堆石料的三维应力分数阶本构模型

为合理反映粗粒土的状态依赖非关联应力应变特性，提出应力分数阶塑性力学模型。已有模型基于三轴试验结果，无法对堆石料真三轴条件下的应力应变特性进行预测，为解决这一问题，基于特征应力法对已有分数阶塑性力学模型进行完善。进一步选取不同初始状态条件下堆石料的真三轴压缩试验数据对模型进行验证，结果表明，三维化后的分数阶岩土塑性力学模型可以合理地模拟不同初始状态的堆石料在真三轴压缩条件下的应力应变行为。与传统塑性力学模型相比，提出的分数阶塑性模型在描述堆石料非关联流动时不需要额外引入塑性势函数，仅需对已有屈服面求解分数阶导数。此外，模型在特征应力空间中推导完成再映射到原应力空间，可描述土体的三维强度特性，无需额外采用三维强度准则。

Three-dimensional stress-fractional constitutive model for rockfill

The stress-fractional plasticity model has been proposed to model the state-dependent stress-strain behavior of granular soils. However, the previous model was established based on triaxial test, which cannot be easily used to predict the three-dimensional (3D) stress-strain characteristics of rockfill. To solve this problem, an attempt is made to modify the fractional plasticity model for rockfill by using a novel concept of characteristic stress to make the model capable of predicting the 3D stress-strain behavior of rockfill. A series of true triaxial test results of rockfills under different initial states are simulated, from which a good agreement between the model predictions and the corresponding testing results is found. Comparing with the classical plasticity model, no additional plastic potential is required; in addition, the model can describe 3D strength characteristics by mapping from the characteristic stress space to the normal stress space, where no specific 3D strength criterion is needed.