Seismic response of end-bearing piles in saturated cross-anisotropic soil subjected to vertically-incident P-waves

Abstract

Due to natural sedimentary consolidation processes or the directional arrangement of soil particles, foundation soils often exhibit cross-anisotropic characteristics. To investigate the coupled dynamic behavior of a pile-soil system in saturated cross-anisotropic soil under vertical seismic P-waves, this study establishes a theoretical framework based on de Boer's momentum balance equations. The constitutive relations for the cross-anisotropic soil skeleton are incorporated to derive the governing equations of saturated soil dynamics in terms of displacement. The method of separation of variables is employed to solve the motion equations of the saturated cross-anisotropic soils. By integrating the boundary and continuity conditions at the pile-soil interface, analytical solutions for the vertical displacement amplification factor and kinematic response factor at the pile head are derived. The validity of the proposed solutions is confirmed through comparisons with existing solutions in the literature. Parametric studies are conducted to evaluate the influence of cross-anisotropic soil parameters, porous fluid volume fraction, fluid-solid coupling coefficient, and pile slenderness ratio on the dynamic interaction characteristics of the coupled system.