Far-field modeling in 3D dam-reservoir interaction analysis

An explicit time-domain transmitting boundary is presented for farfield modeling in the three-dimensional (3D) analysis of dam-reservoir interactions. This transmitting boundary is a semianalytical solution of the governing wave equation of the far field with the assumption that the ground motion is uniform along the upstream direction. By using this transmitting boundary, radiation condition and water compressibility can readily be incorporated in the analysis. Therefore, the finite-element method (FEM) can be used to accurately analyze a dam-reservoir system while maintaining its efficiency in time-domain analysis. The transmitting boundary includes vertical and cross-stream ground motions in the far field. Hence, the near field size can be as small as geometry and nonlinearity allow. This transmitting boundary is more efficient that the implicit one presented by Tsai and Lee in 1990, also because only a few eigenmodes are employed. Numerical results have excellent agreement with the analytical solutions available.