Angular dependence of rock cutting forces due to foliation

Abstract A series of rock cutting tests was conducted with three different metamorphic rock types. Samples were prepared with alpha angles of 0°, 45° and 90° to investigate the influence of foliation angle on the rolling forces ( F R , scaled ) of a mini disc cutter (scale 1:8). Results show that F R , scaled increased by a factor of about 2 at an alpha angle of 0° compared to 90° for all three rock types. In a subsequent step, a way to implement the results into a TBM performance prediction model to derive a correction factor for angular dependence of TBM performance was shown. The resulting correction factor for overall TBM performance ( F N 0 ° / F N 90 ° ) is in the range of 1.33–1.80 which is in good agreement with previously published TBM field data by Buchi (1984) and Thuro (2002).