Abstract: The calculation method of the rock volume broken by TBM disc cutters was discussed by considering different rock fragmentation modes， such as shear failure， tensile failure， extrusion failure and multi-failure modes. Due to the fact that shear failure and tensile failure are the dominate fracture modes of rock under the load of disc cutters， the quantitative relations among the crack length， the projected length of the shear fracture and the width of the cutter edge were used to identify the rock failure mode and calculate the volume of fragmentized rock. The rock crushing work ratio was calculated based on the CSM model to evaluate rock breaking efficiency of the disc cutters. This method was verified through an engineering project and results showed that this method could provide a reference for the performance prediction and optimization of TBM.

Key words: rock crushing work ratio, CSM model, rock fragmentation mode, volume of fragmentized rock, cutter efficiency