Janssen effect and the stability of quasi 2-D sandpiles

TL;DR

This study uses molecular dynamics simulations to analyze the Janssen effect in quasi 2-D sandpiles, revealing how the Janssen coefficient depends on cell thickness and friction coefficients, and demonstrating pressure saturation phenomena.

Contribution

It provides new insights into how the Janssen coefficient varies with cell thickness and friction parameters in quasi 2-D sandpiles through detailed simulations.

Findings

Janssen coefficient depends on cell thickness.

Wall-grain friction increases the Janssen coefficient.

Normal stresses saturate at the bottom of the container.

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.