The shield tunnel's segmental lining comprises precast segments with many longitudinal and circumferential joints. The longitudinal joints would trigger inconsistent deformation between adjacent rings when the staggered assembling strategy is adopted, resulting in interactions between rings (coupling effects) that affect the structure's response under the ground loads. A proper method to simulate the interaction between segmental rings is critical to reveal the coupling effects. This study presents an improved shell spring model to analyze the segmental lining considering coupling effects, in which the contact elements are promoted to simulate the interactions between segmental rings under longitudinal force. The interaction characteristics and the influences of coupling effects are analyzed with this model based on a practical engineering case. Results show that coupling effects weaken the influence of longitudinal joints, and the segmental lining behaves as an intact structure. The bending moment at longitudinal joints, the dislocation at circumferential joints, and the deformation of the structure would decrease while the maximum and minimum bending moment would increase. Moreover, the longitudinal force directly impacts the coupling effects.