基于连续分形理论的土壤非饱和水力传导度的研究

Continuum fractal model for unsaturated soil hydraulic conductivity

土壤的孔隙是具有连续分形性质的物理结构,根据土壤孔隙分形结构建立了非饱和水力传导度模型。模型包括综合系数、分形维数和临界体积比3个参数,综合系数为不同土壤基质势对应的非饱和水力传导度与饱和传导度之间的水力联系,与土壤质地有关;分形维数反映土壤孔隙结构对于非饱和水力传导度的作用,土壤不同尺寸孔隙之间的连通性则通过临界体积加以描述。模型具有较为明确的物理解释。将模型应用于5种不同土壤的结果表明,所提出的非饱和水力传导度模型具有较好的模拟效果。

A model for the unsaturated soil hydraulic conductivity is established based on an assumption that the soil can be represented as a continuum fractal porous medium. The model contains three physical parameters: a coefficient λ, the fractal dimension D and the critical volume fraction αc. The saturated and unsaturated hydraulic conductivities are connected by the parameter λ. The fractal dimension (D) represents the soil porous structure and the critical volume fraction (αc) which accounts for the differential porosity from the smallest pore size for continuous flow to the largest pore size in the soil. The unsaturated soil hydraulic conductivity estimated by the model is compared with the experimental data of various soils.