| 摘要 |
PROBLEM TO BE SOLVED: To improve excavating efficiency by making rotational speed of an outer peripheral cutter head and a central part cutter head of a shield drilling machine respectively specified values and by making a proportion of the rotational speed a specified value. SOLUTION: An outer peripheral cutter head 10 having a large number of cutter heads 11 is provided on a shield excavating machine, and a central part cutter head 20 having a large number of cutter bits 21 is provided. At the time of construction, the outer peripheral cutter head 10 and the central part cutter head 20 are driven in the reversal direction to each other at rotational speed na , nb , and a ratio na /nb of the rotational speed na , nb , is driven within a range of 0.5-0.7. Additionally, as required, the rotational direction of the outer peripheral cutter head 10 and the central part cutter head 20 is driven in the same direction each other. Consequently, as lowering of cutting efficiency of the central part cutter head 20 caused by a difference of peripheral speed can be improved, it is possible to improve the excavating efficiency. |
