黏土的各向异性边界面模型

Anisotropic bounding surface model for clays

基于临界状态理论和边界面本构理论,通过引入各向异性张量建立各向异性的边界面和硬化法则,提出了一个可考虑初始各向异性和诱发各向异性对黏土应力应变行为影响的本构模型。黏土的初始各向异性由不等向的固结过程产生,因此假定各向异性张量的初始值可由初始应力状态确定,并且提出了一个由塑性体应变和塑性剪应变共同决定的各向异性张量的演化规律来描述在后续应力作用下土的各向异性的变化(诱发各向异性)。文中对具有不同初始固结应力状态的多组高岭土试样的三轴试验结果进行了模拟,吻合较好。

A simple and pragmatic anisotropic constitutive model for clays is developed based on the critical state theory and bounding surface plasticity framework. The model can well simulate the effect of initial anisotropy and induced anisotropy on the stress-strain response of normally consolidated and over consolidated clays. A tensor named as anisotropic tensor is introduced to quantify the anisotropic stressstrain characteristics of clays. The initial anisotropy depends mainly on the anisotropic consolidation process, so that the initial value of the anisotropic tensor is assumed to be determined by the initial stress condition. The evolution of induced anisotropy from following loading process is described by a rotational hardening law of the anisotropic tensor both dependent on plastic volumetric strain and plastic deviatoric strain. The validity of the model is verified by the triaxial test data of Kaolin Clay samples with different consolidation stress conditions.