Numerical analysis on micro-damage in bisphere model of granitic rock

摘要

Microcracking in contact with constituent minerals plays an important role in the nonlinear deformation process and micro-damage, leading to shear fracture of brittle materials such as granite. For damage propagation, the surface energy stored in the grain as a result of applied stresses thus tends to be relieved on the plane firstly, and pre-existing intracrystalline microcracks perpendicular to axial stress direction are closed. On the other hand, those parallel or subparallel to the axial stress direction are open. These stress-induced microcracks are predominantly tensile in nature, and the directions are parallel or subparallel to the axial stress direction. Numerical analysis provides some basis for a micromechanics of stress-induced micro-damage occurring at the major constituent mineral contact portions in feldspar. A homogenization theory was applied to analyze the damage development for the vicinity of pre-existing microcrack and stress-induced microcrack at grain contact. Numerical analysis with the bisphere model for damage development at micro-damage portions was discussed, assuming that feldspar grains surround quartz grain.