The drilling in the Pile, foundation pile structure

摘要

An internal excavation method through a pile, comprising the steps of (a) fitting a tip metal device (13) to an existing concrete pile (1), inserting an excavating rod (15) without a soil discharging mechanism into the existing concrete pile, and excavating by a rotary excavating arm (21) of an excavator head (18) to immerse the existing pile (1), (b, c, d) excavating a ground, while loosening, with a diameter 1.4 times the outer diameter of the existing pile (1) or more and stamping the loosened excavated soil to the outside by the outer face of the exiting pile (1), and filling, agitating, and mixing cement mill in stratums (26A, 26B) designated by design to form solidified mixed layers (29A, 29B) with recovered or improved ground strength, (e) forming a foot protection layer (30) filled with cement mill on a pile hole bottom (31) side, and (f) raising the excavating head (18) to the ground, lowering the existing pile (1), and positioning the tip metal device (13) in the foot protection layer (30), whereby a supporting force of approx. two times that of an existing internal excavation method can be developed, and a soil discharge amount can be remarkably decreased.