Abstract
The differential settlements occur in the operation of immersed tube tunnel in clayey foundation, which will cause serious problems such as tube sections cracking and leakage that threaten the operation safety of immersed tube tunnel. The settlement of immersed tube tunnel is essentially caused by the change of underwater undisturbed soil properties caused by tunnel construction disturbance and the significant time-space characteristics of soil deformation. Therefore, it is necessary to accurately quantify the influence and development law of long-term uneven settlement of immersed tube tunnel by time-spatial characteristics. A rate-dependent elastic-viscoplastic constitutive model of clayey soil considering k0 consolidation is proposed, which is programmed into FLAC3D. Then, several years of the settlement monitoring data of an immersed tube tunnel is analyzed, and the long-term settlement of the immersed tube tunnel in operation is calculated and predicted by FLAC3D. The results show that the settlement rate of immersed tube tunnel has been maintained at about 0.0015 mm/d, and the settlement tends to converge to steady state. Timely dredging and reasonable foundation treatment methods are conducive to reducing settlement during operation. The results provide a theoretical for optimizing the design of immersed tube tunnel and ensuring the safety of tunnel operation.