The plugging behaviour of driven and jacked piles in sand

Abstract

A series of model pile tests have been performed in the geotechnical centrifuge at the University of Western Australia to study the plugging behaviour of piles in sand. Open and sleeve-ended piles have been driven and jacked by a miniature pile driving actuator into silica flour of varying densities. The progression of the soil column has been measured during installation and static loading. It was found that the plug length increased with increasing relative density during driving and decreased with increasing relative density during jacking. During installation, the jacked piles exhibited a greater tendency to plug than the driven piles. Piles fitted with an internal driving shoe provided significant stress relief within the soil plug during jacking, leading to longer plug lengths compared with internally flush piles. All static load tests at high embedments behaved in a completely plugged manner. An analysis of the plug capacity is conducted and a model for the variation of the earth pressure coefficient inside the pile is proposed. Differential base pressure on the pile annulus and the internal soil plug is postulated and validated by means of the experimental data.