Numerical Investigation of the Frequency Influence on Soil Characteristics During Vibratory Driving of Tubular Piles

In offshore geotechnics, tubular piles are commonly used as the foundation system. Such piles are installed using vibratory or impact driving. The choice of the proper loading configuration plays an important role in the driving performance, especially in reaching the desired penetration depth. Numerical evaluation of such processes involves handling large material deformation, making it hard for the classical numerical methods to reach a reliable result after significant deformation. In addition, in case of the dynamic cyclic loading, the soil exhibits complex behavior which emphasizes the role of a suitable soil constitutive equation. In this study, a numerical model is developed and utilized to evaluate the effects of the frequency in the vibratory installation of tubular piles on the neighboring soil. The numerical model employs the robust Multi-Material Arbitrary Lagrangian-Eulerian (MMALE) method in conjunction with an advanced material model formulation based on the hypoplasticity concept, and is validated against an experiment done at TU Berlin. Subsequently, a parametric study is performed by applying six different frequencies between 12 and 30 Hz to the dynamic load. The resulting penetration depth, void ratio and the lateral stress distribution in the soil are compared and evaluated. It is concluded that an optimum frequency must be determined to reach the maximum penetration depth by using the same load magnitudes