Single Helix Screw Pile Behavior Under Compressive Loading/Unloading Cycles in Dense Sand

The application of screw pile is increasing in recent times due to its performance under compressive, tensile and lateral loading conditions. However, its performance under repeated loading cycles has not been extensively investigated. As in most cases, piles are under repeated loading/unloading cycles throughout the structure life. Therefore, its performance should be thoroughly examined. In this regard, the present study focuses on the performance of a single helix screw pile under compressive one-way loading/unloading cycles in dense ground conditions. Pile load test in model scale conducted in this study. The model ground prepared in the steel container at 80% of relative density. Pile load tests were conducted under monotonic loading and one-way loading/unloading cycles. An empirical relationship is drawn based on the investigated load distribution under the helix. The test results indicated that the central shaft load below the helix increases with the increase in helix diameter. The ultimate bearing resistance of screw pile decreased by 10.8% under one-way compressive loading/unloading cycles. The test results also indicated that the effect of helix bending deformation was quite high on the screw pile performance (under one-way compressive loading/unloading cycles) as it reduced the ultimate resistance of screw pile by 41.5% if compared with the non-deformed screw pile (monotonic loading). Performance comparison of screw pile and straight shaft pile having a similar tip diameter under one-way compressive loading/unloading cycles is also presented in this study.