THE APPLICATION OF MAXIMUM CIRCUMFERENTIALTENSILE STRAIN CRITERION AND ITS APPLICATION IN 3D CRACK PROPAGATION USED IN MINING SCIENCES

摘要

3D crack hydraulic fracturing is a hot and difficult problem, which is also a classical problem in mining science and technology. In order to study the crack propagation law of 3D crack under different internal water pressure and bi-axial stress, the meaning of hydraulic fracturing crack growth factor D is defined, and the crack propagation process under different D values is analyzed numerically. The propagation length of the crack characteristic point and the stress intensity factor of the crack front arc calculated, and the results arc compared with the existing cxperiinental results. The results show that the numerical simulation of the crack propagation under bi-axial pressure is carried out to match the experimental results. The higher tlic fracturing crack growth factor D is, the more the crack growth pattern changes from the airfoil wrapped crack growth to the self-similar crack propagation. The higher the crack growth factor D. the larger the crack growth rate at the end of long axis and short axis, and tl>c smaller the rate of crack growth at the end of long axis. Crack mode I and mode III stress intensity factor reached the minimum at the end of the long axis of the crack and the maximum at the end of the short axis, while the stress intensity factor of mode II of tlK crack reached the minimum at the end of the short axis of the crack, the stress intensity factor rcached tlw minimum at the end of the crack. The larger the crack grouih factor D. the greater the absolute value of the three stress intensity factors. The research results provide a reference for the understanding of crack propagation law of 3D deep buried crack under hydraulic fracturing and the dcvcl-opment of the mining science.