Dynamic High-Pressure Behavior of Hierarchical Heterogeneous Geological Materials

Abstract : The characteristics of shock-wave propagation in high purity sand of fine (75-150 m) and coarse (425-500 m) particle sizes in dry statat 65% theoretical density, and water-saturated with 35% void space filled with water, were collaboratively investigated, via controlled uniaxial-strain experiments and meso-scale modelling using CTH. The meso-scale features of the sand were resolved by explicitly incorpoprating 3D grains andvoid space into the computational domain. The method involved characterizing the structure and configuration of sand, as a model granular geological material, and explicitly tracking the effects of evolving material heterogeneities and their interactions with shock waves. It was observed that both dry and wet sand follow linear trends, with little difference in overall response between the two sizes of sand particles.Accounting for different strength values into CTH, provided upper and lower bounds to the experimental data. Results suggest effects of microkinetic energy, chipping on grain surfaces, and plastic deformation dominating the experimental response. These are difficult to incorporate in the simulation models. Experiments also reveal significant reduction in bulk wave speeds, which requires incorporation of multiple mechanisms insimulations.