Abstract: Shear dilation is one of the important characteristics of geomaterials. Rowe’s dilatancy equation is of a classic type, which reflects the dilatancy of coarse-grained soil, rock, and even concrete, featuring a simple form and fewer assumptions. It is widely acknowledged in the world and has been improved and developed by many researchers. However, some concepts in the previous derivation of this equation need to be discussed, and its separation planes of a tooth shape may mislead the readers. In this paper, the equation and its improvements and developments are reviewed, and a new derivation method using the concept of a reference plane is presented. It is thought that the new derivation is more rigorous in concept, and the investigation of these two methods sheds some light on our understanding of Rowe’s dilatancy equation.

Key words: dilatancy equation, coarse-grained soil, constitutive model, friction angle, dilatancy angle, reference plane