大直径盾构公路隧道在近工作井区段覆土较浅，施工期易产生上浮现象。借助以往软土地区泥水盾构隧道的设计经验，通过分析影响隧道上浮的物理环境和工艺操作，得到可能产生隧道上浮力的主要因素为地下水、同步注浆浆液、盾构姿态调整、地基回弹、泥浆后窜；间接影响隧道上浮趋势的主要因素有覆土厚度、地下水位、结构尺寸和材料重度、上覆土压缩特性、掘进速度和管片接头刚度。隧道抗浮的主要措施有增加上覆土临时压重、优化盾构施工参数与姿态控制、打设门式抗浮结构、改善注浆工艺及浆液性能、二次注浆、加强管片纵向连接等。

Due to the shallow overburden near the working shaft, tunnel floating often occurs when a largediameter slurry shield bores adjacent to the working shaft. In this paper, the physical environment and operation techniques of slurry shield that affect the floating of shieldbored tunnels are analyzed, with considering the design experience of slurry shieldbored tunnels in soft soil area. The study results show that the main factors that affect the tunnel floating include ground water, simultaneous grouting, shield attitude control, ground reaction and grout backflowing; the main factors that have indirect influence on the tunnel floating include overburden thickness, ground water level, tunnel dimension, material density, overburden compression characteristics, shield boring speed and segment joint stiffness; main countermeasures for tunnel floating include installing artificial overburden, optimizing the shield boring parameters and shield attitude control, installing floatingresistant portal structures, improving the grouting techniques and the grout performance, carrying out secondary grouting and strengthening the longitudinal connections between segments.