| In the geological evolution process, rock masses have developed a lot of cracks,joints and holes due to the complicated load. These defects play an important role in theconstruction safety and structural service life. Therefore, using fracture mechanics tostudy the characteristics of initial cracks in rock masses can help to understand fractureproblems more deeply.The paper, which based on fracture mechanics, studied the stress intensity factor ofthe rockmass before crack initiation and mechanical properties during the crackpropagation process. Compared with the test results, the paper analyzed the effect ofcrack propagation on the specimen.For finite board, it needed to consider the effect of boundary on the stress intensityfactor. The shape factor were introduced to solve the stress intensity factor in the finiteplate on the basis of stress intensity factor in infinite plate. Based on this, this paperanalyzed the influence of crack length and crack eccentricity on the mode I stressintensity factor. And the poly-fit equation and the comparison data with the finiteelement method were presented.This paper has analyzed the inclined crack stress intensity factor under tensilestress and compressive stress respectively. For the compression-shear crack, it is a kindof special mode II crack. Therefore, only mode II stress intensity factor need to bestudied. For limited board, the effect of boundary on the stress intensity factor was takeninto consideration. And the shape factors were introduced to solve the stress intensityfactor in the finite plate. This paper analyzed the influence of the crack angle, the cracklength and the crack eccentricity on the stress intensity factor. And it was concluded thatthe criterion to distinguish the finite plate from the infinite plate. When the parametersatisfys certain conditions, the influence of boundary effect can be ignored.The paper also summarized the fracture mechanism of the rock mass with crackunder uniaxial compression and the work principle of extended finite element method inABAQUS. The extended finite element method is currently most powerfull method todeal with strong discontinuity problems. The crack propagation process were simulatedusing this method. Due to the crack and its crack propagation having an importantinfluence on mechanical properties of rock masses and the compressive strength, thepaper analyzed the stress-strain curve in the process of crack propagation. And the crackgeometry parameters, such as crack location, crack length and crack angle werediscussed to find their impact on the rock peak compressive strength. |
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