Abstract: To improve the seal performance and service life of the main drive seal system of shields,   the common failure forms and reasons in main drive seal systems are investigated and the design optimization of a seal installation structure is performed. Further, the seal installation process based on the deficiencies of the layout, structural design, and installation process of existing seal systems is optimized to improve the seal performance of the main drive. The lip seal, which is widely used currently, is considered as a case study, and the influence of working pressure on the seal system is modeled and analyzed. It is found that (1) the deformation of the seal lip is mainly affected by the pressure difference on seal; (2) the support of the sealspace ring can improve the pressurebearing capacity and service life and prevent overturning of the seal; (3) the pressurebearing capacity of the entire seal system can be improved by generating back pressure and forming a reasonable pressure difference; and (4) the parallel installation of the intermediate ring can effectively prevent the overturning of the seal induced by excessive externalload pressure, thereby preventing the failure of the entire seal system.

Key words: shield, main drive seal, seal failure, seal optimization, structural design, installation process