In response to the problem that rectangular pipe jacking tunnels are prone to produce longitudinal deformation,which can result in joint failure,a shell-joint theoretical model for rectangular pipe jacking tunnels is proposed,and the longitudinal deformation of tunnels under uneven settlement is examined.Firstly,indoor model tests are carried out to explore the mechanical properties of the joints in rectangular pipe jacking tunnels.Subsequently,the shell-joint theoretical model is established,and the stiffness matrix and computational methods for the mechanical elements of the joints are offered.Then,a numerical model is developed and compared with the results of the indoor model tests.Finally,relying on a case study of a rectangular pipe jacking tunnel with 20 segments,the tunnel's longitudinal deformation under uneven settlement is investigated.The results show that joint failure appears in three stages:closure of the gap,force and deformation failure of the steel sleeve ring,with the shear and bending resistance of the joints mainly borne by the steel sleeve ring.The simulation results of the shell-joint theoretical model are in line with the model test results,verifying the practicality and accuracy of the model.The longitudinal deformation of the rectangular pipe jacking tunnel is greatly affected by the stiffness of the foundation.The maximum additional settlements corresponding to the three soil types(gravel,silt,and clay)are 3.72 mm,7.66 mm,and 12.14 mm respectively.As the foundation stiffness decreases,the influence of uneven settlement on the tunnel joints will increase.
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