Dynamic Mechanical Analysis Test for Evaluating Loose Sands on a Wide Strain Range—Application to the InSight Mission on Mars

Abstract

The dynamic properties of loose sands under low stresses are an unexplored topic in soil dynamics because these soil conditions are uncommon in most geotechnical structures on Earth. However, low densities and low-stress conditions prevail on other planets, like, for instance, the surface of Mars, for which particular attention is presently given through the InSight NASA mission. This work presents a new procedure for measuring the dynamic properties of loose sand under low stress by using the dynamical mechanical analysis (DMA) tester, a technique commonly used in asphalt engineering but not in geotechnical engineering. Compared to traditional geotechnical methods (resonant column and cyclic triaxial tests), DMA investigates a broader range of strains using a single apparatus. In this work, we assess the dynamical properties of loose fine sand Dr ≈ 0.2, considered a possible Mars regolith analog, by varying the input strain from γ = 10−6 to γ = 10−2 while applying confining pressures from σ3 = 3 kPa to σ3 = 30 kPa. The results validate the proposed procedure, showing an increment of the shear modulus as the confining pressure increases. Furthermore, they highlight DMA’s advantages for studying the dynamic properties of granular soils under low stress and strain.