Critical state of granular materials at mesoscale: Transition from local to global

Abstract

SummaryCritical state theory is widely accepted for understanding and interpreting the behavior of granular materials such as sandy soils. Recently, motivated by the development of a multiscale analysis method, this paper presents a discrete element investigation on the critical state behavior of granular materials on two scales level, that is, the macroscale and mesoscale. Loops are taken as the basic mesostructures, and the concept of mesoscale critical state is proposed on terms of the local stress and void ratio. Based on series of numerical simulations with varying densities and confining pressures, the characters of critical state lines (CSLs) for each loop type are analyzed. An analytical relationship of the transition from local to global is then obtained for critical state. Besides, the influence of interparticle friction coefficient on CSL is also discussed on both scales. The prominent observation is that each type of loops achieves its own critical state, from which a unique global CSL can be obtained. The CSLs of different loops exhibit same shapes but move upwards with the increasing order.