Issue 27

G. Kuidong et alii, Frattura ed Integrità Strutturale, 27 (2014) 43-52; DOI: 10.3221/IGF-ESIS.27.06 49 Submitted the rock mechanical properties and the geometric parameters of rock fragment to Eq.18, then the k can be obtained as 0.0102. According to the value of k , we can conclude that the fracture energy for generating new fracture surface accounts for only a small part of total work, and the most part of total work is used for rock plastic deformation, rock damage, crushing zone formed and so on. Now, we get the value of k , and if we also get the other parameter values, we can obtain the peak cutting force P c by Eq.8. Figure 7 : Variation curve of cutting force. The peak cutting forces of experiments, this model and Evans model with different rock types and cutting parameters are shown in Tab.2 [5-7]. The relationships between experimental peak cutting force with theoretical peak cutting force from this model and Evans model are investigated by linear regression method, and their linear regression results are shown in Tab.3. The significance of regression result less than 0.05 indicates that the regression relationships are correct and reliable. Fig.8 and Fig.9 shows the fitted relationships between experimental peak cutting force and two theoretical models (Evans model and this model) respectively. The correlation between experimental and theoretical peak cutting force of this model is better than Evans’s, and the slopes of the fitted line equations are 2.11 and 5.13. It indicates that the prediction of peak cutting force by this model has more correctness and reliabilities than Evans theory. Type σ c σ t E K I d =9mm d =5mm P c Exp (N) P c (N) P c E (N) P c Exp (N) P c (N) P c E (N) Chromite1 32 3.7 3.5 0.538 14830 8230 3660 7160 3759 920 Chromite2 47 4.5 2.3 0.654 26490 12642 3690 10210 5773 920 Chromite3 46 3.7 2.9 0.538 16240 9309 2550 8710 4251 3190 Harsburgite 58 5.5 2.1 0.799 26910 17057 4470 14970 7789 1120 Serpantinite 38 5.7 2.3 0.828 20150 16338 7320 7850 7462 1830 Trona 30 2.2 3.4 0.320 12260 4503 1380 3880 2056 350 Anhydrite 82 5.5 11.0 0.799 16300 10558 3160 12520 4822 790 Sandstone1 114 6.6 17.0 0.959 25920 12138 3270 19690 5544 820 Sandstone2 174 11.6 28.0 1.686 48100 20946 6620 23250 9566 1660 Sandstone3 87 8.3 33.3 1.206 15920 11739 6780 9090 5361 1700 Tuff1 10 0.9 1.1 0.131 4020 1911 690 2050 873 170 Tuff2 11 1.2 1.4 0.174 11840 2509 1120 7080 1145 280 Tuff3 27 2.6 2.4 0.378 7200 5993 2140 3770 2735 540 Tuff4 14 1.5 1.6 0.218 7300 3239 1380 2830 1479 340 Tuff5 19 2.3 1.3 0.334 7350 6037 2380 3440 2757 600 Tuff6 6 0.2 0.4 0.029 2180 523 57 1330 238 14 P c Exp : The PCF of experiments ; P c E : The PCF of Evans model; P c : The PCF of this model Table 2 : Rock mechanical property and the PCF.