The Decision-Making Method for the Assembly Point of Universal Segments in Shield Tunnel

To support rational assembly-point selection for universal segmental rings during shield tunneling, a geometric model was established to describe the ring pose. The effects of assembly-point selection on alignment deviation, thrust-cylinder stroke difference, and shield tail clearance were analyzed, and corresponding calculation models were developed. A decision loss function with dynamically adjusted weights was then formulated by integrating the three factors, enabling adaptive optimization of assembly points under multiple constraints. The method was validated using the Kuiqi Station–Yangli Station section of Fuzhou Metro Line 2. The recommended assembly points showed a high level of agreement with the points selected in the field. For rings where the two selections differed, the recommended points generally produced better shield tail clearance, thrust-cylinder stroke difference, and alignment deviation than the field-selected points. The proposed method therefore provides a technical basis for assembly-point decision-making for universal segmental rings in shield tunnels.