Numerical Study on Behavior of Unreinforced and Reinforced Disconnected Piled Raft Foundation-Paper

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This study used PLAXIS 3D finite-element analysis to examine unreinforced and geogrid/geocell-reinforced disconnected piled raft foundations under vertical loading. In these systems, a granular cushion separates the raft from the piles. The analyses varied cushion thickness (0–1 m), pile stiffness, and reinforcement, and assessed settlement, load sharing, and pile forces.<br /><br />Increasing cushion thickness generally reduced settlement beneath the middle pile and across the raft. Pile stiffness also influenced foundation response: the reported results indicate that changing stiffness affected raft and pile settlements and altered axial-load distribution along the piles. Cushion thickness, by contrast, had little effect on axial load sharing along a pile.<br /><br />Adding reinforcement stiffened the cushion and changed the settlement response; the study reports increased settlement beneath the pile and along the raft in the analyzed reinforced case. Reinforcement also slightly increased axial load at the pile head, while axial load decreased slightly down the pile.<br /><br />Overall, the findings suggest that cushion thickness, pile stiffness, and reinforcement can be used to adjust settlement and load transfer in disconnected piled raft foundations. The authors emphasize that these conclusions come from a preliminary numerical study using simplified loading and interface assumptions.

Keywords

PLAXIS 3D

finite element analysis

disconnected piled raft foundation

geogrid reinforcement

geocell reinforcement

granular cushion

vertical loading

pile stiffness

settlement analysis

load sharing