Numerical modeling of pile-soil interface and numerical analysis of single pile Q-S curve

For numerical analysis of Q-S curve for a single pile under vertical load,a new kind of axisymetric iso -parametric interface element of zero thickness has been derived by combining the generalized axisymetric iso-paramteric element and the physical assumption of classical Goodman joint element of zero thickness.Research has been exercised for numerical analysis and prediction of Q-S curve of a large-diameter pile as an engineering example,and has also been utilized to study the Q-S curve variation of single pile under different contact conditions.The comparison made with actual Q-S curve and the FEM numerical predicted complete Q-S curve of single pile shows that the numerical resul t obtained by the method proposed is in good agreement with the tested curve and proves the new proposed axisymetric iso-parametric interface element is good,and it also indicates that the value of tangent siffness k s in interface element model could be rationally specified just as what is suggested in this paper although the other important parameter k n the value of normal stiffness needs further study.