Analysis of Shear Bands in Sand Under Reduced Gravity Conditions

The strength of granular material, specifically sand is of pivotal importance for understanding physical phenomena on other celestial bodies. However, relatively few experiments have been conducted to determine the dependence of strength properties on gravity. In this work, we experimentally investigated three measures of strength (peak, confined flow, and unconfined flow friction angle) in Earth, Martian, Lunar, and near-zero gravity. The angles were captured in a passive Earth pressure experiment conducted on a reduced gravity flight. The results showed no dependence of the peak friction angle on gravity, a weak dependence of the confined flow friction angle on gravity, and no dependence of the unconfined flow friction angle on gravity. These results highlight the importance of understanding strength and deformation mechanisms of granular material at different levels of gravity.