Volume 9, Issue 1

March 2024

Young Members

Pressure Distribution under Multiloop Screw Pile: A
Numerical Study
Kaung Htet
Bachelor Student, College of Engineering, Science and Environment – Civil Engineering
Newcastle Australia Institute of Higher Education (Singapore)
I am Kaung Htet, from Myanmar. I completed my Diploma in Civil Engineering from theBuilding and Construction Authority Academy (BCAA) Singapore in 2018. Currently, I am a
final year bachelor’s student of Civil Engineering at the Newcastle Australia Institute ofHigher Education (a wholly owned entity of The University of Newcastle, Australia, incollaboration with BCA Academy). I have fulfilled all course requirements and will finish theindustrial attachment shortly. After developing a strong interest in geotechnical engineering
throughout my academic career, I ultimately decided to focus my final year project on
geotechnical engineering under the supervision and guidance of Dr. Adnan Anwar Malik.
As the final year project of my bachelor’s program, I conducted numerical studies on bearing response and pressure
distribution under multiloop single helix screw piles. The finite element code PLAXIS 2D models were generated tosimulate the various piles (straight pile, single helix screw pile and multiloop single helix screw piles) to gain a deeper
comprehension of the load transfer mechanism and pile response under compressive pressures. The created model wasvalidated with published experimental data conducted on a model scale. The pile installation effect was not consideredin experimental and numerical studies so that only the effect of the multiloop helix can be investigated. Toyoura sand wasused in the experiments to develop the model ground, and its mechanical properties are validated in the numerical model.
The linear elastic model was considered for piles, whereas the hardening soil model with small strain was considered forthe soil.

(a)
(b)
(c)
(d)
Figure 1. 3D perspective of various piles and pressure distribution (a) Straight pile, (b) Single helix screw pile, (c)Multiloop single helix screw pile, and (d) Pressure distribution under pile tip based on Ho et al., 2022 study,
https://doi.org/10.1061/(ASCE)GM.1943-5622.0002520
In terms of bearing response, it is observed that the performance of the straight pile is better than that of the screw piles(single/multiloop helix) under similar pile tip diameter. When comparing the bearing response of screw piles, i.e., singleloop and multiloop, no significant difference was observed.
Regarding pressure distribution, the average pressure under the straight pile (Figures 1a, 1d) was uniform. Whereas thepressure distribution under the screw pile (Figures 1b, 1d) was not uniform, i.e., higher under the central shaft than thehelix. When comparing the pressure distribution of screw piles, i.e., single loop and multiloop, multiloop screw pilepressure distribution was closer to the straight pile (Shaft ≈ 1750 kPa; Loop1 ≈ 1550 kPa; Loop2 ≈ 1300kPa), which is amore stable condition concerning helix bending. Further studies are required, especially the inclusion of installation
effects, to fully investigate the effectiveness of multiloop single helix screw piles.
19