不同含水率高易溶盐含量的伊犁黄土流变特性

流变学研究方法可以揭示黏弹性物质的流动和变形规律，常被应用于土体结构的力学稳定性及长期变形参数研究。为了深入探究伊犁黄土类土的黏弹性和结构稳定性，该研究采用流变仪对不同含水率和易溶盐(Na₂SO₄)含量的伊犁黄土类土进行了稳态和动态流变试验，引入Bingham模型对小剪切速率下的流变曲线进行了拟合，并分析解释了稳态和动态流变试验的演化过程。同时，讨论了含水率及易溶盐含量对稳态和动态流变参数的影响规律，定量分析了流变参数与各变量之间的关系。结果表明：稳态剪切过程中土体由固态向类固态转化，并最后趋于流态，具有剪切变稀行为；随着含水率及易溶盐含量增大，屈服应力和黏度均减小，且屈服应力在300～1 100 Pa之间。随着含水率和易溶盐含量增大，动剪切强度参数和黏弹性参数均线性减小，土体的结构稳定性降低。当剪切应变小于0.1%时，土体处于线性黏弹区，损耗因子变化不大；剪切应变大于0.1%时，损耗因子逐渐增大。高含水率及高易溶盐含量的土壤最先到达屈服点，说明高含水率和高易溶盐含量不利于土体结构的稳定性。随着含水率的增大，易溶盐含量对流变参数的影响程度变小...

Rheological properties of the high soluble salt content Ili loess with different water contents

Rheology can be often used to reveal the flow and deformation of viscoelastic materials, in terms of mechanical stability and long-term deformation parameters of soil structures. This study aims to explore the influence of moisture content and soluble salt content on the rheological characteristics and structural stability of Ili loessial soil in Northwest China. A series of steady-state and dynamic rheological tests were also carried out for the Ili loessial soil with the different contents of moisture and soluble salt using the rheometer. Firstly, the shear rate/shear strain and shear stress curves were obtained with the different water volume fractions and soluble salt content under steady and dynamics. The Bingham model was introduced to fit the rheological curve under a small shear rate. Secondly, the viscosity curves were also obtained under different water volume fractions and soluble salt content. Finally, an analysis was made on the evolution in the steady-state and dynamic rheological properties of soil structure. Meantime, the influence of moisture and soluble salt content on steady-state and dynamic rheological parameters was investigated to quantitatively analyze the relationship between rheological parameters and each variable. The results show that the soil was changed from the solid to the quasi-solid state in the steady-state shear process, and finally tended to the flow state. The shear stress increased first and then decreased with the increase in the shear rate. The Ili loessial soil conformed to the Bingham model at the low shear rate (10-4-5×10-4 s-1). The yield stress and viscosity decreased with the increase in moisture and soluble salt content. Specifically, the yield stress was between 300 and 1100 Pa. The viscosity with different water content decreased with the increase of shear rate, ranging from 107 to 1 Pa·s. The Ili loessial soil exhibited the shear thinning behavior. The shear stress increased first and then decreased with the increase of shear strain under dynamic shear. There was a linear decrease in both dynamic shear strength and viscoelastic parameters (including the storage and loss modulus, linear viscoelastic shear stress, yield shear stress, the maximum shear stress, shear strain at the maximum shear stress, yield point strain, and integral z) with the increase of moisture and soluble salt content, indicating the decrease in the stability of soil structure. Once the moisture content reached 27.5%, there was a weak influence of soluble salt content on these parameters. There was no change in the loss factor at the shear strain of less than 0.1%, where the soil was in the linear viscoelastic zone. The loss factor increased gradually when the shear strain was greater than 0.1%. The soil with the high moisture and soluble salt content reached the yield point first, indicating that the high moisture and soluble salt content were not conducive to the stability of the soil structure. The influence of soluble salt content on the rheological parameters decreased with the moisture content. Therefore, the rheological properties of Ili loessial soil were characterized qualitatively and quantitatively. The finding can provide a strong reference for further understanding of the viscoelastic properties of loessial soils.