Settlements of immersed tunnel on soft ground: A case study

This paper focuses on the settlement analysis of immersed tunnel on soft ground. Even under careful design, immersed tunnel may have problems of excessive settlement and the resulting concrete cracking or structure leakage during operation period. Yongjiang Tunnel, the first immersed tunnel on soft ground in mainland China, is taken as a case study. The monitored settlement data after a 16-year service is first displayed and analyzed, then a 2D numerical model is built to simulate the ground settlement deformation from tunnel construction to long-term tunnel operation. The effects of back-silting on the stiffness of the foundation layer and further on the settlement is quantitatively analyzed, and the advices on settlement control for immersed tunnel on soft ground are provided.