Uplift performance of FRP tapered piles in dense sand

Abstract

The influence of taper angle on the uplift performance of FRP tapered piles in dense sand at various embedment ratios is investigated using a large-scale testing facility (pressure chamber). The current study evaluates the uplift performance of tapered piles relative to the uplift performance of straight-sided wall piles. Thirteen pile installations were performed in a pressure chamber using conventional head driving and a novel toe driving technique. Twenty­six uplift load tests were performed at different radial and vertical confining pressures in order to simulate pile segments at different depths. The results of uplift loading tests are presented and discussed. The results showed that the uplift capacity of tapered piles is slightly higher than that of cylindrical piles with similar average diameter and length. The taper effect on the pile uplift performance is evaluated using the uplift taper coefficient. A hyberbolic relationship is established between the uplift load and displacement that can be used to determine the soil stiffness for use in non­linear analysis. A simplified design approach for uplift capacity of tapered piles is discussed and evaluated.