溶质入渗土工合成衬垫的化学-渗透特性研究

溶质在土工合成衬垫（GCL）长期入渗过程中具有明显的化学-渗透特性。室内渗透试验表明：阳离子之间的置换效应对GCL衬垫渗透系数影响较大，10 mM的CaCl2溶液使渗透系数上升至2.5×10-11 m/s，而30 mM的CaCl2溶液使渗透系数上升至5.6×10-11 m/s。渗透液体浓度的增加缩短了溶质穿透GCL的时间，且预饱和处理试剂对GCL渗透系数的变化影响较大，采用蒸馏水作为预饱和试剂处理GCL衬垫对其渗透系数的影响明显小于CaCl2溶液；建立了考虑膜效应和离子交换效应条件下溶质运移耦合动力学模型，并对GCL穿透试验过程中溶质浓度的变化进行了预测，仿真计算结果表明，10 mM和30 mM两种CaCl2溶液渗透条件下，Ca2+浓度变化的试验结果和计算结果均相吻合，验证了耦合动力学模型的可靠性；从Ca2+浓度及流量穿透曲线分布可知，化学-渗透效应可有效地延缓溶质的迁移速度。随着溶质浓度的降低，阻滞作用更显著。因此，在分析GCL衬垫中溶质入渗特征时，必须考虑化学-渗透效应的影响。

Chemosmosis performance of solute permeating into geosynthetic clay liners

The chemosmosis performance for long-term solute permeation in the geosynthetic clay liner(GCL) is obvious.The laboratory test of permeation with solute is introduced.And the test result indicates that the cation exchange has largely effect on the hydraulic conductivity of GCL.The hydraulic conductivity of GCL is up to 2.5×10-11m/s and 5.6×10-11m/s permeated with 10 mM and 30 mM CaCl2 solution respectively.The time of solute breakthrough the GCL decreases with the solution concentration increasing.The change of the hydraulic conductivity of the GCL is impacted largely on the presaturation reagent.The effect of the hydraulic conductivity of GCL by using the distilled water for presaturated sample is much smaller than that using the CaCl2solution.Considering the effect of the membrane behavior and cation exchange,the coupling dynamic model of solute transport has been developed.And the coupling model is applied to modeling the variation of the solute concentration in permeation process.The Ca2+ concentration is anastomotic by data match from the test and simulation result;and the reliability of the coupling model is approved.The chemosmosis in GCL is important,which can effectively delay the solute transport velocity described by the breakthrough curve of Ca2+concentration and flux.Moreover,the level of the retardation effect by chemosmosis becomes obviously with decreased of the solute concentration.Therefore,the effect of the chemosmosis should be taken into account for analysis of the solute transport in GCL.