为提高大直径盾构（≥9 m）主轴承密封承压能力及可靠性和安全性，通过研究主流形式大直径盾构主轴承密封结构、工作原理、性能参数及典型案例，对2种形式主轴承密封接触应力进行有限元分析，并对比分析数十台2种主轴承密封保压试验数据和掘进数据。研究表明： 1）带楔形突起的唇形密封结构比不带楔形突起的唇形密封结构承压能力更强，且在不借助压力补偿系统时可承受≤0.6 MPa的开挖舱压力。2）在开挖舱压力＞0.6 MPa或开挖舱压力瞬间波动较大的工况下，压力补偿系统由于人为操作迟滞或响应不及时等不确定性因素，唇形密封系统存在较大被击穿的安全隐患。3）单道指形密封正面最大动态承压能力为1 MPa，建议开挖舱压力在0.4～1 MPa时选用指形密封，不需要配置压力补偿系统，可提高主轴承密封结构的承压和稳压能力。

To improve the bearing capacity, reliability, and safety of main bearing seal of largediameter shield (over 9 m), the structure, working principle, and properties of two main bearing seals are investigated, and case analyses are conducted. Then, finite element analysis is employed to study the contact stress of the seals, and the pressure and tunneling data of the two main bearing seals in dozens of largediameter shields are comparatively analyzed. The results reveal the following: (1) The bearing capacity of labiates seal structure with wedge protruding is higher than that without wedge protruding, which can bear excavation chamber pressure of no larger than 0.6 MPa without compensatory pressure. (2) Under the condition of excavation chamber pressure of larger than 0.6 MPa or momentary large fluctuation of excavation chamber pressure, the labiates seal structure is potentially brokendown due to delay operation or response of pressure compensation system. (3) The maximum positive dynamic bearing capacity of singlechannel fingertype seal is 1 MPa, thus the fingertype seal is recommended when the excavation chamber pressure ranges from 0.4 MPa to 1 MPa without arrangement of a pressure compensation system, which still can improve the bearing and pressurizing capacity of main bearing seal structure.