- Flexible cross section
Shield tunnels of various cross sections can be constructed.
- 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.
- 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.
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.