汾渭盆地是我国乃至世界上地裂缝最为发育、灾害最为严重的地区。考虑在漫长的地质历史过程中黄土的流变特性对地裂缝破裂扩展模式的影响，采用分级循环加卸载方式，对西安地区长安地裂缝（fc1）带Q3原状黄土进行了不同围压下的固结不排水三轴流变特性试验，得到了地裂缝带Q3原状黄土的蠕变加、卸载曲线和应变速率与时间关系曲线。试验结果表明，不同围压下地裂缝带Q3原状黄土表现为低应力下为减速蠕变，高应力下为减速蠕变和等速蠕变的特征。并基于统一流变力学模型理论，建立了适用于西安地区地裂缝带Q3原状黄土的三维蠕变本构模型，获得了相应的本构模型参数。该成果为研究隐伏地裂缝破裂扩展模式及其力学机制奠定了基础。

The Fenhe River-Weihe River Basin is one of the areas with the most developed ground fissures and related geohazards in China and even in the world. The effect of the rheological properties of loess during the long geological history is considered as the fracture extension mode of ground fissures. Applying stepwise loading and cyclic unloading, a series of consolidated undrained triaxial tests is conducted on Q3 intact loess sampled from Chang'an ground fissures belt in Xi'an region, to examine the rheological properties of the loess with different confining pressures. The loading and unloading creep curves, strain rate vs. time curves of Q3 intact loess within ground fissures are obtained. The experimental results show that the Q3 intact loess is featured with slow creep under low stress and slow creep or constant creep under high stress. Based on the unified rheological theory, a three-dimensional creep constitutive model which is suitable for Q3 intact loess within ground fissures belt in Xi'an region is established; and parameters of the model are obtained. The results lay a foundation for studying the fracture extension model of concealed ground fissures and the mechanism behind.