Vertically loaded piles in non-homogeneous media

Analytical methods for the axial responses of piles can be classified under three broad categories of (1) simple but approximate analytical solutions, (2) one-dimensional numerical algorithms, (3) full axisymmetric analyses using boundary or finite element approaches. The first two categories rely on the so-called load transfer approach, with interaction between pile and soil determined by independent springs distributed along the pile shaft and at the pile base. The non-linear spring stiffness is related to the elastic-plastic properties of the actual soil partly by empirically based correlations and partly by theoretical arguments based on simplified models of the pile-soil system. This paper presents new closed-form solutions for the axial response of piles in elastic-plastic, non-homogeneous, media, The solutions fail in the first of the three categories above, and have been verified through extensive parametric studies using more rigorous one-dimensional and continuum analyses. The effect of non-homogeneity and partial slip on the load and displacement profiles along the pile shaft is explored, and comparisons are presented with experimental data. (C) 1997 by John Wiley & Sons, Ltd.