Site liquefaction is the main reason for the damage of bridge pile foundations due to earthquakes. Seismic performance of pile foundations of a highway bridge are presented in this paper. Considering the condition of liquefiable and non-liquefiable site, the model of pile-soil system of the bridge is developed by using FLAC3D to study the impact of soil liquefaction on the bridge pile. Numerical simulations show that the liquefiable site would increase the response of pile relative to the non-liquefiable site. In the bending moment, the liquefiable site would increase the bending moment of the pile. Moreover,the location of the maximum bending moment shift down compared with the non-liquefiable site. The axial force is similar to the bending moment. The lateral displacement of the top of pile markedly enlarge when the soil become liquefying. Much attention needs to be paid for the effect of the displacement of site soils due to the seismic liquefaction on the bridge pile foundation.%目的 研究液化场地与非液化场地对桩基的影响,找出场地液化对桥梁桩基的影响规律.方法 以某高速公路特大桥可液化场地为研究对象,利用FLAC3D有限差分软件,分别考虑液化和非液化两种情况,对其建立桩-土体系数值分析模型,对桩基在地震作用下的动响应过程进行模拟分析.结果 相对于非液化场地而言,场地液化会增加桩的效应,使桩的承载能力降低.在弯矩方面,场地的液化会增加桩的弯矩极值,并且弯矩极值点下移；轴力变化规律与弯矩变化规律相似；在位移方面,液化明显增大桩顶节点水平位移,但是位移变化规律基本相同.结论 相对于非液化场地,场地液化会减低桩的承载能力,桩基设计时,应该考虑液化对其的影响.
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