Geophysics and Geophysical Exploration (지구물리와물리탐사)

Korean Society of Earth and Exploration Geophysicists (한국지구물리·물리탐사학회)
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Subcritical crack growth in rocks in an aqueous environment

수성환경에서 암석 내의 임계하 균열성장 연구

  • Published : 2009.02.28
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Abstract

Subcritical crack growth is one of the main causes of time-dependent fracturing in rock. In the present study, we investigated subcritical crack growth in rock in distilled water (pH = 5.7) and in an aqueous solution of sodium hydroxide (NaOHaq, pH = 12), comparing the results to those in air. We also investigated the effect of the pH in an aqueous environment. We used andesite and granite for all our tests. We determined the relationship between the crack velocity and the stress intensity factor using the double-torsion test under conditions of controlled temperature. We showed that crack velocities in water were higher than those in air, in agreement with other research results indicating that crack velocity increases in water. When we compared our results for NaOHaq with those for water, however, we found that the crack velocity at the same stress intensity factor did not change even though the pH of the surrounding environment was different. This result does not agree with the accepted understanding that hydroxide ions accelerate subcritical crack growth in rocks. We concluded that the pH at the crack tip influences subcritical crack growth, and not the bulk pH, which has little effect.

임계하 균열성장(subcritical crack growth)은 암석 내에서 오랜 시간 동안 일어나는 균열시스템 발달의 주된 원인으로 그 중요성이 매우 크다. 본 연구에서는 증류수(pH = 5-7)와 수산화나트륨(NaOHaq, pH = 12)용액으로 포화된 암석과 건조암석에서의 임계하 균열성장에 대해 고찰하였다. 아울러 공극유체의 수소이온농도(pH)의 영향도 함께 살펴보았으며, 안산암과 화강암이 연구에 사용되었다. 연구방법은 온도가 조절된 환경에서 이중-비틀림 실험(double-torsion test)을 실시하여 균열성장속도와 응력확장계수와의 상관관계를 파악하였다. 연구의 결과 수성환경에서 균열성장속도가 건조한 경우보다 크게 나타났으며, 이는 기존 연구에서 물이 첨가되었을 때 균열성장속도가 빨라지는 결과와 잘 일치한다. 증류수와 수산화나트륨 사이의 결과에서는 수소이온농도의 차이에도 불구하고 균열성장속도의 차이가 나타나지 않았으며 이는 수산화이온이 균열성장을 가속한다는 기존의 결과와는 차이를 보였다. 따라서 균열의 첨단부(crack-tip)에서의 수소이온농도의 차이는 균열의 성장에 영향을 미치지만, 공극유체의 전체적인 수소이온농도(bulk pH)의 영향은 매우 적다는 결론을 얻을 수 있었다.

Keywords

References

  1. Anderson, O. L., and Grew, P. C., 1977, Stress corrosion theory of crack propagation with applications to geophysics: Reviews of Geophysics andSpace Physics, 15, 77–104. doi: 10.1029/RG015i001p00077
  2. Atkinson, B. K., 1984, Subcritical crack growth in geological materials: Journal of Geophysical Research, 89, 4077–4114. doi: 10.1029/JB089iB06p04077
  3. Atkinson, B. K., and Meredith, P. G., 1981, Stress corrosion cracking ofquartz: a note on the influence of chemical environment: Tectonophysics,77, T1–T11. doi: 10.1016/0040-1951(81)90157-8
  4. Charles, R. J., 1958, Static fatigue of glass I: Journal of Applied Physics, 29,1549–1553. doi: 10.1063/1.1722991
  5. Freiman, S. W., 1984, Effects of chemical environments on slow crack growthin glasses and ceramics: Journal of Geophysical Research, 89, 4072–4076. doi: 10.1029/JB089iB06p04072
  6. Jeong, H. S., Kang, S. S., and Obara, Y., 2007, Influence of surrounding environments and strain rates on the strength of rocks subjected to uniaxialcompression: International Journal of Rock Mechanics and Mining Sciences, 44, 321–331. doi: 10.1016/j.ijrmms.2006.07.009
  7. Kies, J. A., and Clark, A. B. J., 1969, Fracture propagation rates and times tofail following proof stress in bulk glass: in Platt, P.L. (ed.), Fracture 1969: Chapman and Hall, pp. 483–491
  8. Kodama, N., Fujii, Y., and Ishijima, Y., 2003, The effect of temperature onthe mechanical properties of Inada granite and Shirahama sandstone: Kyoto, Japan: Proceedings of The First Kyoto International Symposium on Underground Environment – Role of Geo-technology to the Underground Environment, pp. 193–200
  9. Kudo, Y., Hashimoto, K., Sano, O., and Nakagawa, K., 1987, Relation between physical anisotropy and microstructures of granitic rock in Japan: Montreal, Canada: Proceedings of 6th International Congress on Rock Mechanics, pp. 429–432
  10. Michalske, T. A., and Freiman, S. W., 1982, A molecular interpretation of stress corrosion in silica: Nature, 295, 511–512. doi: 10.1038/295511a0
  11. Nara, Y., 2004, Study of subcritical crack growth in rock: Ph.D. Thesis, Hokkaido University (in Japanese)
  12. Nara, Y., and Kaneko, K., 2005, Study of subcritical crack growth in andesiteusing the Double Torsion test: International Journal of Rock Mechanics and Mining Sciences, 42, 521–530. doi: 10.1016/j.ijrmms.2005.02.001
  13. Nara, Y., and Kaneko, K., 2006, Sub-critical crack growth in anisotropic rock:International Journal of Rock Mechanics and Mining Sciences, 43, 437–453. doi: 10.1016/j.ijrmms.2005.07.008
  14. Nara, Y., Koike, K., Yoneda, T., and Kaneko, K., 2006, Relation between subcritical crack growth behavior and crack path in granite: InternationalJournal of Rock Mechanics and Mining Sciences, 43, 1256–1261. doi: 10.1016/j.ijrmms.2006.03.016
  15. Peacock, S., McCann, C., Sothcott, J., and Astin, T. R., 1994, Seismicvelocities in fractured rocks: an experimental verification of Hudson’stheory: Geophysical Prospecting, 42, 27–80. doi: 10.1111/j.13652478.1994.tb00193.x
  16. Pletka, B. J., Fuller, E. R., Jr, and Koepke, B. G., 1979, An evaluation of double-torsion testing – Experimental: ASTM Special Technical Publication, 678, 19–37
  17. Sano, O., and Kudo, Y., 1992, Relation of fracture resistance to fabric forgranitic rocks: Pure and Applied Geophysics, 138, 657–677. doi: 10.1007/BF00876343
  18. Sano, O., Kudo, Y., and Mizuta, Y., 1992, Experimental determination ofelastic constants of Oshimagranite, Barre granite, and Chelmsford granite: Journal of Geophysical Research, 97, 3367–3379. doi: 10.1029/91JB02934
  19. Trantina, G. G., 1977, Stress analysis of the Double-Torsion specimen: Journal of the American Ceramic Society, 60, 338–341. doi: 10.1111/j.1151-2916.1977.tb15556.x
  20. Waza, T., Kurita, K, and Mizutani, H., 1980, The effect of water on the subcritical crack growth in silicate rocks: Tectonophysics, 67, 25–34. doi: 10.1016/0040-1951(80)90162-6
  21. Wiederhorn, S. M., 1972, A chemical interpretation of static fatigue: Journalof the American Ceramic Society, 55, 81–85. doi: 10.1111/j.1151 2916.1972.tb11215.x
  22. Wiederhorn, S. M., 1978, Mechanisms of subcritical crack growth in glass:in Bradt, R.C., Hasselman, D.P.H. and Lange F.F. (eds.), Fracture Mechanics of Ceramics vol. 4: Chapman and Hall, pp. 549–580
  23. Wiederhorn, S. M., and Bolz, L. H., 1970, Stress corrosion and static fatigue ofglass: Journal of the American Ceramic Society, 53, 543–548. doi: 10.1111/j.1151-2916.1970.tb15962.x
  24. Wiederhorn, S. M., and Johnson, H., 1973, Effect of electrolyte pH on crackpropagation in glass: Journal of the American Ceramic Society, 56, 192–197. doi: 10.1111/j.1151-2916.1973.tb12454.x
  25. Williams, D. P., and Evans, A. G., 1973, A simple method for studying slowcrack growth: Journal of Testing and Evaluation, 1, 264–270