Helical Piles Defined Presentation by: Howard A. Perko, Ph.D., P.E. Magnum Geo-Solutions, LLC Copyright 2011 – Magnum Piering, Inc., All Rights reserved. May be distributed and printed by express written permission of the author only. MAGNUM Informational Bulletin ISO-MAG2-11A
Copyright 2011 – Magnum Piering, Inc. HELICAL PILES Definition Installation Advantages/Disadvantages Bearing & Pullout Capacity Minimum Embedment Group Efficiency Specifying Helical Piles
Copyright 2011 – Magnum Piering, Inc. Helical Piles Defined Helical Piles: Central Steel Shaft with One or More Helix Shaped Bearing Elements that is Screwed Into the Ground to Support the Loads of Structures (a.k.a. Helical Piers, Screw Piles, Torque Anchors, Auger Screw Piles, Helix Piers) Plate Cap Extension Coupling Lead Helix Pitch Pilot Point
Copyright 2011 – Magnum Piering, Inc. January 2007 Helical Pile Installation Position and Install Pile Halt at Required Torque Cut-Off Pile Mount Cap Cast Concrete
Copyright 2011 – Magnum Piering, Inc. Machine Installation From Perko (2009) Helical Piles
Copyright 2011 – Magnum Piering, Inc. Hand Installation From Perko (2009) Helical Piles
Copyright 2011 – Magnum Piering, Inc. Advantages Low noise and vibrations Small, maneuverable installation equipment Removal and replacement Ease of transport Compression or tension All-weather installation Rapid installation Does not produce drill spoil Immediate post tensioning Shorter bond length Do not require casing
Copyright 2011 – Magnum Piering, Inc. Disadvantages Cannot penetrate very hard rock (SPT N>100) Concrete and construction debris is problematic Difficult in cobble and boulders Ease of installation means contractor pre-qualification important Slender shaft makes lateral bracing imperative
Copyright 2011 – Magnum Piering, Inc. See Magnum Bulletin ISO-MHP4-11A Reliability and Theory of Helix Sizing for more information about calculating capacity. Bearing & Pullout Capacity From Perko (2009) Helical Piles
Copyright 2011 – Magnum Piering, Inc. Minimum Embedment Bottom below potential unstable soils Penetrate a certain stratum Provide sufficient cover to resist shallow pullout Improper Length
Copyright 2011 – Magnum Piering, Inc. Minimum Embedment From Perko (2009) Helical Piles
Copyright 2011 – Magnum Piering, Inc. Minimum Embedment From Perko (2009) Helical Piles
Copyright 2011 – Magnum Piering, Inc. Group Efficiency Generally 3 to 4 Helix Diameter Pile Spacing Required to avoid Group Effects From Perko (2009) Helical Piles
Copyright 2011 – Magnum Piering, Inc. Specifying Helical Piles Pile Locations Pile Type/Size Required Pile Capacity Comp., Tension, Lateral Minimum Depth/ Bearing Stratum Required Torque Load Tests if Required See for example plans and written specifications.
Contact Information Magnum Piering, Inc PIER (7437) 6082 Schumacher Park Drive West Chester, OH 45069