A coupling finite-infinite element method is proposed to calculate the stress and
deformation of pile-subsoil coupling systems under large deflection. A new kind of interface elements
with thickness is inserted in the interface between the soil and pile, which can dovetail with
elastoplastic models of soil and reflect the deformation in the interface and its nearby shear failure
area reasonably. The result of an example is reasonably in accord with data of on-site observation,
verifying the feasibility of the proposed method.