非饱和带柴油入渗实验研究及HSSM模拟

Experimental study and HSSM simulation of diesel infiltration in unsaturated zone

通过土柱模拟实验研究了柴油在不同含水率、不同粒径砂土中的入渗及残留特征,并采用HSSM（Hydrocarbon Spill Screening Model）模拟了柴油在含水率为6%中砂介质中的入渗过程.结果表明：随着介质含水率增加,柴油在介质中湿润锋推进速度先增大后减小,最快速度对应含水率处于相应介质最大残余含水率40%-50%范围内,残余柴油量随介质含水率增大而减小.在细砂、中砂和粗砂3种介质,柴油入渗平均湿润锋推进速度分别为0.42,0.52,0.73cm/min；平均残余柴油量分别为98.10,68.70,48.79mL.湿润锋推进速度及残余柴油量均与介质粒径呈负相关.HSSM 拟合柴油在含水率为6%中砂介质中的湿润锋推进速度为0.5832cm/min,与实验值0.5689cm/min 相比,相对误差为2.51%.HSSM能较好的模拟柴油在非饱和带入渗过程,对于土壤及地下水污染预报具有重要意义.

This paper presents the results of laboratory investigation and simulation of diesel infiltration in unsaturated zone. A series of one-dimensional column experiments were conducted to study the infiltration and residue characteristics of diesel in sandy soils under varied soil moistures and media sizes. Then, Hydrocarbon Spill Screening Model （HSSM） was used to simulate the infiltration processes of diesel in medium sand with soil moisture equals to 6%. The results indicated that as soil moisture grew, the migration velocity of soil wetting front first increased and then decreased, and the fastest migration velocity corresponded to 40%-50% of maximum residue moisture content. Negative correlation was found between the amount of residual diesel and soil moisture content. In fine, medium and coarse sand, the average migration velocity of soil wetting front were 0.42, 0.52, 0.73cm/min, and the average amount of residual diesel were 98.10, 68.70, 48.79mL, respectively. The migration velocity of soil wetting front and the amount of residual diesel were negatively correlated with media size. Fitted migration velocity by HSSM of soil wetting front in medium sand with moisture content equals to 6% was 0.5832cm/min, while the experimental value was 0.5689cm/min. The relative percentage error between fitted value and the experimental value was 2.51%. HSSM can accurately simulate the infiltration process of diesel oil in the unsaturated zone, and has great significance to soil and groundwater pollution forecast.