中文摘要：

通过改装的剪应力控制式直剪仪对南宁非饱和膨胀土进行系列室内试验研究，探讨非饱和膨胀土的非线性流变特性。试验结果表明：当剪应力小于或等于25.5kPa时，土体表现为衰减蠕变，当剪应力高于25.5kPa时，土体具有明显的非线性流变特性。同时，通过对剪切蠕变曲线的拟合发现，南宁非饱和膨胀土的流变可以用Bu体模型来描述，并能得出其相应的本构方程和蠕变方程。

英文摘要：

On the basis of a series of indoor tests for unsaturated Nanning expansive soils through creep testing apparatus controlled by shearing force, nonliner rheological characteristics of the expansive soils were researched. The results show that the soil performs for attenuation when shear stress is less than or equal to 25.5 kPa, but the soil has obvious non linear rheological behavior when shear stress is higher than 25.5 kPa. Through the experiment creep curve can be described by Burgers model,the constitutive equation and the creep equation of the expansive soils also be obtained.