The Estimation Mode I Fracture Toughness of Rocks using Brittleness Index

Document Type : Research Article

Authors

Department of Mining Engineering, Imam Khomeini International University, Qazvin, Iran

Abstract

Mode I fracture toughness is a signifcant parameter for investigating the failure behavior of rocks. This parameter has several applications in many different felds, such as mining and tunneling.As the determination of fracture toughness by conducting tests is very time consuming and expensive, using empirical relationships is recommended in this regard. In this study, uniaxial compression, the Brazilian and three-point bending tests were conducted on the specimens of limestone, sandstone, tuffte, lithic tuffs, andesite and travertine. This study aims to determine an empirical relation that enables us to estimate mode I fracture toughness of rock using the brittleness index. The study indicates that of the three brittleness indices (B1, B2 and B3), mode I fracture toughness only has a relationship with brittleness index B1 which has the coeffcient of determination R2= 0.995. This relationship, which is an exponential one, reveals that as the brittleness index increases, the magnitude of mode I fracture toughness increases non-linearly. The proposed relationship equivalent was compared with that of Kahraman and Altindag, and the root-mean-square error was calculated in two equations. Given this calculation, it can be said that the proposed equation, with higher precision than the one proposed by Kahraman and Altindag, can be used to estimate mode I fracture toughness of rocks.                               

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References

[1] N. Perez, Fracture Mechanics, Kluwer Academic Publisher, Boston, 2004.
[2] H. Haeri, K. Shahriar, M. Fatehi Marji, P. Maarefvand, Using the Discontinuity Displacement Method for the Analysis of notch Expansion in Quasi-Rocky Materials, Journal of Analytical and Numerical Methods in Mine Engineering, (5( (2013( 38-49.
[3] T. Funatsu, M. Kuruppu, K. Matsui, Effects of temperature and confning pressure on mixed-mode (I–II) and mode II fracture toughness of Kimachi sandstone, International Journal of Rock Mechanics and Mining Sciences, (67) (2014( 1-8.
[4] M.R. Ayatollahi, M.M. Seyyed Mousavi, Investigating the effects of lateral pressure on the depth of the earth on the stress intensity factors of the mixed mode (I and II), Journal of Mining Engineering, 3(5) (2008) 21-32.
[5] Ç. Alkılıçgil, DEVELOPMENT OF SPECIMEN GEOMETRIES FOR MODE I FRACTURE TOUGHNESS  TESTING WITH DISC TYPE ROCK SPECIMENS, Doctoral Dissertation, MIDDLE EAST TECHNICAL UNIVERSITY, 2010.
[6] K.t. Gunsallus, F. Kulhawy, A comparative evaluation of rock strength measures, in: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, Elsevier, 1984, pp. 233-248.
[7] R.B. Bhagat, Mode I fracture toughness of coal, International Journal of Mining Engineering, 3(3) (1985) 229-236.
[8] B. Whittaker, Singh, RN, Sun, G., Rock Fracture mechanics: Principles, design and application, Elsevier., Amsterdam, 1992.
[9] R. Bearman, The use of the point load test for the rapid estimation of Mode I fracture toughness, International Journal of Rock Mechanics and Mining Sciences, 36(2) (1999( 257-263.
[10] G. Brown, D. Reddish, Experimental relations between rock fracture toughness and density, INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING & GEOMECHANICS ABSTRACTS, 34(1) (1997)153- 155.
[11] Z. Zhang, An empirical relation between mode I fracture toughness and the tensile strength of rock, International Journal of Rock Mechanics and Mining Sciences, 39(3) (2002( 401-406.
[12] S. Kahraman, R. Altindag, A brittleness index to estimate fracture toughness, International Journal of Rock Mechanics and Mining Sciences, 41(2) (2004) 343-348.
[13] T.Y. Ko, T.K. Kim, Y. Son, S. Jeon, Effect of geomechanical properties on Cerchar Abrasivity Index (CAI) and its application to TBM tunnelling, Tunnelling and Underground Space Technology, 57 (2016) 99-111.
[14] F. Meng, H. Zhou, C. Zhang, R. Xu, J. Lu, Evaluation methodology of brittleness of rock based on postpeak stress–strain curves, Rock Mechanics and Rock Engineering, 48(5( (2015( 1787-1805.
[15] S. Yagiz, Assessment of brittleness using rock strength and density with punch penetration test, Tunnelling and Underground Space Technology, 24(1) (2009) 66-74.
[16] V. Hucka, B. Das, Brittleness determination of rocks by different methods, in: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, Elsevier, 1974, pp. 389-392.
[17] R. Altindag, Correlation of specifc energy with rock brittleness concepts on rock cutting, Journal of The Southern African Institute of Mining and Metallurgy, 103(3( (2003( 163-171.
[18] R. Altindag, A. Guney, Predicting the relationships between brittleness and mechanical properties (UCS, TS and SH) of rocks, Scientifc research and Essays, 5(16) (2010( 2107-2118.
[19] R. Altindag, The evaluation of rock brittleness concept on rotary blast hold drills, Journal of the Southern African Institute of Mining and Metallurgy, 102(1) (2002) 61-66.
[20] B. Das, V. Hucka, Laboratory investigation of penetration properties of the complete coal series, in: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, Elsevier, 1975, pp. 213-217.
[21] Q. Gong, J. Zhao, Influence of rock brittleness on TBM penetration rate in Singapore granite, Tunnelling and underground space technology, 22(3) (2007) 317-324.
[22] H. Inyang, J. Pitt, Standardization of a percussive drill for measurement of the compressive strength of rocks, in:  The 31th US Symposium on Rock Mechanics (USRMS), American Rock Mechanics Association, 1990.
[23] M.K. Özfırat, H. Yenice, F. Şimşir, O. Yaralı, A new approach to rock brittleness and its usability at prediction of drillability, Journal of African Earth Sciences, 119 (2016( 94-101.
[24] S. Kahraman, Correlation of TBM and drilling machine performances with rock brittleness, Engineering Geology, 65(4( (2002( 269-283.
[25] K. Thuro, Drillability prediction: geological influences in hard rock drill and blast tunnelling, Geologische Rundschau, 86(2) (1997) 426-438.
[26] O. Yarali, S. Kahraman, The drillability assessment of rocks using the different brittleness values, Tunnelling
 and Underground Space Technology, 26(2) (2011) 406- 414.
[27] F. Ouchterlony, Extension of the compliance and stress intensity formulas for the single edge crack round bar in bending, in: Fracture Mechanics for Ceramics, Rocks, and Concrete, ASTM International, 1981.
[28] C. Haberfeld, I. Johnston, Determination of the fracture toughness of a saturated soft rock, Canadian Geotechnical Journal, 27(3) (1990) 276-284.
[29] M.R. Ayatollahi, Mohammad Aliha, M., Heidari Khavas., M., Investigating the Growth of crack in Rock Masses Using Cylindrical Cracked Specimens, in: 14th Iranian Geophysical Conference, 2010.
[30] ISRM, Suggested methods for determining tensile strength of rock materials, Int J Rock Mech Min Sci Geomech Abstr, (1978) 99-103.
[31] ISRM, Suggested methods for Determining the Uniaxial Compressive Strength and Deformability of Rock Materials, Int J Rock Mech Min Sci Geomech Abstr, (1979) 99-103.
[32] Z.P. Bazant, M. Kazemi, Determination of fracture energy, process zone longth and brittleness number from size effect, with application to rock and conerete, International Journal of fracture, 44(2) (1990) 111-131.
[33] B. Minaeian, K. Ahangari, Estimation of uniaxial compressive strength based on P-wave and Schmidt hammer rebound using statistical method, Arabian Journal of Geosciences, 6(6) (2013) 1925-1931.
Amirkabir Journal of Civil Engineering
Volume 50, Issue 2
May and June 2018
Pages 391-400

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