New rock material definition strategy for FEM simulation of the rock cutting process by TBM disc cutters

Traditional Finite Element Method (FEM) simulations on the rock cutting process by TBM disc cutters may be improved considering the following shortcomings: (1) the troughs of the numerical forces are usually much lower than those of the field or experimental forces; and (2) the rocks beneath the cutter tip are usually cut off excessively, while the chipping of the rocks between the cutting kerfs is usually less than real. The reasons for these shortcomings are tentatively discussed as follows: (1) the plastic hardening and failure behaviours are assigned the same for different rock parts, which is different from the real rock breaking principle; and (2) directly using the element deletion strategy to simulate the rock chipping cannot consider the crushing process between the cutter tip and rock specimen. In order to find a reasonable rock material definition strategy, four rock cutting models with different strategies were simulated and the results were compared with rock cutting test on a Rotary Cutting Machine (RCM). The comparison indicates that the rock material should better be defined considering the rock crushing process beneath the cutter tip and the difference of the rock tensile and compressive strength.