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非饱和黄土是典型的结构性土,对4种含水率的原状非饱和黄土和重塑非饱和黄土进行了3种围压下的三轴剪切试验。基于二元介质理论,通过原状非饱和黄土和重塑非饱和黄土的应力-应变曲线对比,定义了结构性参数结构应力分担比。考察了不同围压和含水率对结构应力分担比随应变变化的影响,并给出了其定量表达式。试验结果表明,围压和含水率是影响结构性的两个主要因素;随着应变增长,结构应力分担比分先线性增长后指数形式减低,其最大值可以表示成围压和含水率的函数。最后给出了考虑结构性的原状非饱和黄土本构模型的建模思路。
Unsaturated loess is a typical structural soil. Triaxial shear tests under three kinds of confining pressures are carried out on four types of undisturbed unsaturated loess and remodeled unsaturated loess. Based on binary medium theory, stress-strain curves of intact unsaturated loess and remolded unsaturated loess were compared to define the stress-sharing ratio of structural parameters. The influences of confining pressure and water content on the stress-strain ratio of structure are investigated, and their quantitative expressions are also given. The results show that the confining pressure and water content are the two main factors that affect the structure. As the strain increases, the index of structural stress share decreases linearly and then decreases exponentially. The maximum value can be expressed as a function of confining pressure and water content. Finally, the modeling method of considering the structural intact unsaturated loess constitutive model is given.