非均质介质中重非水相污染物运移受泄漏速率影响数值分析

重非水相污染物(DNAPL)在地下介质中运移和分布受多种因素控制,包括DNAPL本身的物理化学性质,土的性质,泄漏条件等等。由于介质的非均质性,使得多相流运移行为更为复杂。基于地下水随机理论构建渗透率随机场,采用蒙特卡罗方法探讨泄漏速率对非均质饱和介质中DNAPL运移的影响。数值结果表明,在泄漏总量一定的情况下,泄漏速率越低,介质非均质性对DNAPL运移的影响程度越高。反之,DNAPL的渗漏速率越高,小尺度地层的非均质性影响越低。由于DNAPL运移过程中在垂直方向受重力的影响,污染羽在空间上的质心位置(一阶矩)以及展布范围(二阶矩)在垂直方向上的变异程度要高于水平方向。

Numerical analysis of the effect of leakage rate on dense non-aqueous phase liquid transport in heterogonous porous media

The transport and distribution of Dense Non-Aqueous Phase Liquid(DNAPL) in subsurface media are affected by many factors,which include DNAPL physical and chemical properties,soil properties,and leakage conditions,etc.The structure of multiphase flow can be more complex due to the effects of porous media heterogeneity.In this study,the Monte Carlo method is applied to a synthetic case in an effort to investigate the effect of the spatial variability of permeability on the fate and transport of DNAPL contaminant plumes.Numerical results show that the lower the leakage rate,the higher the heterogonous effects are on DNAPL migration in the case of fixed total leakage flux.Since the transport of DNAPL is affected by the gravity,for both centroid of the plume(first moment) and the distribution of the plume(second moment),the variability in the vertical direction is found to be greater than that in the horizontal direction.