A Comparative Study on the End-Bearing Capacity of Toe-Wing & Spiral Screw Piles in Cohesionless Soil

The use of screw piles has grown rapidly, yet their varied configurations and behavior in different soils remain key research areas. This study examines the performance of Toe-wing (Tsubasa) and Spiral screw piles with similar tip areas under similar ground conditions, focusing on how the helix position (Wp) and tip embedment depth (Ed) affect the ultimate pile capacity. In the case of a fixed helix/toe-wing position with increasing pile tip depth, Spiral screw piles exhibited higher load-carrying resistance than toe-wing piles at relative densities of 55%, 80%, and 90% fine sand. Moreover, load-carrying resistance increased as the position of the helix/toe-wing increased (Wp > 0). For a fixed pile tip depth (Ed) and varying helix/toe-wing positions, spiral screw piles showed higher resistance than toe-wing piles when Wp < 90 mm. Moreover, the resistance decreased as the helix moved away (Wp/Dh > 0), and the pile tip acted independently when Wp/Dh > 1.38. Whereas, for toe-wing piles, ultimate pile capacity increased as the toe-wing moved away from the tip up to Wp/Dh = 2.15, then decreased to reflect the independent behavior of the toe-wing and pile tip. Empirical equations are presented to convert installation effort and ultimate capacity from one type to another.