基于Green-Ampt模型的变水头积水入渗模型建立及其参数求解

通过对变水头积水入渗物理机制的分析,将入渗水头对入渗的影响归结为对表面饱和导水率的影响,基于Green-Ampt入渗模型,引用了湿润区的平均含水率的概念,并考虑了湿润区平均含水率随入渗时间的变化,建立了具有物理意义的3种变水头积水入渗模型,分析了利用入渗率-累积入渗量及入渗率-真实湿润锋图形获得模型参数的求解方法。通过室内试验,得到了湿润区的平均含水率与入渗时间之间呈乘幂函数变化的规律。利用实测资料对模型及其参数求解的方法进行检验,结果表明所建立的3种模型是正确的,求解参数的方法合理。

Varying head infiltration model based on Green-Ampt model and solution to its key parameters

During the course of varying head infiltration, higher initial head has compacted effect on the infiltration surface, and then the infiltration features of topsoil can be changed.In this paper, the physical mechanism under varying head infiltration was analyzed, and the effect of head on infiltration was reflected by the surface saturation coefficient of hydraulic conductivity.Based on the Green-Ampt Equation, the con-cept of mean water content Δθ(t) in wetted zone was used, and also the change of mean water content in infiltration was considered.Three simulating models with physical meaning for varying head infiltration have been established.Methods of determining key parameters in graphic characteristics were analyzed on the basis of the relationships of infiltration rate with cumulation infiltration or with actual wetted front.The power function relation of Δθ(t) with infiltration time was found through indoor experiment.The modified equation and determining methods of parameters were checked by lab experimental data and the results show that the models are accurate, and the method is reasonable.