The experimental determination of the angle of dilatancy in soils

Abstract

The effective shear strength of overconsolidated soils (OCR ≥ 3) without cementation among particles or aggregates of particles is frequently described in terms of the cohesion and the angle of internal friction. An alternative, that is more consistent with the physical behaviour of these materials when sheared (a frictional behaviour) and which is strictly related to the volumetric strains, makes use of the angle of dilatancy and the effective angle of friction. In practical applications concerning the types of soils mentioned above, the elastic perfectly plastic non-associated Mohr-Coulomb model is still widely used and a quantification of the angle of dilatancy through soil testing is then necessary. Nevertheless this quantification is not always obvious due to ambiguous definitions present in the literature. The paper deals with the interpretation of the results for different types of soil tests, focusing on the procedures to correctly evaluate the angle of dilatancy. Some cases are presented and discussed.