# 짧은 보 압축 시험법을 이용한 암석의 모드 II 파괴 인성 측정

• Ko, Tae Young (SK Engineering & Construction, Infra Engineering Team 2) ;
• Kemeny, J. (University of Arizona)
• Accepted : 2013.10.03
• Published : 2013.11.30

#### Abstract

The mode II fracture toughness and strength due to shear stress are important parameters in the stability of caprock and injection zone with application to geological sequestration of carbon dioxide. In this research, a short beam compression test has been used to determine the shear strength and the mode II fracture toughness for Coconino sandstone. The average value of the shear strength and mode II fracture toughness are estimated to be 23.53 MPa and 1.58 MPa${\surd}$m respectively. The stress intensity factor is suggested by finite element analysis using the displacement extrapolation method. The effect of biaxial stress and water saturation on the fracture toughness has also been investigated. The fracture toughness increases with confining stresses, but decreases by 11.4% in fully saturated condition.

#### References

1. Backers, T., Stephansson, O., Rybacki, E. (2002), "Rock fracture toughness testing in Mode II-punch-through shear test", International Journal of Rock Mechanics and Mining Sciences, Vol. 39, No. 6, pp. 755-769. https://doi.org/10.1016/S1365-1609(02)00066-7
2. Chan, S.K., Tuba, I.S., Wilson, W.K. (1970), "On the finite element method in linear fracture mechanics", Engineering Fracture Mechanics, Vol. 2, No. 1, pp. 1-17. https://doi.org/10.1016/0013-7944(70)90026-3
3. Donovan, J.G., Karfakis, M.G. (2004), "Adaptation of a simple wedge test for the rapid determination of mode I fracture toughness and the assessment of relative fracture resistance", International Journal of Rock Mechanics and Mining Sciences, Vol. 41, No. 4, pp. 695-701. https://doi.org/10.1016/j.ijrmms.2004.01.001
4. Fowell, R.J., Hudson, J.A., Xu, C., Chen, J.F. (1995), "Suggested method for determining Mode-I fracture-toughness using cracked chevron notched Brazilian disc (CCNBD) Specimens", International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, Vol. 32, No.1, pp. 57-64. https://doi.org/10.1016/0148-9062(94)00015-U
5. Kim, J.D., Baik, S.K. (1994), "A study on the size and shape effects of specimen for the measurement of fracture toughness in rock", Journal of the Korean Institute of Mineral and Energy Resources Engineers, Vol. 31, pp. 49-59.
6. Ko, T.Y., Kemeny, J. (2006), "Determination of Mode II stress intensity factor using short beam compression test", Proceedings of the ISRM international symposium 2006 and the 4th Asian rock mechanics symposium, Singapore.
7. Ko, T.Y., Kemeny, J., Moon, H.K. (2008), "Determination of the Mode I fracture toughness of rock using the Compact Tension specimen and the effect of specimen size and loading rate on the fracture toughness", Journal of the Korean Society for Geosystem Engineering, Vol. 45, No. 3, pp. 234-241.
8. Lee, S.E. (2010), "Characterization of microstructures and fracture toughness of SR specimen in granitic rocks", Journal of Korean Society for Rock Mechanics, Vol. 20, No. 3, pp. 217-224.
9. Ouchterlony, F. (1988), "Suggested methods for determining the fracture toughness or rock", International Journal of Rock Mechanics and Mining Science & Geomechanics Abstracts, Vol. 25, No. 2, pp. 71-96.
10. Rao, Q., Sun, Z., Stephansson, O., Li, C., Stillborg, B. (2003), "Shear fracture (Mode II) of brittle rock", International Journal of Rock Mechanics and Mining Sciences, Vol. 40, No. 3, pp. 355-375. https://doi.org/10.1016/S1365-1609(03)00003-0
11. Rutqvist, J., Birkholzer, J.T., Tsang, C.F. (2008), "Coupled reservoir-geomechanical analysis of the potential for tensile and shear failure associated with $CO_2$ injection in multilayered reservoir-caprock systems". International Journal of Rock Mechanics and Mining Sciences. Vol. 45, No. 2, pp. 132-143. https://doi.org/10.1016/j.ijrmms.2007.04.006
12. Rutqvist, J., Tsang, C.F. (2003), "TOUGH-FLAC: a numerical simulator for analysis of coupled thermal-hydrologic-mechanical processes in fractured and porous geological media under multi-phase flow conditions", Proceedings of the TOUGH Symposium 2003, Lawrence Berkeley National Laboratory, Berkeley.
13. Watkins, J., Liu, K.L.W. (1985), "A finite element study of the short beam test specimens under mode II loading", Int J Cem Compos Lightweight Concr, Vol. 7, No. 1, pp. 39-47. https://doi.org/10.1016/0262-5075(85)90025-9
14. Yang, H.S., Kim, J.G. (2007), "Trends of research in fracture toughness of rocks", Journal of Korean Society for Rock Mechanics, Vol. 17, No. 6, pp. 448-452.
15. Yoon, J.S., Choi, Y.S. (1993), "A study on fracture toughness following ISRM suggested method", Journal of the Korean Institute of Mineral and Energy Resources Engineers, Vol. 30, pp. 83-92.
16. Yoon, J.S., Jeon, S.W. (2003), "An experimental study on Mode II fracture toughness determination of rock", Journal of Korean Society for Rock Mechanics, Vol. 13, No.1, pp. 64-75.