Field Study of Capacity Helical Piles in Sand and Silty Clay

Abstract

Helical piles have been increasingly used as a deep foundation system for small to large load ranges. They are suitable for various applications, including residential housing, solar farms, utilities, retrofitting projects, power transmission lines, oil facilities, and industrial applications. Hence, many researches have been conducted recently on qualifying and quantifying axial capacities and performance characteristics of helical piles. This paper discusses design considerations, installation procedures, and results of full-scale field load tests. In this study, axial static loading tests on single, double, and triple helix helical piles under grouted and un-grouted conditions have been conducted. The field study has been performed on two different soil types including sand and silty clay soil to investigate the behavior of helical piles. Results showed that in the silty clay soil, grouted and un-grouted helical piles had a similar performance while grouted piles showed greater axial compressive strength. In the sandy soil, cylindrical performance in helical piles was not satisfactory and in triple-helix piles, the axial compressive strength was less than that of double-helix piles even though the number of helixes has been increased.