Analysis of the disc cutters spacing in the face area of a small diameter TBM

When designing a TBM cutter head, Disc cutters spacing is an important design variable because it greatly affects the excavation efficiency of TBM. The excavation efficiency by the disc cutter can be confirmed through the specific energy, and the specific energy can be calculated by dividing the cutting energy by the excavated volume. The specific energy varies according to the disc cutter spacing and the penetration depth. As the spacing between the disc cutters increases, the specific energy decreases and then increases again after a certain value. In this case, the disc cutter spacing in the section showing the minimum specific energy is called the optimal cutter spacing. As a result of investigating the 14-inch disk cutter spacing of the small shield TBM used in Korea, the disk cutter spacing was found between 80 mm and 100 mm. However, the clear basis for this cutter spacing is not known. Therefore, in this study, we investigated the disc cutter spacing of TBM used in Korea and study to verify it through numerical analysis of the discrete element method. As a result of performing the numerical analysis of the discrete element method, it was confirmed that the optimum specific energy was shown between 70 mm and 100 mm the disc cutter spacing. These results show that the cutter spacing of the currently used TBM is reasonable.