著者

石田 毅 直井 誠 陳 友晴 奈良 禎太

出版者

京都大学

雑誌

基盤研究(A)

巻号頁・発行日

2013-04-01

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地球温暖化の速効的対策であるCO2(二酸化炭素)地中貯留では,大量のCO2を地下深部に圧入するが, CO2は地下深部ではさらさらとして粘度が小さい超臨界状態となるため周辺地層に与える影響を検討して必要がある.本研究では,現場の岩盤に超臨界CO2の圧入しその際の微小な破壊音であるAEを測定した.その結果,超臨界CO2は水の圧入に比べてAEの震源が広く分布するが,圧入位置での亀裂造成後時間が経過すると亀裂閉合によると思われるAEが観測された.このようなAEは岩盤の破壊ではなくガス抜けよるものと思われ,例えAEの震源分布が広がっても周辺地層に安定性に与える影響は小さいと思われた.

著者

奈良 禎太 加藤 昌治 佐藤 努 河野 勝宣 佐藤 稔紀

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.138, no.4, pp.44-50, 2022-04-28 (Released:2022-04-28)

参考文献数

34

被引用文献数

1

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It is important to understand the long-term migration of radionuclides when considering rock engineering projects such as the geological disposal of radioactive waste. The network of fractures and pores in a rock mass plays a major role in fluid migration as it provides a pathway for fluid flow. The geometry of a network can change due to fracture sealing by some fine-grained materials over long-term periods. Groundwater usually contains finegrained minerals such as clay minerals, and it is probable that the accumulation of such minerals occurs within a rock fracture upon groundwater flow, thereby decreasing the aperture of a fracture and the permeability. It is therefore essential to conduct permeability measurements using water that includes fine-grained minerals to understand the permeability characteristics of a rock; however, this has not been studied to date. In the present study, we use a macro-fractured granite sample to investigate the change of permeability that occurs under the flow of water that includes two different amounts of clay. Findings showed that clay accumulated in a fracture and that the permeability (hydraulic conductivity) of the granite sample decreased over time, which was greater in for the higher clay content. We concluded that the accumulation of clay minerals in the fracture decreased the permeability of the rock. Furthermore, we consider that the filling and closure of fractures in rock is possible under the flow of groundwater that includes clay minerals.