Accurate predictions of displacements for axially and laterally loaded piled foundations is a formidable problem that hasn’t been resolved despite sustained research spanning over a century. Employing “t-z”, “m-θ”, “p-y” and “q-z” curves in the load-transfer method is a straightforward approach which reduces the three-dimensional non-linear problem of pile response to one-dimension, greatly simplifying the analysis. Analytical and semi-analytical formulations to develop these physically motivated models have well-defined assumptions and are easy to implement. However, existing theoretical solutions of this type are limited in number and are generally confined to linear-elasticity, despite the inherent non-linear behaviour of soil materials. Motivated by this gap in knowledge, the focus of this work is on developing novel, non-linear load transfer curves that can be used to predict the response of statically loaded piles in clay under undrained conditions. To this end, (1) an approach that models a horizontal pile/soil slice of infinitesimal thickness (plane-strain model) is employed to develop novel non-linear solutions for the shaft response under vertical, lateral and moment loading. These solutions are further developed to incorporate the following effects: (a) a reduction of stiffness in the soil immediately surrounding a bored pile due to its installation; and (b) the contact behaviour (notably slip) due to the lower strength at the pile/soil interface. (2) After thorough review of existing methods and reformulation into a consistent generalised framework, the similarity approach proposed by Skempton in 1951 for surface footings is extended to derive novel transformation factors using analytical and numerical methods for “t-z”, “m-θ” and “q-z” curves. (3) Novel non-linear solutions for “q-z” curves are developed using cavity expansion and energy minimisation methods. The above novel solutions are compared against available theoretical and numerical solutions or case studies leading to useful conclusions as to their application in practice.
Simplified Solutions for the Non-Linear Analysis of Axially and Laterally Loaded Piles in Clay
Bateman, A. H. (Author). 4 Feb 2025
Student thesis: Doctoral Thesis › Doctor of Philosophy (PhD)