An evaluation of cutting head design of current tunnel Boring machines and suggestions to improve machine Performance

ABSTRACT

This paper evaluates cutterhead design of current tunnel boring machines (TBMs) in considerations with the actual cutting action of discs observed on the most common cutter heads. The discs on the current TBM cutter heads were found to predominantly perform asymmetrical cutting action, which generates excessive sideway forces impairing steering action of the machine. The effective s/p ratios related to actual cutting action of discs emerge to be significantly higher than those of the laboratory-determined values, and this consequently leads to adverse cyclic deepening effect. The gross lateral loads arising from excessive side forces were stated to be minimised if the adjacent discs are arranged to cut in symmetrical position by adopting appropriate cutterhead design methods suggested in this paper. Furthermore, a dynamic analysis was carried out in terms of reaction forces on cutter heads of different geometries, and it was indicated that flat face cutter heads have better steering abilities than conical or domed types, in mixed face conditions. Similar analysis on disc angular spacing also inferred that scattered type disc arrangements with equal angular spacing are preferable to cutterheads with spoke or star type lacing, in terms of cutterhead balance.

KEYWORDS:

• Cutter head design
• tunnel boring machines
• tool lacing
• machine steering

Acknowledgments

The author wishes to thank to Dr. R. J. Fowell (Reader in Mining Engineering), formerly at the University of Newcastle Upon Tyne (U.K.), now at the University of Leeds, for his invaluable supervision and sincere help, during the research on disc cutting of rocksalt, at the University of Newcastle Upon Tyne. Thanks are also due to Dr. O.R. Fauvel (formerly at University of Calgary, Canada) for his valuable discussion. The views presented here are those of the author’s own.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/17480930.2023.2286750