THE EFFECT OF GROUND SETTLEMENTS ON THE AXIAL RESPONSE OF PILES: SOME CLOSED FORM SOLUTIONS

Simple closed form expressions are presented for the problem of ground settlement effect on the axial response of a vertical pile. The solutions are based on Winkler model, and allow evaluation of soil-pile interaction under a variety of green field ground settlement profile. An example on soil-pile interaction subject to tunnel induced ground settlements is given to demonstrate the use of the proposed solutions. The solutions presented in this note are for a pile in homogenous soil. Vertical ground movements may result from numerous sources (e.g. tunnelling induced ground deformation, heave by excavation, consolidation settlement, etc.). Each of these problems is associated with a particular profile of ground settlements and a specific solution may be found. For example, Poulos and Davis (1980) derived a continuum elastic solution for the case of soil settlement that decreases linearly with depth. Loganathan et al. (2001) proposed a solution for piles behaviour due to tunnelling induced ground deformation using boundary element analysis. Although these solutions are very valuable, they are associated with a specific ground settlement pattern and cannot be used for other cases. The closed form solutions presented in this note utilise general shape functions for the green field ground settlements (i.e. the vertical displacements that would occur in the absence of the pile). These general shape functions may be fitted to the anticipated settlement profile, which may be obtained from field measurements, analytical solutions, or empirical relations. Methods of fitting shape functions are not covered in this note.