Design Studies On The Cutterhead Of Hard Rock TBM

Full face hard rock tunnel boring machine(TBM) is giant and significant equipment with integrated technology of Mechanics-Electronics-Hydraulics Laserguided. The research and design of cutterhead is the key to master the vital technology of TBM. For layout design of cutterhead, engineers have to take into account of geological and hydrological conditions, high efficient rock break theory,manufacturing technology and other factors.TBM cutterhead design theory and method are becoming an important step in the development of overcoming the technical challenges for long and deep overburden tunnel excavation in our country.The subject of this paper belongs to one of National “863” Programs titled with large diameter Hard Rock TBM key technology research and application. This paper studies mainly about design theory of TBM cutterhead geological adaptability of special ground conditions and TBM cutterhead design methodology as well as manufacturing technology.The main research works are as the following:(1) Analyze TBM research background and application situations domestic and abroad. List TBM application cases in different development stages in China;highlight the main shortcomings in TBM design and key manufacturing technology and indicate the direction of our future development efforts.(2) Summarize geological conditions of the TBM driven tunnel section in Gansu Yintao diversion project, analyze the formations, lithologic and hydrogeologic conditions and the influence of soft rock like loose sandstone and silty mudstone on the cutterhead opening ratio. Highlight the disadvantage of hexagonal rhombus segment design: unstabitily in soft rock or swelling rock, resulting in lack of shield skin frication force and then rolling. Based on the above studies, optimized cutterhead layout principle and proposal are presented by this paper.(3) Introduce the structure of disc cutter, study the theory of disc cutter rock breaking, and analyze the loading situation of disc cutter. Explain the basic principle of disc cutter arrangement, determine cutter spacing and design requirements ofcutterhead in unbalanced force, and finally, examin the disc cutter spacing and unbalanced force based on the real layout of cutterhead.(4) Establish three-dimensional model of cutterhead. Finite element is made in three loading situations: ultimate load of cutterhead, uneven load of cutterhead and eccentric load of cutterhead. Stress and deformation conditions of cutterhead in this three working conditions are studied. Therefore the applicability of TBM cutterhead layout is confirmed.