부산대학교 도서관

This paper presents a mathematical model for the seismic analysis of end-bearing piles founded in a homogeneous saturated soil of finite thickness. Seismic loading is modelled as harmonic horizontal strong motion of the rigid bedrock, that generates vertically-propagating shear SH-waves. The transfer function of the soil layer is first established, considering soil as uniform isotropic poroelastic medium that obeys Biot’s governing equations. Accordingly, free-field and scattered soil displacements are co-evaluated, to establish a series-form expression that provides the dynamic lateral force acting on an Euler-Bernoulli elastic beam representing the pile. We employ the model to show that energy dissipation due to relative movement between the pore fluid and the solid matrix may have a noteworthy effect on the amplitude of high-frequency components of the strong motion in high permeability soils, and this in turn affects the kinematic response of piles. Finally, we use arithmetic examples to identify the soil permeability threshold, beyond which simpler single-phase soil models will produce reliable results for piles embedded in saturated two-phase soil.