Boring with the rod is performed to specified depth by special earth auger, and it is pulled up injecting fixed slurry for skin of pile. Grouting is switched to root hardening slurry and an expansion bit is operated to build the bulb more than pile diameter.

The pile is inserted in a bored hole and is made fix to predetermined depth by rotating or by gravity, in addition to this, made the same diameter of boring and expansion.

By hardening of root hardening slurry and surface of pile fixed slurry, the bearing layers is made to unify and bearing capacity is ensured.

Evaluation of bearing capacity in a bearing capacity calculation formula, higher than a Pre-boring with root hardening cement slurry.

It can construct in low vibration and low noise, and economical.
For application pile diameter, 300-1000mm and the maximum pile length are about 110 times of pile diameter and 80m.

• 1Boring with the rod, which attaches expandable wings, injecting out boring slurry (bentonite solution or water) from a bit tip is performed.
• 2If bit tip reaches at bearing soil layers, the expandable wings will be operated and expansion boring will be performed.
• 3Grouting hardening slurry in root is performed.
• 4Pull up a rod, injecting and fill with root hardening slurry in bulb part in closed wings.(Pile circumference fixed slurry may be used or it may not)
• 5Insert a pile in a bored hole.
• 6Rotate a pile and into bulb part.