(铁道第三勘察设计院有限公司， 天津市 300251)
张杰（1987—）， 男， 硕士， 工程师， 从事桥梁设计工作。
以天津-潍坊高铁双线海河隧道下穿既有市政桥梁工程为依托，为探究盾构施工过程对地表沉降及市政桥梁桩基变形的影响规律，采用有限元分析软件Midas/GTS NX 对盾构开挖全过程进行模拟。模拟结果表明，高铁隧道开挖至市政桥梁附近时地表沉降速率变大；地表沉降量最大的位置并不是桥梁桩基附近；在地质条件不好的情况下，隧道穿越桩端位置时，桩基础容易发生向内的倾斜，同一排桩的位移值基本一致，桩端的水平位移大于桩顶，且同一个墩台下的前排桩的水平位移小于后排桩、竖向位移大于后排桩。
Relying on Haihe Tunnel of Tianjin-Weifang High-speed Double-line Railway tunneling the existing municipal bridge, by studying the influencing rule of the shield construction process on the settlement of ground surface and the deformation of municipal bridge pile, the whole process of shield tunneling is simulated by using the finite element software Midas/GTS NX. The simulation results show that the settlement velocity of the ground surface increases when the high-speed railway tunnel is tunneled near the municipal bridges. The location of the maximum surface settlement is not near the pile foundation of bridge. The pile foundation is prone to inward inclination when the tunneling is through the end of the piles in bad geological conditions. The displacement value of the same row of piles is basically the same. The horizontal displacement of the pile end is greater than the pile top. And the horizontal displacement of the front pile under the same pier abutment is less than that of the rear pile, and the vertical displacement is greater than that of the rear pile.