The Recycling Torque of a Single-Plate Helical Pile for Offshore Wind Turbines in Dense Sand

Ding Ding,Qi Qi,Tian Tian,Liang Liang,Wang Wang,Zhang Zhang

doi:10.3390/app9194105

Abstract

The helical piles have been being treated as a kind of novel foundation for offshore wind turbines recently, due their fast installation, high uplift capacity, convenience for recycling, and other advantages. The recycling of the helical pile especially will reduce the cost significantly and protect the environment as much as possible. However, the research for this area is basically in infancy and there is no reference for predicting the recycling torque of a helical pile in sand. In order to predict the recycling torque of single-plate helical piles in dense sand: a theoretical model, which was inspired by the way to predict the installation torque of single-plate helical pile in sand, was developed, and a series of single gravity model tests were conducted to verify that theoretical model. The theoretical model can predict the recycling torque of single-plate helical pile considering the influences of the size of helix and the vertical force on the shaft. This model fills in the blank of predicting the recycling torque of a single-plate helical pile in sand and it is also useful guidance for the choice of suitable recycling equipment.

Highlights

Helical piles have been used as the foundations of offshore structures over 100 years [1] to resist tension and compression
The test results consist of three parts: (i) the test results about the recycling process of single-plate helical pile in dense sand under different outer diameters of helix, DH-out = 0.12 m, 0.16 m, and 0.20 m; (ii) the test results about the recycling process of a single-plate helical pile in dense sand under different recycling speeds, vR = 1 p/r, 0.8 p/r, and 0.5 p/r; and (iii) the test results about the recycling process of a single-plate helical pile in dense sand under different pitches of helix, p = 0.03 m, 0.06 m, 0.10 m, and 0.16 m
The test results about the recycling torque (TR ) of a single-plate helical pile; the embedment depth (z) responses of single-plate helical piles; the vertical force on the central shaft (Fpush ) of a single-plate helical pile; and the embedment depth (z) responses of single-plate helical piles with same size of the pitch of helix, p = 0.03 m, different outer diameters of helixes, DH-out

Summary

Introduction

Helical piles have been used as the foundations of offshore structures over 100 years [1] to resist tension and compression. Helical piles have been employed extensively to support both tensile and compressive forces in telecommunication towers, energy transmission, distribution lines, solar panels, and onshore wind turbine foundations.

Objectives

Methods

Results

Conclusion