Nonlinear soil and pile behaviour on kinematic bending response of flexible piles

Dynamic 3D finite element (f.e.) analyses were performed in the time domain through a simple scheme of a single pile embedded in a soil deposit made of two cohesive layers. The parametric study elucidates the role of soil nonlinearity (stiffness degradation, hysteresis, soil plasticization) on pile kinematic bending response in respect of the adopted input signal, mobilized transient and permanent shear strain developed in the soil layers. For some accelerometric inputs the diffuse plasticization of the soil around the pile leads to compute high kinematic bending moments especially in soil deposits with the upper layer made of low-plasticity index soft clay. Finally, pile nonlinearity has also been considered by implementing bending moment-pile curvature relationships typical of reinforced-concrete piles.