ABSTRACT
In this chapter, simplified methods for static and dynamic analysis of pile foundations under axial loads are discussed. Firstly, a number of analytical solutions for Winkler springs and dashpots are briefly reviewed. Secondly, exact and approximate solutions for stiffness of single piles are derived for both homogeneous and inhomogeneous soil profiles using the Winkler model. The approximate solutions are based on energy principles obtained my means of shape functions analogous to those used in finite-element formulations. Thirdly, solutions for grouped piles are derived using the superposition approach of Poulos and Davis. To this end, a family of interaction factors accounting for pile-soil-pile interaction is reviewed. It is shown that soil inhomogeneity and pile-to-pile interaction may have a profound impact on pile head stiffness and ensuing settlement. Results are presented in the form of dimensionless graphs and charts that elucidate critical aspects of the problem, and detailed comparisons with more rigorous numerical continuum solutions are provided. Application examples are presented and discussed.
