Hydraulic and transport behavior of a variable aperture fracture by a transmitted-light optical measurement system

Sawada, Atsushi ; Sato, Hisashi

To evaluate groundwater flow and nuclide migration for safety assessment of radioactive waste disposal, an appropriate model capable of describing the characteristics of the host rock should be used. There is need for a fundamental understanding of fluid flow in a fracture to provide a correlation between hydraulic and transport properties of the parallel plate model suitable to be used for modeling the behavior of a natural fracture. To this end, it is useful to obtain quantitative geometrical properties of the void space in a fracture and their relationship to hydraulic and transport properties. We have, therefore, measured both the fracture aperture distribution and the groundwater flow within the plane of a fracture, under the same condition as hydraulic tests, quantitatively by a transmitted-light optical measurement system applied to a transparent replica of a single fracture.