基于组合模型法的贯通节理岩体动态损伤本构模型

Dynamic damage constitutive model for persistent jointed rock mass based on combination model method

针对贯通节理岩体动态变形特点并结合已有岩石动态本构模型的相关研究成果,将贯通节理岩体变形过程中的动态应力视为贯通节理岩体静态应力分量与相应动态应力分量的叠加。其中贯通节理岩体静态应力分量采用考虑岩石细观损伤的非线性元件、节理面闭合及剪切变形元件等3个基本元件的串联来模拟,动态应力分量采用黏性元件来模拟,从而建立了贯通节理岩体动态单轴压缩损伤本构模型。其次,根据贯通节理岩体在单轴压缩荷载下往往会沿节理面发生剪切破坏的特点,在前述已建立的损伤本构模型中引人节理剪切破坏准则对该模型进行修正,从而更好地考虑了节理剪切强度对该模型的影响,最终建立了考虑节理剪切强度的贯通节理岩体单轴压缩损伤本构模型。最后利用该模型对贯通节理岩体在压缩荷载作用下的力学特性进行了分析计算,重点讨论了节理倾角对岩体单轴动态压缩峰值强度的影响规律。研究结果表明随着节理倾角的变化,节理岩体将发生岩块张拉或剪切破坏、沿节理面的剪切破坏及上述两种破坏模式的复合破坏,相应地节理岩体的单轴压缩动态峰值强度也随之有较大变化。

According to the dynamic deformation characteristics of the persistent jointed rock mass and the relevant results of the existing rock dynamic constitutive models, the dynamic stress of the persistent jointed rock mass is regarded as the summation of two components, which are the static stress and the dynamic stress components respectively. The static stress component of the persistent jointed rock mass is simulated using three basic deformation components connecting in series such as the nonlinear component reflecting the rock mesoscopic damage, joint closure and shear deformation components. The dynamic stress component is simulated using the viscous component. Then the uniaxial dynamic compression damage constitutive model is set up. Next, according to the fact that the persistent jointed rock mass often shears to fail along the joint face under the uniaxial load, the joint shear failure criterion is introduced into the damage constitutive model established above to revise it, which can perfectly consider the effect of the joint shear strength on this model, and the uniaxial compression damage constitutive model of persistent jointed rock mass considering the joint shear strength is established finally. Then this model is adopted to calculate the mechanical properties of the persistent jointed rock mass under compression load, and the effect law of the joint dip angle on the rock mass uniaxial compression dynamic climax strength is especially discussed. The results show that the failure modes of the jointed rock mass include the tensile or shear failure of the intact rock, the shear failure along the joint face and the mixed one of the above two ones with the joint dip angle, and accordingly the uniaxial compression dynamic climax strength of the jointed rock mass greatly varies with it.