Abstract：Shield machines have been widely used in tunnel constructions recently. When a shield machine is driving，its cutter head is pushed on tunnel face and complex interactions between disc cutters and tunnel face will be induced. In order to study the distribution law of thrust force of each cutter，influencing factors on the interaction are analyzed firstly. Rock strength and stiffness are the main factors during shield driving. On the hypothesis of elastic and point contact between cutters and rocks，the mechanical model of three-dimensional elastic supports is developed and is simplified. Acting forces on the disc cutters are calculated by finite element method(FEM)，and are compared with the results of simplified mechanical model. Thrust forces of the disc cutters are not uniform on the cutter head. The thrust forces of some disc cutters，where the disc cutter is rare，are higher than those of the others. The thrust forces of face cutters are 40%–60% higher than those of marginal cutters on the cutter head. For the same cutter head style，the thrust forces distribution vary obviously with different cutter layouts. Finally，the effects on thrust force distribution of disc cutters by rock stiffness are analyzed using Monte Carlo FEM. The softer the rock is，the more uniform the disc cutters¢ thrust force is，and vice versa. When the shield is driving in hard rock，those disc cutters of high thrust forces are heavily abraded and need be replaced frequently. This will bring negative influences on the shield performance. The layout for these disc cutters on the cutter head should be improved in the future.
