Numerical modeling of pile installation in clay.

Penetration of prefabricated piles in saturated clay leads to significant alterations in stress state of the surrounding soil during and after the pile installation. Generation of excess pore water pressure (EPWP), its dissipation and the stress state variations result in important changes in pile capacity. Increasing pile bearing capacity over time that is known as “soil setup” is of great importance in engineering practice. Various parameters such as type of pile, pile diameter and behavioral properties of the soil can affect rate of bearing capacity variations with time which is called “setup ratio”. In this study, effects of pile diameter and Over Consolidation Ratio (OCR) on variations of stress state in the soil and pile bearing capacity are evaluated.
A numerical finite element model (FEM) has been used to simulate a pile penetration in saturated clay and subsequent pore water pressure dissipation. Reasonable agreements between the numerical analysis results and laboratory tests and field data are indications of the reliability of the numerical results.
Based on the results, a series of equations have been extracted for determination of “coefficient of lateral soil pressure” at two different times (end of penetration and end of consolidation) and “setup ratio”.