1998 Fiscal Year Final Research Report Summary
Study on time-dependent failure of rock and geological discontinuity under high temperature and pressure.
| Project/Area Number |
08455217
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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 |
Geotechnical engineering
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| Research Institution | Saitama University |
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Principal Investigator |
ODA Masanobu Saitama Univer., Dept.Civil & Environ.Engrg, Prof., 工学部, 教授 (90008855)
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| Co-Investigator(Kenkyū-buntansha) |
TANIYAMA Hisashi Saitama Univ., Dept.Civil & Environ.Engrg, Assis., 工学部, 助手 (80236710)
OSADA Masahiko Saitama Univ., Dept.Civil & Environ.Engrg, Assis., 工学部, 助手 (00214114)
OKUI Yoshiaki Saitama Univ., Dept.Civil & Environ.Engrg, Asso.Prof., 工学部, 助教授 (40214051)
TSUNODA Fumio Saitama Univ., Dept.Civil & Environ.Engrg, Prof., 工学部, 教授 (80092021)
SHIMAMOTO Toshihiko Kyoto Univ., Dept.Earth & Planetary.Sci., Prof., 理学部, 教授 (20112170)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Brittle materials / Rock / Failure / Creep / Microcrack |
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| Research Abstract |
This research can be concluded as follow :
1) To study the effects of temperature and time on mechanical properties of crystalline rocks, a laboratory test was carried out by immersing granite in 90ﾟC water for 2000 days. During the test, various measurements were made, in parallel, to investigate the long term changes in the specimens' physical properties. Growth of microcracks and synthesis of clay minerals were also investigated to supply fundamental data for the time-dependent strength properties. It is found that microcracks grow due to stress corrosion induced by residual stress. 2) Time dependent behavior of rocks is closely related to microcrack growth in a similar manner to short term behavior. It is found that a failure surface can be defined in terms of invariants of crack tensor. 3) A micromechanics-based continuum theory called interaction field theory can reproduce localization phenomena such as shear faulting and axial splitting of rock under compression. The growth of the microcracks is assumed to occur through two mechanisms : stress-induced crack growth and stress corrosion. This theory introduces a new field quantity which represents the interaction effect and the associated governing integral equation, and reproduces not only inelastic deformation of rock but also eventual macroscopic failure due to localization of microcracking. 4) High-velocity friction experiments have been performed on a pair of hollow- cylindrical specimens of gabbro. Steady-state friction increases slightly with increasing slip rate at slip rates to about 100 mm/s (velocity strengthening) and it decreases markedly with increasing slip rate at higher velocities (velocity weakening).
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Research Products
(13 results)
