Particle‐Scale Mechanics of a Regolith‐Type Soil

ABSTRACT

The existing studies have reported that the surface of Mars shows the presence of materials having igneous origin, including basalt and regolith‐type coarse soils. These findings are affected by significant uncertainties and, therefore, the selection of simulants for various exploration applications, including surface mobility of rovers, should take into account the potential complications that might arise if unexpected materials are found. The present study focusses on the micromechanical characterisation of a regolith‐type soil (Eglin sand), comparing the results obtained with those determined for a quartz sand (Leighton Buzzard sand), that is also used as a Mars‐soil simulant. Eglin sand is constituted by a complex composition and the various minerals identified were tested and analysed separately. The testing activities included the characterisation of the particle shape and surface morphology, and the determination of particle strength, contact response, contact stiffness and inter‐particle friction. Differences in terms of particle morphology and surface properties were recorded for the two sands studied, and, along with grain mineralogy, these have been found to have an impact on the mechanical response, affecting both particle strength and inter‐particle behaviour. This study aims to provide realistic soil data and information to be used in numerical simulations performed using the Discrete Element Method, which is often adopted for the analysis of surface mobility problems.