[H-CG28] Nuclear Energy and Geoscience

[HCG28-03] Regional hydraulic structure modeling by division of hydraulic test data considering permeability of fractures and rock matrix

*Taiki Kubo¹, Koki Kashiwaya¹, Katsuaki Koike¹ (1.Graduate School of Engineering, Kyoto University)

Keywords:fracture system, groundwater flow system, matrix flow, permeability

In order to evaluate the safety of geological disposal facilities for high-level radioactive waste (HLW), it is important to understand the ground water system around the construction site, and to construct a regional hydraulic structure model. Hydraulic test data using boreholes are taken into hydraulic structure model as an actual data set. Improvement of the spatial resolution of the model needs division of hydraulic test data for, because hydraulic test data are usually representative values for test sections of several to several tens of meters. However, a simple equipartition causes underestimate or overestimate of hydraulic conductivity due to a presence of geological elements with different permeability in the test section such as fracture, alteration, and intact zones. In this study, we tried to divide the hydraulic test data by evaluating the permeability of fractures and rock matrix separately based on a statistical analysis using borehole logging data and core sample measurement data by Kubo et al. (2019) for the Mizunami area in Gifu Pref., central Japan. As the result, effectiveness of the constructed hydraulic model is demonstrated.



Kubo, T., Matsuda, N., Kashiwaya, K., Koike, K., Ishibashi, M., Tsuruta, T., Matsuoka, T., Sasao, E., Lanyon, G.W., 2019. Characterizing the permeability of drillhole core samples of Toki granite, Central Japan to identify factors influencing rock-matrix permeability. Eng. Geol. 259, 105163. https://doi.org/10.1016/J.ENGGEO.2019.105163