Centrifuge and numerical modeling of geometrical effects on XCC piled rafts

Abstract

The geometry of a pile can improve the bearing capacity by changing the load transfer mechanism, such as that of X-section cast-in-place concrete piles (XCC piles). Although the geometrical effects of a single pile and pile group are investigated, the geometrical effects on piled rafts are rarely understood. This paper investigates the geometrical effects on single piles and embedded piled rafts by centrifuge tests and numerical simulations, and non-embedded piled rafts by numerical simulations. The performances of circular single piles, non-embedded and embedded circular piled rafts are included for references. The geometrical effects alter the pile-soil interaction by changing the effective normal stress acting on the pile shaft, causing nonuniform skin friction and considerable side resistance. Compared with that of the circular pile, the advantages of the XCC single pile are mainly contributed by the pile perimeter and weakened by the pile geometry; the advantages of the non-embedded XCC piled raft are mainly determined by the pile perimeter and geometrical effects, which eliminate the group effects; the advantages of the embedded XCC piled raft are mainly contributed by the pile perimeter and geometrical effects, which weaken the group effects and stress concentration and enhance the load sharing on the piles. It is concluded that XCC piles are superior in shaft resistance, especially when used in embedded piled rafts.