FAR-FIELD MODELING IN 3D DAM-RESERVOIR INTERACTION ANALYSIS

An explicit time-domain transmitting boundary is presented for far-fie ld modeling in the three-dimensional (3D) analysis of dam-reservoir in teractions. 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 t his transmitting boundary, radiation condition and water compressibili ty can readily he incorporated in the analysis. Therefore the finite-e lement method (FEM) can be used to accurately analyze a dam-reservoir system while maintaining its efficiency in time-domain analysis. The t ransmitting boundary includes vertical and cross-stream ground motions in the far field Hence, the near field size can be as small as geomet ry and nonlinearity allow. This transmitting boundary is more efficien t that the implicit one presented by Tsai and Lee in 1990, also becaus e only a few eigenmodes are employed. Numerical results have excellent agreement with the analytical solutions available.