Undrained creep deformation of a strip load on clay

Time-dependent creep effects can play an important role in the stress distributions and deformations of foundations. Using a phenomenological model, the analysis of undrained creep behaviour has been introduced into an elasto-plastic finite element programme. The creep behaviour of a strip load on a finite layer of soil has been illustrated and a study has been made of the effects of small changes in the values of the creep parameters on the overall analysis of creep deformation. Time dependent creep deformations of a strip load are also compared with those occurring due to consolidation. The treatment of creep behaviour has been restricted to the modelling of deviatoric creep. When comparing creep effects on different clays, the shape of the yield surface is an important consideration. Sensitivity analyses on the creep parameters revealed a necessity for their accurate evaluation. Small variations in these parameters caused correspondingly large variations in predicted settlements. The inclusion of creep behaviour in a consolidation and creep analysis resulted in a marked increase in settlements, creep settlements causing have at points distant from the loading. Consolidation and creep settlements have opposite effects on horizontal displacements below the edge of a strip load.