Abstract: The service life of the main bearing cannot be calculated resulting from the difficulty in load spectrum prediction during the operation of the fullsection hard rock tunnel boring machine(TBM). Therefore, a method to predict the load spectrum of the TBM main bearing based on the disc cuttermain bearing force flow model is studied. Based on tunnel engineering geological conditions, a prediction model of disc cutter rock breaking load is established based on code security module model and Akisanto Saburo model. Based on TBM operating conditions and disc cutter distribution on cutterhead, a cutterheadmain bearing force flow model under multiple working conditions is established based on theoretical calculation model and finite element analysis model to obtain the original load. Considering the influence of the strong impact working environment on the load spectrum of TBM, the impact load coefficient is introduced and the calculation model is established to obtain the load spectrum of the main bearing. The results show the following: (1) The working time of TBM under the full thrust accounts for 65%. (2) The axial force and overturning moment vary greatly under the four working conditions, whereas the radial force is stable. (3) Under the full thrust, the main bearing mainly bears the axial force, up to 14 374 kN, which is 5% different from the result of finite element analysis. The calculation results are compared with the actual construction data of TBM to verify the accuracy of the model and provide a reference for the design and life prediction of the TBM main bearing.

Key words: tunnel boring machine, main bearing, impact load coefficient, force flow model, disc cutter rock breaking model