Helical Piles for Moderate to High Lateral Loads in Soft Soils: Case Studies from South Louisiana-PPT Presentation

PPT Presentation

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The presentation examines how helical piles can resist moderate to high lateral loads in the soft, waterlogged soils common in South Louisiana. Lateral performance depends on pile type and size, head restraint and projection, loading, and soil behavior. Analyses using tools such as LPile and GROUP, site-specific p-y curves, and load-test data inform pile sizing, stiffness, embedment, buckling, and combined-stress checks. Design choices also affect material, installation, handling, torque, and equipment costs.

Three projects demonstrate alternatives to conventional foundation designs:

- <strong>St. Gabriel:</strong> Very soft organic clay, high groundwater, wood debris, and restricted access made drilled shafts costly and disruptive. Helical piles reduced spoils and site disturbance, avoided slurry drilling, shortened the schedule, and lowered costs while preserving the required above-ground appearance and function.
- <strong>Centerville:</strong> For a gas compressor station with scour concerns and deep bearing soils, a composite “transition” pile used a larger upper shaft for lateral and moment resistance and a more efficient lower shaft for axial loads.
- <strong>Golden Meadow:</strong> At a marsh site with extremely soft clay and storm-surge scour, fixed-head modular moment frames reduced the pile diameter and length needed compared with free-head pile bents. The design also enabled shorter pile segments, improved clearance, and faster installation, with overall savings despite using more piles.

The cases challenge the perception that helical piles are only suitable for light axial loads or anchors, or are unsuitable for soft soils. The presenters recommend engaging experienced designers, fabricators, and installers early to develop project-specific solutions. Helical piles’ adaptability, custom fabrication, and composite designs can make them viable where conventional deep foundations are difficult or disruptive to install.

Keywords

helical piles

lateral loads

soft soils

South Louisiana

pile design

LPile

GROUP software

site-specific p-y curves

foundation alternatives

composite transition pile