2021 Fiscal Year Final Research Report
Evaluation of risk for fault reactivation and migration by means of sequential scratch test using core specimens
| Project/Area Number |
19K04603
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 22030:Geotechnical engineering-related
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| Research Institution | Nihon University |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | スクラッチテスト / 岩石の硬度 / 摩擦係数 |
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| Outline of Final Research Achievements |
Rock core samples were used to continuously evaluate their mechanical properties using the scratch test. In the scratch test, the rock surface is scratched with a hard material (e.g., diamond indenter) under a vertical load. The ratio of the horizontal to the vertical load is the coefficient of friction, and its continuous variation can be obtained. A rock sample that shows short-period oscillations is a rock sample with ductile behavior, and the rock samples with large amplitude and periodic oscillations are considered to be brittle rocks. We can infer that areas of sedimentary rocks with locally low friction coefficients are surfaces with the potential to become slip surfaces. The horizontal stresses are related to the Young's modulus of the rock, and a comparison with the hardness of the rock shows a positive correlation. The scratch test can evaluate the brittle behavior of rock cores, because fractures that cause cracks occur when differential stress is applied.
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| Free Research Field |
岩石力学，岩盤力学，応用地質
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では，地下空間の利用，廃棄物の地層処分や二酸化炭素地下貯留などにおいて，その流体移動経路となりえる亀裂が新たに形成されるかどうかを評価するための手法の開示を行った．流体移動経路の評価は地域全体で行うことはできず，ボーリングコアなど限られた試料から推定せざるを得ない．そのような中，本研究で開発したスクラッチテストはコア試料を用いて連続的に物性値を得ることを可能としている．また，スクラッチテストでは使用する領域が表面のみであることから，その後のコア試料の観察や室内試験への影響も極めて少ない．そのため，まず初めにコア試料を使って連続的な物性評価をするにはスクラッチテストが最適であると考える．
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