TIME-DOMAIN PROCEDURE OF FE-BE-IBE COUPLING FOR SEISMIC INTERACTION OF ARCH DAMS AND CANYONS

A procedure for three-dimensional (3-D) coupling of finite elements (FEs), boundary elements (BEs) and infinite boundary elements (IBEs) is presented for the numerical modelling of seismic interaction between arch darns and rock canyons. First, a system of coupling 3-D boundary and infinite boundary elements is developed for simulation of infinite and irregular canyons and for determination, in the frequency domain, of impedance functions on the dam-canyon interface. Secondly, the impedance functions for all degrees-of-freedom are transformed approximately into frequency independent discrete parameters by a curve fitting technique. Finally, these discrete parameters are combined with the dam structure which is discretized by finite elements, thus allowing the response of the arch dam-canyon system to be evaluated. The proposed procedure is efficient because it permits the seismic analysis of arch dam-canyon interaction by the substructure technique in the time domain. To demonstrate both the validity and efficiency of the present procedure, the response of an arch dam-canyon system is obtained under unit impulse acting on the dam-canyon interface as the free field input. Very good agreement is noted when comparing the frequency response determined from the time domain with that from the frequency domain under harmonic excitation applied on the interface of the dam-canyon.