为保证在地表注浆加固等常规措施难以实施的情况下盾构隧道顺利施工，以合肥市轨道交通1号线三期合肥站—瑶海公园站区间隧道在黏土地层中下穿变形控制标准严格的合肥火车站站房为例，结合工况分析盾构隧道施工引起车站变形的主要因素，提出以盾构姿态控制和同步注浆优化为主的盾构露空长度控制措施，并建立有限元仿真模型分析不同工况下车站受盾构隧道下穿施工的影响。研究表明： 1）盾构刀盘超挖和盾构尾部露空均是引起盾构施工期间地层变形的主要因素，控制刀盘超挖和盾尾露空长度可以减小周边地层变形； 2）在拟定优化施工方案下，隧道下穿施工对合肥火车站的影响基本可满足要求； 3）建议采用洞内注浆和盾尾同步注浆优化方案降低施工风险，同时应控制盾构姿态以降低甚至消除刀盘超挖。

To ensure the smooth construction of shield tunnel when conventional surface grouting reinforcement is difficult to implement, a case study is conducted on the tunnel between Hefei railway station and Yaohai park station of phase 3 of Hefei rail transit line 1 crossing underneath the Hefei railway station with strict deformation controlling standard in the soft soil stratum. The main factors causing the station deformation during shield tunneling are analyzed, the countermeasures for controlling shield exposed length such as shield attitude control and synchronous grouting optimization are put forward, and a finite element simulation model is established to analyze the influence of shield tunnel underpass construction on the station under different working conditions. Research results indicate the following: (1) The overbreak of the cutterhead and the exposed length of the shield tail are the factors causing the ground deformation during shield tunneling, which should be controlled to minimize the ground deformation around the tunnel. (2) The optimized construction scheme can minimize the influence of the tunnel undercrossing construction on Hefei railway station. (3) It is suggested to conduct intunnel grouting and shield tail synchronous grouting to reduce the construction risk. At the same time, the shield attitude should be controlled to reduce the cutterhead overbreak.