed-base model. Then, several three-dimensional frequency-domain Boundary Element models of both the concrete dam and the surrounding topography are built. All of these models include the actual geometry of the dam wall and different approximations of the surrounding soil, ranging from a very simplified straight prismatic canyon to an elaborate model of the actual topography. These BEM models are used not only to estimate compliant-base natural frequencies and mode shapes, but also to study the seismic response of the system when subjected to incident planar seismic waves. The results show that the influence of the soil—structure interaction effects on the dynamic response of the system is quite significant. At the same time, the relevance of developing a very precise mesh of the surroundings is not important when studying the dynamic response of the dam itself, unless the response around the abutments is of interest.