| Vibratory pile driving was investigated through a large-scale experimental model study, whose results were numerically verified by a 3-dimensional finite element analysis (FEA). Drivability of 100-mm-diameter open-ended, closed-ended pipe piles, and 50-mm and 100-mm H piles were studied in a large-scale pressure chamber. The piles were driven into layered and uniform sand deposits under dry and saturated conditions. The effects of saturated or dry sand, pile size, confining pressure, bias weight, unbalanced moment, and redrive on the drivability of piles were investigated parametrically. Tests were performed under confining pressures of 69 and 138 kPa, and the driving frequencies varied from 25 to 35 Hz. A total of 30 tests was performed in homogeneous and layered soils.; The driving was most difficult in a dense layer of blasting sand with a relative density of 90%, but the piles exhibited an increased static bearing capacity in such material. H piles were installed faster than the pipe piles under similar sand and vibrator conditions. The open-ended pipe pile plugged during driving in dry sand but did not plug during continuous driving in the medium-dense saturated sand.; The pore pressure that developed near the pile shaft during driving was significantly higher than that measured in the far-field and was closely related to the rate of penetration, Vp, of the piles. Using a finite element analysis, it was shown that the pore pressure increased (1) with the increase in Vp, and (2) with the decrease in sand permeability below 1.02 mm/sec. The maximum pore pressure was observed beneath the pile toe and sometimes was larger than the effective confining pressure, indicating the possibility of local sand liquefaction.; Static capacity in compression was the highest for the closed-ended pipe pile, followed by the open-ended pipe pile, and the H piles. However, uplift capacity for the open-ended pipe pile was the highest. Finite element analyses indicated that the confining pressure was the most important factor on the static behavior of vibro-driven piles. A static method, considering various soil, pile shape, and installation factors is proposed to predict the static capacity of vibro-driven piles with a good agreement. |
