Characterization of Shear Damage and Channel Reinforcement of Circumferential Joints between Shield Tunneling Segments Based on Numerical Simulation

Shield misalignment is a common problem in shield tunnels, which seriously affects the safety and durability of tunnels. However, at present, there is a lack of research on the influence of shield misalignment on the shear capacity of the circumferential joint structure, and the failure mechanism of the circumferential joint structure before and after reinforcement is not clear. Therefore, this paper simulates the influence of misalignment on the performance mechanism of segmented circumferential connection and the effect of channel reinforcement on the ABAQUS platform. The simulation results are compared with the full-scale test results, and the results show that the shear failure process of the circumferential joint can be divided into three stages under the condition of no reinforcement. In the first stage, the vertical load increases, but the misalignment between the shield tunneling sections is very small. In the second stage, the load almost does not increase, but the degree of misalignment increases. In the third stage, the load–displacement relationship is nonlinear, indicating that the bending bolt has been sheared. Under the condition of unreinforced, the bolt will form two plastic hinges when it fails. After reinforcing the channel, the removal of the bolt forms only one plastic hinge. After channel steel reinforcement, the boundary area between the channel steel web and the steel plate first reaches the ultimate tensile strength of the steel plate, and the failure mode becomes channel steel reinforcement failure. Under the same shear load, the misalignment of the circumferential joint reinforced with channel steel is reduced. In this paper, the misalignment relationship of shear load and the yield of the bending bolt obtained through numerical calculation is consistent with the conclusion of the full-scale test. However, the circumferential connection misalignment obtained via numerical calculation is relatively small. The yield position of the bending bolt is also in good agreement with the test results, and the bolt strain obtained through the test is relatively small.

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