非饱和土渗流及其参数影响的数值分析

A numerical analysis of the infiltration and parameter effects in unsaturated soil

摘要: 基于一维的Richards方程,考虑van Genuchten提出的土-水特征曲线和水力传导系数的表达式,采用差分方法进行求解,研究该土-水特征曲线对孔隙水压力分布的影响,分析该模型四个参数θs、θr、α和n对孔隙水压力分布的作用特征。结果表明经验参数α和n对孔隙水压力分布产生显著的影响。α影响土-水特征曲线的位置和水力传导系数斜率,其值越大,基质吸力越滞后,孔隙水压力分布弯曲度随着α值的增大而明显;n决定土-水特征曲线的斜率,其值大意味着基质吸力易消散。计算分析显示θr值变化引起孔隙水压力分布微弱的差异,这差异随着时间的增长而增大;饱和含水量θs对孔隙水压力分布也产生不小的影响,随θs的降低孔隙水压力消散减慢。

Abstract: Rainfall infiltration is a complex problem involving unsaturated-saturated seepage and pore-water pressure change.The van Genuchten model is one of the most popular models describing a soil-water characteristic curve(SWCC).Numerical solution is used to investigate the influence of the soil-water characteristic curve on rainfall infiltration in unsaturated soil.In a one-dimensional Richards equation,SWCC and hydraulic conductivity expressions with van Genuchten are considered.The equation is solv...