1994 Volume 34 Issue 1 Pages 119-125
The rotary penetration steel pipe pile method (called the drill pile method here) is a new type of low-noise/low-vibration piling method which emplaces thin-walled steel pipe piles by rotary penetration but without discharging displaced soil. The drill pile method also achieves a high skin friction resistance by minimizing soil disturbance around the pile. As penetration continues, spiral ribs located on the inner wall of the drill pile provides the inner soil cylinder with sufficient resistance to prevent further soil intrusion, resulting in pressure on the ground under the pile toe. Therefore, the drill pile has the characteristics of a displacement pile. The setting depth into the bearing stratum can be checked by measuring the penetration data (e.g. penetration torque, penetration speed) in real time at the construction site. Scaled model tests clarified the penetration/bearing capacity mechanism of the drill pile. The compaction effect of peripheral soil and the soil plugging behavior inside the pile were confirmed by filed experiments at various sites with different bearing strata. The skin friction and point bearing capacity of the pile were separately evaluated through vertical loading tests, and an adequate bearing capacity formula was derived.