Strategies for numerical simulation of cast-in-place piles under axial loading

Pile foundations are constructed using a variety of installation methods, which can significantly influence their behavior under axial loading. In this study, numerical simulations of a bored pile, a full-displacement pile and a full-displacement pile with attached expander body have been carried out using standard finite-element analysis where constitutive model parameters are estimated based on various geotechnical field measurements. Considering variations of in situ test measurements, conservative, best estimate and optimistic sets of the calibrated model parameters have been used for the subsurface soil. In order to capture the effect of pile installation method, different numerical strategies have been examined and their applicability to each of the installation methods evaluated. By studying the load-movement response and load distributions along the pile under head-down loading tests, results of the numerical simulations have been evaluated and compared to those obtained from a monitored field study. Finally, local and global sensitivity analyses, as well as a parameter identification procedure have been, respectively, used to find out the most contributing model parameters and to improve model predictions. Results of the numerical simulations signify the importance of a verified staged procedure for modeling the bored and full-displacement piles, as well as the expander body to best capture the pile bearing capacity and load-movement behavior. Furthermore, the parametric study undertaken reveals that acceptable predictions can only be achieved if the most contributing model parameters are identified and calibrated adequately.