A finite element benchmark study based on experimental modeling of vibratory pile driving in saturated sand

The present study reports the approach and extensive results of FE back-calculations of model tests on vibratory pile installation in saturated sand. The model tests represent a half model setup with a half-pile driven into the soil body along an observation window. Due to this test setup, the soil displacements in vicinity to the penetrating pile have been successfully evaluated by application of high-frequency image recording and Digital Image Correlation (DIC) techniques. Additionally, an extensive instrumentation has enabled the measurement of pile motion, penetration resistance and pore water pressure during the penetration process. An axisymmetric model which incorporates the pile-oscillator system in contact with the soil has been developed in the FE-software Abaqus/Standard for the simulation of the tests. The dynamic analysis of water-saturated soil is based on a u-p formulation using a user-defined element. A hypoplastic constitutive model with intergranular strain has been selected to describe the mechanical behavior of the soil. The various comparison opportunities establish a comprehensive and quantitative validation benchmark of the numerical calculations. The generally good agreement between the results confirms that the pile installation process can be satisfactory reproduced numerically.