Achieving highly efficient extrication of the tunnel boring machine(TBM)cutter-head driving system from the collapsed surrounding rock has become a key problem globally,and significant effort has been directed to improve TBM cutter-head extricating ability.In this study,the characteristics of a hydro-viscous device have been investigated to improve extricating performance of the TBM cutter-head.A numerical method based on an explicit pressure-linked equation is presented for computing the film parameters of the HVC,which is then applied to investigate extrication characteristics of a TBM cutter-head with a hydro-viscous clutch(HVC).The explicit pressure-linked equation is derived from the Navier–Stokes equations and the conservation equation,where boundary conditions are involved.The model of a cutter-head driving system with an HVC is established,and the extrication characteristics of the cutterhead driving system are analyzed and compared with three extrication strategies.The variation in extrication torque shows that the linear strategy or positive parabolic strategy are preferred for their relatively high extrication efficiency and low rigid impact,and the effects of throughflow rate on torque transmission are also investigated.The test rig of the TBM cutter-head driving system was set up to validate the numerical method and the model of a cutter-head driving system,and the feasibility of the proposed numerical method for researching the extrication of the TBM cutter-head is verified.
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