Performance Prediction of TBM Disc Cutting on Marble Rock under Different Load Cases

A series of disc cutting tests was conducted with a single disc cutter (216 mm diameter) and a single rock type (a marble) by applying different loads. Normal, rolling and side forces were measured for a series of spacings and penetrations, from which other cutting parameters also were calculated. The rock chips and fines were carefully collected and analyzed. Specific Energy (SE) considerations indicate that the optimum cutting condition is existed with the ratio of S/P between 9 and 12 when applying the static loading. However, when the combination of static and impact loading is applied, the optimum cutting conditions was estimated with the ratio of S/P between 16 and 19. It shows that the optimal spaces become larger after adding the combination of static and impact loading. The relationship between rolling force and normal force is close and consistent: whether applying the static loading or the combination of static and impact loading, a nearly linear rise of the ratio of rolling force to normal force with increased penetration, and, conversely, a nearly unchanged ratio with increases in spacing. The grain size distribution curves show that larger chip size and lesser fines are produced when applying the combination of static and impact loading and the degree of crushing size tends to be uniform distribution.