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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2.5×10-11m/s,而30 mM的CaCl2溶液使渗透系数上升至5.6×10-11m/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。
Solute has obvious chemical-osmotic characteristics during long-term infiltration of geosynthetic liner (GCL). The results of indoor infiltration experiments showed that the displacement effect of cation was greatly affected by the displacement coefficient of GCL liner. The permeability coefficient increased to 2.5 × 10-11m / s with 10mM CaCl2 solution, while the permeability coefficient increased with CaCl2 solution of 30mM 5.6 × 10-11m / s. The increase of osmotic liquid shortens the time when solute penetrates into GCL, and the effect of pre-saturation treatment reagent on the permeability coefficient of GCL is greater. The effect of using distilled water as pre-saturation reagent to treat GCL liner is obviously lower than that of CaCl2 solution. The coupling kinetic model of solute transport considering membrane effect and ion exchange effect was established and the change of solute concentration during GCL penetration test was predicted. The simulation results show that the infiltration of 10 mM and 30 mM CaCl2 solutions Under the condition of Ca2 + concentration, the experimental results and the calculated results are in good agreement, which verifies the reliability of the coupled dynamic model. It can be seen from the distribution of Ca2 + concentration and flux breakthrough curve that the chemical-osmotic effect can effectively delay the migration speed of solute. As the solute concentration decreases, the blocking effect is more pronounced. Therefore, in analyzing the solute infiltration characteristics in GCL liners, the effects of chemo-permeation effects must be considered.