节理倾角对单节理岩样变形破坏影响的数值模拟

Effect of Joint Inclination on Deformation and Failure of Rock Specimen with a Single Joint in Plane Strain Compression

采用FLAC模拟了节理倾角对各向异性岩样峰值强度、力学行为及剪切带图案的影响。节理由实体单元模拟。对于节理之外的岩石,采用莫尔库仑与拉破坏复合的破坏准则,峰后本构关系选择线性应变软化模型;对于节理,采用理想弹塑性的莫尔库仑准则。结果表明,无节理密实岩石的峰值强度最高。节理岩样的剪切应变或集中在节理上,或集中在新剪切带上,峰值强度随节理倾角而改变。新剪切带启动于节理的端部,然后沿其固有方向传播。当节理倾角适中时,节理岩样的峰值强度较低,岩样的行为受控于节理。当节理倾角较高或较低时,可观测到应变软化行为。若节理倾角较低,新剪切带的长度随节理倾角的降低而增加,这导致了陡峭的峰后应力-应变曲线。若节理倾角较高,由于节理倾角对新剪切带的厚度和倾角几乎没有影响,因此,峰后斜率不依赖于节理倾角。

Peak strength, mechanical behavior, and pattem of shear band （SB） of anisotropic jointed rock specimen were modeled by FLAC. The failure criterion of intact rock was a composite Mohr-Coulomb criterion with tension cut-off and the post-peak constitutive relation was linear swain-softening. Joint was treated as quadrate elements of ideal plastic material beyond peak strength. Intact rock without joint has a higher peak strength. Shear strain of jointed rock is concentrated into joint or new generated SBs. Peak strength of jointed rock depends on the joint inclination （JI）. The new SBs are origanated from the two ends of joint and propagate along their inherent directions. For moderate JI, lower strength and the behavior of jointed rock specimen are mainly governed by joint. For lower or higher JI, the peak strength of jointed rock specimen is higher and the strain-softening behavior is apparent. For lower JI, slip along SB has a greater contribution to the axial strain of jointed rock, leading to steeper post-peak stress-strain curve. For higher JI, the slope of postpeak stress-strain curve is not dependent on JI since JI does not influence the thickness and the inclination of SB.