Abstract: Herein, a case study is conducted on the spiral ramp of the Beishan underground laboratory, in which statistical and mechanical analyses are employed to investigate the consumption characteristics and failure modes of disc cutters across the entire cutterhead and within different cutterhead regions. The results indicate the following: (1) The disc cutter replacement frequency for the entire cutterhead is 297 replacements per km. The dominant causes of cutter replacement are normal wear of the cutter ring (68.97%), breakage (17.23%), and chordal wear (11.76%). In addition, the tunnel alignment and the presence of high-strength, wear-resistant rock significantly increase the cutter replacement frequency. (2) Chordal wear results from local spalling of the cutter ring under high loads, as well as from the failure of lubrication oil and seals within the cutter body caused by elevated temperatures, which leads to poor rotation of the cutter ring. Cutter ring breakage is primarily attributed to the combined effects of installation height differences between adjacent disc cutters and lateral sliding during turning. (3) Compared with linear sections, the proportion of cutter ring breakage is markedly higher in curved sections, whereas the proportion of chordal wear is lower. (4) The ratios of disc cutter consumption per unit volume of rock breakage in the plane, conical, and arc regions are 1.0∶1.9∶2.6. In terms of disc cutter consumption per unit volume of rock broken, the conical region exhibits the lowest consumption, followed by the plane region, while the arc region shows the highest consumption. (5) In curved sections, disc cutter consumption in the plane, conical, and arc regions of the cutterhead is 1.90, 1.35, and 1.25 times that in linear sections, respectively. (6) The plane region predominantly exhibits cutter ring breakage and normal wear, the conical region involves all three failure modes, and the arc region is mainly characterized by normal wear. (7) From the plane region to the arc region, the proportion of normal wear increases in an approximately linear manner, whereas the proportion of breakage decreases nonlinearly. Compared with linear sections, cutter ring breakage and chordal wear in curved sections tend to be concentrated in the plane region.

Key words: Beishan underground laboratory, spiral ramp, TBM, conical cutterhead, disc cutter, failure modes, cutter consumption, regional analysis