考虑滞后效应与吸附作用的非饱和土SWCC分形模型

传统土-水特征曲线(SWCC)模型的研究仅考虑了土壤基质势的毛细组分而忽略了吸附组分,高估了土壤在低饱和度范围的基质吸力。针对该问题,假设土壤孔隙系统可用一簇带有孔喉的毛细管表示,且其孔径分布服从分形规律。在此基础上将土壤中水分运移分为2个阶段,即毛细水与吸附水共同参与水分运移阶段,以及仅吸附水参与水分运移阶段,推导得到了可以反映全基质吸力范围土壤持水特征及滞后效应的SWCC模型。最后采用已有的试验数据与研究结果对得到的本构模型进行验证,结果表明所提出的SWCC模型预测曲线与试验数据吻合良好,且相比已有方法可更好地描述非饱和土SWCC的持水特性,证明了该模型的合理性与可行性。

Fractal Model of Soil Water Characteristic Curve of Unsaturated Soil in Consideration of Hysteresis Effect and Adsorption

In traditional research on SWCC model, only the capillary component of soil matrix potential was taken into consideration, while the adsorption component was ignored, which makes it overestimate the matric suction in the low saturation range. In view of this, the soil pore system is assumed to be represented by a cluster of capillaries with pore throats with the pore size distribution obeying the fractal power law. On this basis, the water movement in soil can be divided into two stages, i.e., capillary water and adsorbed water both participate in water movement, and only adsorbed water participates in water movement. The SWCC model reflecting soil’s water holding capacity and the hysteresis effect in the whole range of matric suction is derived.By existing test data and research results,the present constitutive model is verified to be rational and feasible with the predicted curve agreeing well with test data,and capable of better reflecting the water holding capacity of unsaturated soil than existing methods.