不同含盐类别和干密度盐渍土的三轴试验变化特征研究

Research on Variation Characteristics in Triaxial Test for Saline Soil under Different Salt Type and Dry Density

对罗布泊地区的盐渍土进行三轴剪切试验研究,获得了盐渍土在不同含盐类别和干密度的剪切变形和体积变形的变化特征。分析认为:在较低干密度下,盐渍土呈现应变硬化型,硫酸盐渍土在较高干密度下呈现弱应变软化型;在相同的干密度下,硫酸盐渍土的破坏强度大于氯盐渍土的破坏强度;运用邓肯-张模型,求出不同含盐类别及不同干密度下盐渍土的8个参数,并进行拟合,结果表明:邓肯-张模型应用于盐渍土时对于应变硬化型应力-应变曲线具有良好的拟合效果,但不能反映应变软化特性和剪胀性。

Through making the triaxial shear experiment and study for the saline soil taken from the Lop Nor region,the saline soil＇s shear deformation and volume deformation characteristics are got under the different salt type and dry density.The analysis indicate that the saline soil would show the strain hardening type under low dry density,and the sulphate salty soil would show the low strain softenting type in opposite condition.The failure strength of sulphate salty soil is bigger than that of chlorine saline soil in the same dry density.The eight parameters of saline soil under different salt-bearing types and dry densities are solved with Duncan-Chang model.The fitting result shows that Duncan-Chang model has great effect for fitting the stress-strain curve of strain hardening type in saline soil condition,but the strain softening characteristics and shear dilatation could not be reflected by using the model.