Issue 27

G. Kuidong et alii, Frattura ed Integrità Strutturale, 27 (2014) 43-52; DOI: 10.3221/IGF-ESIS.27.06 50 Item DF SS MS F-value Prob>F P c exp - P c Model 1 2.5e9 2.5e9 133.7 1.4e-12 Error 30 5.6e8 1.9e7 Total 31 3.1e9 1.6 P c Exp - P c E Model 1 1.6e9 1.6e9 31.7 3.7e-6 Error 30 1.5e9 5.0e7 Total 31 3.1e9 DF: Degrees of freedom; SS: Sum of squares; MS: Mean square Table 3 : The regression analysis results of the PCF obtained from different method. Figure 8 : The relationship between the predicted and experimental PCF. Figure 9 : The relationship between the PCF of Evans model and experiments. C ONCLUSIONS n this paper, a theoretical model for predicting the peak cutting force has been set up and verified, we get following conclusions: (1) The theoretical model of rock vertical fracture has been established by maximum tensile criterion and verified I