高岭土胶体絮凝导致滨海地层堵塞的试验研究

Experimental Study on Clogging of Coastal Aquifer Caused by Kaolin Colloid Flocculation

人工回灌容易导致滨海地层堵塞,已有研究主要集中在外源悬浮物的浓度和粒径对多孔介质地层堵塞的影响,而关于内源黏土颗粒胶体絮凝引起的堵塞规律仍不清楚。本文通过静水絮凝实验和定水头砂柱实验,研究了高岭土胶体的动水絮凝对含水介质渗透性的影响,且通过扫描电子显微镜观察其絮凝后的微观形态,并借助DLVO理论分析了高岭土胶体之间、高岭土胶体与多孔介质间的总相互作用能,揭示了高岭土胶体絮凝对滨海地层堵塞的影响规律。实验结果表明:高岭土的胶体絮凝对滨海地层堵塞有显著影响。砂柱渗透性降低变化曲线与高岭土胶体静水絮凝过程中溶液浊度的变化曲线非常相似,符合指数函数关系Y=C′e,参数D′代表含水介质的堵塞速率,D′愈大,含水介质渗透性的下降速率愈快。另外,多孔介质渗透性下降速率滞后于高岭土胶体的静水絮凝速率。此研究可为预防滨海含水层堵塞提供一定的科学理论依据。

The clogging of aquifers occurs during the artificial recharge of coastal strata.Previous stu-dies have focus on the influence of the concentration and particle size of suspended solids on the damage of porous media.The clogging of porous media caused by colloidal flocculation of clay particles is still unclear.In this paper,the influence of kaolin flocculation on the permeability of porous media was studied by hydrostatic flocculation experiments and constant head sand column experiments.The microscopic morphology of flocculated kaolin was observed through scanning electron microscope.The total interaction energy in kaolin colloid and porous media was analyzed by DLVO theory,and the effect of kaolin colloid flocculation on the damage of coastal was revealed.Results showed that the flocculation of kaolin colloid has a significant effect on coastal damage.The variation curve was similar between sand column permeability and the solution turbidity in kaolin colloid hydrostatic flocculation process,which was consistent with exponential function relationship:Y=C′e,The D′represents the clogging rate of the porous media,and the decrease rate of permeability of porous media was accelerated due to the increase of D′.However,the rate of permeability decline of porous media is slower than its hydrostatic flocculation.