Issue 49

O. Y. Smetannikov et alii, Frattura ed Integrità Strutturale, 49 (2019) 140-155; DOI: 10.3221/IGF-ESIS.49.16 152 b r   , (4) 2 3 4 1 0,5(1 0,5 0, 375 0, 363 0, 731 ) 1 f            Here the notation corresponds to that of Fig. 10. Figure 10 : Diagram of loading of the rock specimen with o-ring fracture for estimating К 1C [15] Figure 11 : Correlation relationship between К 1C and the static modulus of elasticity under the oil bed conditions We tested 25 specimens and based on the obtained results calculated the mean value of К 1С , which was equal to 0.108 MPa·m 1/2 at the maximum and minimum values of 0.044 MPa·m 1/2 and 0.168 MPa·m 1/2 , respectively. The tensile