The effect on anisotropy of rotating the principal stress axes during consolidation

It is well known that K_o-consolidated natural sediments have anisotropic strength, yielding and stiffness characteristics, particularly at low overconsolidation ratios. For example, the undrained triaxial compression shear strengths developed after K_o-consolidation far exceed those available in extension. This paper describes recent hollow cylinder apparatus research into other types of stress-induced anisotropy, reporting experiments on dense silt samples that involved rotation of the principal stress axes during consolidation. The results show strikingly different anisotropies from those developed by K_o-consolidated samples. The effective stress paths chosen for the laboratory studies were guided by the conditions expected under multi-stage embankments built on soft ground, but the results have considerable significance in other practical geotechnical problems.