含透镜体多孔介质中溶质二维运移实验与模拟研究

Experimental and simulation study of solute transport in two-dimensional porous medium packed with lenticular formation

为了研究透镜体对污染物运移的影响,文章设计了二维承压含水层物理模型,以惰性溶质亮蓝为例,开展了不同流速下多孔介质溶质运移实验和模拟研究。研究结果表明:透镜体加入模型后,污染物会优先从透镜体周围流过,出现绕流现象,透镜体对溶质运移具有明显的阻碍作用;采用解析解模型和IGW(Interactive Groundwater)模型对溶质运移穿透曲线进行拟合,都出现早到和拖尾等非费克现象,IGW模型拟合精度明显好于解析解模型,能较好地拟合溶质运移中的非费克现象;透镜体的存在相当于增加了介质的非均质性,因此含有透镜体时弥散系数D增大;当仅考虑流速变化时,D随着流速的增加而变大。

To study the contaminant transport affected by lenticular formation,a two-dimensional physical model standing for a confined aquifer was designed,and a case study of porous medium transport using brilliant blue was taken.Batch experiments and numerical simulations were conducted under different flow conditions respectively.The results show that when the lenticular formation is placed in the model,the pollutants will give priority to bypass the lenticular formation to flow away.The lenticular formation has a significant hindering effect on the solute transport.The breakthrough curves of the solute transport were fitted by the analytic solution model and the Interactive Groundwater(IGW)model.Non-Fickian transport with early arrival and long tails was found.The fitting results of two kinds of models show that the IGW model can fit the non-Fickian phenomenon in solute transport well,it has better fitting accuracy than the analytical solution model.It is found that the addition of the lenticular formation means increasing the heterogeneity of the medium,thus the dispersion coefficient D increases with the addition of the lenticular formation.When only considering the change of flow velocity,the dispersion coefficient D becomes larger with the increase of the flow velocity under the same condition.