Tunnel and Underground Space (터널과지하공간)

Korean Society for Rock Mechanics and Rock Engineering (한국암반공학회)
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Characterization of Microstructures and Fracture Toughness of SR Specimen in Granitic Rocks

화강암에서 SR 시편의 파괴인성과 미세구조적인 특징

  • 이상은 (강원대학교 삼척캠퍼스 에너지자원공학과)
  • Received : 2010.06.18
  • Accepted : 2010.06.25
  • Published : 2010.06.30
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Abstract

Three relatively homogeneous granitic rocks were studied to investigate the relationship between their microstructural properties and fracture toughness. Fracture toughness and ultrasonic velocity were varied with the orientation of mineral's long axis and microcrack, obtained from optical microscope. The lowest fracture toughness values are obtained, when the fracture propagates parallel to weakness planes which have the orientation of mineral's long axis and microcrack, in other words, when weakness planes develop perpendicular to the direction of tensile stress agrees with that of rift plane. The fracture toughness values, measured with the short rod method, varied from 1.63 to 2.62 MPa $m^{0.5}$, and their values are related with the average grain size and average microcrack length.

비교적 균질한 3가지 화강암이 암석의 미세구조적 특성과 파괴인성 사이의 관계를 조사하기 위하여 연구되었다. 광학 현미경 관찰로 분석된 광물입자의 장축과 미세균열의 방위에 의하여 파괴인성 및 초음파 속도의 변화를 보였다. 가장 작은 값을 나타내는 파괴인성은 인장응력 방향과 수직하게 발달된 광물입자의 장축 및 미세균열의 방향이 주결에 일치할 때로서 파괴가 연약면인 광물입자의 장축이나 미세균열의 우세방향에 평행하게 전달될 때이다. SR 시편으로 측정된 파괴인성값은 1.63~2.62 MPa $m^{0.5}$의 변화를 보이며, 그 값들은 광물입자의 평균크기 및 미세균열의 평균길이와 관련된다.

Keywords

References

  1. Atkinson, B. K., 1987, Fracture mechanics of rock, New York, Academic Press.
  2. Whittaker, B. N., R. N. Singh and G. Sun, 1992, Rock fracture mechanics; principles, design and application, Amsterdam, Elsevier.
  3. Nasseri, M. H. B., B. Mohanty and P. Y. F. Robin, 2005, Characterization of microstructures and fracture toughness in five granitic rocks, Int. J. of Rock Mech. & Min. Sci., Vol. 42, pp. 450-460. https://doi.org/10.1016/j.ijrmms.2004.11.007
  4. Inoue, M. and M. Ohomi, 1981, Relation between uniaxial compressive strength and elastic wave velocity of soft rock, Porceedings of the int'l Symp. on Weak Rock, Tokyo, pp. 9-13.
  5. D'Andrea, D. V., R. L. Fisher and D. E. Fogelson, 1965, Prediction of compressive strength from other rock properties, US Bureau of Mines Report of Investigations, Vol. 6702.
  6. King, M. S., N. A. Chaudhry and A. Shakeel, 1995, Experimental ultrasonic velocities and permeability for sandstones with aligned cracks, Int'l J. Rock Mech. Min. Sci., Vol. 32(2), pp. 155-163. https://doi.org/10.1016/0148-9062(94)00033-Y
  7. Gaviglio, P., 1989, Longitudinal waves propagation in a limestone: the relationship between velocity and density, Rock Mech. Rock Eng., Vol. 22, pp. 299-306. https://doi.org/10.1007/BF01262285
  8. Yasar, E. and Y. Erdogan, 2004, Correlating sound velocity with the density, compressive strength and Young's modulus of carbonate rocks, Int'l J. Rock Mech. Min. Sci. Vol. 41, pp. 871-875. https://doi.org/10.1016/j.ijrmms.2004.01.012
  9. Sano, O., Y. Kudo and Y. Mizuta, 1992, Experimental determination of elastic constants of Oshima granite, Barre granite, and Chelmsford granite, J. Geophys. Res., Vol. 97, pp. 3367-3379. https://doi.org/10.1029/91JB02934
  10. Nasseri, M. H. B. and B. Mohanty, 2008, Fracture toughness anisotropy in granitic rocks, Int. J. of Rock Mech. & Min. Sci., Vol. 45, pp. 167-193. https://doi.org/10.1016/j.ijrmms.2007.04.005
  11. Barker, L. M., 1977, A simplied method for measuring plane strain fracture toughness, Eng. Fract. Mech., Vol. 9, pp. 361-369. https://doi.org/10.1016/0013-7944(77)90028-5
  12. Ouchterlony, F., 1988, Suggested method for determing the fracture toughness of rock, Int. J. of Rock Mech. & Min. Sci., Vol. 25, pp. 71-96.
  13. Ouchterlony, F., 1990, Fracture toughness testing of with core based specimens, Eng. Fract. Mech., Vol. 35, pp. 351-366. https://doi.org/10.1016/0013-7944(90)90214-2
  14. Nasseri, M. H. B., A. Schubnel and R. P. Young, 2007, Coupled evolutions of fracture toughness and elastic wave velocities at high crack density in thermally treated Westerly granite, Int. J. of Rock Mech. & Min. Sci., Vol. 44, pp. 601-616. https://doi.org/10.1016/j.ijrmms.2006.09.008
  15. Douglass, P. M. and B. Voight, 1969, Anisotropy of granite: a reflection of microscopic fabric. Geotechnique, Vol. 19, pp. 376-398. https://doi.org/10.1680/geot.1969.19.3.376