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Home > R & D and Technologies > Shield Tunneling Methods > DPLEX Shield
To drive through long-distance in urban underground where various structures already exist, needs of new shield tunneling method, which can excavate narrow or shallow overburden underground without changing bit, had been increased in late 1980's in Japan. To meet with the urgent but difficult technical requirments, Daiho started study and challenged development of new machine in 1986 and successfully carried out 1st test drive with a machine equipped with 4 sets of cutter drive axis of which rotation radius is 0.15m in 1990. For this epoch-making achievement and applications to various projects, Daiho was awarded "New Technology Development Prize" for the year 1996 by the Civil Engineers' Association of Japan.

Prize Medal for New Technology Development Award for the year 1996 by the Civil Engineers' Association of Japan.
Image of DPLEX Shield Tunneling Work
Simplified Cutter Drive Portion (Rectangular Type)
1. Technical Advantages;
1) Flexible cutting section shape:
Circular Circular with Projections Oval (Vertical)
Rectangular Horse-shoe Circular Ring
2) Smaller cutter torque and thus less energy consumption
3) Long distance continuous excavation without changing bit
4) Easier chemical injection for ground stabilization from inside of machine
5) Easier transportation, assembly and disassembly of machine because of its compactness
2. Cutting Mechanism & Typical Cutter Drive Sections;
Diagram of soil improvement (chemical injection from machine inside)
The cross-roof bit unique to this method enables cutting in all directions with the rake and relief angles being equal to each other.

Cross-roof bit
All-direction cutter bit which works for cutting by horizontal-linked movement has been newly developed. For 4-direction vertical movements, super-hard chip is equipped to drive through NOMST wall.

Circular Section Rectangular Section
3. Real Application to Projects
Narashino Kikuta River Trunk Sewer Line No.2 (H3.98m x W4.38m)
(Completed in Sep. 1996)
Minami-suna~Kita-suna 1-Chome Trunk Sewer Line (F 3.48m)
(Completed in Feb. 1998)
Kusamuta Water Discharge Tunnel (H2.35m x W 2.95m)
(Completed in May. 1999)
Doi-Kawa Rain-water Collection Sewer Line (F 3.93m/F 2.14m)
(Completed in Mar. 2002)
Subway MM21 Line (F 7.15m)
(Completed in May. 1999)
Honjyo Section of Tokyo Metro Line
(F 9.60m)
(Completed in Apr. 2001)