Augered minipiles: A cost-effective foundation for light structures

A simple yet innovative pile foundation is proposed for lightly loaded structures. The piles are constructed using a standard soil boring rig, thus eliminating the high mobilization costs usually associated with conventional piles, Design curves are developed in advance between the standard penetration test N-values and the targeted capacity of the minipiles for later use in the field to reliably determine the termination depths of the piles. Comparisons with traditional piles, caissons, as well as other minipiles show that substantial savings can be achieved in using the proposed piles. Detailed construction steps are included with emphasis on dealing with various soil and groundwater conditions. Advantages and limitations are clearly indicated. This foundation was successfully utilized to support five canopy columns of a warehouse in Norristown Pennsylvania, where a nearby sewer line prevented the use of spread footings.