THE COMPRESSION AND UPLIFT BEARING CAPACITIES OF HELICAL PILES IN COHESIONLESS SOIL

Abstract

Helical piles have been used widely in engineering application .They can be used to provide structural stability against axial compression ,uplift and lateral forces. . In recent years, helical pile foundations have become more widely used in many countries. There are few studies about helical piles, for this reason the aim of the present paper is to study how to improve the prevision of the compression and uplift capacities of helical piles, and study the effect of embedded depth and helical area of helical piles in sand soil on the compression and uplift bearing capacities. Studies of helical piles with different areas of helices provided are in continuation. Compression and uplift loads were applied at different height within the soil. The embedment length of screw anchor piles was also varied to study the behavior of helical piles under compression and uplift loads. Various size and numbers of helices have been used in the laboratory tests with diameters 5 ,6.7 , 8.2 and 10cm with varying lengths. The embedment ratios for each ,D/d are 1 ,2 ,3 ,4 ,5 ,6 and 7 . An experimental setup instrumented to allow the measurement of the compression and pullout loads which affect on the helical pile installed into prepared layers of sand until failure. The results show that the compression and pullout resistance of helical anchors is strongly affected by the area and composition of helical plates welded to the pile steel shaft . The compression and uplift loads are increased with increasing of the embedment ratios, D /d and helix diameter, d. In addition to some other useful results are indicated in this paper.