Study The Inclined Rock Crack Propagation Under Uniaxial Compression

Cracks are widely existed in rock, and many engineering accidents(such as building collapse, slope instability, tunnel collapse, etc.) are closely related to the crack propagation. Therefore, it is very important to study crack propagation in engineering construction. Rock crack propagation has attracted much attention, and it has achieved a lot of achievements, but the study on the crack propagation path is not enough, and the influence of plastic deformation on the crack propagation process is mostly neglected. In this paper, the propagation law of the inclined crack is studied, the objects are brittle rock material(neglect the plastic deformation) and rock material with obvious plastic deformation.To brittle rock material, consider the frictional effects of crack surface, solve the initiation angle and propagation path with the circumferential tensile stress criterion and Mohr-Coulomb failure criterion as fracture criterion respectively, and then compared with experimental data. Results show: the initiation angle and propagation path solved by the circumferential tensile stress criterion can match well with experimental data and friction has less impact on crack propagation when slope angel of inclined crack is large; the initiation angle and propagation path solved by Mohr-Coulomb failure criterion can match well with experimental data and friction has a great influence on crack propagation when slope angel of inclined crack is small.To rock material with obvious plastic deformation, the edge dislocation is used to instead the defect on the extended surface, the formation of dislocation is the process of plastic deformation, the plastic zone is the most likely to form a crack. The corresponding crack dislocation models are established to study the law of crack propagation in the form of compression shear failure and tensile failure, and compare the results with the experimental data. For compression shear failure, reduce the plastic zone is to 50 equal spaced dislocation points,utilize MATLAB to solve the initiation angle and propagation path when stress of region between dislocations meet the Mohr-Coulomb criterion, results show that the propagation path can match well with experimental data when slope angel is small. For tensile failure, calculate the propagation path when tensile stress achieves the yield stress, and compare with experimental data, results show that the propagation path can match well with experimental data when slope angel is large.Overall, the circumferential tensile stress criterion and Mohr-Coulomb failure criterion can be used to research the brittle crack propagation rules, crack-dislocation model can be used to consider the rock plastic deformation and analyze the effect to the propagation of rock crack.