目前普遍采用的传统盾构始发工艺，存在首负环管片悬空拼装、管片后部无支撑空推失圆、下沉、倾斜、效率低等风险和弊端，大直径盾构管片自重和空间效应更大，相关问题也更加突出。为解决和规避相关技术难题及风险，并综合考虑目前管片结构设计创新和自动化快速拼装需求等发展趋势，通过在多个工程开展理论模拟和检算试验研究，最终提出一种新型负环管片免后推快速拼装推进始发技术。其基本步骤为： 首先，在首负环管片拼装前，于反力装置上精准安设并焊接特定长度的型钢支撑，使其延伸至盾尾加强环断面； 其次，在盾尾内按照预定点位进行首负环管片拼装，拼装过程中充分利用推进油缸和型钢支撑，按顺序压紧整环各块管片； 最后，利用盾体摩擦力或施加额外阻力，促使各环空推管片形成稳固的传力结构，从而实现负环管片的快速拼装与推进始发。研究结果表明： 通过设置合适长度、截面和轴力的型钢支撑，可以使首负环管片达到与常规掘进段一致的快速拼装成环效果，并直接推进盾构前行，形成连续的负环拼装和空推盾构施工，实现快速安全始发。

The conventional shield launching technology currently is accompanied by multiple risks and drawbacks, including suspended assembly of the negative ring segments and segment roundness, settlement, and inclination induced by empty propulsion. These enlarge self-weight and spatial effects of large-diameter shield tunnel segments, posing greater challenges. To address such technical challenges and risks, based on the development trends of innovative segment structural design and automatic rapid assembly, an innovative launching technology featuring rapid assembly and propulsion of negative ring segments without back-push is proposed. The proposal is verified through theoretical simulation, calculation, and field tests implemented in a number of practical projects. The detailed construction steps are described as follows: (1) Prior to assembling the negative ring segments, shape steel bracing with designated lengths is installed and welded on the reaction device with high precision, extending the bracing to the shield tail reinforcing ring. (2) The negative ring segments are assembled at preset positions inside the shield tail. During the assembly process, the thrust cylinders and shape steel bracing are fully used to compact each segment of the full ring in sequence. (3) The friction of the shield body or additional resistance applied result in a stable force transmission structure for all segments under empty propulsion, thus enabling rapid assembly of negative ring segments and shield launching. Research results indicate that shape steel bracing with appropriate length, cross-section, and axial force enables rapid ring formation of the negative ring segments, realizing continuous negative ring segments assembly and shield propulsion without thrust.