Abstract: According to the bearing capacity of bridge pile in steep slope, a finite bar element method of calculating internal force and displacement of pile is presented to consider the effect of pile-soil nonlinear interaction. Firstly, based on the result of bar element division, equivalent nodal load vector is obtained according to the distribution of lateral friction force and residual sliding force of slope. Secondly, with the introduction of p-y curve, nonlinear analysis of soil resistance is carried out using line elastic foundation reaction method. Then element stiffness matrix correction method is employed after cooperating with the calculating method of P-? effect (P is the axial load of pile top, and ? is the horizontal displacement of pile top). A finite bar element method using nonlinear analysis of pile internal force and displacement is proposed and relevant MATLAB program is edited. Finally, the calculated results are compared with measured values and theoretical values of other papers for an engineering example. The results show that method of considering pile-soil nonlinear interaction in this paper is reasonable and the influence of pile P-? effect on pile internal force and displacement is so large that cannot be ignored in the actual engineering design.

Key words: steep slope, pile foundation, finite bar element method, p-y curve, P-? effect