Horizontal Resistance Characteristics of Batter-Coupled Spiral Piles under Monotonic and Cyclic Loading

Abstract

Spiral piles have high axial resistance and are used as foundations for small structures. On the other hand, spiral piles
have a lower bending rigidity than steel pipe piles of the same diameter, resulting in a problem of lower horizontal resistance.
The authors have focused on a two-pile coupled pile structure with spiral piles, which is also resistant to horizontal forces, and
have conducted research to understand its resistance characteristics. In this study, model tests were mainly
conducted on coupled piles with two spiral piles as batter piles to understand their horizontal resistance characteristics.
Monotonic loading tests on a dense dry sand showed that the use of spiral piles as batter piles provided higher elastic limit
spring rigidity and horizontal yield load than single piles or vertically-coupled piles. Furthermore, the highest elastic limit
spring rigidity was obtained when the angle of inclination of the batter pile was 45°. The durability of the batter piles under the
sand conditions of this study was demonstrated by cyclic loading tests at a load equivalent to the horizontal yield load.