考虑系数非定常性的成都黏土非线性蠕变本构模型

为了研究成都黏土蠕变规律，展开固结不排水三轴蠕变试验，分析了成都黏土变形的非线性特性及参数的非定常特性。结果表明：当应力小于黏土屈服强度时，蠕变以线性变形为主，包括瞬时弹性变形和黏弹性变形；当应力大于屈服强度时，蠕变以非线性变形为主，包括黏弹塑性变形，具有显著的非线性特性；蠕变过程中，黏土的弹性模量和黏滞系数均为应力和时间的函数，具有显著的非定常特性。结合元件模型理论和分数阶导数模型理论的优点，构建了考虑弹性模量和黏滞系数非定常特性的成都黏土非线性蠕变本构模型，并对模型进行了拟合验证分析，发现蠕变模型对蠕变各阶段的拟合度较高，充分发挥了元件模型和分数阶导数模型的优点，可以很好地反映成都黏土的蠕变全过程。

Nonlinear creep constitutive model of Chengdu clay considering coefficient non-definite constancy

In order to study the creep law of Chengdu Clay, consolidate the undrained triaxial creep test are completed. The nonlinear characteristics of Chengdu clay deformation are analyzed, and the unsteady characteristics of parameters are also analyzed. The results show that, when the stress is less than the yield strength of the clay, the creep is dominated by linear deformation, it includes transient elastic deformation and viscoelastic deformation. When the stress is greater than the yield strength, the creep is dominated by nonlinear deformation, it includes viscoelastic deformation and has significant nonlinear properties. During the creep process, the elastic modulus and viscous coefficient of clay are both a function of stress and time, and they have significant unsteady characteristics. Combining the advantages of component model theory and fractional derivative model theory, a nonlinear creep constitutive model of Chengdu clay considering the unsteady characteristics of elastic modulus and viscous coefficient is constructed. The model is fitted to the validation analysis, it is found that the creep model has a high degree of fitting to each stage of creep, and the advantages of the component model and the fractional derivative model are fully reflected, and the whole process of creeping of Chengdu clay can be well reflected.