Abstract:  During shield tunneling, the bolt of the rearmounted disc cutter barrel of the atmospheric composite cutterhead of a largediameter shield is prone to damage caused by frequent alternating stress. To address this problem, a frontmounted barrel is designed by referring to relevant global research results. The force mode of the boltbearing disc cutter thrust is directly changed to that of a tool barrelbearing disc cutter thrust, which greatly strengthens the bolt protection. By combining theory and finite element analysis, including static analysis, modal analysis, and harmonic response analysis, a structural analysis of the frontmounted atmospheric disc cutter barrel is conducted to verify the reliability of the frontmounted atmospheric disc cutter barrel. The static analysis results show that the maximum von Mises stress does not exceed the material′s allowable stress. The dynamic analysis results reveal how the operating frequency of the tool barrel is far less than the natural vibration frequency of the structure, effectively avoiding the occurrence of a resonance failure. The results validate the rationality of the tool barrel design. Accordingly, the design scheme is applied to an actual engineering project. The results demonstrate that the bolt loosening and fracture phenomenon does not occur in the tool barrel. No seat is broken, and the tool barrel failure phenomenon does not happen. In conclusion, the structural design of the tool barrel is reasonable and suitable for the project, providing a reference for the selection design of the tool barrel for similar projects in the future.

Key words: largediameter shield, atmospheric composite cutterhead, rearmounted type disc cutter barrel, frontmounted type disc cutter barrel