Study on Longitudinal Stress Relaxation Effect and Reinforcement Technology of Segment Lining during Shield Docking

Shield docking technology is widely used in underwater shield tunnels. As the technology is not perfect, the instability of the tunnel face and the stress relaxation of segment lining caused by shield dismantling need to be solved. Using a cross-sea tunnel project, the segment lining reinforcement technology with steel channel in the process of shield docking is studied. The longitudinal stress relaxation effect of segment lining after thrust unloading is analyzed, and the theoretical solution of segment circumferential joint opening, with or without steel channel reinforcement, is derived. The accuracy of the theoretical model and the shell connector numerical model is verified by comparison. Then, the influence of key parameters, such as reinforcement range, steel channel quantity and steel channel model, on reinforcement effect is discussed. The results show that: (1) with the increase in the range of reinforcement, the maximum longitudinal displacement and the opening of the circumferential joints decrease first and then increase; (2) with the increase in the quantity and model of the steel channel, the maximum longitudinal displacement and the opening of the circumferential joints gradually decrease, and the reduction rate also decreases. The farther away from the shield tail, the weaker the reinforcement effect on segment lining.