基于SFG模型的非饱和膨胀土本构模型研究

Gens和Alonso提出了非饱和膨胀土本构概念模型(G–A模型),将土体膨胀分为微观层次和宏观层次,能够预测土体变形趋势。但G–A模型框架内建立的膨胀土模型参数多且难确定。在SFG模型的框架下,推导膨胀土的中性加载面(NL屈服面)方程,建立了膨胀土本构模型。该模型以总变形来反映土体微观层次变形,不再区分微观层次和宏观层次的结构变形,减少了非饱和膨胀土本构模型的参数。试验数据和数值模拟结果表明,中性加载屈服面和膨胀势曲线基本一致。通过与膨胀土的膨胀试验结果对比,本模型数值计算结果和试验结果较吻合,证实了所提模型的正确性。

Constitutive model for unsaturated expansive clays based on SFG model

The framework for the behaviour of unsaturated expansive clays (G-A model) proposed by Gens and Alsono can explain the mechanical behaviour of expansive clays, in which the fundamental characteristic is the explicit consideration of microstructural and macrostructural deformations. The constitutive models based on the framework of G-A model have a lot of parameters which are hard to be determined. The constitutive model in this work deduces the neutral loading lines in the framework of SFG model. The total deformations reflect micro-level deformation, therefore it is not necessary to distinguish between micro-level and macro-level structural deformations. It allows the constitutive model for unsaturated expansive clays to reduce parameters. A mathematical formulation of the model is assessed by comparison with the experimental data available in literatures. The model predictions agree with the experimental results.