Experimental Study on Configuration and Spacing of Screw Pile Group Effect Subjected to Lateral Cyclic Loading

Azhar S Ibrahim,Hassan O Abbas,Omar K Ali,M Karkush,D Choudhury,M Fattah

doi:10.1051/e3sconf/202131801004

Abstract

Despite the great development in the manufacture of the helical pile and the development of their use, especially in transmission towers and wind turbines, there is little research on their lateral behavior. In this laboratory study investigate the behavior of screw piles group (2×1) and (1×2) with the spacing to the diameter of helix ratio (S/Dh =1.5, 3, and 4.5) having a diameter (10 mm) and embedded length to diameter ratio (L/D = 40) by using single and double helix embedded in soft clay and extend to stiff clay under a cyclic lateral load of frequency (0.2 Hz). The results showed that increasing the distance between the piles had a great effect on increasing the lateral resistance. the increase of pile spacing in the groups from (1.5 Dh) to (3 and 4.5 Dh) increases the lateral resistance about 34-38% and 50% respectively. Also, from result showed that the group (2×1) gave a lateral resistance more than the group (1×2) about 11% for single helix and about 6% for a double helix, and for the same spacing and configuration the screw pile with double helix gives an increase in lateral resistance about 5-10 % from the single helix.

Highlights

Screw piles or helical piles are deep foundation elements used to resist forces exerted by tension, axial compression, and lateral loading [1]
The soil model was chosen for this study to represent the soil of southern Iraq relatively, especially Basra, whose soil is mostly composed of soft clay extending into stiff clay [16, 24]
The load-deflection curve for screw piles group model (1×2) and (2×1) under cyclic lateral load with three spacing (1.5, 3, and 4.5) Dh at 100 number of cyclic are shown in Fig. 4 and 5

Summary

Introduction

Screw piles or helical piles are deep foundation elements used to resist forces exerted by tension, axial compression, and lateral loading [1]. Screw piles consist of one or more circular helical plates (or flanges) welded onto a solid steel shaft or hollow [2]. Screw piles are installing into the soil by applying a torque at the head of the shaft of the pile, which produce penetrate the helix or helices to the ground in circular motion [3]. During the past few years, great progress has been made in installing and increasing the axial capabilities of helical piles. Using helical piles with axial capacities over 3MN, the availability of high torque rotary heads has made it easier to install screw piles of large diameter in competent soils such as very stiff clay and very dense sand. Helical piles of diameters more than 508 mm have been successfully installed into hard soils [4]

Methods

Results

Conclusion