Effect of Density on Uplift Capacity of Model Piles in Sand

Abstract

For the offshore structure, the pile is subjected not only the compressive force but also thetensile force or uplift force due to the hydrostatic pressure. This research aims to study the effectsof sand density and the soil-pile friction resistant on the uplift capacity of pile in sand. The modelpiles were 19.6 mm in diameter. Sixteen tests on smooth and rough steel piles embedded in densesand (Dr = 80%) and loose sand (Dr = 25%) were carried out. The soil-smooth pile friction angleswere 29.5 ํ and 33.8 ํ in loose and dense sand. In the case of rough pile, the soil-pile friction angleswere 34.0 ํ and 35.8 ํ in loose and dense sand. The ratios of the embedment length diameter (L/d)were 8, 16, 24 and 28. The piles were subjected to pull out load though a double pulley arrangementwith flexible wire. The experiment results indicated that the uplift capacity increased with increasingof the embedment length/diameter ratios. At the small L/d, the uplift capacity has slightly differencebetween smooth and rough pile, but the differences increase rapidly when L/d increase. The upliftcapacity depends on sand density and the soil-pile resistant.