With the acceleration of urbanization, the development of underground space has become an important means to alleviate urban congestion and resource shortages. Shield tunneling, as an efficient and safe construction technique for tunnels, is widely used in subway, highway, and other underground engineering projects. However, traditional shield tunnels with bolted segmental linings often suffer from structural defects such as segment misalignment, cracking, and water leakage during long-term operation. In severe cases, these issues may lead to instability of the lining structure and progressive failure of the tunnel.

To address these problems, this study proposes a standardized stacked quick-assembly self-locking joint for shield tunnel segments, and systematically investigates the mechanical behavior during construction and service performance of the joint induced by its detailed structural design. The main research contents include:

(1) A detailed analysis of the structural features and design concept of the quick-assembly self-locking joint was conducted, focusing on the force evolution during segment assembly in the construction stage and the influencing factors of fastening and assembling forces. A segment assembly model was established using Abaqus to analyze the effects of the angle between the joint connector and the segment concrete end face, as well as the thickness of the waterproof rubber strip, on joint fastening. The results show that increasing the angle and rubber strip thickness both enhance the joint's pre-tightening and assembling forces. Moreover, a thicker rubber strip can induce pre-tightening force at an earlier stage of assembly.

(2) A constitutive model applicable to the quick-assembly self-locking joint was proposed, and an analytical solution for the bending performance at the joint was derived. The accuracy of the model was validated through comparison with joint bending failure tests. Based on this model, the effects of axial force and joint spring stiffness on the bending performance of the segment joint were analyzed. Results indicate that increasing axial force and joint spring stiffness can both improve the bending resistance of the joint to varying degrees.

(3) A finite element model of the joint under bending was developed using Abaqus. The structural deformation and failure evolution were compared with experimental results to verify the model's reliability. Based on the simulation, the bending performance and failure process under two loading conditions—equal eccentric distance and equal axial force—were investigated. The results show that an increase in eccentric distance reduces the bending performance of the structure, although the rate of reduction gradually decreases. Theoretically, an increase in axial force improves the bending capacity, but excessive axial force may lead to premature failure of the segment.

This study focuses on the detailed design of a self-developed quick-assembly self-locking joint, exploring the mechanism of pre-tightening force generation during segment assembly. Based on bending failure test results, both analytical and numerical models of the joint's bending performance were established, and a comprehensive parametric study was conducted under various structural and loading conditions.

Key words:Shield, Precast Segment, Quick-Assembly Self-Locking Joint Connector, Analytical Solution for Bending Performance, Finite Element Numerical Simulation