Abstract: With the stiffness characteristics and boundary conditions considered， L-P theory and slicing method were introduced to calculate the rated life of the main bearing in the tunnel boring machine (TBM) used in the second section of the diversion project’s main line for the central region of Jilin province. The statistical analysis of TBM thrust force record was carried out to calculate the life of the main bearing based on Miner’s cumulative damage theory. The results showed that the internal load distribution of the main bearing is greatly affected by the stiffness characteristics of the connection structures， and the slicing method is suitable well for calculating the main bearing’s rated life. With the modified size and form of the connection structure， the uniformity of raceway load distribution is improved greatly and the main bearing’s rated life is extended. In statistics， the TBM thrust forces are truncated normal distribution approximately， and the service life of the main bearing could be calculated based on the rated thrust force.

Key words: TBM(tunnel boring machine), main bearing, load distribution, life calculation, cumulative damage