考虑残余强度的层状岩体损伤演化规律

Damage Evolution Law of Layered Rock Mass Considering Residual Strength

为更加真实准确地描述层状岩体的损伤演化过程,结合横观各向同性材料的弹性理论和损伤力学理论,采用修正的Lemaitre应变等价假设,建立了考虑残余强度的层状岩体损伤本构模型,通过页岩、千枚岩和板岩的三轴试验数据验证了模型的准确性,并分析了不同层理角度岩体的全过程损伤演化规律.研究表明:模型既可以描述层状岩体的弹性变形,又可以较好地反映峰后应变软化过程;在初期加载过程中岩体的损伤值基本为0,随着应力增加,损伤值呈现出缓慢增长、加速增长、减速增长以及达到残余强度后稳定于1;页岩层理角度为60°时损伤演化曲线最陡,损伤发展速度最快,最先破坏,千枚岩层厚较薄,强度更低,层理角度为90°时最先破坏,而板岩相对较厚,强度更高,层理角度为45°时最先破坏;岩体层理弱面的存在,导致了力学性能和破坏模式的各向异性,损伤演化规律也表现出明显的差异性.

In order to describe the damage evolution process of layered rock mass more truly and accurately,a damage constitutive model for layered rock mass considering the residual strength was established,which adopted modified Lemaitre strain equivalence hypothesis,combining the elastic theory of transversely isotropic materials and the damage mechanics theory.The accuracy of the model was verified by the triaxial test data of shale,phyllite,and slate,and the whole process damage evolution law of rock mass with different bedding angles was analyzed.The research results showed that the model could describe the elastic deformation of layered rock mass,but also reflect the post-peak strain softening process well.In the initial loading process,the damage value of rock mass was near zero.With the increase of stress,the damage value showed slow growth,accelerated growth,and decelerated growth,until it reached the residual strength and then stabilized at one.When the bedding angle of the shale was 60°,the damage evolution curve was the steepest,the damage speed was the fastest,and it shale failed first.Because the phyllite was thinner in thickness and lower in strength,it failed first when the bedding angle was 90°.However,the slate was relatively thick and had higher strength,and it failed first when the bedding angle was 45°.The existence of a weak bedding surface of rock mass led to the anisotropy of mechanical properties and failure modes,and the damage evolution law showed remarkable differences.