High-Strain Rate Compressive Behavior of Dry Mason Sand Under Confinement

Abstract

Uniaxial compressive behavior of Mason sand, a poorly-graded local sand supplied by Colorado Materials (Longmont, CO), was investigated on a long split Hopkinson pressure bar. Sand grains were confined inside a hardened steel tube and capped by tungsten carbide rods. This assembly was subjected to repeat shaking to consolidate sand to attain desired bulk mass density, then sandwiched between incident and transmission bar ends for dynamic compression. Unsorted dry sand was characterized at high strain rates to determine the volumetric and deviatoric behavior through measurements of both axial and transverse response of cylindrical sand sample under confinement. Effects of sand mass density on the constitutive behavior were investigated. The stress–strain relationship was found to follow a power law relationship with the initial bulk density. The Young’s modulus and hardness of individual sand grains were determined by nanoindentation. The sand deformation was observed through sapphire tube using ultra-high speed photography to determine the elastic deformation and compaction behavior. The energy absorption density and compressibility were determined as a function of axial stress. These results can be analyzed further for constitutive modeling and for mesoscale simulations to understand the soil behavior under blast subject to high pressure and high rate deformations.