南宁膨胀土剪切蠕变特性及流变模型研究

Experimental Study on Shear Creep Characteristic and Rheological Model of Nanning Expansive Soils

利用改装的剪应力控制式直剪仪对南宁非饱和膨胀土进行了一系列直剪蠕变试验和加–卸载剪切回弹试验,得到了剪切蠕变曲线和剪切回弹曲线。试验结果表明,膨胀土在同一竖向应力条件下,剪应力和含水率越大其塑性和流变特性越明显;在同一含水率、同一剪应力条件下,竖向应力越小其塑性和流变特性越明显。根据对试验曲线的分析得到了膨胀土的剪切变形是由瞬时弹性变形、瞬时塑性变形,弹性滞后变形,粘塑性变形等组成。提出了膨胀土剪切蠕变的九元件模型,并通过拟合确定了相应的剪切蠕变方程和流变参数.研究结果为膨胀土流变问题的进一步研究提供可靠理论依据。

A series of direct shear creep tests were carried out on Nanning expansive soils by means of stress controlled direct shear apparatus.The shear creep curves and the loading-unloading creep curves were obtained.The test shows that the plasticity and rheological properties were more and more obviously when the moisture content or stress is increased under the vertical stress is a constant value.When the moisture content or shear stress is constant,the vertical stress smaller the plasticity and rheological properties of this soil is more obviously too.Based on the experiment results,it was explored that the deformation of soil was found were composed of instantaneous elastic deformation,plastic deformation,elastic hysteresis deformation and viscoplastic deformation and so on.A new rheological components model of expansive soils is presented in this paper,and the rheological parameters of this soil is obtained.The research results provides a reliable theoretical basis for the rheological model of expansive soils to further study.