Performance Prediction Model for Disc Cutters Considering Joint Spatial Location and Degradation Effects

Disc cutters are critical components of tunnel boring machines because their performance directly affects construction safety and efficiency. Accordingly, an accurate prediction of disc cutter performance is essential. In practical engineering, joints are widely distributed, and when a disc cutter interacts with jointed rock, the presence of joints significantly alters deformation behavior, failure modes, and rock strength, thereby complicating performance prediction. To address this issue, this study investigated the crack propagation induced by disc cutter intrusion into jointed rock and identified six rock-breaking modes: nonsynergistic, synergistic, synergistic compression, intercutter synergistic, cutter–rock synergistic, and cutter–rock synergistic compression. Based on rock failure mechanisms under compression, shear, and tension, as well as cavity expansion theory, a rock-cutting force model was developed with both intercutter synergy and the spatial distribution of joints incorporated. Moreover, the model introduced a rock strength deterioration coefficient (TR) to account for joint-induced degradation in rock strength. The model’s reliability was validated through comparison with laboratory experiments and numerical simulations. This study offers a novel perspective for understanding disc cutter performance in jointed rock.