Helical anchors, sometimes referred to as screw anchors, screw piles, and helical piles, are a steel screw-in piling and ground anchoring system used for building deep foundations. Screw piles are manufactured using varying sizes of tubular hollow sections for the pile or anchor shaft. This paper presents an innovation of the helical anchor for horizontal drains, a form of subsurface drainage systems for slope protection. To address the adverse effect of groundwater, an expansion of the application of the helical anchor structure in civil engineering is needed, and new drainage solutions are being considered. The features of the helical anchor type for horizontal drainage equipment, analyses of some of its advantages, and conditions of application are presented. Generally, a helical anchor for horizontal drainage is convenient for installation, maintenance, or removal, and is effective for both horizontal drainage and for anchoring the revetment. It is also a typical construction in drainage works, generally performed by a cranking handle or a rotary-percussion-type drilling machine. The helical anchor pipe for horizontal drainage has many segments with joints using a cranking hand for installation and is quite effective where the installation space is narrow or there is no machine. In particular, the installation of this equipment differs significantly from other drilling methods because it can be driven into a sand layer without a hole wall.

1. [1] Okuyama Boring Co. Ltd., “A simplified drilling system Karuwaza Sakkun,” Utility model registration No.3186011, 2019, https://okuyama.co.jp/patent.html#patent—sakkun [accessed February 1, 2021]
2. [2] S. N. Rao and Y. V. S. N. Prasad, “Estimation of Uplift Capacity of Helical Anchors in Clays,” J. of Geotechnical Engineering, Vol.119, No.2, pp. 352-357, 1991.
3. [3] H. V. Hung and T. M. Thu, “The screw anchor of placed block revetments with detailed structure and application to seadike slope protection,” Int. Symp. on Lowland Technology (ISLT 2018), 2018.
4. [4] N. M. Chi, T. M. Thu, and N. Chien, “The plate revetment made from polymer of composite for protection slope of canal,” Int. Symp. on Lowland Technology (ISLT 2018), 2018.
5. [5] H. V. Hung, “Research on structural measures to strengthen for stability of overlap blocks revetment under wave over topping,” Doctoral thesis, Thuyloi University, 2012 (in Vietnamese).
6. [6] H. V. Hung, “The field test for pulling out bearing capacity of screw anchor with application for overlap blocks of revetment seadike,” Vietnam J. of Water Resources and Environmental Engineering, No.43, pp. 48-53, 2013 (in Vietnamese).
7. [7] H. V. Hung, “The installation procedure of screw anchor to strengthen for overlap blocks revetment of seadike,” Vietnam J. of Water Resources and Environmental Engineering, No.47, pp. 58-62, 2014 (in Vietnamese).
8. [8] Brennan, “Helical Piles 101: Strengthening Foundations,” https://www.jfbrennan.com/blog/helical-piles-101-strengthening-foundations [accessed February 1, 2021]
9. [9] K. Forrester, “Subsurface Drainage for Slope Stabilization,” ASCE Press, 2001.