Janssen effect and the stability of quasi 2-D sandpiles

Abstract

We present the results of three dimensional molecular dynamics study of global normal stresses in quasi two dimensional sandpiles formed by pouring mono dispersed cohesionless spherical grains into a vertical granular Hele-Shaw cell. We observe Janssen effect which is the phenomenon of pressure saturation at the bottom of the container. Simulation of cells with different thicknesses shows that the Janssen coefficient $\kappa$ is a function of the cell thickness. Dependence of global normal stresses as well as $\kappa$ on the friction coefficients between the grains (${\mu }_p$) and with walls (${\mu }_w$) are also studied. The results show that in the range of our simulations $\kappa$ usually increases with wall-grain friction coefficient. Meanwhile by increasing ${\mu }_p$ while the other system parameters are fixed, we witness a gradual increase in $\kappa$ to a parameter dependent maximal value.

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