为解决盾构主驱动密封系统在掘进过程中失效，造成主驱动、主轴承或齿轮损坏的问题，以某系列土压平衡盾构主驱动密封系统的结构和工作原理为基础，首先，采用适用于现场施工条件的主驱动密封气压检测技术，即分别向内、外密封各腔体内通入100 kPa压缩空气，保压30 min后，压降值在允许范围内为合格，超出为不合格，进而判定主驱动密封是否失效。然后，结合现场经验和理论分析，从设计、装配、操作、磨损4个方面对密封失效的原因进行分析，得出装配不合格、操作不当和正常磨损等问题均是目前最常见的密封失效原因。最后，针对密封失效原因，分别从设计、安装、操作、日常维保等各个环节进行预防把控，以保证主驱动密封系统达到设计使用寿命。

In order to solve the problem that the main drive seal system of shield machine fails in the process of tunneling, which causes damage to main drive, main bearing or gear. Based on the structure and working principle of the main drive sealing system of the earth pressure balance shield, firstly, under suitable field construction condition, the air pressure detection technology for main drive sealing is adopted, that is to inject 100 kPa of compressed air into the inner and outer sealing cavities respectively, after keeping pressure for 30 min, the pressure drop value is qualified when it is within the allowable range, and unqualified when it exceeds, which can judge whether the main drive seal is invalid. Secondly, combined with field experience and theoretical analysis, the causes of seal failure are summarized and analyzed from four aspects of design, assembly, operation and wear. It is concluded that the most common failure causes include unqualified assembly, improper operation and normal wear. Thirdly, in view of the failure causes, it is proposed to prevent and control from design, installation, operation, daily maintenance and other aspects, to ensure the main drive sealing system reach the design service life.