| The hard rock tunnel boring machine(TBM)is a kind of construction machine integrated with mechanical design,electrical science,hydraulic technology,optical measurement and tunnel engineering,which is mainly used for tunnel constructions of railway,highway,water conservancy and municipal transportation.In the rock-breaking process,the TBM cutter-head is easily squeezed because of shrinkage or even collapse of surrounding rock when tunneling in the fault-fracture,uneven-rock or unstable-stratum zone.If the driving torque of cutter-head is not large enough for the TBM to dig forward,the cutter-head will be completely stuck.Therefore,how to achieve highly-efficient extrication from the collapsed surrounding rock has become a key problem internationally,and to improve extricating ability of the TBM cutter-head driving system is a focus of effort.In this thesis,the key technologies of hydro-viscous device have been investigated for improving extricating performance of the TBM cutter-head,which will provide a reference for academic research and engineering applications.The existing extricating technologies of the TBM cutter-head driving system are:the electro-hydraulic compound drive and the variable-frequency drive.The former includes double-speed motors and hydraulic motors,while the latter includes the variable-frequency motors only.In this thesis,a new TBM cutter-head driving system has been proposed with variable-frequency drive(VFD)and hydro-viscous drive(HVD).The power-capacity and extricating torque of the system are increased by the HVD inertial flywheel,at the same time the number and installed-power of the VFD are reduced.According to the calculated results,the maximum extricating torque of the new design is 1.5 times more than the only-VFD-used one,and the installed power of cutter-head driving system decreases by 10%.In addition,this new system not only can perform well in normal tunneling condition but also reduce manufacturing cost and occupied space.The governing equations of hydro-viscous film have been established with consideration of centrifugal effect,Coriolis effect and viscosity-temperature effect.Then the variation of Coriolis force is analyzed in different conditions,the combined effects of temperature rise and Coriolis force on viscous torque are investigated.It is highlighted for the first time that the Coriolis force results in torque loss and efficiency reduction,what’s more,the Coriolis effect becomes significant in large flow-rate condition.The maximum ratio of Coriolis torque loss to all torque loss is up to 80%and the maximum relative Coriolis torque loss is more than 10%.In addition,a type of inclined-ring disk groove in hydro-viscous clutch has been developed,which characterizes in fast cooling,fast torque rising and avoiding local high-temperature.The characteristics of film flow,steady transmission and dynamic transmission have been researched with the new structure.Compared with the ungrooved disk,the relative Coriolis torque loss decreases by 3.5%and the average temperature-rise during extrication drops by 21%at least.The above research will be used as a reference for the HVD design in TBM cutter-head extrication.Chapters are briefed as follows.In chapter 1,the current studies about the TBM cutter-head extrication are firstly analyzed.Secondly,the feasibility of application of hydro-viscous driving technology to the TBM cutter-head extrication is discussed.At last,the methodology and contents of this thesis are presented.In chapter 2,a novel TBM cutter-head driving system is designed to solve current problems in cutter-head extrication.Then the hydro-viscous extricating test rig with single friction pair is built.The test rig consists of mechanical driving system,hydro-viscous device,electrical system and software control system.In chapter 3,the Coriolis effects on hydro-viscous transmission are investigated under constant-viscosity condition and temperature-viscosity dependency condition.Firstly,the principle of Coriolis force affecting hydro-viscous transmission is introduced.The characteristics of viscous film are analyzed and the corresponding physical parameters are given.Secondly,the relationship between throughflow rate and Coriolis force is studied in approximate analytic method,and the Coriolis effects on film backflow,pressure distribution and hydro-viscous torque are focused on.At last,the combined effects of Coriolis force and temperature rise on hydro-viscous transmission are investigated.The consequent conclusions are validated in experiment.In chapter 4,a kind of inclined-ring disk groove in hydro-viscous clutch is designed for highly-efficient extrication of the TBM cutter-head.After that,the modified Reynolds equation and thermal equation considering Coriolis effects are established and numerically solved.At last,the shear stress,temperature,pressure,viscous torque and transmission efficiency of new friction pair are studied under steady and dynamic cases.The satisfying groove and flow parameters are obtained by theoretical analysis and experimental verification.In chapter 5,at first the mechanical dynamic models of extricating test rig are built in the AMESim(Advanced Modeling Environment for performing Simulation of engineering systems).The modified Reynolds equation is established with consideration of both full lubricant stage and mixed lubricant stage.After that,the co-simulation models,from the Fortran(Formula Translation),AMESim and Matlab/Simulink,are obtained by transplanting the numerical codes in Fortran into Matlab/Simulink and building data interface between AMESim and Matlab/Simulink.Secondly,the main physical parameters of extricating test rig are given and several extricating methods are introduced:positive parabola method,straight-line method,negative parabola method and cosine method.At last,the effects of these methods on extricating performance are analyzed and compared,and some guiding suggestions are given on which to choose. |
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