Numerical and centrifugal physical modelling on soft clay improved with floating and fixed sand compaction piles

Abstract

A comparative study on floating and fixed sand compaction piles (SCPs) subjected to embankment loading are performed by centrifuge physical modelling and numerical analysis. In the numerical analysis, the settlement and pore water pressure behaviours are studied using a soil-water coupled finite element method with an elasto-plastic constitutive model. The constitutive model has the capability to predict the mechanical behaviour of both soft clay and sand under different loading and drainage conditions with individual sets of soil parameters. The centrifuge modelling results under embankment loading and long-term consolidation stages show more settlement in clay improved with floating SCPs than the fixed SCPs. The numerical analysis results depict the outcomes of the centrifuge modelling at different stages and also reveal the settlement mechanism. The settlement and pore water pressure from numerical analysis of composite soil for both cases are consistent with the experimental outcomes. In addition, an alternate fixed and floating SCPs combination is analysed which reveals less settlement compared to an alternate floating SCPs combination under embankment loading and long-term consolidation. This study helps to understand the SCPs behaviour to be used for ground improvement in soft clay. Overall, this numerical approach contributes to the economical design of SCPs improved soft clay under various loading and consolidation conditions.