| Project/Area Number |
11450395
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
資源開発工学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
OKUBO Seisuke Graduate School of Frontier Sciences, The University of Tokyo Professor, 大学院・新領域創成科学研究科, 教授 (90092155)
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| Co-Investigator(Kenkyū-buntansha) |
AKIYAMA Masao Graduate School of Engineering, The University of Tokyo, Assistant, 大学院・工学系研究科, 助手 (00011172)
FUKUI Katsunori Graduate School of Engineering, The University of Tokyo Associate Professor, 大学院・工学系研究科, 助教授 (70251361)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥8,000,000 (Direct Cost: ¥8,000,000)
Fiscal Year 2000: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1999: ¥6,300,000 (Direct Cost: ¥6,300,000)
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| Keywords | Rock / Failure Criterion / Long-Term Strength / Underground Structures / Rock Stress / Creep / Relaxation / Constitutive Equation / 粘弾性 / 時間依存性 / 緩み領域 / 圧密 |
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| Research Abstract |
At first, study on loading-rate dependency of strength was briefly summarized. It is well known that uniaxial (unconfined) compression strength increases with loading rate. Though only limited data are available, some authors reported that confined strength increases with loading rate. Also, tensile strength obtained by uniaxial tension, indirect tension and bending tests increases with loading rate.
Based on the summarized experimental results, a failure criterion in which loading-rate dependency of strength is considered was proposed ; high criterion for high loading rate and low criterion for low loading rate. As an extreme case, long-term strength or failure criterion at extremely low loading rate can be obtained. The simplest form of the long-term strength is σ_1=a σ_3 where σ_1, σ_3 are major and minor principal stresses, and constant 'a' varies from 2 to 6 depending on rock.
For validation of the proposed failure criterion, rock stresses were plotted on σ_1 vs. σ_3, diagram. It was found that all data except one were plotted under the line σ_1=4_<3σ>. It is reasonable to consider that, in relatively stable rock mass, rock stress is maintained at a certain value or condition lower than a long-term strength. If so, this result supports the validity of the proposed failure criterion.
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