Influence of Loading Angle on Pullout Behavior of Helical Pile

This paper presents experimental and numerical analysis conducted under inclined loading for three helical piles with distinct helix diameters of 45 mm, 60 mm, and 90 mm and a shaft of 30 mm in air-dried cohesionless soil. The experimental program was conducted on piles subjected to inclined loading at 0°, 30°, 45°, 60°, and 90° with respect to the vertical and installed into medium-dense (relative density = 60%) sand. The load–displacement characteristics observed in the experimental model study were compared with those derived from numerical analysis employing three-dimensional finite element software, PLAXIS 3D. The pile lateral displacement throughout the depth and contact pressure on helices and pile shaft were analyzed in numerical analysis. The investigation shows that the arrangement of helices with different diameters plays an important role in the ultimate pullout capacity. The bottom helical plate plays a significant role in resisting inclined pullout load. The significance of the middle helix plate was observed to be relatively diminished under 60° and 90° load inclination. The pullout capacity of the helical pile under inclined loading significantly decreased as the angle of load inclination (from vertical) increased up to 60°. Under 90° loading conditions, the influence of the helix arrangement on pile behavior is minimal.