中文摘要：

在各向同性损伤条件下，考虑岩石损伤过程中的刚度降低和体积扩容，通过理论推导建立了岩石发生分又失稳时的最大硬化模量和临界局部化方向，探讨了局部化方向角对于岩石的损伤程度和初始泊松比的依赖关系，并对平面应力与平面应变两种条件下单轴拉伸试件的分叉特性进行了对比分析。研究表明，岩石的初始泊松比与损伤程度越大，局部化方向角越大：尽管平面应力与平面应变条件下单轴拉伸问题的局部化方向角具有相似的变化趋势，但平面应力条件下的局部化方向角低于平面应变条件下同样情况下的局部化方向角。

英文摘要：

The critical bifurcation orientation and its corresponding hardening modulus for rock-like geomaterials are derived considering the effect of stiffness degradation and volumetric dilatancy under the assumption of isotropic damage. The dependency of the localized orientation on damage degree and initial Poisson s ratio of rock is examined and the bifurcation behavior of uniaxial tension sample under plane-stress condition is compared with that under plane-strain condition. It is shown that the localization orientation angle intimately depends on both initial Poisson＇s ratio and damage degree for the rock sample under uniaxial tension condition. As the initial Poisson＇s ratio or damage degree increases, the orientation angle of the plane on which＇localization tends to be initiated gets to increase. At the same time, the localization orientation angle of rock sample under plane-stress condition is lower than that under plane-strain condition.