非饱和土土-水特征曲线预估方法研究

在Wei等[1]基于多相孔隙介质非平衡渗流理论提出的多孔介质热动力学混合物理论模型的基础上，建立了一个能描述不考虑土骨架变形的非饱和土土-水特征曲线动态模型。依据非饱和土土-水特征曲线动态模型，推导出不考虑土骨架变形的气-水两相非饱和土的饱和度演化方程。利用饱和度演化方程并结合多步流动瞬态试验的成果，通过数值反演，提出了一种能利用多步流动瞬态试验数据快速确定非饱和土土-水特征曲线的方法。通过对低液限粉土及低液限黏土的多步流动瞬态试验研究发现，饱和度演化方程能较好地模拟非饱和土在小基质吸力步长变化下饱和度的变化规律。此外，通过对多步流动瞬态试验试样饱和度的模拟确定的非饱和土土-水特征曲线与联合测试系统测得的土-水特征曲线的结果较为一致。

Research on prediction method of soil-water characteristic curve of unsaturated soils

Based on the non-equilibrium flow theory of multiphase porous media, the thermodynamic mixed theoretical model is proposed by Wei et al[1]. According to the model, the dynamic water-soil characteristic curve of unsaturated soil, which describes the incremental relationship between capillary pressure and saturation, is deduced. Within the context of the dynamic water-soil characteristic curve, an evolution equation of saturation in an unsaturated sample is developed. The equation describes well the variation of saturation with time in a multistep transient outflow experiment provided that the deformation of the matric of the unsaturated sample is ignored. On the basis of the evolution equation and the characteristic of the multistep transient outflow experiment, a new predicted method is proposed to determine the soil-water characteristic curve. For the low liquid limit silt and the low liquid limit clay, by comparing the theoretical simulation with experimental data in the multistep transient outflow experiment, it is shown that the saturation evolution equation can very well describe the constitutive relationship between saturation and time provided that the incremental step of matric suction is small. In addition, the calculated results of the soil-water characteristic curve agree well with the measured results of that measured by the laboratory combined system.