Patent ID: 7326004
Filing Date: 2008-02-05
Classification: E02D

Abstract:
1. A mandrel for forming aggregate piers, comprising a substantially hollow steel shell elongated body having an upper end, a central axis, a blunt lower end with a sacrificial bottom cap configured to prevent clogging of the mandrel during soil penetration and to be left in place at a bottom of the pier during pier construction, an outer surface with a continuous outer perimeter and which tapers inwardly from adjacent said upper end to said lower end at a taper of less than about 5.0 degrees relative to the central axis, and a conduit extending internally of the body from the body upper end to an aperture in the body lower end generally along said central axis, the conduit being configured to deliver aggregate through the body lower end and to obviate withdrawal of the mandrel prior to the delivery of said aggregate, said elongated body configured to form an elongated hole in a ground surface while densifying soil in sidewall surfaces of said hole through direct engagement of said outer surface with said sidewall surfaces, and further configured to compact said aggregate placed in said hole such that said aggregate penetrates said sidewall surfaces through direct engagement of said mandrel with said aggregate.