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2015
Conference Paper
Titel
Mesoscale simulation of quartzite and porous sandstone at high loading rates
Abstract
In this paper, the failure behavior of geological dry sandstone is numerically investigated at mesomechanical ("grain") scale. The investigated type of sandstone essentially consists of cemented quartz grains and interstitial pores. Quartz exhibits an anisotropic crystalline structure with preferential stiffness orientations. We use the material model of Purton et al. (1992) to simulate the anisotropic behavior of grains. Inter-granular failure is described by the "Initially Rigid Cohesive Zone Elements" methodology used by Knell et al. (2012): after having overcome a threshold activation stress, grain interfaces expand while the stress drops, followed by nucleation and coalescence of cracks, and eventual macroscopic rupture. The considered loading case is a stress wave in a modified Split Hopkinson Bar (spallation configuration) with moderate strain rates of about 30 per second. The simulation results are compared to experimental measurements from tests with compact quartzite and sandstone, and the effect of anisotropy and porosity on inter-granular failure will be quantified.