Single Helix Screw Pile Behavior Under Compressive Loading/Unloading Cycles in Dense Sand
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ORIGINAL PAPER
Single Helix Screw Pile Behavior Under Compressive Loading/Unloading Cycles in Dense Sand Adnan Anwar Malik
. Jiro Kuwano
Received: 29 December 2019 / Accepted: 21 May 2020 Springer Nature Switzerland AG 2020
Abstract 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 oneway compressive loading/unloading cycles) as it reduced the ultimate resistance of screw pile by A. A. Malik (&) J. Kuwano Department of Civil and Environmental Engineering, Saitama University, Saitama, Japan e-mail: [email protected]
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. Keywords Screw pile Single helix Compressive one-way loading/unloading cycles Dense sand
1 Introduction The screw pile is not a new technology in the field of deep foundations. Its history is quite old, but its application tremendously increased in recent years due to the advancement in the heavy machinery. Moreover, its sustainability and eco-friendly installation procedure further enhance usability. The high performance of screw pile under axial compression, axial tension, overturning moment and lateral force widened its application (Mittal et al. 2010). It consists of a circular or square shaft with one or more helices attached to the shaft (Li and Deng 2019). The attached helices are generally 2 to 2.5 times the shaft diameter which is the main reason for its high performance. These piles installed by pressing and rotation. Its installation procedure may affect the in situ density of the ground. The effect of pile installation on ground density is less in cohesive soils, but in the sand, the
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