Improved vertical displacement calculation model for immersed tube tunnel considering tidal load

Most of the major cross-sea cluster projects in China, such as the Hong Kong–Zhuhai–Macao bridge, Shenzhen–Zhongshan bridge, and Dalian Bay Tunnel, have adopted the immersed tube tunnel method. In traditional theoretical analyses, the soil continuity of the foundation is neglected. In this study, the elements of an immersed tube tunnel are considered equivalent to the Timoshenko beams placed on a Vlasov double-parameter foundation, and a formula for calculating the vertical deformation of the immersed tube tunnel is derived. Moreover, the Timoshenko beam calculation model placed on a Winkler foundation is adopted for comparison, in order to verify the rationality of the proposed calculation method. Considering the Yongjiang immersed tube tunnel project as an example, the vertical displacement of an element–joint in this tunnel under the influence of the tidal load is analysed, and the theoretical calculation results of both models are compared with the field observation results. The comparison reveals that the proposed model based on the hypothesis of a Vlasov double-parameter foundation yields results more comparable to the observed data than the other model. These research results are expected to have certain guiding significance in the design and calculation of immersed tube tunnels.