Seismic Pile-Soil Kinematic Interaction with emphasis on Soil Nonlinearity and Group Effects

Abstract

The kinematic soil-pile interaction is numerically investigated by conducting nonlinear dynamic effective stress analysis with the finite element method. Both the pile and the soil are simulated by considering their actual 3D geometry and assuming linear response of the foundation elements and elastoplastic response of the soil elements. A suitably calibrated plasticity model is employed for treating the nonlinear soil behaviour in cyclic loading ensuring compatibility with published shear modulus and damping ratio curves. The influence of soil yielding, load intensity, stiffness contrast ratio between foundation soil layers and relative position of a pile in a 3 x 3 pile group on the bending moment profiles, is investigated and discussed. Analytical expressions for the kinematic structural forces at the interface with large stiffness contrast of the consecutive soil layers are also drawn aiming to a preliminary seismic design.