Prediction Model for Normal and Flat Wear of Disc Cutters during TBM Tunneling Process

The accurate prediction of disc-cutter wear has been a longstanding topic that affects the tunneling efficiency and performance of tunnel boring machines, especially the prediction of flat wear extent in mixed ground. In the present study, a novel method for predicting the wear depth of the disc cutter is proposed based on energy analysis. Initially, the critical condition for the occurrence of normal and flat wear is determined. Subsequently, according to the geometry of disc cutters and the relationship between wear loss and friction work, the normal and flat wear depth of the disc cutter are obtained, respectively. By comparing calculated wear with Ren's prediction model and a case study, the effectiveness of the present model was verified. Finally, the influences of penetration depth and installation radius on cutter wear in mixed ground were analyzed. The research results indicate that the critical condition for the occurrence of flat wear is that the resistance moments acting on disc cutters exceed the driving moment. In addition, it was found that flat wear extent was much larger than the normal one. The disc cutter is prone to wear abnormally in mixed ground. Sensitivity analyses on penetration depth and installation radius show that wear from of disc cutters is determined by penetration depth. Furthermore, both normal and flat wear exert positive correlations with installation radius. The present work may provide some primary understanding about the determination of the critical condition for the occurrence of flat wear under different engineering environments.