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 solved with a differential method in order to examine the effect of SWCC on unsaturated seepage. Four parameters in the model are analyzed. The calculated results show that α and n have a strong effect on the pore-water pressure distribution. The parameters α influences the position of SWCC, the greater α is, the slower the pressure profile moves. The pressure profile shape is affected by α value. It can be obtained from the analysis that n determines the slope rate of SWCC. The greater n is, the quicker the matric suction in unsaturated soil dissipates. The results indicate that residual water content has a very light effect on the pressure profile, and that saturated water content plays a marked role in the pressure distribution. The pressure difference induced by the parameters becomes obvious with time.%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θx、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.
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