Abstract: Based on the dynamic governing equations of elastic waves, a hybrid finite-infinite element method is proposed for analyzing axisymmetrically vertical vibration of saturated media. Using the compiled program, the surface vertical displacements of the air-saturated ground (dry soil) are calculated under a surface point excitation, which are agree well with the theoretical solutions of the Lamb’s problem. The velocity admittance curves of block on single-piled composite foundations in saturated soil with varied permeability are calculated with the conclusions that the soil permeability will have few effects on the velocity admittances of block at low frequencies and on the resonant frequency, while the velocity admittances of block at high frequencies will increase with increasing permeability coefficient of soil. The conclusion will be of guide significance on further research of dynamic test method for engineering parameters of composite foundations in saturated soil.

Key words: saturated soil, composite foundation, block, admittance, hybrid finite-infinite element method