为研究城际铁路盾构隧道下穿既有高速公路连续梁新、老桥桩群的影响并确定保护方案，以广佛城际下穿佛开高速桥桩为例，通过线路方案论证、允许变形反演分析、三维数值模拟分析及现场验证的方法，寻求线路安全位置、桥桩容许扰动沉降限制、桥梁保护方案及变形监测的规律，提出合理方案。结果表明: 1）通过采用“选择线路竖向安全线位+补偿顶升+盾构微扰动掘进+管片背后补偿注浆”综合保护方案，盾构隧道下穿桥桩群是可行的; 2）有限元分析可获取桥桩的允许扰动值，预测隧道下穿桥桩的变形，为安全下穿提供监测控制指标; 3）盾构施工期间加强参数控制，对桥桩实施动态监测，最终桥桩沉降控制为2 mm以内。

To study the influence of the intercity railway shield tunnel underpassing the new and old bridge pile groups of existing expressway and determine the protection plan, the safe project route, allowable disturbance settlement limit of the bridge pile, bridge protection scheme, and deformation law of the GuangzhouFoshan intercity underpassing the FoshanKaiping highspeed bridge piles are analyzed using deformation inversion analysis, allowable deformation back analysis, threedimensional numerical simulation analysis, and field verification, thus providing rational scheme. The results show the following. (1) A comprehensive protection scheme of "selecting the vertical safety line of route + compensation jacking + microdisturbance tunneling of shield + compensation grouting behind segment" is adopted to guarantee the underpassing of shield tunnel. (2) The allowable disturbance value of bridge pile can be obtained by finite element analysis, and can predict the deformation of the bridge pile when shield underpassing, thus providing monitoring and control indices for safe shield underpass. (3) The strengthened parameter control of shield and dynamic monitoring on bridge piles are carried out, resulting in small bridge pile settlement within 2 mm.