Model study of single pile with wings under uplift loads

Abstract

Several structures as in the case of offshore structures like jetty, flood wall and wind turbines are mostly subjected to uplift loads. Thereby, the safe design for such cases is using piles. In this research a novel recent technique is adopted to improve the uplift capacity of the pile. In this paper, the uplift capacities of single regular piles (without wings) and anchor winged vertical piles installed in dry sand with different densities are investigated. A total number of sixty experimental model single regular and anchor winged piles tests were performed. Model test series were performed at a fixed embedment depth, and pile diameter. The effect of wings which were designed at the tip of the pile at different values of length and diameter was studied. The test results demonstrated that the uplift capacity of anchor winged piles increases with the increase of sand relative densities. At the ratio of wing length to pile length (Lw/Lp) = 0.50 and at the ratio of the maximum diameter between the outer edges of the wing to pile diameter (Dw/Dp) = 3.0 the efficiency of improvement in the uplift capacity reached to 2.0, 2.38 and 2.77 times of regular piles without wings at sand relative densities of 30 %, 50 % and 80 % respectively. The presence of such wings at the tip of the mono-pile provided an ideal anchorage system because of the significant locking-up influence of the wings within the soils, ensuing improved uplift capacity and reduced the pile movement. The existence of such wings can significantly increase the earth pressure and skin friction around the pile shaft in the form of (K) and (Fs) respectively.