ANALYSIS OF 3-D FOUNDATION WAVE PROBLEMS BY MAPPED DYNAMIC INFINITE ELEMENTS

From wave equations of 3-D visco-elasticity and Garlerkin weighted residual approxima-tion, discretized formulations for 3-D visco-elastic foundations Lave been derived. In addition,a 3-D mapped dynamic infinite element （IFEM） and its basic principle and constituting pro-cedure are presented. This IFEM can easily be coupled with the normal FEM, and it retainsthe advantages of being suitable for simulation of complicated media and boundary conditions,and of reducing the degrees of freedom by a large number. The example given in this paperverifies the excellent accuracy of IFEM. Finally, study has been made to evaluate the effectsof plate flexibility on dynamic compliances of a 3-D foundation on elastic half space. Re-sults show that only if the elastic modulus ratio of the plate and foundation E/E≥10- 10,can the plate be treated as a rigid base.