Dynamic Problem for the Deformation of Saturated Soil in the Vicinity of a Vibrating Pile Toe
A numerical study conducted recently by the authors showed that the vibration of a pile in saturated granular soil leads to the formation of a zone with nearly zero effective stresses (liquefaction zone) around the pile toe. The dynamic problem was solved with the finite-element program Abaqus/Standard using a hypoplasticity model for soil with the assumption of zero soil permeability and without a mass force. A question which still remained open was the influence of the soil permeability and the gravity force on the solutions. In the present study, the problem is solved with nonzero permeability and gravity, and the solutions are compared with those obtained earlier. For this purpose, a user-defined element has been constructed in Abaqus to enable the dynamic analysis of a two-phase medium with nonzero permeability. The solutions show that high permeability and gravity do not prevent the formation of a liquefaction zone around the pile toe in spite of the fact that a build-up of the pore pressure is inhibited by the pore pressure dissipation.