复杂应力状态下粉质黏土流变模型及参数试验分析

Experimental analysis of rheological model and parameters of silty clay under complex stress state

针对无锡地区③2层粉质黏土,通过设置主应力轴位于水平方向和竖直方向,研究分析③2层粉质黏土在不同固结方式、不同加载方式时三轴应力状态下的流变特性。根据统一流变理论对流变模型进行识别,推导三轴应力状态下的广义Kelvin模型,并以最小二乘法拟合试验曲线,分析不同应力状态下的流变模型参数。研究结果表明:无锡地区③2层粉质黏土的流变特性可用广义Kelvin模型进行描述,但不同固结方式和不同加载方式作用下的广义Kelvin模型参数不同,复杂应力状态下的流变模型参数不仅与应力水平有关,还与围压、加载方式有关。等压固结的模型参数较K0固结的模型参数小,水平向加载的模型参数较竖向加载的模型参数大,由此说明等压固结和竖向加载时③2层粉质黏土流变特性明显,这可为计算处于不同应力状态下粉质黏土的流变变形提供模型及模型参数。

Experiment on rheological properties of （~）2 silty clay layer under complex stress state of different consolidation methods and different loading methods was carried out by setting principal axis of stress in horizontal and vertical directions. And rheological model was identified based on the unified rheological theory and generalized Kelvin model was derived under triaxial stress state. It was feasible to fit experimental curves with the method of least-squares and analyze model parameters under different stress states. The results show that the rheological properties of （~）2 silty clay layer can be described with generalized Kelvin rheological model, but the parameters of generalized Kelvin model are different with different consolidation methods and loading methods. Parameters of rheological model under complex stress state are related not only to stress level, but also confining pressure and loading method. The model parameters of isobaric consolidation are smaller than that of Ko consolidation, and the model parameters of horizontal loading are bigger than that of vertical loading. It means that rheological properties are obvious for isobaric consolidation and vertical loading. This can be used to provide theological model and model parameters for calculating rheological deformation of silty clay under different stress states.