Lace Design Optimization for Hard Rock TBMs

Optimization in TBM cutterhead design is essential for increasing its performance. Lace design for the cutters, buckets, and manholes, is one of the major considerations in the design of the cutterheads. An optimum lace design is necessary to avoid cutterhead deviation, vibration, stress concentration, etc. during its operation. TBM manufacturers usually utilize two common lace designs of radial and spiral configurations. Each of these designs have its own disadvantages which may cause difficulties in achieving an efficient design of the cutterhead. This paper presents the basis of the lace design of the hard rock TBMs. With the consideration of the problems of the radial and spiral configurations, a new method of “evenly distributed lace design” is introduced and the steps of achieving the final layout of the cutterhead is explained with its required parameters. The parameters are obtained from statistical analyses conducted on the gathered design information of many TBM cutterheads from around the world. The results, show that the new method is very efficient in both evenly distributing the cutters on the cutterhead surface as well as in minimizing the unbalanced forces and moments.