Long-term setup of a displacement pile in clay: An analytical framework

This paper integrates the effects of pile installation, reconsolidation, pile loading and soil ageing into an analytical framework to predict the long-term setup of a displacement pile in clay. The increase of mean effective stress and the decrease of void ratio of surrounding clay during reconsolidation and soil ageing are determined to quantify the changes in undrained shear strength and shear modulus, which are the two key soil parameters controlling load carrying behaviours of piles. The bearing capacity factors and load-transfer curves are developed by incorporating the developed soil parameters. The analytical framework is then proposed and validated by predicting a well-documented pile field test. Good agreements between the analytical results and the measured data demonstrate that the pile setup can be reasonably predicted by the proposed framework. Comprehensive parametric studies are conducted to investigate the influences of overconsolidation ratio, secondary compression index and pile loading on the pile setup. The results indicate that a displacement pile in clay with a smaller overconsolidation ratio or a larger secondary compression index, or subjected to a larger load, exhibits a larger long-term bearing capacity. •An analytical framework is proposed for assessing the long-term setup of displacement piles in clay.•Undrained shear strength and shear modulus are incorporated into bearing capacity factors and load-transfer curves.•Secondary compression index, OCR and magnitude of pile loading significantly affect long-term setup of displacement piles.•The proposed framework is expected to provide significant guidance for reusing existing displacement piles in practice.