Dynamics of Earth Dams with Foundation Interaction

An analytical procedure to determine the dynamic properties (natural frequencies, mode shapes, and radiation damping) of dams including foundation interaction effects, which has been presented earlier in the literature, is briefly mentioned. In this procedure, the dam-foundation system is idealized as a plane strain problem. The dam is represented as an assemblage of two-dimensional finite elements, and the foundation is considered as an elastic half space. This procedure is employed to determine the dynamic properties of earth dams including foundation interaction effects for different values of E_f/E_d(E_f, E_d = elastic moduli of foundation and dam, respectively) and dam geometry. The numerical results presented indicate that: (1) Foundation interaction may have significant influence on the frequencies and mode shapes of vibration of earth dams; (2) the influence of foundation interaction depends significantly on the geometry of the earth dam cross-section, being relatively more important for dams with flatter side slopes; and (3) the magnitudes of radiation damping computed for idealized dam-foundation systems appear to be unrealistically large. Further research is necessary to obtain realistic estimates of radiation damping.