Introduction : Wagging Cutter Shield Tunneling Method

Excavantion mechanism

  1. Flexible cross section
    Shield tunnels of various cross sections can be constructed.
  2. Compact shield tunneling machine
    Rectangular shield tunnels can be constructed using a simple excavation mechanism.
    The weight and length of the shield tunneling machine, and the cost of excavation can be reduced by using hydraulic jacks.
  3. Structure of lining of rectangular shield tunnel
    The lining of the rectangular shield tunnel has an effective sandwiched structure. The outside of the tunnel has a steel-concrete composite structure composed of steel shells that are used as main tension members. The inside has a reinforced concrete structure.
    Using steel shells not only for temporary linings during temporary work but also for the main tunnel upon completion of tunnel linings leads to the reduction of construction cost.


  • Cutter wagging system
    Cutters are expanded and contracted like pistons by hydraulic jacks. Thus, the structure is mechanically simple and the weight and length of the tunneling machine can be reduced.
  • Overcutters
    The rotation of cutters and the expansion and contraction of overcutters are automatically  controlled to enable accurate excavation of corners of the cutting face.
  • Spike bits
    Long stroke cutters essential to the non-circular wagging cutter shield method are required to have higher durability and reliability than ordinary cutters.
    The newly developed high-performance "spike" bit is capable of penetrating and cutting the earth when the overcutter is expanded or contracted, and before and after the cutterhead is wagged.

Applications to actual tunneling