Shear Strength Investigations for a Class of Extraterrestrial Analogue Soils

Abstract

A class of granular materials is presented that was obtained from quarried intrusive igneous rock, further processed to match the grain-size distribution of typical Apollo samples. Texture, mineralogy, and chemical composition have been investigated; and the material is classified as basaltic andesite. A series of triaxial compression tests have been performed to assess the influence of confining stress on the shearing behavior at medium to low stress levels. A medium sand is used as reference. In one of the test series, corundum was added to simulate the glass particles found in the lunar regolith. Both stress-strain curves and volumetric strains are reported. All samples tested exhibit a purely dilatant behavior at low confining stress levels. Shear strength can be expressed either by a curved Mohr-Coulomb envelope or by a linear one with a cohesion intercept. Results are shown to agree well with those obtained on common lunar soil simulants.