Components of Dynamic Subgrade Reaction on Pile in Saturated Sand

The dynamic lateral subgrade reaction generated on a pile foundation in saturated ground consists of an effective stress component and a pore water pressure component. These components were measured through a shaking table test using a centrifuge facility. The total stress and the pore water pressure acting on the pile surface were measured directly using earth pressure meters and pore pressure meters, respectively. These components were measured on opposing sides of the pile in the direction of shaking. The effective stress was evaluated as the difference between the total stress and the pore water pressure. It was found that the compressive effective stress dominates on the side of a pile where the adjacent soil is under compression. On the other hand, the tensile pore water pressure dominates on the side of a pile where the adjacent soil is under extension.