Elucidation of solar-induced thermal weathering process of rock using acoustic emission method
Project/Area Number |
18K01124
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 04010:Geography-related
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Research Institution | Nihon University |
Principal Investigator |
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Project Period (FY) |
2018-04-01 – 2021-03-31
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Project Status |
Completed (Fiscal Year 2020)
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Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2020: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2018: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
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Keywords | 熱風化 / 日射風化 / アコースティックエミッション / マイクロクラック / 熱破砕 / 熱サイクル / 岩石物性 / 温度勾配 / 非破壊調査 / 乾燥地域 |
Outline of Final Research Achievements |
We experimentally investigated the fracture of rock specimens based on changes in pore-size distribution, P-wave velocity, and the occurrence of acoustic emission (AE). Three rock types which are often used as stone materials were used in the experiment. We repeatedly subjected the rock specimens to changes from 4℃ to 84℃ using a temperature-controlled chamber at a rate from ±4℃/min to ±0.5℃/min. Consequently, the P-wave velocity decreased by approximately 5%, 28%, and 2% for the granite, marble, and sandstone, respectively. Furthermore, the pore-size distribution changed by approximately 5-6% and 16% for the granite and marble, respectively. The variation in pore size of the sandstone was negligible. The occurrence of AE was detected in all rock types, but its amplitude for the granite was the largest, followed by the marble and sandstone, respectively. Therefore, a low-temperature thermal cycle causes thermo-mechanical fracture inside rocks.
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Academic Significance and Societal Importance of the Research Achievements |
日射や熱による岩石の破砕機構は,地形学における重要課題のひとつであるが,十分な解明は進んでいない。本研究が岩石内部における弾性波の発生を実験的に捉えたことは,加熱―冷却の繰り返しに伴う微小な亀裂の形成やその伸展が熱による岩石破砕のきっかけになることを示唆する。実験に用いた3種類の岩石は,文化財の建築石材として多用されている。このため本研究の成果は,石造文化財の劣化や保全の対策を検討するうえで有効な基礎資料となるであろう。
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Report
(4 results)
Research Products
(17 results)