Method for transient analysis of threedimensional dam-reservoir interactions

The nonlinear behavior of dam-reservoir interactions is not well understood, especially when the system is formulated as a three-dimensional problem. One of the major difficulties is a lack of time-domain transmitting boundary for the far field (extending to infinity in the fluid domain). An efficient timedomain analysis procedure for a three-dimensional fluid-structure system based on a semianalytical method is developed, which takes into consideration the radiated waves in the far field. The cross section of the far field, which may have an arbitrary shape, is assumed to extend uniformly to infinity in the upstream direction. The irregular near field with arbitrary geometrical shape and boundary conditions is modeled using the conventional finite element method. Accuracy of the proposed method is established by comparing the numerical results with piecewise exact form of analytical solutions for a vertical rigid dam with vertical valleys subjected to actual earthquake and ramp loadings. In the proposed method, all of the procedures are processed directly in the time domain, which is efficient for nonlinear analyses of dams with infinite reservoirs formulated as a three-dimensional problem.