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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. [ABSTRACT FROM AUTHOR]

• Laboratory tests provide data for simulation using modified Cam-clay model. • The influence zone partition of multi-line tunnels is obtained. • The parameters in Peck formula for a clay stratum are determined and validated. • An improved Peck formula is proposed for multiple-tunnel induced settlements. The tunnelling-induced ground settlement is a key concern during urban underground construction. This paper examined the ground settlement caused by multi-line tunnelling with earth pressure balance shield in the clay stratum in Tianjin, China. Laboratory tests are conducted to determine the soil parameters used in the modified Cam-Clay model. The real-data numerical simulation achieves a good agreement with in-situ monitoring data. The influence zone partition of multi-line tunnel construction is obtained and then used to evaluate the safety risks. An improved Peck formula is proposed based on the combination of superposition, overlapping and grouting effects. The parameter ranges are calibrated by means of statistical and numerical analysis. This study provides a reliable reference and practical tool for design and construction of multiple tunnels in a clay stratum. [ABSTRACT FROM AUTHOR]