Issue 27

G. Kuidong et alii, Frattura ed Integrità Strutturale, 27 (2014) 43-52; DOI: 10.3221/IGF-ESIS.27.06

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.

d =9mm

d =5mm

σ c

σ t

E

K I

Type

P c E (N)

P c E (N)

P c Exp (N)

P c

P c Exp (N)

P c

(N)

(N)

Chromite1 Chromite2 Chromite3 Harsburgite Serpantinite Anhydrite Sandstone1 Sandstone2 Sandstone3 Trona

32 47 46 58 38 30 82 87 10 11 27 14 19

3.7 4.5 3.7 5.5 5.7 2.2 5.5 6.6 8.3 0.9 1.2 2.6 1.5 2.3 0.2

3.5 2.3 2.9 2.1 2.3 3.4

0.538 0.654 0.538 0.799 0.828 0.320 0.799 0.959 1.686 1.206 0.131 0.174 0.378 0.218 0.334 0.029

14830 26490 16240 26910 20150 12260 16300 25920 48100 15920

8230 3660 12642 3690 9309 2550 17057 4470 16338 7320 4503 1380 10558 3160 12138 3270 20946 6620 11739 6780 1911 690 2509 1120 5993 2140 3239 1380 6037 2380

7160

3759 920 5773 920 4251 3190 7789 1120 7462 1830 2056 350 4822 790 5544 820 9566 1660 5361 1700 873 170 1145 280 2735 540 1479 340 2757 600

10210

8710

14970

7850 3880

11.0 17.0 28.0 33.3

12520 19690 23250

114 174

11.6

9090 2050 7080 3770 2830 3440 1330

Tuff1 Tuff2 Tuff3 Tuff4 Tuff5 Tuff6

1.1 1.4 2.4 1.6 1.3 0.4

4020

11840

7200 7300 7350 2180

6

523 57

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.

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