Comparative study on the cutting performance of super-large diameter atmospheric cutterhead and pressurized cutterhead under the same stratum

The difference in cutter arrangement between the atmospheric cutterhead and the pressurized cutterhead leads to a significant difference in the cutting performance of the two cutterheads. Due to the lack of quantitative comparison and analysis of the cutting performance, the selection of cutterheads lacks a quantitative and scientific basis. In this paper, an atmospheric cutterhead and a pressurized cutterhead with 15.07 m diameters are taken as the research objects, which were excavated in the same slightly weathered argillaceous siltstone strata for a certain tunnel project in Guangzhou. Rotary cutting rock simulations of cutter groups in the central area, front area and edge area of the two cutterheads are established, where the rock damage form, load characteristics and specific energy of the three areas of the two cutterheads are comparatively analyzed. Furthermore, the actual engineering tunneling performance of the two cutterheads was analyzed to verify the simulation results. The vertical force and rolling force of each disc cutter on the pressurized cutterhead are 75.7% and 78.2% of those on the atmospheric cutterhead, respectively, where the cutter spacing of the pressurized cutterhead is smaller. The rock-breaking specific energy of the cutter group in each area of the pressurized cutterhead is 95.6-73.4% of that of the atmospheric cutterhead. Meanwhile, the total thrust and torque of the pressurized cutterhead are 111.4% and 115.2% of those of the atmospheric cutterhead, respectively, where the pressurized cutterhead is equipped with more cutters. Therefore, the overall cutting performance of the pressurized cutterhead is better than that of the atmospheric cutterhead in slightly weathered argillaceous siltstone strata. This study provides a quantitative comparison method for the atmospheric cutterhead and the pressurized cutterhead under the same geological conditions, which can be extended to the structure selection of large-diameter cutterheads of shield machines under other geological conditions.