Abstract：Shield tunnels are often subjected to differential settlement and longitudinal structural deformation during long-term operation. In order to obtain the additional internal forces and joint deformation induced by longitudinal deformation, it is necessary to establish a longitudinal structural model. This paper investigates the deformation pattern of shield tunnel in longitudinal direction. The deformation patterns are divides into the following two types: a) bend mode; and b) dislocation mode. The existing longitudinal structural models are summarized and divided into the following two categories: a) segmental ring-spring model; and b) equivalent continuous model. The advantages and disadvantages of these models are discussed. An equivalent continuous model based on Timoshenko theory, which is able to consider the shearing dislocation of the tunnel, is highlighted. Based on a case study, the advantages of the Timoshenko simplified model are verified.
