颗粒粒径和水溶液性质对多孔介质渗透性的影响

Effects of Particle Size and Solution Properties on Permeability of Porous Media

水化膜厚度对多孔介质渗透性的影响已为人们所认知,很多文献对此进行了定性的阐述,但这方面的量化研究至今尚处空白。本文首先总结了不同领域有关水化膜厚度的研究成果,确定不同水溶液环境中水化膜厚度的范围在0-200nm,并在此基础上,模拟计算了水化膜厚度对不同粒径球体多孔介质渗透性的影响。为验证模拟结果,试验选用平均粒径分别为8.86（S1）和1.67μm（S2）的2种玻璃微珠进行渗透试验,利用变水头渗透仪,测定不同浓度NaCl和CaCl2溶液在S1和S2样品中的渗透系数。试验结果表明,水化膜对多孔介质渗透性影响显著,在水化膜厚度为75.4-79.4nm的淡水环境中,S1样品的渗透系数为（12.07-12.61）×10^-8 m/s,而S2样品的渗透系数仅为（2.05-2.28）×10^-8 m/s;水化膜厚度的变化对渗透性也有显著影响,5%NaCl溶液中,水化膜厚度被压缩至60.6nm,从而导致S1样品的渗透系数由12.07×10^-8 m/s升高至13.15×10^-8 m/s,S2样品的渗透系数则由2.28×10-8 m/s升高至3.91×10^-8 m/s;5%CaCl2溶液中,水化膜厚度被压缩至32.4nm,从而导致S1样品的渗透系数由12.61×10^-8 m/s升高至15.55×10^-8 m/s,S2样品的渗透系数则由2.05×10^-8 m/s升高至8.86×10^-8 m/s。

Effect of hydration film thickness on the permeability of porous media has been perceived and described qualitatively in many literatures,but quantitatively research in this field is still blank.In this paper,we first collected and analysed large amounts of data on hydration film thickness from different research areas,summarized the approximate range of hydration film thickness at the range of 0-200nm,and then calculated and simulated theoretically the effect of hydration film thickness on the permeability of porous media in different size spheres.Two kinds of micro-glass ball,with the average size of 8.86 mfor S1and 1.67 mfor S2,were used for permeation tests by variable-head permeameter in different concentrations of NaCl and CaCl2 solutions,for verifing the theoretical simulation mentioned above.The results showed that the permeability coefficient of S1 and S2in pure water were（12.07-12.61）×10^-8 and（2.05-2.28）×10^-8respectively,with the hydration film thickness 75.4-79.4.When the hydration film thickness decreased from 75.4to 60.6nm in 5% NaCl solution,the permeability coefficient of S1 increased from 12.07×10^-8 to 13.15×10^-8m/s,and S2 from 2.28×10^-8 to 3.91×10^-8 m/s;while in 5% CaCl2 solution,the hydration film thickness decreased from 79.4to 32.4nm,which made the the permeability coefficient of S1 increased from 12.61×10^-8 to 15.55×10^-8m/s,and S2 from 2.05×10^-8 to 8.86×10^-8m/s.