非饱和土毛细滞回内变量模型的修正

A modification for capillary hysteresis internal variable model of unsaturated soils

土-水特征关系是基质吸力和含水率之间关系。在反复干湿循环路径下土-水特征曲线呈现出毛细滞回特性。基于毛细滞回内变量理论和传统的土-水特征关系经验模型,提出了能模拟在任意干湿循环路径下土-水特征关系的修正模型。该模型比原模型增加了一个可逆参数,考虑了含水率的可逆变化,使扫描线在靠近边界线的时候斜率不会无限大,同时保留了原模型精度。通过与文献中的试验结果进行比较,修正模型可以更好地模拟非饱和土的土-水特征关系的循环滞回特性,并讨论了可逆参数的确定方法。

Soil-water characteristic curve（SWCC） describes the relationship between suction and volumetric water content of unsaturated soil which are not one-to-one correspondence. This curve performs hydraulic hysteresis during arbitrary drying-wetting suction changes are applied to the material. Based on capillary hysteresis internal variable model and conventional soil-water characteristics theory of unsaturated soils, a modified model which can simulate soil-water characteristic relationship during arbitrary suction changes is proposed. This model increases one parameter compared with the capillary hysteresis internal variable model, which describes the reversible changes of water content and ensures the slope of scanning curve not to be infinite when scanning curves approach the boundary of SWCC. The modified model retains the precision of the capillary hysteresis internal variable model simultaneously. Compared with experimental results in references, this model is able to simulate soil-water characteristics relationship of unsaturated soils better than the capillary hysteresis internal variable model. Determination method of the new parameter is also discussed.