Of the many improvements in the design of highway pavements during the past two decades, it is doubtful that any have been more important to the life and service of the pavement than the incorporation of the granular base course as a design feature. The true significance of the base course can be more thoroughly understood if one considers the merits of this practice. First, the properly design...

A boundary structure is observed in beds of vertically vibrated granular materials separating regions of opposite phase. This structure is investigated and it is identified as giving rise to both a global kink and hexagonal patterns. A global phase diagram of surface patterns on a vibrated bed is presented. c © 1998 Published by Elsevier Science B.V. In recent years, there has been a dramatic s...

The paper presents results of numerical experiments on a large assembly of smooth circular disks. The assembly was subjected to quasi-static biaxial loading at small to moderate strains by using the Discrete Element Method. Unlike the usual particle-based and coordination number approaches, the fabric was locally measured in relation to the shapes and orientations of voids. Deformation was meas...

There have been many attempts to derive continuum models for dense granular flow, but a general theory is still lacking. Here, we start with Mohr-Coulomb plasticity for quasi-two-dimensional granular materials to calculate (average) stresses and slip planes, but we propose a "stochastic flow rule" (SFR) to replace the principle of coaxiality in classical plasticity. The SFR takes into account t...

The macroscopic friction of particulate materials often weakens as the flow rate is increased, leading to potentially disastrous intermittent phenomena including earthquakes and landslides. We theoretically and numerically study this phenomenon in simple granular materials. We show that velocity weakening, corresponding to a nonmonotonic behavior in the friction law, [Formula: see text], is pre...

The maintenance of turf on shoulders, berms, and ditches of our highways and on airports has received little attention until very recent years. Frequently a good turf is desirable where the soil has been stabilized or where granular materials are necessary to obtain sufficient supporting power for the anticipated load. Under such conditions attention must be given to the factors which influence...

Shear flows of granular materials are studied in an open channel. The wall shear is calculated from an open channel momentum equation which includes the density variations in the flow. An experimental technique was developed that allowed the measurement of the average density of the flow at different longitudinal locations in the channel. Two sizes of glass beads are examined and results show t...

We are honouring the memory of Ioannis Vardoulakis through this special issue of Granular Matter, which is devoted to developments in micromechanical modelling of granular materials. Ioannis Vardoulakis will be forever remembered as an innovative experimentalist, a brilliantmechanician, an enthusiastic scientist, a devoted teacher, and above all an exceptional human being. The impression he mad...

We show that a mixture of two species of granular particles with equal sizes but differing densities can be either segregated or mixed by adjusting the granular temperature gradient and the magnitude of the gravitational force. In the absence of gravity, the dense, heavy particles move to the colder regions. If the temperature gradient is put into a gravitational field with the colder regions a...

We study numerically the propagation of an acoustic pulse through a loaded granular material under the hypothesis that the conventional modeling of solid friction used in soft sphere discrete element modeling remains valid at acoustic time scales. As a pulse crosses the material, it temporarily suppresses sliding contacts, making it difficult to prepare states that correspond to experimental co...