Abstract: To achieve full-section mechanical excavation for enlarged-diameter vertical shaft boring machines and improve overall excavation efficiency, a cone-shaped cutterhead for enlarged-diameter vertical shafts is developed based on circular planar cutterhead design theory and combined with the bottom slag discharge method. First, the excavation method, overall machine composition, and slag discharge principle of enlarged-diameter vertical shafts are introduced, and digital simulation technology is used to compare and analyze the bottom slag discharge efficiency for four pilot hole diameters (2 000, 1 600, 1 200 and 800 mm). Then, based on planar cutterhead theory, the cone-shaped cutterhead is designed with respect to cutter spacing, cutter arrangement, cutter selection, cutter seat structure, and main body structure. Finally, excavation tests are conducted at a designated test site to verify the practicality of the cone-shaped cutterhead for enlarged-diameter vertical shafts. The results show that (1) a pilot hole diameter of ≥1 200 mm is recommended; (2) the overall structural design and structural strength of the cone-shaped cutterhead are reasonable and feasible; (3) at a cone angle of 45°, the cutter force satisfies operational requirements; and (4) during testing, the cutterhead effectively completes cone-surface rock breaking, meeting the excavation and slag discharge requirements of enlarged-diameter vertical shaft boring machines and enabling mechanization and automation of these systems.

Key words: enlarged-diameter vertical shaft boring machine, cone-shaped cutterhead, cutter, pilot hole, bottom slag discharge