重非水相流体在黄土中入渗与再分布试验研究

为研究重非水相流体在非饱和土壤中的运动过程,以四氯乙烯(PCE)为例,对其在重壤土和砂壤中的入渗与再分布规律进行了试验研究。结果表明,入渗结束后其含量和饱和度随着密度的增大而减小。在相同密度下,饱和度砂壤大于重壤土;Green-Ampt公式i=ic+b/I和Kostiakov经验公式i=Bt-n可以用来拟合PCE入渗速率、入渗量和入渗时间之间的关系,前者拟合最初入渗速率与累积入渗量关系情况较差,后者在较短或中等长度时间范围内入渗速率与时间的关系较好;随着再分布的进行,土体内PCE的饱和度降低。同一密度下,土体PCE含量砂壤大于重壤土;在入渗及入渗结束较短时间内,可以由幂函数形式描述,而随着再分布的继续进行,由对数函数拟合效果更好。

Infiltration and Redistribution of Dense Non-aqueous Phase Liquid in Loess Soil

To investigate the behavior dense DNAPL in the vadose zone,infiltration and redistribution experiments of perchloroethylene(PCE) in heavy loam and sandy loam were conducted.The results show that the PCE saturation and volumetric contents become lower under higher bulk density,and which are higher in sandy loam than that in the heavy loam at the same bulk density.The Green-Ampt and Kostiakov formula can be introduced to describe the relation of the rate,volume and time during infiltration.It is less fit for the initial infiltration rate and accumulative volume using the Green-Ampt formula,and it is much better describe the relation of the rate and time using Kostiakov formula under short or middle time of infiltration.With the continuing of distribution,the PCE saturation decrease in the profile and PCE saturation is higher in the sandy loam than that in the heavy loam.The infiltration depth with time can be described in power when the time is relative short and in logarithm when the time is long.