SIMILARITY SOLUTIONS FOR DRAINED AND UNDRAINED CAVITY EXPANSIONS IN SOILS

A procedure for analysing the expansion of cylindrical and spherical cavities in hardening/softening soils is described, with the aim of providing a realistic and theoretically sound model on which to base analyses of the action of penetrometers and piles. Similarity solution methods are used to analyse the expansion of created cavities from zero initial radius. They circumvent the need to solve partial differential equations, and require the use of relatively simple computational methods involving the numerical solution of a small number of first-order ordinary differential equations. The procedure can be applied to any of the existing plasticity models used to model the deformation of soils and sands, and is illustrated here by use of a modified Cam clay critical state model. Both drained and undrained expansions are studied. Attention is concentrated on the relation between the values of the far-field, in situ and state variables and of the 'measurable' stress components on the cavity wall.