Abstract: Due to the unique advantages and technology intensive characteristics of shield in the full face excavation of underground soil engineering, it is given the “national heavy equipment”. However, the shield used at present is plane cutterhead shield, so the shield construction in the geological section such as Boulders, ancient tree roots or building pile foundation has always been a problem in the engineering field. Therefore, the concept of conical cutterhead shield is put forward through in-depth study; further study found that its main parameters—shield thrust and cutterhead torque are essentially different from that of plane cutterhead shield. Therefore, based on the theory of soil mechanics, the mechanical characteristics of conical cutterhead shield in the process of operation is studied and the mechanical model of thrust and torque of conical cutterhead shield is established. When the cone tip angle is 180°, the relative errors between the model solution and the main parameters of the corresponding plane cutterhead shield are: the thrust of the shield is 10.6%, and the torque of the cutterhead is 0.024%. The simulation results show that the pressure difference between the excavation face and the excavation chamber decreases monotonously with the increase of the cone top angle of the conical cutterhead, that is, when the pressure of the excavation face is constant, the pressure of the excavation chamber increases monotonically with the increase of the cone top angle. This shows that the excavation chamber pressure of the conical cutterhead is less than that of the plane cutterhead, and the soil mass of the excavation face has a larger flow thrust than that of the plane cutterhead, and the requirements for the plunger effect in the screw conveyor are reduced, that is, the conical cutterhead Shield has better soil adaptability.

Key words: shield, conical cutterhead, thrust, torque, calculation model, simulation analysis