人工回灌过程中水温对滨海非均质地层物理堵塞的影响

Effect of water temperature on physical clogging ofcoastal heterogeneous layer during artificial recharge

人工回灌容易引起滨海地层堵塞,回灌水温度与多孔介质的非均质性是发生物理堵塞的重要影响因素。本文通过改变多孔介质的颗粒级配模拟不同渗透性的非均质地层,进行定水头渗流实验,探究非均匀多孔介质在10~25℃回灌条件下渗透系数的时空演变规律,定量分析悬浮颗粒在多孔介质内的沉积分布特征,揭示水温与含水层非均质性对滨海地层物理堵塞的影响规律。结果表明:水温影响多孔介质颗粒物堵塞过程受介质不均匀性的限制,存在不均匀系数临界值。当不均匀系数低于临界值,随回灌水温度升高,介质堵塞速率加快。当不均匀系数高于临界值时,水温对多孔介质物理堵塞的影响很小。回灌水温度恒定的情况下,多孔介质不均匀系数越大,表层堵塞越严重。研究成果可为预防滨海含水层物理堵塞提供一定的科学理论依据。

Artificial recharge is easy to cause clogging in coastal strata.The temperature of recharge water and the heterogeneity of porous media are important influencing factors for physical clogging.In this paper,by changing the particle gradation of porous media to simulate heterogeneous layers with different permeability,constant head seepage experiments were carried out to explore the spatio-temporal evolution law of permeability coefficient of heterogeneous porous media under the condition of 10~25℃recharge,and to quantitatively analyze the sedimentary distribution characteristics of suspended particles in porous media,and to reveal the influence of water temperature and aquifer heterogeneity on the physical blockage of coastal strata.The results showed that the effect of water temperature on the clogging process of particles in porous media was limited by the heterogeneity of the media,and there existed a critical value of coefficient of uniformity.When the coefficient of uniformity was below the critical value,the clogging rate increaseed with the increase of the temperature of recharge water.When the coefficient of uniformity was higher than the critical value,the water temperature had little effect on the physical clogging of porous media.Under constant temperature of recharge water,the larger the coefficient of uniformity of porous media was,the more serious of the surface clogging.The results can provide scientific basis for preventing physical clogging of coastal aquifer.