断续节理对岩体力学性能的影响

Effect of intermittent joints on the mechanical properties of rock mass

采用颗粒流数值模拟程序,建立不同节理状态的岩石试样模型,对其进行双轴试验模拟,从岩桥长度、节理长度和倾角三个方面对断续节理影响下的岩体破裂形式和力学性质进行了数值模拟分析.岩桥的破裂方式为翼裂纹扩展下的拉剪复合破坏,模型破裂大致经历了翼裂纹的扩展、次生裂纹的延伸以及岩桥的贯通三个过程,而且表现出明显的蠕变特性以及延性破坏.岩桥长度的变化对峰值强度和弹性模量影响较小;相比岩桥长度,节理岩样的力学特性对节理长度更加敏感.对于不同的节理倾角,岩石试件表现出不同的初始破裂形式,0°倾角岩样的破裂方式为翼裂纹的扩展和次生裂纹的延伸,中间岩桥没有被贯通,15°倾角岩样的初裂强度和峰值强度最大.

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°.