Effect of clay mineral type on the physical and mechanical properties of barriers for the geological disposal of radioactive waste

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K21174
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Earth system and resources engineering; Geotechnical engineering
• Research Institution: Tottori University
• Principal Investigator: KOHNO Masanori 鳥取大学, 工学研究科, 講師 (60640901)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 粘土鉱物 / ベントナイト / 変質 / 一軸圧縮強度 / 膨潤圧 / 透水係数 / 放射性廃棄物地層処分 / バリア材

Outline of Final Research Achievements

Clay-mineral type and content are very important factors for the ultra-long-term stabilization of barriers in radioactive waste disposal. Firstly, in order to clarify that effect of only clay mineral content, a series of experiments has been carried out on artificial rock by the use of gypsum specimen mixed with clay minerals. Secondly, this study investigates the effects of clay-mineral type and content on the swelling characteristics and permeability of bentonite-sand mixtures with clay minerals using one-dimensional swelling-pressure and constant-pressure permeability tests. These experiments produced the following results: (1) Comparative tests revealed that the difference of clay mineral content or type in the clay mineral-bearing rock material specimens influences the physical and mechanical properties of rock materials. (2) The hydraulic conductivity of bentonite-sand-clay mineral mixtures increased with increasing content of non-swelling alteration products of montmorillonite.

Free Research Field

地盤工学，岩石力学，土木地質学

Academic Significance and Societal Importance of the Research Achievements

本研究成果は，放射性廃棄物の人工・天然バリア材のより確実な長期安定性の実現，さらに，地下環境の状況に応じた粘土バリア材の適切な選定に貢献できると考える．一方，近年のエネルギー資源の多様化，地震・津波・火山噴火による地表での被害を考えると，力学的に安定した地下岩盤利用の可能性を広げることは必須である．様々な環境下での透水性や力学特性の把握により，地下環境の有効利用やエネルギー資源抽出・掘削の際の安定性評価，さらに，遮水壁，人工軟岩開発，地すべり面粘土に関する研究にも展開できると予想される．このように，資源工学および地盤工学分野で幅広い波及効果が期待される．