The assessment of rock brittleness effect on drillability


1 Department of Geology, Faculty of Sciences, Bu-Ali Sina University of Hamedan, Iran

2 Department of Mining Engineering, Faculty of Engineering, Tarbiat Modares University of Tehran, Iran

3 Department of Geology, Faculty of Sciences, Ferdosi University of Mashhad, Iran


The brittleness is an important rock property and effective in rock excavation. Recognition of the relationship between drillability and brittleness will increase performance the rock excavations. In this study, the number of 16 samples has been studied rock mechanical properties of granite, granodiorite, dolomite, hornfels and marble in the area of Glass water conveyance tunnel project in the margin of Naghadeh city. The number of 16 brittleness indices were calculated with stress-strain curve, modulus and rocks strength properties. In addition, Sievers’ J-miniature drill test and the brittleness test are carried out and DRI values were calculated. The statistical relationships between the brittleness indices and the drilling rate index are showed a strong correlation between B3 brittleness index (R2= 0.76 and RMSE= 1.02 coefficients) and B4 brittleness index (R2= 0.79 and RMSE= 0.95 respectively) with rocks drilling rate index. The statistical relationships are compared with study former between the brittleness indices and the drilling rate index of rocks. The Precision and accuracy of relationships are confirmed with relationships former. In addition, a model was presented with multiple regression analysis. It can use for the assessment of rock drillability.


Altindag, R., 2002. The evaluation of rock brittleness concept on rotary blast hold drills. Journal of the Southern African Institute of Mining and Metallurgy 102(1), 61-66.
Altindag, R., Guney, A., 2010. Predicting the relationships between brittleness and mechanical properties (UCS, TS and SH) of rocks. Scientific research and Essays 5(16), 2107-2118.
 Andreev, G.E., 1995. Brittle failure of rock materials: Test results and constitutive models. A.A. Balkema, Rotterdam, p. 446.
ASTM, 2001. Standard Practice for Preparing Rock Core Specimens and Determining Dimensional and Shape Tolerances. American Society for Testing and Materials, D4543.
ASTM, 2004. Test method for compressive strength and elastic moduli of intact rock core specimens under varying states of stress and temperatures, D7012-04.
ASTM, 2008. Standard test method for splitting tensile strength of intact rock core specimens, D3967-08.
Chen, J., Zhang, G., Chen, H., Yin, X., 2014. The Construction of Shale Rock Physics Effective Model and Prediction of Rock Brittleness. SEG Annual Meeting, Society of Exploration Geophysicists, 2861-2865.
Copur, C., 2003. A set of indices based on indentation tests for assessment of rock cutting performance and rock properties. Journal of The Southern African Institute of Mining and Metallurgy 103, 589-599.
Dahl, F., 2003. DRI, BWI, CLI and NTNU Standards. Angleggsdrift, Trondheim, p. 21.
Dahl, F., Bruland, A., Jakobsen, P.D., Nilsen, B., Grov, E., 2012. Classifications of properties influencing the drillability of rocks based on the NTNU/SINTEF test method. Tunneling and Underground Space Technology 28, 150-158.
Gong, Q.M., Zhao, J., 2007. Influence of rock brittleness on TBM penetration rate in Singapore granite. Tunnelling and Underground Space Technology 22(3), 317-324.
Goodway, B., Perez, M., Varsek, J., Abaco, C., 2010. Seismic petrophysics and isotropicanisotropic AVO methods for unconventional gas exploration. The Leading Edge 29 (12), 1500-1508.
Hajiabdolmajid, V., Kaiser, P., 2003. Brittleness of rock and stability assessment in hardrock tunnelling. Tunnlling Underground Space Technology 18, 35-48.
Hucka, V., Das, B., 1974. Brittleness determination of rocks by different methods. International Journal Rock Mechanics and Mining Sciences & Geomechanics Abstracts 11, 389-392.
Jarvie, D.M., Hill, R.J., Ruble, T.E., Pollastro, R.M., 2007. Unconventional shale-gas systems: The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessment. American Association of Petroleum Geologists Bulletin 91(4), 475-499.
Lawn, B.R., Marshall D.B., 1979. Hardness, toughness, and brittleness: an indentation  analysis. Journal of the American Ceramic Society 62(7-8), 347–350.
Luan, X., B, Di., J, Wei., X, Li., K, Qian., J, Xie., P, Ding., 2014. Laboratory Measurements of Brittleness Anisotropy in Synthetic Shale with Different Cementation. SEG Annual Meeting. Denver, Society of Exploration Geophysicists, 3005-3009.
Macias, J.F., Dahl, F., Bruland, A., Kasling, H., Thuro, K., 2017. Drillability Assessments in Hard Rock. 3rd Nordic Rock Mechanics Symposium, Helsinki, Finland, Johansson & Raasakka (Eds.), 1-12.
Meng, F., Zhou, H., Zhang, C., Xu, R., Lu, J., 2015. Evaluation methodology of brittleness  of rock based on postpeak stress-strain curves. Rock Mechanics and Rock Engineering  48(5), 1787-1805.
Nejati, H., Moosavi, S.A., 2017. A new brittleness index for estimation of rock fracture toughness. Journal of Mining and Environment 8, 83-91.
Ozfırat, M.K., Yenice, H., Simsir, F., Yarali, O., 2016. A new approach to rock brittleness and its usability at prediction of drillability. Journal of African Earth Sciences 119, 94-101.
Quinn J.B., Quinn, G.D., 1997. Indentation brittleness of ceramics: a fresh approach. Journal of Materials Science 32(16), 4331–4346.
Reichmuth, D.R., 1967. Point load testing of brittle materials to determine tensile strength and relative brittleness. The 9th US Symposium on Rock Mechanics (USRMS). American Rock Mechanics Association, pp. 134–159.
Rickman, R., Mullen, M.J., Petre, J.E., Grieser, W.V., Kundert, D., 2008. A practical use of shale petrophysics for stimulation design optimization: All shale plays are not clones of the Barnett Shale, SPE Annual Technical Conference and Exhibition, Society of Petroleum Engineers.
Sun, S.Z., Wang, K.N., Yang, P., Li, X.G., Sun, J.X., Liu, B.H., Jin, K., 2013. Integrated Prediction of Shale Oil Reservoir Using Pre-Stack Algorithms for Brittleness and Fracture Detection, Beijing, International Petroleum Technology Conference.
Suorineni, F.T., Chinnasane, D.R., Kaiser, P.K., 2009. A procedure for determining rock- type specific Hoek-Brown brittle parameter s. Rock Mechanics and Rock Engineering 42(6), 849–881.
Tarasov, B., Potvin, Y., 2013. Universal criteria for rock brittleness estimation under triaxial compression. International Journal of Rock Mechanics & Mining Sciences 59, 57- 69.
Tarasov, B.G., Potvin, Y., 2012. Absolute, relative and intrinsic rock brittleness at compression. Mining Technology 121(4), 218-225.
Yagiz, S., 2009. Assessment of brittleness using rock strength and density with punch penetration test. Tunnelling and Underground Space Technology 24(1), 66-74.
 Yarali, O., 2007. Investigation of the relations between rock brittleness and drilling rate index. In: Proceedings of the 20th International Mining Congress of Turkey, (in Turkish), Ankara, Turkey, pp. 217-224.
Yarali, O., Kahraman, S., 2011. The drillability assessment of rocks using the different brittleness values. Tunnelling and Underground Space Technology 26, 406-414.
 Yarali, O., Soyer, E., 2011. The effect of mechanical rock properties and brittleness on drillability. Scientific Research and Essays 6(5), 1077-1088.
Yenice, H., Mehmet, V., Ozdogan, M., Ozfırat, K., 2018. A Sampling Study on Rock Properties Affecting Drilling Rate Index (DRI). Journal of African Earth Sciences, pp. 1-18.
Zare, S., Bruland, A., 2013. Applications of NTNU/SINTEF drillability indices in hard rock tunneling. Rock Mechanics and Rock Engineering 46(1), 179-187.