Evaluation of Key Parameters Affecting the Bearing Capacity of Helical Piles

Document Type : Regular Paper

Authors

1 Ph.D. Candidate, Department of Civil Engineering, Islamic Azad University, Arak, Iran

2 Professor, Department of Civil Engineering, Payame Noor University, Tehran, Iran.

Abstract

This experimental study examined the axial performance of helical piles subjected to compressive and tensile loads, with a particular focus on the effects of helix spacing, number of helices, soil compaction, and loading type. Employing a large-scale frustum-confining vessel (AUT-FCV) to accurately simulate in-situ stress conditions, the behavior of single- and double-helix piles was analyzed in medium- and low-density sandy soils. The findings revealed that soil compaction significantly enhanced pile performance, with medium-dense soils markedly increasing both the compressive and tensile capacities. Optimal performance was observed in double-helix piles with a helix spacing of 1.5 times the diameter, which demonstrated an improved load-bearing capacity and reduced displacement. Notably, in well-compacted soils, the tensile bearing capacity approached or equaled the compressive capacity, underscoring the suitability of helical piles for uplift-resisting applications in such conditions. These results contribute to the advancement of more effective design methodologies for helical pile foundations in sandy soils, particularly in coastal and urban geotechnical contexts.

Graphical Abstract

Evaluation of Key Parameters Affecting the Bearing Capacity of Helical Piles

Highlights

  • Investigates the effects of helix spacing, number of helices, and soil compaction on bearing capacity.
  • Uses the large-scale AUT-FCV device for testing helical piles under compressive and tensile loads.
  • Finds that medium soil compaction improves bearing capacity by up to 320% under tensile loading.
  • Identifies optimal helix spacing of 1.5 times the helix diameter for maximum bearing capacity.
  • Demonstrates that helical piles exhibit significant tensile capacity, reaching up to 99% of their compressive capacity.

Keywords

Main Subjects

References

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History

  • Receive Date: 14 April 2025
  • Revise Date: 10 August 2025
  • Accept Date: 17 August 2025

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