Method and apparatus for building support piers from one or more successive lifts formed in a soil matrix

摘要

A method and apparatus for forming a support aggregate pier having compacted aggregate lifts in a soil matrix, includes an elongate, hollow tube with a bulbous leading end bottom head element that is forced or lowered into the soil matrix. The hollow tube includes a mechanism for releasing aggregate from the lower head element of the tube as the tube is lifted in predetermined increments. The same hollow tube is then lowered or pushed in predetermined increments to vertically compact the released aggregate in thin aggregate lifts, while forcing a portion of the compacted aggregate transaxially into the soil matrix at the sidewalls of the cavity. The process may be repeated to form a series of compacted aggregate lifts comprising an aggregate pier or the process may include forming only a single lift for the aggregate pier while densifying adjacent matrix soils and imparting lateral stress in these soils.

主权项

1. A method for forming an aggregate pier in a matrix soil comprising the steps of:
(a) forming an elongate cavity having a bottom and a longitudinal axis in the matrix soil by lowering a hollow tube with a bottom head element having an open end at the extreme end thereof including a closure mechanism for closing the extreme open end, said bulbous bottom head element configured with a greater cross sectional area portion than the cross sectional area of the adjacent connected hollow tube, said bottom head element comprising a leading edge tapered upwardly and outwardly from the extreme open end, a trailing edge tapered downwardly and outwardly at a top thereof at the connection between the bottom head element and the tube, and having a length between the leading edge and the trailing edge of at least one times the head element diameter, and said bottom head element configured to provide axial and transaxial vector forces on the soil matrix, said closure mechanism closed during formation of the elongate cavity to prevent aggregate material discharge from the bottom head element during formation of the cavity and to prevent clogging of the 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 bottom head element open end into the portion of the cavity revealed by raising the hollow tube said first incremental distance; and (e) lowering the hollow tube a predetermined second incremental distance to compact the discharged aggregate material in the cavity by axial and 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 into the sidewalls of the filled cavity.