岩石塑性变形条件下的Mohr-Coulomb屈服准则

传统的Mohr-Coulomb强度准则仅描述了峰值强度状态下正应力和剪应力之间的关系,作为岩石破坏的判据.本文拓展概念,提出Mohr-Coulomb屈服准则表述岩石发生塑性变形后不同应力状态下屈服面的应力应变关系.在总结实验研究的基础上建立了使用三轴压缩试验数据确定塑性参数c和φ随内变量κ变化的实验技术方法,给出了评价各向同性模型精度的参量表达以及某些测试结果.采用具有各向同性强(软)化规律的Mohr-Coulomb屈服准则,利用岩石的初始屈服、峰值屈服和残余屈服三组参数可以将全过程应力应变曲线简化表征为四直线模型,它比三线性模型有更广泛的适用性.本文的结果为工程地质数值模拟提供了理论和实验基础,具有指导意义.

Mohr-Coulomb yield criterion in rock plastic mechanics

Conventional Mohr-Coulomb strength criterion only describing the relationship between normal stress and shear stress on the failure surface at the peak strength is used as a criterion to determine whether the rock has failed. This study expands the concept of the Mohr-Coulomb strength criterion by suggesting that the Mohr-Coulomb yield criterion can express the stress relationship of strain and stress of failure surface under various stress states after plastic deformation occurs. Based on the experimental study, an experiment approach which employs triaxial compression testing data to determine plastic parameters c and φ which vary with the internal variable κ was established, and parameter expression used to assess the accuracy of isotropic modeling and some testing results were given. The Mohr-Coulomb yield criterion of isotropic hardening or softening, in which stress-strain curves of whole process is simplified into a four-line model using initial, peak and remnant parameters of rock, is more applicable than the trilinear model by Toshikazu. The result in this study provides theoretical and experimental basis for engineering and geological numerical simulation, thus being of instructive importance.