Home > R & D and Technologies > Shield Tunneling Methods > DK Shield
Daiho developed the DK Shield Method for safe & constant tunnel excavations by stabilization of the cut face in soft underground conditions. Through repeated experiments onsite with 0.7MPa of water pressure and various types of soil conditions, this tunneling method has been proven to be applicable to wider ranges of soil conditions due to constant stability of the cut face through use of the muddy soil produced in the chamber.

This DK Shield Method has been proven to be technically superior for use during tunneling application cases both in Japan and abroad, since the establishment of "DK Shield Association" in 1982, where Daiho as a core member, played the main role for development of the Method. Today approximately 70% of shield tunneling projects in Japan are carried out by this Method.

1. Characteristics
1) Muddy Soil Stabilizing Cut Face
Excavated material mixed with bentonite in the chamber, forms a muddy soil of high impermeability and plastic fluidity, which is used for cut face stabilization.

2) Maintaining Pressure Balance: Muddy Soil vs Earth Pressure + Water Pressure
Muddy soil produced and filled in the chamber is discharged by screw conveyor maintaining muddy soil pressure balance against earth pressure and water pressure as the excavation proceeds by shield jack and cutter. The cut face is stabilized perfectly even under soft underground conditions with spring water.

3) Applicable to Great Deep Excavation under High Water Pressure
Driving tests under maximum water pressure of 0.7Mpa have verified sasisfactory performance of the Method under high water pressure. This Method is suitable for great depth tunneling work exceeding 50m.

2. Principle of Excavation
3. Soil-Rock System
Soft Muck Treatment for Recycling System
4. Real Apprication to Projects
Amano River Main Sewerage Line (2002)
Kobe MRT Nakanoshima Sec. (2000)
Underground Shinjuku Sec. of Metropolitan Central Ring Road-Shinjuku Line (2005)

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