抄録
In this study, we developed a method for creating on a computer a specimen of polycrystalline rock composed of monomineral, and using joint elements with normal (kn) and shear (ks) stiffnesses for the intergranular cracks, 3D finite element analysis was performed for the mechanical model of the polycrystalline rock in uniaxial compression to estimate the elastic properties and the stress distributions in the intergranular cracks. The effective Young's modulus of the polycrystalline rock is mainly governed by kn of the intergranular cracks and increases with kn, while the effective Poisson's ratio is mainly governed by the ratio of the shear stiffness to the normal stiffness (ks/kn) and increases with a decrease in ks/kn. As the ratio ks/kn decreases, the shear stress in the intergranular cracks decreases and the normal stress in the intergranular cracks with a large inclination angle relative to the loading axis increases in tension while that with a small inclination angle increases in compression. Thus, the normal and shear stresses in the intergranular cracks deviate more from the values in a homogeneous body as the ratio ks/kn decreases. Furthermore, it was found that the normal and shear stresses in the intergranular cracks that penetrate the upper and lower end surfaces, where the boundary conditions of displacement are given, are much smaller than those in other points, since the relative displacements in such intergranular cracks are constrained by the boundary conditions of displacement.
