When walking on wet sand, each footstep leaves behind a temporarily dry impression. This counterintuitive observation is the most common illustration of the Reynolds principle of dilatancy: that is, a granular packing tends to expand as it is deformed, therefore increasing the amount of porous space. Although widely called upon in areas such as soil mechanics and geotechnics, a deeper understan...

Liquid foams have been observed to behave like immersed granular materials in at least one respect: deformation tends to raise their liquid contents, a phenomenon called dilatancy. We present a geometrical interpretation thereof in foams squeezed between two solid plates (2D GG foams), which contain pseudo Plateau borders along the plates, and in 3D foams. While experimental observations eviden...

We demonstrate that lateral vibrations of a substrate can dramatically increase surface diffusivity and mobility and reduce friction at the nanoscale. Dilatancy is shown to play an essential role in the dynamics of a nanometer-size tip which interacts with a vibrating surface. We find an abrupt dilatancy transition from the state with a small tip-surface separation to the state with a large sep...

The behavior of sand crushing will appear when the confining pressure is up to a certain value, which results in disappearing of the positive dilatancy of sand. Adopting a new hardening parameter with the crushing stress, an elastoplastic constitutive model considering sand crushing is proposed. Comparing the conventional triaxial compression test results with the model prediction, it shows tha...

This paper proposes a new approach for the analysis of shear-induced volume change of granular materials. Following a revisit to the micro-mechanical deformation mechanism and the ˆndings from discrete element method simulations, it is concluded that the double slip-rotation rate mechanism is appropriate for the description of granular materials subjected to shear. The implementation of energy ...

-Theoretical constraints on the stress-dilation relation for a deforming Coulomb material require v -< 0 if C = 0 and v -< sin-l(Tm/e,n) always, where v is the dilation angle, 0 is the friction angle, C is cohesion, z,, is the maximum shear stress, and a,~ is the mean effective stress. Recent laboratory measurements of friction and dilatancy of simulated fault gouge show that small amplitude sh...

Field observations of major earthquake fault zones show that shear deformation is often confined to principal slipping zones that may be of order 1–100 μmwide, located within a broader gouge layer of order 10–100 mm wide. This paper examines the possibility that the extreme strain localization observed may be due to the coupling of shear heating, thermal pressurization, and diffusion. In the ab...

We introduce a model of granular matter and use a volume/strain ensemble to analyze infinitesimal shearing. Monte Carlo simulation suggests the model exhibits a second order phase transition associated with the onset of dilatancy.

Shear dilatancy, a significant nonlinear behavior of nonequilibrium thermodynamics states, has been observed in nonequilibrium molecular dynamics (NEMD) simulations for liquid n-hexadecane fluid under extreme shear conditions. The existence of shear dilatancy is relevant to the relationship between the imposed shear rate gamma and the critical shear rate gamma(c). Consequently, as gamma<gamma(c...