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应变局部化分叉的产生强烈依赖于本构模型的弹塑性矩阵。以基于伏斯列夫面超固结黏土三维本构模型为研究对象,推导了三维应力下产生分叉的应力条件,求出了该模型在常平均应力时不同应力路径下分叉三维解析结果。解析结果表明:该模型在应力洛德角为-26.5°～7.5°时,有分叉现象产生,分叉产生于土体应力应变的硬化阶段,且分叉后剪切带倾角变化趋于稳定;而应力洛德角在-30°～-26.5°及7.5°～30°时无分叉现象出现。最后,利用有限元软件ABAQUS的材料子程序接口,采用回映应力更新算法,编写了材料特性子程序,实现了该模型在有限元数值分析中的应用,对均匀各向同性多单元立方体进行常平均应力时真三轴试验数值模拟,并比较数值计算结果与解析结果,验证了解析解与数值模拟结果的一致性。
Strain localization bifurcation strongly depends on the elastic-plastic matrix of the constitutive model. Based on the three-dimensional constitutive model of over-consolidated clay in Fleshivian surface, the bifurcation stress conditions under three-dimensional stress were deduced. The bifurcation three-dimensional analytical results under different stress paths of the model were obtained . The analytical results show that the bifurcation occurs in the stress-strain hardening stage of soil with the stress Rhod’s angle of -26.5 ° ~ 7.5 °, and the dip angle of the shear band after bifurcation tends to be stable ; While the stress Lode angle at -30 ° ~ -26.5 ° and 7.5 ° ~ 30 ° no bifurcation occurs. Finally, by using the material subroutine interface of finite element software ABAQUS, the material property subroutine was written by using the back-stress updating algorithm. The application of the model in the numerical analysis of finite element was realized. For the isotropic multi-unit cube, The true triaxial test is simulated with average stress, and the results of numerical calculation and analytical results are compared to verify the consistency between analytical solution and numerical simulation results.