Modelling the inflight construction of sand compaction piles in the centrifuge

Sand compaction piles are used in practice for ground improvement of weak subsoil. These columnar inclusions improve the consolidation behaviour as well as reduce the compressibility of the soft ground. The current design procedure of these sand piles is based on simple empirical calculations, which does not fully take account of the sand pile behaviour. In order to gain a deeper understanding of the behaviour of sand compaction piles, physical and numerical investigations are being conducted. The basic system behaviour of soft soil and column is simulated physically by centrifuge modelling. Because the stress situation in the soil changes significantly due to installation, a sand compaction pile installation tool was developed and applied successfully in the first tests. This allowed the stress paths encountered by the soil during the construction process of a displacement sand pile to be modelled realistically. The results will be compared to real geometries and the behaviour is also studied numerically by means of finite element modelling. These findings provide the basis for further analysis of this geotechnical interaction problem extending the model by including geotextiles below embankments to be able to formulate some recommendations for the design procedure of sand compaction piles under embankments.