Evaluation of Fracture Aperture Using X-Ray CT

Shimo, Michito*; Fumimura, Kenichi*; Obara, Yuzo*; Sato, Akira*; Sugawara, Katsuhiko*

Understanding the influence of small scale structure and its heterogeneity onto flow through rock fractures is important for improving the reliability of performance assessment of Geologic Disposal of High Level Nuclear Waste. An established technique for measuring the fracture aperture profile is required to achieve the above purpose. There are several aperture measuring techniques: (1) estimation of aperture from roughness measurement results, (2) direct measurement of the fracture from rock surface, (3) non-destructive method, such as tomography. Among above, tomography method, which is rather new technique and its applicability to aperture measurement is not well known, is expected to become an effective and feasible approach since the aperture profile can be obtained without destroying the rock specimen. In this work, we investigated problems associated with fracture aperture measurement using X-Ray, then we proposed several approaches to improve measurement accuracy, finally