Abstract: To master the running state of the main bearing in real time, a case study is conducted on the Zhoushan subsea highway tunnel project in Zhejiang, China, and a set of online monitoring system for the homemade main bearing of largediameter slurry shield is designed. Based on the distributed control system, the professional sensors are used to collect the parameters such as vibration, temperature, and gear oil pollution of the main bearing of the shield, and the data collected are analyzed and processed. The results reveal the following: (1) The system can avoid the interference of largediameter slurry shield tunneling and monitor the running state of the main bearing stably in real time. (2) During shortterm and continuous shield tunneling, the vibration data of the main bearing and the state parameters at each time are analyzed to realize the comprehensive test evaluation of the vibration and oil characteristics of the main bearing. (3) Through the online monitoring abnormal data comparison mechanism, the discrimination and early warning of main bearing wear and impurity pollution in gear oil cavity are implemented to provide a direct basis for judging the status of main bearings.

Key words: highway tunnel, largediameter slurry shield, main bearing, shock pulse, gear oil, particle count, online monitoring