多孔介质溶质运移机理实验研究

发布时间：2018-05-01 19:05

本文选题：多孔介质 + 示踪剂　；参考：《合肥工业大学》2015年硕士论文

【摘要】：多孔介质溶质运移是当今水文地质和工程地质学一个重要的研究内容,示踪实验是其研究中的一个重要手段。为了研究非反应性及反应性溶质运移机理,本文在总结和分析国内外地下水溶质运移的基础上,建立了一维多孔介质溶质运移的物理实验模型,在达西流条件下,利用惰性示踪剂氯化钠和亮蓝进行示踪非反应性溶质运移的适用性对比实验,运用ADE模型和TPL模型对溶质运移穿透曲线进行数值模拟,并对拟合结果进行处理分析,总结得到多孔介质中非反应性溶质运移的机理及规律。利用反应性示踪剂1,2-萘醌-4-磺酸钠和苯胺模拟地下水污染物进行反应性溶质运移实验,得到反应物和生成物的穿透曲线并结合ADRE模型拟合结果对结果进行分析讨论。总结归纳本文的实验成果,得出如下结论：(1)吸附性实验中,氯化钠在多孔介质中的吸附性比亮蓝的要强；而在溶质运移实验中,氯化钠随水流运动的移动性比亮蓝要差,且弥散性比亮蓝要强,拖尾现象较明显。因此在实验室尺度下,亮蓝比氯化钠更适合作为惰性示踪剂示踪多孔介质溶质运移实验。(2)在模拟多孔介质溶质运移时,TPL模拟精度比ADE的要高：在均质多孔介质中,两者的拟合评价参数r2和RMSE非常接近,均可以很好的拟合溶质运移过程；而在非均质多孔介质中,TPL的r2值比ADE的要更接近1,RMSE要更接近0,TPL模型具有更高的拟合精度。(3)ADE模型拟合时,模型参数弥散系数D随运移距离的增大、粒径的增大和流速的增大均增大；氯化钠的延迟系数R比亮蓝的大,随速度和粒径变化的规律不明显。在TPL模型拟合非均质多孔介质溶质运移时,评价溶质运移不规则性的参数β2的值随流速增大和运移距离的增大均减小,说明在非均质多孔介质中,随水流和运移距离的增大,溶质运移的非费克程度也会相应变高,而在均质多孔介质中,溶质运移符合费克定律。(4)反应性实验中,理想情况下生成物的浓度峰值为0.10mmol/L,而实验中浓度峰值只达到0.05mmol/L左右,证明多孔介质中介质阻隔会对其中的化学反应产生一定的影响。ADRE模型拟合后预测误差减小到2%,拟合效果理想,模型参数D,随流速和介质孔隙度增大而增大,而m和β0仅与流速相关,与介质孔隙度关系不大,其机理有待进一步研究。
[Abstract]:Solute migration in porous media is an important research content in hydrogeology and engineering geology, and tracer experiment is an important method in its research. In order to study the mechanism of non-reactive and reactive solute migration, a physical experimental model of solute transport in one-dimensional porous media was established on the basis of summing up and analyzing the solute migration in groundwater at home and abroad. Using inert tracer sodium chloride and bright blue to compare the applicability of tracing non-reactive solute migration, ADE model and TPL model were used to simulate the solute transport penetration curve, and the fitting results were processed and analyzed. The mechanism and law of non-reactive solute migration in porous media were summarized. Reactive solute migration experiments were carried out by using reactivity tracer (1) -naphthoquinone-4-sulfonate and aniline to simulate groundwater pollutants. The breakthrough curves of reactants and products were obtained and the results were analyzed and discussed with ADRE model fitting results. Summing up and summarizing the experimental results of this paper, we draw the following conclusion: in the adsorption experiment, the adsorption of sodium chloride in porous media is better than that of bright blue, while in the solute transport experiment, the mobility of sodium chloride with water flow is worse than that of bright blue. And the dispersion is stronger than bright blue, and the phenomenon of tail-dragging is obvious. Therefore, on a laboratory scale, bright blue is more suitable than sodium chloride to trace solute migration in porous media as an inert tracer. The simulation accuracy of TPL is higher than that of ADE when simulating solute migration in porous media: in homogeneous porous media, The fitting evaluation parameters R2 and RMSE are very close to each other and can fit the solute migration process very well, while in heterogeneous porous media, the r2 value of TPL is closer to that of ADE, and the fitting accuracy of the model is higher than that of ADE. The dispersion coefficient D increases with the distance of migration, the particle size and flow rate increase, and the delay coefficient R of sodium chloride is larger than that of bright blue, but the law of variation with velocity and particle size is not obvious. When the TPL model fits the solute migration in heterogeneous porous media, the value of 尾 _ 2, which evaluates the irregularity of solute migration, decreases with the increase of flow velocity and migration distance, which indicates that in heterogeneous porous media, the value of 尾 _ 2 increases with the increase of water flow and migration distance. In homogeneous porous media, the solute transport obeys Fecker's law. In the reactivity experiment, the peak concentration of the product is 0.10 mmol / L in ideal condition, but the peak concentration in the experiment is only about 0.05mmol/L. It is proved that the medium barrier in porous media will have a certain effect on the chemical reaction. The prediction error of the ADRE model is reduced to 2 and the fitting effect is ideal. The model parameter D increases with the increase of the flow rate and the porosity of the medium. However, m and 尾 _ 0 are only related to the flow rate, but have little to do with the porosity of the medium. The mechanism of m and 尾 _ 0 needs to be further studied.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P641.2

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