Abstract: Shield machine is a kind of typical equipment for tunneling, it is featured by heavy body, complex structure and high load. The load acting on cutterhead during tunneling is a core mechanical parameter for the equipment. The reliable calculation of the load is important in terms of positive equipment design and load control of tunnel constructions under different geological conditions. The center tool of shield cutterhead bears a large proportion of axial load in the tunneling process. To further analyze the effects of center tool with different structures on the load on shield cutterhead, the studies of the interaction between the shield cutterhead and the soil of tunnel face are conducted by means of numerical simulation and model experiment. The dynamic cutting load distribution along the normal and tangential directions of cutterhead is obtained; and the temporal variations of the total thrust and torque during the process of excavation are also achieved. The effects of the offset center tool on the total thrust and torque on cutterhead are emphatically analyzed. By comparing the loads acting on different types of cutterheads, one can see that the offset center tool produce lower total thrust and torque than the fishtail center tool does. The results of numerical simulation are in good agreement with the experimental results. The offset center tool installed on a cutterhead can reduce the total thrust effectively. From the loading point of view, the offset center tool is better than the fishtail center tool. The research results can provide some useful guidelines for the design of new shield cutterheads.

Key words: shield cutterhead, offset center tool, total thrust, total torque, numerical simulation, model experiment