A simplified analytical model for developing “t-z” curves for axially loaded piles

Pile settlement estimation can be simplified using one-dimensional “t-z” curves to describe the relationship between shear stress and settlement at the pile-soil interface at a specific depth. This simplifies the two-dimensional continuum problem to that of a one-dimensional rod. Some analytical “t-z” curves are available in literature; however, to employ these solutions a suitable soil constitutive model, expressed in a flexibility form γ = γ(τ), must be chosen. This must be carefully calibrated against laboratory test data to accurately represent soil behaviour. This paper explores an alternative approach for piles in clay employing a direct similarity-based relationship between a shear stress-strain curve and a “t-z” curve. A linear-transformation factor is derived which can be applied to a representative soil test directly from the site to produce a “t-z” curve, thus removing the need to calibrate/integrate a suitable soil constitutive model. Suitable values for this factor have been obtained through comparison with existing analytical “t-z” curves.