寒区多孔介质中LNAPL迁移的多场耦合模拟

建立了包含水、气、NAPL、固(冰)四相的温度场、流场及化学场多场耦合模型,适用于定量模拟LNAPL泄漏过程中发生冻结后的迁移分布.通过与非冻条件下LNAPL迁移模型对比,模拟结果显示,冻结条件下因冰的形成LNAPL会发生与非冻条件下不同的迁移行为,冰的形成阻碍LNAPL下渗,并产生冻结势使LNAPL向地表方向迁移.相比非冻结条件,冻结条件下渗达到稳定时LNAPL相的质量通量偏差为-51.1%.冻结条件LNAPL溶解相在水平方向的迁移速度大于非冻结条件,冻结条件下如果不考虑冻结,下渗过程中LNAPL溶解量与挥发量最大偏差分别为2.4%、-24.9%.而冻结条件对LNAPL下渗达到稳定时的溶解量、挥发量影响很小,仅挥发量产生1.8%的偏差.但会减少LNAPL的吸附量,其偏差为-6.6%.

Multi-field coupling simulation of LNAPL migration in cold regions

A multi-field coupling model of temperature, flow and chemical fields including water, gas, NAPL, and solid (ice) phases was established to quantitatively simulate the migration and distribution of LNAPL under freezing condition during LNAPL leakage. By comparing the LNAPL flow model under non-freezing conditions, the simulated results found that LNAPL would undergo different migration behavior due to the formed ice under freezing conditions. The formed ice prevented LNAPL from infiltrating and generated freezing potential to make LNAPL migrate to the surface. The difference of LNAPL mass flux was -51.1% when the LNAPL infiltration reached stable under freezing/non-freezing conditions. Under freezing conditions, the speed of LNAPL plume in the horizontal direction was greater than that under non-freezing conditions. The maximum predicted error of LNAPL dissolved and volatilized components during the infiltration process was 2.4% and -24.9%, respectively, if freezing condition was not considered. However, the freezing condition had little effect on the dissolved and volatilized components of LNAPL when the LNAPL infiltration reached stable, and only the volatilized component had an error of 1.8%. But the adsorbed component was reduced, and the error was -6.6%.