Recent advances in the design of axially-loaded piles in sandy soils

The research performed in the last decade at Purdue University on the vertical load response and design of piles (particularly drilled shafts and pipe piles) is reviewed. Both numerical and experimental investigations were performed, and values for unit base and shaft resistance normalized with respect to cone resistance are proposed for design. The study takes into account the loading processes associated with the pile installation, and the corresponding alteration of soil properties that affect the pile response. The normalized unit resistances are provided for a relative settlement of 10%, which is widely used as a design criterion. A strong dependence of the normalized unit resistances on relative density has been observed and the suggested values account for the effect. Thus, the proposed normalized unit resistances account for the soil state and the loading processes, and can be used in design. Results with respect to IFR and PLR are provided as well, for open-ended piles.