Effect of Pile Pitch Variation on the Uplift Capacity Using UTM Apparatus

Document Type : Research Article

Authors

1 Faculty of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran

2 Assistant Professr, Faculty of Civil Eng., Shahid Rajaee Teacher Training University, Tehran, Iran.

Abstract

Using helical piles to reinforce the soil is of little cost and time. The purpose of this paper is to investigate the effects of utilizing helical piles on performance improvement in the uplift capacity and displacement. For this purpose, laboratory specimens of simple and helical piles with the pitch of 13, 20, and 25 mm were investigated. Shahriar sand was used with a relative density of 70% and the compression operation has been performed using hammering. The universal Zwick/Roell Z150 apparatus was employed for tensile. The physical modeling of the helical pile was carried out using dimensional analysis and non-dimensionalization by the Buckingham π  theorem. The results showed that the maximum uplift capacity of helical piles with the pitch of 13, 20, and 25 mm in comparison with the simple pile increased 453.57%, 518.66%, and 436.24%, respectively. When the ratio of the pitch/central shaft diameter is between 1 and 1.5, the tensile capacity was improved by the generated friction and the weight of sand on the blade as a resisting factor. By increasing the ratio of pile pitch to pile diameter to 1.92, the blade torsional angle increased and the sand weight on the blades decreased. Therefore, the uplift capacity was reduced compared to the previous two. The outputs showed that the displacements of the helical piles with different pitch-to-diameter ratios are approximately equal.

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References

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Amirkabir Journal of Civil Engineering
Volume 53, Issue 5
August 2021
Pages 1871-1888

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