Physical modelling for pile performance combined with ground improvement using frustum confining vessel

Abstract

Piles were physically modelled using a frustum confining vessel device made in Amirkabir University of Technology, to examine the effect of density and soil improvement from grouting on piles. Piles scales were ranged from ∼13 to 19. The results of pile tests on Babolsar sand under different compaction (density) states were used to study the effects of soil improvement on pile performance. Increasing the soil–pile interaction by post-grouting of the base and sides of the piles also improved the soil capacity. Post-grouting of the base was applied for bored piles and post-grouting of the side was applied for precast concrete piles. According to the results by soil densification, capacity increase from loose to medium state is more than from medium to dense soils. Bored concrete piles showed a greater increase in bearing capacity than steel piles under compression testing as the capacity reduction factors due to installation were minimised. In tensile tests, the capacity increase of open-ended steel piles is more than that of concrete piles because of more surfaces of soil–pile interaction. Post-grouting increased bored and precast concrete pile performance by enhancing soil–pile interaction and soil densification around the pile.