Patent ID: 8079780

Claim:
A system for constructing aggregate piers, the system comprising: a hollow mandrel having an open internal diameter and having elongated slots spaced vertically in a sidewall of said mandrel, said elongated slots comprising two series of said elongated slots each slot having a minimum width at least twice the maximum diameter of aggregate to be used with the system, each series spaced vertically and continuously on opposite sidewalls along the length of said mandrel from a proximal end to a distal end, the sum of the width of slots located at any elevation on the mandrel being less than 50% of the perimeter length of the mandrel cross-section at that elevation and a centerline horizontally spaced between the two opposing series of slots comprising vertically continuous sidewall material from the proximal end to the distal end, said slots adapted to allow for the continual flow of the aggregate therein, and said mandrel having a width substantially the same width as a cavity being formed, the aggregate filling the interior of the mandrel and preventing soils from entering the mandrel due to the aggregate in the mandrel; a mandrel head connected to the distal end of the mandrel and configured for compacting the aggregate after discharge of the aggregate from the distal end of said mandrel, and said mandrel head being shaped like a tamper foot and attached to said mandrel, and having a beveled surface at bottom sides thereof; a base machine operatively connected to the proximal end for driving said mandrel generally vertically into the ground; and a hopper at the ground surface through which said mandrel passes, said hopper filled with the aggregate to flow into said mandrel through said series of elongated slots.