A Consideration about Rowe’s Minimum Energy Ratio Principle and a New Concept of Shear Mechanism

Abstract

Rowe (1962) introduced a new concept called minimum energy ratio principle to get a stress-dilatancy relation of granular materials under axisymmetric stress condition. According to the principle, the slinding contacts are restricted to those with the preferred angle βc=(π/4)-(φμ/2). However, the physical basis of this principle is questioned by many investigators. In this paper, the author investigates this principle only on the basis of equilibrium between interparticle forces with the following results ;(1) Horne's study on Rowe's stress-dilatancy equation is incomplete to clarify the physical meaning of the minimum energy ratio principle. Accordingly, his indication such that the principle could be rigorously established as an equilibrium condition is not acceptable.(2) The minimization of the incremental energy ratio E in Rowe's theory is equivalent to maximize a driving tangential force Fd acting in the same direction as sliding direction and a resisting one Fr in the opposite direction of Fd. The physical ground is not clear.A new and simple concept of shear mechanism of granular materials can be proposed only on the basis of equilibrium between interparticle forces without using the minimum energy ratio principle. The concept is characterized by such a description that the positions of sliding contacts shift as shear stress increases. According to the concept, the development of anisotropy of grain structure during shear and the deformation behaviours under cyclic loadings can be explained well.