Hydro-Mechanically Coupled Numerical Modelling on Vibratory Open-Ended Pile Driving in Saturated Sand

Vibratory pile diving with resonance-free technique is an advanced construction approach that can play an important part in underground engineering. This paper aims to propose a numerical model for this construction approach, which commonly involves soils below the groundwater table. Such simulations are still challenging tasks as dynamic analyses considering hydro-mechanical interactions are very complicated. Several simulations have been performed by constructing a user-defined element in the finite element code ABAQUS or developing an inhouse finite-element program for this issue. These simulations have some limitations and pay less attention to open-ended piles. This paper presents a way to simulate the vibratory open-ended pile driving in saturated sand using the finite difference code FLAC3D. The model computation efficiency is increased around 67 times by the density scaling method and this method has little effect on the numerical stability. The proposed model can generally replicate the pore pressure results of a model test. The maximum excess pore pressures are predicted with a percent error of 2–22%, and these maximums occur near the pile toe. The excess pore pressure of an observation point slowly decreases after the pile toe passes the point. This work could provide an efficient and effective method for simulating vibratory open-ended pile driving in saturated sand.