Study of natural fracture topography and fracture aperture distribution in 50 cm scale granitic rock block measured by a precision grinder

Tetsu, Keiichi*; Sawada, Atsushi 

In this study, we measured fracture aperture by using a series of the digital image data of a single natural fracture in the 50 cm scale of the granite rock block by grinding the rock surface in 1 mm increment perpendicular to the fracture. The fracture aperture was measured by scaling of the width of void space in between fracture walls, without taking account fracture infilling materials. Thus, we obtained both fracture characteristics, fracture width (separation distance between the fracture walls) and fracture aperture, in 50 cm scale of a natural rock. Ratio of infilling to fracture width is large in which fracture width is relatively small. In this area, fracture aperture tended to become small. Consequently, the flow channel by connecting the fracture aperture become to be localized.