MECHANICAL PROPERTIES AND EVOLUTION OF SHAPE FABRICS IN NUMERICAL RIGID-PARTICLE BEARING SYSTEMS: A DISTINCT ELEMENT METHOD APPROACH

Fabric development in deforming biphase granular material is numerically modelled with PFC (Particle Flow Code, developed by Itasca Consulting Group), a commercial software based on distinct element method. The numerical biphase granular material consists of rectangular rigid particles and matrix phase showing power-law behavior. It is also investigated how flow strengths vary with the volume fraction of rigid particles and evolve with the degree of fabric development. From the numerical experiments, three observations are made; (i) the degree of preferred orientation intensifies with strain, but the rotation patterns of individual rigid particles are complicated due to particle-to-particle interactions, (ii) there is a rheologically critical fraction (~0.6) of rigid particles above which the strength of the bulk material increases abruptly, (iii) bulk-system hardening is observed in systems with high volume fraction of rigid particles. The results from this type of numerical biphase experiments may be applied to the interpretation of granular flow in some geological processes such as flow-related pattern formation of phenocrysts in magmas and pattern formation in some porphyroblast-laden metamorphic rocks.