基于真三轴试验的黄土结构性变化规律研究

基于综合结构势理论，通过自主研发的真三轴仪，研究了原状黄土、重塑黄土和饱和黄土的应力-应变关系和土的结构性变化规律，针对反映黄土变形过程结构性演变的应力比结构性参数，揭示了不同含水率黄土结构性参数与广义剪应变关系随固结压力、应力路径的变化规律，建立了数学描述模型，同时验证了真三轴仪和应力比结构性参数的可靠性。结果表明，土的状态不同，其应力-应变关系存在明显差异。原状土更易呈现应变软化或双曲线特性，而重塑土或饱和土更易呈现双曲线或应变硬化特性。随着剪切变形和含水率的增大，土的结构性均逐渐减小，而固结压力? c和中主应力参数b值也会影响土的结构性变化规律。提出的结构性参数的拟合公式与理论和试验结合吻合较好，可推广工程应用。

Research on change structural characteristics of loess based on true triaxial tests

Based on the theory of comprehensive structure potential, the stress-strain relations of intact loess, remolded loess and saturated loess have been researched by independent developed true triaxial apparatus. It has been reflected that the relationship between stress ratio structure parameter and generalized shear strain along with consolidation pressure and stress path. The mathematical model has been established. Meanwhile, the reliability of true triaxial apparatus and stress ratio structure parameter has been validated. It is shown that the stress-strain relations have distinct difference for different soil states. The stress-strain relations tend to the characteristic of strain softening or hyperbola for the intact loess. The stress-strain relations tend to the characteristic of hyperbola and strain hardening for the remolded or saturated loess. The soil structure reduces gradually with the increasing of shear deformation and water content. The consolidation pressure ? c and intermediate principal stress patameter b are the influential factors for soil structure. The simulation formula can accurately reflect the theory and experimentation. It is convenient for application in projects.