非饱和土的渗透系数

Permeability coefficient of unsaturated soils

非饱和土的渗透系数是分析水分和物质迁移的重要参数,直接测量非饱和土渗透系数的代价较高,且直接测量的精度较差,因此间接估算非饱和土渗透系数成为很好的选择。分形理论适合用来描述多孔介质的结构和透水性。本文建立了土体孔隙分布的分形模型,导出用分维和进气值表示的水分特征曲线和渗透系数的理论表达式。与实验结果的比较表明,用分形模型计算得到的水分特征曲线和渗透系数与试验结果一致。

The fractal theory is applied to study the properties of unsaturated soils. The fractal model for the distribution of pore size in soil is established in which the distribution of pore size is expressed by fractal dimension and maximum pore size. The fractal dimension of pore size distribution is determined according to the slope of the correlative line between pore volume and pore diameter in logarithmic graphics. By using this model the soil-water characteristics and permeability coefficient of unsaturated soil are deduced and expressed in fractal dimension and air-entry value. The validity of the model is verified by experimental data.