Experimental Fracture Analysis of Individual Sand Particles at High Loading Rates

High strain rate loading conditions such as blast, impact, or projectile penetration cause major damages to infrastructure and soils. Sand particles will likely fracture if they are exposed to such loading conditions. Modeling the constitutive behavior of sand deposits when they are subjected to dynamic loading requires a high-fidelity particle-scale analysis, calibration, and validation using experimental measurements. In this paper, natural sand particles with complex morphology, mineralogy, and grain size were randomly selected from the bulk material and were separated based on particle size and mineralogy. Intact particles were first imaged using a desktop X-ray computed tomography (CT) scanner to calculate morphology and provide further input to the mineralogy and internal structure. Each particle was placed between incident and transmitter bars of a Kolsky bar setup, and two optical images (side and top views) were collected to visualize the loading geometry and direction. Each particle was then dynamically loaded to failure, at which load and compressive displacement were measured. Some of recovered particle fragments were imaged using synchrotron microcomputed tomography (SMT) to determine the fracture mode and fracture surface. Weibull statistical analyses were performed and multivariable nonlinear regression was implemented, using particle characteristics as predictors. The paper discusses the influence of morphology, mineralogy, internal structure, and size of particles on dynamic particle failure strength.