Abstract: Dilatancy of coarse granular material is an important mechanical issue on its strength and deformation. It depends on micro effects such as arrangement of particles and inter-particle pressure, and hence is affected by macro factors such as relative density and stress state. In this article, research progress around the dilatancy of coarse granular material under complex stress condition is reported in the aspects of mechanical properties of coarse granular material, strength criteria, and critical state and dilatancy. Trends of development in future are presented below. Firstly, based on laboratory investigation of dilatancy of coarse granular material based on true triaxial tests and related theoretical analyses, constitutive theory could be greatly promoted. Secondly, development of dilatancy equation can be achieved from that under traditional triaxial condition to that under complex stress condition, and leads to unification of strength and deformation issues. Thirdly, stress state and void ratio can be coupled with consideration of state parameter in the evaluation of soil’s loose or dense state and dilatancy, and then avoid a particular material with multiple sets of parameters. It indicates a more scientific and systematic approach in the research on the mechanical properties of coarse granular material.

Key words: coarse granular material, dilatancy, true triaxial test, strength criterion, state parameter