TN-X MethodMethod for forming expanded foot protections at tips of steel pipe piles

About The TN-X Method

The TN-X method uses a hydraulic expansion/contraction drilling head to form expanded foot protections of up to 2,400 millimeters at the tips of steel pipe piles. TN-X is a steel pipe pile method for high bearing capacity.
The TN-X method was certified by the Minister of Land, Infrastructure, Transport and Tourism in 2005. TN-X is used for large distribution warehouses, government buildings, hospitals, airport facilities, and other important building structures that require high pile strength.

contraction blade diameter → expansion blade diameter
Foot Protection (situation of dug up)
(Steel pipe diameter Ø1200mm, Expanded foot protections diameter Ø2400mm)


  1. Achieves high bearing capacity. By forming foot protections of up to 2,400 millimeters at the tips of steel pipe piles, this method achieves high bearing capacity with a maximum of 17,900 kilonewtons. (long-term allowable bearing capacity when the average tip sample value is 60)
  2. Achieves high seismic performance with steel pipe piles. This method uses steel pipe piles with high toughness, so it can also be used for foundation structures which are resistant to major earthquakes.
  3. Uses an inner excavation method to enable construction of long structures. The inner excavation method is used to support lengths of up to 70 meters (construction length) for 1,400 millimeter diameter steel pipe piles.
  4. Method for small amount of surplus construction soil. Uses an inner excavation method without drilling fluid (stabilizer), thus realizing construction with low soil removal.
  5. Achieving thorough quality control. Via the control device installed on the construction machine, it is possible to perform real-time confirmation at a control monitor of the drilling depth, drilling speed, cement milk injection amount, and expansion/contraction blade diameter via the hydraulic pressure of the expansion/contraction drill head.

Construction Method

*The methods listed above are just a few examples of construction methods. We also perform other methods for construction of expanded foot protections depending on design conditions such as pile diameter, pile length, and soil properties.

Click Here for the Leaflet of the TN-X Method

Construction Methods

Pile Method

Ground improvement method