| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2015: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Outline of Final Research Achievements |
The strengths of crustal faults are lower than those determined from laboratory measurements. Because long-term changes of rock strength cannot be directly monitored, so an explanation for fault weakening remains an unsolved problem. We showed laboratory evidence that supports the concept that long-term weakening of the rock strength is caused by microfracturing at asperity contacts, which is a result of crack growth at subcritical stress levels. We conducted a series of rock tests under the high-temperature and high-pressure conditions to accelerate reaction processes so that they were observable at laboratory time-scales. Our results suggest that long-term weakening of rock strength is related to chemical reactions that take place in the presence of water. The fluids underground has an important influence on time-dependent rock strength.
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