Experimental studies on the behavior of a single shaped pile under oblique pullout loads

Shaped piles are widely used as the foundation of power transmission towers and photovoltaic panels because of its high bearing capacity and material utilization. In this paper, two shaped piles as well as one traditional circular pile with a length of approximately 2.0 m and a length-to-diameter ratio of approximately 17.7 were produced with the same volume of the reinforced concrete. The vertical compressive load capacities are firstly presented to verify the superiority of the shaped pile. Then, 1- g large-scale model experiments were carried out to investigate the behaviors of a single shaped pile and a referenced circular pile in sand under oblique pullout loads at angles of θ = 30°, 45°, and 60°, as well as the pure lateral loads ( θ = 90°) and vertical pullout loads ( θ = 0°). The load–displacement responses and earth pressure distributions were measured, and the inclinations of the load and the pile top movement at each step were also observed. The ultimate resistances of the shaped piles under oblique pullout loads and the earth pressure distributions with depth under ultimate lateral loads were analyzed, and the differences from traditional circular pile were discussed. Test results show that the oblique pullout ultimate resistance of a single shaped pile is relatively higher than that of a traditional circular pile of the same material. The ultimate bearing capacities of the shaped pile are approximately 1.2–1.7 times as large as that of the reference pile.