Method and apparatus for forming cemented ground support columns

A method for constructing a support column, comprising the steps of:

• providing a mandrel assembly having a feed tube operatively connected to an expansion head, wherein the expansion head comprises an expansion chamber and an egress port within the expansion chamber, the egress port being adapted for crimping wherein the egress port is a tube made of a material, such as concrete hose, Kevlar tubing, or aramid fiber tubing, selected to be sufficiently flexible such that the tube is adapted to compress radially inwards to prevent backflow or infill material upward into the tube;
• driving the mandrel assembly into a ground surface to a prescribed initial depth with respect to the ground surface level;
• adding infill material to the feed tube, wherein the infill material has sufficient mobility for advancing within the feed tube and through the egress port;
• driving the mandrel assembly further into the ground surface to a prescribed driving termination depth with respect to the ground surface level;
• raising the mandrel assembly above the prescribed driving termination depth;
• forming a space at the bottom of the mandrel assembly;
• allowing a first portion of the infill material to exit through the egress port by gravity into the expansion chamber and into the space;
• and
• forming a first placed infill material at the prescribed driving termination depth.