高易溶盐非饱和伊犁原状黄土的临界状态特性

Critical state characteristics of high soluble salt unsaturated undisturbed Ili loess

为探究伊犁地区高易溶盐含量黄土的临界状态特性,针对不同易溶盐含量的非饱和伊犁原状黄土,开展了控制吸力和净围压的三轴固结剪切试验。研究结果表明:在常吸力固结剪切条件下,非饱和伊犁原状黄土的强度随含盐量的增加存在峰值;含盐量一定,不同吸力非饱和土的q-p或e-p临界状态线均为平行直线,q-p’临界状态线可归一为饱和土临界状态线表示的一条直线,其斜率随含盐量的增加呈幂函数降低;非饱和土e-p临界状态线的斜率λ1大于饱和土的斜率λ0,两者均随含盐量的增加先减后增,相同有效净平均应力下非饱和土和饱和土的临界状态孔隙比之比e/es与气体饱和度1-Sr可以归一化;q-p平面上初始屈服曲线和后继屈服曲线均可近似假定为对称于k0线的椭圆,吸力和应力对屈服曲线的硬化作用是等向的。

In order to explore the critical state characteristic of high soluble salt loess in Ili area,a series of triaxial consolidation shear tests controlling suction and net confining pressure is performed on the unsaturated undisturbed Ili loess with different soluble salt contents.The results show that the strength of the unsaturated undisturbed Ili loess has a peak value with the increase of soluble salt content under the consolidation shear of constant suction.The q-p or e-p critical state lines are parallel lines of unsaturated soil with a certain soluble salt content under different suctions.The q-p’critical state lines under different suctions can be normalized as a straight line represented by the saturated critical state line,and the slope of the straight line decreases as a power function with the increase of soluble salt content.The slope(λ1)of e-p critical state line of unsaturated soil is larger than the counterpart(λ0)of saturated soil,both first decrease and then increase with the increase of soluble salt content.Under the same effective net mean stress,the ratio of critical state void ratio(e/es)between unsaturated soil and saturated soil and gas saturation(1–Sr)can be normalized.The initial and subsequent yield curves in the q-p plane can be approximately assumed to be ellipses that symmetrical to the k0 line.The hardening effect produced by suction and stress on the yield curve is isotropic.