Lot JC3 of the Xianmen Airport Highway Project in China involved building a twin-tube tunnel with each tube serving three-lane one-way traffic. The existence of 79 overlying buildings brought great challenges to the tunnel construction. To safeguard these buildings, two building blocks located above the nearby tunnel portal were approved by the owner of the project to be the trial blocks. Compensation grouting was adopted for ground settlement compensation at this lot. Free-field compensation grouting tests were conducted to derive the suitable grouting parameters. Pretreatment to reinforce the ground prior to the tunneling passage, concurrent grouting to compensate the excessive settlements during the tunneling passage, and regrouting to uplift the distorted buildings after the tunneling passage were designed to protect the trial blocks. According to the monitoring data of the trial blocks and the ground, the characteristics of the soil-structure interaction were studied and the criteria for the ...

With the increasing intensity of underground development, the planned metro lines will inevitably pass through water-rich soft stratum. The existing research results show that shield tunneling in water-rich stratum is prone to ground settlement and segment cracking due to the large moisture content and the low soil strength, which will pose risks to the safety of construction. The prediction of ground deformation characteristics and influencing ranges caused by shield tunneling in water-rich soft stratum has been a topical issue among the tunnel research community. Based on the shield tunnel project of Tianjin Metro Line 6, supported by the monitoring data, this paper analyses the ground deformation characteristics caused by shield tunneling in water-rich soft stratum. The results suggest that the surface settlement ranges from −14.20 mm to −28.00 mm in Tianjin’s water-rich soft stratum, which is at an acceptable level of engineering. A refined 3D model addressing fluid–structure interactions is developed to consider the construction process in water-rich soft stratum. Based on this technique, this article focuses on the effect of the support pressure at the excavation surface, the friction between the shield skin and the soil, and synchronous grouting quantity on the ground settlement and structural deformation. The results show that the friction between the shield skin and the soil is the most detrimental to deformation control, whereas the synchronous grouting quantity is the most advantageous to ground and segment deformation control. In practice, timely injection of bentonite slurry reduces friction between the shield skin and the soil, and effective synchronous grouting reduces shield tunneling disruption. This technique can provide calculation support in the optimization of shield tunneling schemes in water-rich soft stratum.