Commonly used transport models of unsaturated flow assume that the movement of pore water is dominated mainly by capillary flow and they neglect adsorbed film flow. These models have been proven to be successful at high and intermediate saturations but typically underestimate the hydraulic conductivity in the dry range, where water movement in equilibrium conditions is dominated by adsorbed film flow. Given these considerations, this paper proposes a simplified configuration of pore water that accounts for the transport processes of both capillary and film flow. Based on the mechanisms of soil water retention, a conception of the specific thickness of the adsorbed film is defined to describe the adsorption strength and adsorption capacity of porous media. Furthermore, a statistical physically based model of relative hydraulic conductivity in the full range of suction is derived. Fractal and Monte Carlo methods are used to determine the pore size distribution of porous media and then the corresponding specific model of relative hydraulic conductivity is derived. The results show that the proposed model agrees well with the experimental data in the entire suction range. It is also found that the pore size distribution of porous media controls the transport characteristic of capillary water but not adsorption film flow which is only related to the mineral content, mineral species, and specific surface area. Additionally, the influences of the model parameters on the transport of porous media are also addressed.

常用的非饱和流输运模型假设孔隙水的运动主要由毛细流控制，而忽略了吸附膜流。这些模型已被证明在高饱和度和中等饱和度下是成功的，但通常会低估干燥范围内的水力传导率，在干燥条件下，平衡条件下的水运动主要由吸附的膜流决定。考虑到这些因素，本文提出了一种简化的孔隙水配置，该结构考虑了毛细流和薄膜流的传输过程。基于土壤保水机理，定义了吸附膜的特定厚度的概念，以描述多孔介质的吸附强度和吸附能力。此外，得出了在整个吸力范围内相对水力传导率的基于统计的物理模型。使用分形和蒙特卡罗方法确定多孔介质的孔径分布，然后推导相应的相对水力传导率的特定模型。结果表明，所提出的模型与整个吸力范围内的实验数据吻合良好。还发现，多孔介质的孔径分布控制着毛细管水的传输特性，而不控制吸附膜的流动，而吸附膜的流量仅与矿物含量，矿物种类和比表面积有关。另外，还解决了模型参数对多孔介质传输的影响。使用分形和蒙特卡罗方法确定多孔介质的孔径分布，然后推导相应的相对水力传导率的特定模型。结果表明，所提出的模型与整个吸力范围内的实验数据吻合良好。还发现，多孔介质的孔径分布控制着毛细管水的传输特性，但不影响吸附膜的流量，而吸附膜的流量仅与矿物含量，矿物种类和比表面积有关。另外，还解决了模型参数对多孔介质传输的影响。使用分形和蒙特卡罗方法确定多孔介质的孔径分布，然后推导相应的相对水力传导率的特定模型。结果表明，所提出的模型与整个吸力范围内的实验数据吻合良好。还发现，多孔介质的孔径分布控制着毛细管水的传输特性，但不影响吸附膜的流量，而吸附膜的流量仅与矿物含量，矿物种类和比表面积有关。另外，还解决了模型参数对多孔介质传输的影响。结果表明，所提出的模型与整个吸力范围内的实验数据吻合良好。还发现，多孔介质的孔径分布控制着毛细管水的传输特性，但不影响吸附膜的流量，而吸附膜的流量仅与矿物含量，矿物种类和比表面积有关。另外，还解决了模型参数对多孔介质传输的影响。结果表明，所提出的模型与整个吸力范围内的实验数据吻合良好。还发现，多孔介质的孔径分布控制着毛细管水的传输特性，而不控制吸附膜的流动，而吸附膜的流量仅与矿物含量，矿物种类和比表面积有关。另外，还解决了模型参数对多孔介质传输的影响。