The effect of model scale, acceleration history, and soil condition on closed-ended pipe pile response under coupled static-dynamic loads

This paper analyzes the effect of scaling-up model and acceleration history on seismic response of closed-ended pipe pile using a finite element modeling approach and the findings of 1g shaking table tests of a pile embedded in dry and saturated soils. A number of scaling laws were used to create the numerical modeling according to the data obtained from 1g shake table tests performed in the laboratory. The current study found that the behaviors of the scaled models, in general have similar trends. From numerical modeling on both the dry and saturated sands, the normalized lateral displacement, bending moment, and vertical displacement of piles with scale factors of 2 and 35 are less than those of the pile with a scale factor of 1 and the shaking table test. In general, the pile deformation factor was higher in saturated sand models than the dry sand models. Liquefaction ratios were increased by increasing the seismic intensity; hence the maximum liquefaction ratio was observed with the model of scale 1 under the effect of the Kobe earthquake (0.82g). In another full-scale model, the liquefaction ratio decreased significantly; i.e., it was decreased from 1.64% (λ=1) to 1.04% (λ=35) in the same mentioned model. Pile frictional resistance was numerically investigated and the overall results were compared with previous studies in the literature. In general, the frictional resistance at the pile tip was slightly higher than the frictional resistance around the pile body, and the frictional resistance factor on the ground surface of dry soil models was slightly higher than those of saturated soil models.