Patent ID: 8573892

Claim:
A method of forming an aggregate pier comprising the steps of: (a) driving a downwardly tapered mandrel having a flat lower end surface and a non-tapered edge around the periphery of the flat lower end surface, with the width of the flat lower end surface and non-tapered edge being no greater than the width of the mandrel at a lower end thereof, into the ground by a power driven apparatus to form a downwardly tapered cavity to a desired depth for said aggregate pier while outwardly compacting the sidewalls of the cavity as the cavity is being formed; (b) moving the tapered mandrel upwardly a sufficient distance to permit access to the lower end of the cavity; (c) depositing a layer of aggregate in the cavity; (d) lowering the tapered mandrel downwardly in the cavity so that the flat lower end of the mandrel engages the aggregate in the cavity and densifies the aggregate in the cavity, and displaces a portion of the aggregate laterally into the adjacent wall of the cavity by force applied by the flat lower end and non-tapered edge of the mandrel; and (e) repeating steps (b), (c) and (d) until a pier component of a desired height is formed.