基于成都地铁3号线一期工程土建5标熊猫大道站—动物园站区间隧道穿越川陕立交桥工程为研究对象，针对盾构隧道纵断面为泥岩地层，且地面立交桥对沉降要求高，主要采取以下措施： 1)在施工过程中使用特殊化学改良剂来控制掘进参数； 2)对沉降要求高的区段，首先于盾构经过前在地面进行预加固，盾构经过后在隧道内再加固的双加固方法。施工证明： 在泥岩地层中通过在盾构掘进过程中采用化学改良和地面、隧道双加固措施，可以有效控制地面沉降，保证隧道施工顺利进行和地面立交桥功能的正常发挥，为其他盾构工程在泥岩层，尤其是黏土地层中下穿既有桥梁施工提供了参考和借鉴。

The shieldbored running tunnel from Panda Avenue Station to Zoo Station of No. 5 bid section of Phase I project of Line 3 of Chengdu Metro crosses underneath Chuanshan interchange. The mentioned running tunnel is located in mudstone and clay ground, and the interchange above the running tunnel has strict requirement on the ground settlement. The following countermeasures are taken: 1) Special chemical ground conditioning agents are used to control the boring parameters; 2) For sections with high settlement control requirement, prereinforcement from the ground surface is executed before shield passes and reinforcement from inside the tunnel is executed after the shield passes. The construction practice shows that the countermeasures taken can bring the ground surface settlement under effective control and can ensure the safety of the tunneling and the normal operation of the interchange. The paper can provide reference for similar projects in the future. 