Modeling on stiffness of gripper in hardrock TBM

Grippers are matched to the excavated section and lie against the tunnel wall in the braced condition, which invariably subjected to the impulse loads. To reduce the TBM vibrations levels and improve the stability of gripper, this paper takes dynamic stiffness of gripper as research object, model and analysis are developed: firstly, using force equilibrium equations and flow continuity equation of gripper hydraulic system on different conditions, by linearization near the equilibrium point, expressions on dynamic nonlinear stiffness and static stiffness of gripper cylinder are obtained; secondly, combined with gripper - rock contact stiffness, proposed gripper TBM machine - liquid - rock (MLR) coupling stiffness; gripper stiffness can be controlled, consequently reducing the vibration levels of TBM.