Lateral soil resistance on soldier piles or king posts in clay

Abstract

The undrained ultimate lateral soil resistance pu on soldier piles (king posts) is investigated using three-dimensional finite-element analysis. Ultimate lateral resistance variations with depth are determined for different pile spacings, pile–soil adhesion factors and retained soil heights. Based on the numerical results, simple design equations are developed, which give the variation of the lateral bearing capacity factor Np with depth for soldier piles of different spacings and retained soil heights. The proposed equations are used in limit equilibrium calculations to determine the required pile length plotted against retained soil height curves for two typical soldier pile wall examples, a cantilever and a single-propped wall, examining different pile spacings, pile–soil adhesion factors and undrained soil shear strengths. These curves are compared to those produced using the six most commonly used methods, including two-dimensional finite-element analysis. Three-dimensional finite-element analysis results of the typical soldier pile wall examples are also presented in order to verify the proposed method.