Evaluation of axial performance of tapered piles from centrifuge tests

The performance of tapered piles under axial compressive loading was investigated using centrifuge model tests. Model tapered and cylindrical piles were installed in cohesionless soil and subjected to axial loading. The objectives of this study were to understand the performance characteristics of tapered piles and develop a rational approach for their design. The results of axial compressive loading tests on 12 one-tenth scale model piles with different taper angles in a centrifuge setup are presented and discussed. Six piles were instrumented and six piles were not. The load distribution along the shaft of instrumented piles was measured and the results were compared with an analytical solution in terms of the taper coefficient K-t. The comparison showed a reasonable agreement between K-t values established from the experiments and those obtained from the analytical solution. A simple rational approach was proposed for the design of tapered piles. The proposed approach was used to calculate the bearing capacity of the tested piles, and reasonable agreement with the measured values was obtained. The results of this study suggest that the pile taper should be limited to the top 20-25 pile diameters of the pile length for optimum efficiency.