Effect of intermittent joints on the mechanical properties of rock mass

The models of rock mass with different joint states were established by using particle flow code (PFC) numerical simulation procedures, and then their biaxial test was simulated. The effects of intermittent joints on the rupture forms and mechanical properties of rock mass were numerically analyzed from three aspects of rock bridge length, joint length, and dip angle. The failure mode of rock bridges is mainly tensile-shear failure because of the extension of wing cracks, but the failure mode of the models can be concluded to be the extension of wing cracks and secondary cracks and the failure of rock bridges, exhibiting obvious creep properties and ductile failure. The peak strength and elastic modulus are less influenced by the change in length of rock bridges; however, compared to the length of rock bridges, the mechanical properties of the jointed rock samples are more sensitive to the length of intermittent joints. As far as models with the different dip angles of intermittent joints are concerned, the initial rupture forms of the models are different, the failure mode of the model with the dip angle of 0° is the extension of wing cracks and secondary cracks, but the middle rock bridge has not been run through, and the initial crack strength and peak strength of the model with the dip angle of 15° is maximum.