2018 Fiscal Year Final Research Report
Observation of pressure solution on rock fracture surface
| Project/Area Number |
16K14306
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Geotechnical engineering
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| Research Institution | Yamaguchi University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | 岩石亀裂 / 圧力溶解沈殿 / 微小圧子 / X線CT |
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| Outline of Final Research Achievements |
In measuring rock fracture apertures and contact area from X-ray CT images, a binarization method has generally been used to separate the air void parts (fractures) from the rock parts. However, reasonable thresholding is often an essential problem in this method, especially for heterogeneous rock materials. This study suggests a new method for detecting fracture surfaces from CT images using an edge detection algorithm that is known well in the field of image processing as Canny edge detection. Applying this edge detection method to the CT images of a single granite fracture, 15 mm in diameter and 30 mm in length, this study successfully measures the fracture surface geometry, the aperture distribution, and the contact ratio. This image processing approach will be a useful measuring tool for micro-indentation experiment for rock fractures.
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| Free Research Field |
岩盤力学
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| Academic Significance and Societal Importance of the Research Achievements |
地震発生メカニズムの解明や高レベル放射性廃棄物の地層処分の計画，地中深部で行われる強化地熱システム（EGS）の開発などの地中深部のプロジェクトにおいて，亀裂の透水性や摩擦強度の長期変化は極めて重要な課題である．本研究では，亀裂接触部近傍で発生する圧力溶解沈殿現象を室内実験で直接観測する微小圧子押込み実験のための基礎技術として，X線CTによる亀裂開口・接触状況の計測技術を開発した．この技術により，亀裂内部の接触位置・面積を非接触で高精度に計測することが可能となった．
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