Vertical displacement calculation of immersed tube tunnel under tidal load

Immersed tube tunnel is adopted to cross the deepwater channel in both the Hong Kong-Zhuhai-Macao Bridge and the Shenzhen-Zhongshan Bridge. In traditional theoretical analysis, the foundation was usually simplified as a set of unrelated springs, the continuity of soil was ignored. The previous models were widely used in primary design calculation for its simplicity. In this paper, the cyclic effect of tidal load is considered, the pipes of the immersed tube tunnel are equivalent as Timoshenko beams placed on the Vlasov double-parameter foundation. Based on these assumptions, a calculating formula for vertical deformation of the immersed tube tunnel is derived, and then compared with the Timoshenko beam calculation model based on the Winkler foundation to verify the rationality of the proposed calculation method. Taking Yongjiang immersed tube tunnel project as an example, the vertical displacement of pipe joint in immersed tube tunnel under the influence of tidal load is analyzed, and the theoretical calculation results of the two models are compared with the field monitoring results. The results show that the proposed model based on the hypothesis of Vlasov double-parameter foundation can better describe the vertical displacement of pipe joint in immersed tunnel, which is more consistent with the monitoring data. The research results might have certain guiding significance for the design and calculation of immersed tunnel.