Longitudinal vibration of piles in 3D axisymmetric soil based on fictitious soil pile method

A new treatment way for the supporting soil under physical piles, the fictitious soil pile method, is introduced, in which the projection zone of the soil from immediately below the physical pile till the bedrock is simplified as a fictitious soil pile. A three-dimensional axisymmetric coordination is established with the axial line of pile as the Z axis. Firstly the complex stiffness of the fictitious pileblock is obtained by solving the vibration equation with its boundary condition. Further, regarding the complex stiffness of the fictitious pileblock as the supporting stiffness of physical pile, both complex stiffness and velocity response function of the physical pilebolck are obtained using the complex impedance transfer method based on the boundary condition of the physical pile. Effects of length, velocity of shear wave and Poisson ratio of the fictitious soil pile on dynamic responses of the physical pile are also investigated. Finally, compared to some other methods for the pile supporting, the advantages and rationality of the fictitious soil pile method are identified. It is indicated that the fictitious soil pile method is a more precise computational modeling for simulating elastic (viscous) and fixed supporting, and is worth further studing.