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...

Based on the micro-mechanical model recently developed by Nemat-Nasser S. (J. Mech. Phys. Solids 48 (2000) 1541), a three-dimensional continuum mechanics model is presented for the deformation of granular materials which carry the applied load through frictional contacts. The model incorporates the anisotropy (or fabric) which develops as a frictional granular mass is deformed in shear, and inc...

On a microscopic scale, a pyrotechnic material is made of a polymer matrix containing grains with different sizes and shapes. Its physical behaviour can be predicted by homogenization. Information about the morphology of the grains can be obtained by different ways. One of these ways is 3D image processing. This has been made easier by the use of a new imaging technique, the microtomography, al...

We systematically investigate the incremental response of various equilibrium states of dense 2D model granular materials, along the biaxial compression path (σ11 < σ22, σ12 = 0). Stress increments are applied in arbitrary directions in 3dimensional stress space (σ11,σ22,σ12). In states with stable contact networks we compute the stiffness matrix and the elastic moduli, and separate elastic and...

We investigate shear strength properties of wet granular materials in the pendular state (i.e., the state where the liquid phase is discontinuous) as a function of water content. Sand and glass beads were wetted and tested in a direct shear cell and under various confining pressures. In parallel, we carried out three-dimensional molecular dynamics simulations by using an explicit equation expre...

Granular materials segregate. Small differences in either size or density lead to flow-induced segregation, a complex phenomenon without parallel in fluids. Modeling of mixing and segregation processes requires the confluence of several tools, including continuum and discrete descriptions (particle dynamics, Monte Carlo simulations, cellular automata computations) and, often, considerable geome...