基于有限杆单元法的陡坡基桩非线性分析

根据陡坡段桥梁基桩承载特性，提出了一种可考虑桩土非线性作用的基桩内力与位移分析有限杆单元方法。首先，基于单元划分结果，结合桩侧摩阻力和坡体侧向推力的分布规律，得到了相应的等效结点荷载向量表示方法；其次，在线弹性地基反力法的基础上，引入p-y曲线开展了桩周土抗力非线性分析，并结合桩身P-?效应（P为桩顶轴向荷载，?为桩顶水平位移）计算方法给出了单元刚度矩阵修正方法，进而提出了适用于基桩内力位移非线性分析的有限杆单元法并编制了MATLAB计算程序；最后，结合某工程实例，将计算结果与工程实测值及已有理论值进行对比。结果表明：考虑桩土非线性作用的计算方法是合理的；当桩身具有自由段时，P-?效应对基桩内力位移的影响较大，在实际工程设计中不可忽视。

Nonlinear analysis of pile in steep slope based on finite bar element method

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.