Constitutive behavior of granular materials under high rate of uniaxial strain loading

The uniaxial compressive behavior of Colorado Mason sand at high strain rates was investigated on a split Hopkinson pressure bar. The sand grains were placed inside a hardened steel tube and end-capped by tungsten carbide rods. This assembly, with a desired bulk mass density for sand, was then sandwiched between incident and transmission bar ends for dynamic compression. Unsorted dry sand and partially saturated sand were impacted at high strain rates to determine the volumetric and deviatoric behavior. Quasi-static compression under the same confinement was also conducted to compare with the high strain rate data. The effect of initial mass density and moisture content level on the constitutive behavior was investigated. The constitutive behavior of dry sand was analyzed using a recently developed adaptive particle fracture algorithm implemented in the poly-ellipsoidal discrete element method, to further understand the mesoscale behavior of sand under high-rate compressive deformations.