SIMILARITY SOLUTIONS FOR DRAINED AND UNDRAINED CAVITY EXPANSIONS IN SOILS

A procedure for analysing the expansion of cylindrical and spherical c avities in hardening/softening soils is described, with the aim of pro viding a realistic and theoretically sound model on which to base anal yses of the action of penetrometers and piles. Similarity solution met hods are used to analyse the expansion of created cavities from zero i nitial radius. They circumvent the need to solve partial differential equations, and require the use of relatively simple computational meth ods involving the numerical solution of a small number of first-order ordinary differential equations. The procedure can be applied to any o f the existing plasticity models used to model the deformation of soil s and sands, and is illustrated here by use of a modified Cam clay cri tical state model. Both drained and undrained expansions are studied. Attention is concentrated on the relation between the values of the fa r-field, in situ and state variables and of the 'measurable' stress co mponents on the cavity wall.