Pressure Grouted Displacement Helical Pile - A case of study on soft clays and highly expansive Yazoo Clay-PPT Presentation

PPT Presentation

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The presentation examines Pressure Grouted Displacement Helical Piles (PGDHPs), a hybrid deep-foundation system combining helical flights, a steel shaft, a soil-displacing body, and controlled, multi-phase pressure grouting. The authors argue that installation displaces and densifies surrounding soil while pressure grouting increases grout-to-ground bond, potentially improving capacity over conventional helical piles and reducing defects associated with some other grouted systems.<br /><br />The proposed design approach draws on FHWA micropile guidance and is supported by structural finite-element analysis and field load testing. Tests in highly expansive Yazoo Clay in Mississippi included compression, tension, and lateral loading. A production pile reached 805 kip in compression; estimated capacities were 150 kip in tension and 50 kip laterally. Reported test results were within 10% of static design predictions.<br /><br />At Belle Chasse, Louisiana, paired conventional helical and PGDHP piles with identical helix configurations and installation depths were compared in soft coastal clay. At 0.5 inches of deflection, the presentation reports capacities of 17 tons for the conventional pile and 122 tons for the PGDHP—a 7.2-fold increase attributed to pressure grouting.<br /><br />The system is presented as offering higher capacity per pile, smaller equipment and site footprint, no spoils, and potentially shorter installation schedules and reduced exposure to crane-related hazards. These are described as potential project benefits rather than independently quantified outcomes in the presented test data.<br /><br />The authors recommend further work, including instrumenting piles during installation and testing, separating skin-friction and end-bearing contributions, excavating piles to assess grout consolidation, and developing post-installation testing methods.

Keywords

pressure grouted displacement helical piles

PGDHPs

deep foundation system

helical piles

pressure grouting

soil displacement

load testing

finite element analysis

expansive clay

grout bond