基于分数阶微积分的变参数黄土蠕变损伤模型

Variable parameters creep damage model of loess based on fractional calculus

为了准确认识黄土的流变特性,以不同含水率的咸阳Q_2黄土为研究对象,采用分级加载的方式进行室内三轴蠕变试验,获得该黄土蠕变试验数据和曲线。选用包含软体元件的四元件蠕变模型来模拟黄土的流变。借鉴变参数牛顿元件的建造思路,应用SN元件及引入能反映应力水平、时间及含水率影响的损伤变量,改进四元件蠕变模型中的2个常参数软体元件为变参数软体元件,得到能反映黄土非线性流变及损伤特征的蠕变模型。利用黄土蠕变试验数据对改进所得的模型进行验证。研究结果表明:该模型在描述黄土整体流变特征时具有较好的效果。

Triaxial creep test was performed on the Xianyang Q2 loess specimen at different moisture contents with multi-staged loading condition to obtain the creep curves of the loess material for better characterization on its rheological properties. A four-element creep model containing soft-matter element was selected to simulate the rheology of loess specimen. On the basis of the variable parameter Newton element with the application of SN element and damage variables for stress level, times and moisture content, the proposed creep model reflected the nonlinear rheological and damage characteristics of loess specimen was obtained by modifying two constant parameters in the soft-matter elements of the conventional four-elements creep model into variable parameters. The proposed creep model was validated by experimental results. The results show that the model can well characterize the rheological properties of loess specimen.