Failure analysis of a tunnel boring machine cutter holder system

Tunnel boring machines (TBMs) are large-scale construction equipment used to excavate tunnels. Cutter holder systems are core components of TBMs that connect the disc cutters to the cutter head; however, they are vulnerable to be damaged under the strong impact loads that occur during excavation. To maximize the service life of cutter holder systems, this study proposes a method for predicting the residual life under random loads. First, dynamic analysis was used to determine the stress history at the weak points of the cutter holder system, and load spectra are compiled using the rainflow counting method. Subsequently, the crack propagation life model under random loads is established. Finally, the parameters required to predict the fatigue life of the cutter holder material were determined experimentally, and the residual fatigue life of the cutter holder system under typical geological conditions was predicted. The results showed that, under geological conditions with hard rock, when the initial cracks in the cutter holder system exceeded 1 mm, the remaining excavation distance was only 0.15 km. Overall, this study provides a scientific basis for crack detection, life prediction, and reliability assessments in TBM cutter holder systems.