为考虑土壤孔隙中禁锢空气对入渗水流的阻滞作用,引入饱和度系数Sa（Sa小于1）来量化湿润区的饱和程度,建立了改进的层状土壤Green-Ampt入渗模型（MGAM）,并提出了由土壤物理特性参数估算Sa的计算公式。为检验MGAM的适用性,分别在室内长土柱和田间进行层状土壤的积水入渗试验,并采用MGAM、传统的Green-Ampt模型（TGAM）和由Bouwer法修正的Green-Ampt模型（BGAM）对入渗过程进行模拟。结果表明：估算得到的Sa反映了湿润区的真实饱和程度与持水能力;TGAM模拟的入渗速率和累积入渗量均明显大于实测值,BGAM则低估了入渗速率和累积入渗量,而且TGAM和BGAM预测的湿润锋位置明显滞后于实测值;与TGAM和BGAM相比,MGAM的模拟结果与入渗试验结果更加吻合,表明MGAM对层状土壤中水分入渗过程的模拟具有较高的精度。%A modified Green-Ampt model（MGAM） was proposed in this study to simulate water infiltration in layered soils with entrapped air.A saturation coefficient Sa（less than 1） was introduced in MGAM to account for the effect of air entrapment on infiltration.The Sa could be approximately determined from soil physical properties.Infiltration experiments in a laboratory layered soil column and field layered soil profile were conducted to test the applicability of MGAM.For comparison,the infiltration process was also simulated by the traditional Green-Ampt model（TGAM） and the Bouwer Green-Ampt model（BGAM）.The estimated Sa values by these model were very close to the measured saturation degree of soil layers at the termination of experiment.The simulation results indicate that the TGAM significantly overestimated the infiltration rate and cumulative infiltration,whereas the BGAM considerably underestimated the infiltration rate and cumulative infiltration.Furthermore,the depths of wetting front simulated by TGAM and BGAM were considerably smaller than the measured values.The comparison result shows that,the MGAM provided satisfactory simulation results,and it adequately described the infiltration process in both the laboratory soil column and field soil profile.
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