Issue 27

G. Kuidong et alii, Frattura ed Integrità Strutturale, 27 (2014) 43-52; DOI: 10.3221/IGF-ESIS.27.06 51 through experiments. The regression formula of vertical fracture angle also has been obtained by numerical analysis and polynomial regression. All of these work can provide a basis for the research on rock cutting theory. (2) A theoretical model for predicting peak cutting force of conical pick in rock cutting process has been established by elastic fracture mechanics theory. The regression analysis between the results of experimental and predicted by this model shows that correlation coefficient is equal to 0.81 and significance is less than 0.05. (3) The relationships between experimental peak cutting force and calculated values by the present model and Evans model are investigated by linear regression analysis, and it shows that the prediction of peak cutting force of this model has more correctness and reliabilities than Evans model. The model established by this paper can provide a better guidance for design and study of conical pick and cutting mechanism. A CKNOWLEDGEMENTS he paper was financially supported by the National 863 Plan of China(2012AA062104), National Natural Science Foundation of China(51005232), Jiangsu Ordinary University Graduate Students Scientific Research Innovation Project(CXZZ11-0289), the Jiangsu Provincial Natural Science Foundation of China (No. BK20131116), the Fundamental Research Funds for the Central Universities (Project No.2012QNA22) and the Priority Academic Program Development of Jiangsu Higher Education Institutions. R EFERENCES [1] Evans, I., A theory of the picks cutting force for point-attack, International Journal of Mining Engineering, 2(1) (1984) 63-71. [2] Roxborough, F.F, Liu, Z.C., Theoretical considerations on pick shape in rock and coal cutting. Proceedings of sixth underground operator’s conference, Australia, (1995) 189-193. [3] Goktan, R. M., A suggested improvement on Evans’s cutting theory for conical bits, Proceedings of fourth symposium on mine mechanization automation, 1 (1997) 57-61. [4] Copur, H., Bilgin, N., et al., A set of indices based on indentation tests for assessment of rock cutting performance and rock properties, The Journal of The South African Institute of Mining and Metallurgy, 11 (2003) 589-599. [5] Bilgin, N., Demircin, M. A., et al., Dominant rock properties affecting the performance of conical picks and the comparison of some experimental and theoretical results, International Journal of Mining Engineering, 43(1) (2006) 139-156. [6] Tiryaki, B., Boland, J.N., Li, X.S., Empirical models to predict mean cutting forces on point attack pick cutters, International Journal of Rock Mechanics & Mining Sciences, 47(5) (2010) 858-864. [7] Su O., Akcin N.A., Numerical simulation of rock cutting using the discrete element method, International Journal of Rock Mechanics & Mining Sciences, 48(3) (2011) 434-442. [8] Rojek, J., Onate, E., et al., Discrete element simulation of rock cutting, International Journal of Rock Mechanics & Mining Sciences, 48 (2011) 996 -1010. [9] John, P., Loui, U.M., Rao K., Numerical studies on chip formation in drag-pick cutting of rocks, Geotechnical and Geological Engineering, 30(1) (2011) 145-161. [10] Sneddon, I.N., Boussinesq’s problem for a rigid cone, Mathematical Proceedings of the Cambridge Philosophy Society, 44(4) (1948) 492-507. [11] Chiaia, B., Fracture mechanics induced in a brittle material by hard cutting indenter, International Journal of Solids and structures, 38 (2001) 7747-7768. [12] Li, L.Y., Ju, Y., Zhao, Z.W., et al., Energy analysis of rock structure under static and dynamic loading conditions, Journal of China Coal Society, 34(6) (2009) 737-741.(In Chinese) [13] Xie, H.P., Ju, Y., Li, L.Y., Criteria for strength and structural failure of rocks based on energy dissipation and energy release principles, Chinese Journal of Rock Mechanics and Engineering, 24(17) (2005) 3003-3010. (In Chinese) [14] Lawn, B., Fracture of brittle solids, Cambridge: Cambridge University Press (1993). [15] Zhang, Z.X., An empirical relation between mode I fracture toughness and the tensile strength of rock, International Journal of Rock Mechanics & Mining Sciences, 39 (2002) 401-406. [16] Almond, E., McCormick, N., Constant-geometry edge-flaking of brittle materials, Nature, 321(3) (1986) 53-55. T