花崗岩内に発生するクラックと鉱物粒の関係

抄録

Stress-induced cracks in granite obtained from the double-torsion test and three-point bending test were observed with the aid of optical microscope, and crack paths were classified into two types, transgranular cracks (T) and intergranular cracks (I). Transgranular cracks were subdivided according to their association with individual mineral grains. Intergranular cracks are subdivided according to neighboring minerals. Thin section analysis shows that in spite of the extensive range of crack velocities the T/I ratio changes little and the stress-induced crack path tends to propagate along relatively weak portions because of strong heterogeneity around the crack tip. Furthermore, in order to know the scaling of crack path roughness, power-spectra of all data were calculated as the function of spatial frequency. Each spectrum is approximately linear in log-log space and the fractal dimensions calculated from the slopes in spatial frequency-power-spectrum diagrams have ho definite tendency associated with the crack velocities.