Abstract: Shield tunnel uplift is a common phenomenon in tunnel construction,where excessive uplift often leads to engineering problems such as dislocation and leakage of tunnel segments.Existing theoretical studies typically rely on the Euler-Bernoulli beam theory,which only considers the bending effect of the structure and neglects the shearing effect,resulting in an inadequate estimation of segment uplift.In this study,the traditional beam model is divided into three sections,with the shield tailing part added,considering the constraints of the shield shell on the two rings within the shield machine.Furthermore,based on the Timoshenko beam theory,both the bending and shearing effects of tunnel uplift are considered,and the load distribution and constraints on the beam structure(are) optimized.The proposed theoretical model is thereafter validated by utilizing field monitoring data from the Jiangyin-Jingjiang Yangtze River Tunnel,as well as numerical simulations.The study demonstrates the applicability and effectiveness of the model.Through further numerical simulations,taking into account the influence of different tunnel design gradients,the shortcomings of the proposed theoretical model are analyzed,and the modified formula of the floating load is imposed,providing support for the further improvement of tunnel floating theory research.