The full-face tunnel boring machine (TBM) has been widely used in projects nowadays; it is significant to understand the key technology of rock breaking by TBM disc cutters. In order to study the rock breaking mechanism and consider the effect of disc cutter rings’ cross-section shape

rock strength and joint orientation

we build a series of two-dimensional numerical models of rock broken by disc cutlers using UDEC method and simulate the process of rock fragmentation by TBM disc cutters. The case study and comparative analysis show that rock breaking mechanism is a composition of shear failure and tensile failure; tensile failure is the main reason for crack initiation and propagation. From the numerical results

it is also shown that wider flat cutters and blunter wedge cutters are good at breaking rock; and flat cutters is better than wedge cutters to break hard rocks

while they are same in soft rocks; and disc cutter is good at breaking the jointed rocks which have a joint angle between thirty degrees and sixty degrees; wedge cutter is better than flat cutter to penetrate jointed rocks due to its splitting effect.