Evaluation of High Capacity Helical Piles in Silty-Clay Soil

Helical piles have been extensively used as a deep foundation system for small to large load ranges and are thus suitable for various applications. Therefore, a concern over qualifying and quantifying their axial bearing capacities and performance characteristics seems to be warranted. 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 silty-clay soil, to investigate the behavior of helical piles. Also, the results of the piles load tests were interpreted using six methods presented in literature to predict the ultimate load capacity (Qu) for each pile. 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. According to various limit load methods evaluation, it was concluded that the values for two methods of Chin, Decourt were close to the site values.