Centrifuge modelling of jacked piles

Pile jacking techniques use static load to install pre-formed displacement piles without the environmental impact of dynamic installation methods. Centrifuge modelling of the pile jacking process has been conducted to quantify the axial response of displacement piles jacked into sand. Software and equipment has been developed to install and load test piles under feedback control. This degree of control is necessary since pile jacking comprises both load and displacement-controlled stages. Both maintained and constant rate of penetration load tests were conducted. These two types of load test provide near-identical results in dry sand, and high repeatability is observed. The lateral COV of penetration resistance is an order of magnitude less than that for typical field test sites. These test conditions, coupled with a flexible control system, allow parametric studies into pile behaviour to be carried out with less ambiguity than at field scale, whilst faithfully replicating the installation process.