随着西部黄土地区经济和工程建设的快速发展,与时间相关的黄土变形、强度及稳定性等工程实际问题也日益增多,在解决黄土地区的工程问题时,需要考虑时间效应或流变性。通过三轴循环加卸载流变试验,得到了Q₃重塑黄土不同围压下的加卸载蠕变曲线,基于统一流变力学模型理论,辨识出适合于Q₃重塑黄土减速蠕变阶段的三维流变本构模型即改进西原模型。为了描述加速蠕变阶段,将黏塑性体中的黏性参数写成时间的函数,建立了非线性改进西原模型,推导出相应的蠕变本构方程,获得了其模型参数。将模型参数代入相应的本构方程中,绘制非线性改进西元模型不同阶段的蠕变曲线与蠕变试验曲线的对比图,进行对比后发现吻合较好,说明该模型能很好地反映Q₃重塑黄土的蠕变性质。

With the rapid development of the western loess region and engineering construction, the time-related practical problems of the loess deformation, strength, and stability in engineering construction are increasing. Time effect or rheology should be considered when solving engineering problems in the loess area. The load and unload creep curves of the Q₃ remolded loess under different confining pressures are obtained through triaxial cyclic loading and unloading rheological tests. Based on the unified rheological mechanical model theory, the three-dimensional rheological constitutive model, namely the improved Nishihara model, which is suitable for the deceleration creep stage of Q₃ remolding loess is identified. In order to describe the accelerated creep stage, the viscosity parameters in a viscoplastic body are written as a function of time, a nonlinear improved Nishihara model is proposed, the corresponding constitutive equation of creep is derived, and the model parameters are obtained by the creep test data. By substituting the model parameters under different confining pressures into the corresponding constitutive equations, the creep curves of the nonlinear improved Nishihara model were compared with the creep test curves. After comparison, it was found that the creep properties of the Q₃ remolded loess could be well reflected by the model.