Patent ID: 8152415

Claim:
A method for forming an aggregate pier in a matrix soil comprising the steps of: a) forming an elongate cavity having a bottom, sidewalls, and a longitudinal axis in a matrix soil by lowering a hollow tube with a bulbous bottom head element having an open end at the extreme end thereof including a closure mechanism for closing the extreme open end, the open end being in-line with the hollow tube, said bulbous bottom head element configured with a greater cross sectional area portion than the cross sectional area of the adjacent connected hollow tube and further comprising a leading edge tapered upwardly and outwardly from a bottom thereof, and a trailing edge tapered downwardly and outwardly at a top thereof at the connection between the bulbous bottom head element and the hollow tube, defining surfaces configured to provide axial and outwardly transaxial vector forces upon a matrix soil when being lowered into and raised out of the matrix soil, said bulbous bottom head element having a length between the leading edge and the trailing edge of at least one times the bulbous bottom head element diameter, and said closure mechanism closed during formation of the elongate cavity to prevent aggregate material discharge from the bulbous bottom head element during formation of the cavity and to prevent clogging of the bulbous bottom head element or hollow tube with matrix soil materials during penetration and formation of the elongate cavity; b) raising the hollow tube a predetermined first incremental distance in the formed cavity; c) opening the closure mechanism when the hollow tube is raised; d) feeding pier forming aggregate material through the bulbous bottom head element extreme open end into the portion of the cavity revealed by raising the hollow tube said first incremental distance; and e) lowering the hollow tube and bulbous bottom head element in unison a predetermined second incremental distance to compact the discharged aggregate material in the cavity by axial and outwardly transaxial force impact from the bulbous bottom head element onto the discharged aggregate material surface while displacing a portion of the pier forming aggregate material transaxially outwardly against and into the sidewalls of the filled cavity.