低渗透介质中轻非水相流体迁移转化规律

本文利用COMSOL软件建立轻非水相流体（LNAPL）纵向迁移转化模型，采用有限单元法进行求解，预测污染物分布规律，并利用局部分析法进行参数敏感性分析.结果表明，大部分LNAPL会在水面以上聚集形成高的质量分布峰值区域，少部分克服毛细压力向下迁移，在自由相迁移范围内，其溶解相浓度达到或接近饱和溶解度；当顶部污染源消失后，降水会使最大饱和度和浓度出现的深度逐渐下移；多孔介质中的低渗透镜体会使污染物垂向入渗受阻，在其表面聚积形成污染池；渗透系数是控制LNAPL纵向迁移速度及饱和度分布的关键参数.

The migration and transformation of light non-aqueous fluid in silty clay

The LNAPL longitudinal migration transformation model was established by COMSOL software, and was solved with the finite element method. It was applied to predict the distribution of pollutants, meanwhile parameter sensitivity was performed with local analysis method. The research results showed that most of the LNAPL aggregated above the water surface and formed a high mass distribution peak area, and a small part overcame the capillary pressure and migrated downward. In the free phase migration range, the dissolved phase concentration reached or approached the saturated solubility. When the top pollution source disappeared, the precipitation gradually lowered the maximum saturation and the depth of its concentration occurrence. The local low permeability lens in the porous medium caused of the pollutants blocked which will be accumulated on its surface and formed a pollution pool. The sensitivity analysis results demonstrated that the permeability coefficient was a key parameter to control the longitudinal migration speed and saturation distribution of LNAPL.