盐溶液对石英粉-膨润土混合土渗透系数的影响与表征

EFFECT AND CHARACTERIZATION OF SALT SOLUTION ON HYDRAULIC CONDUCTIVITY OF QUARTZ POWDER-BENTONITE MIXTURE

采用变水头渗透试验对蒸馏水与不同浓度的NaCl、CaCl2溶液下石英粉-膨润土混合土的渗透系数进行了测定,为探讨盐溶液及膨润土含量对混合物渗透系数的影响作用机理,使用核磁共振试验(MRI)、环境扫描电镜(ESEM)对混合物在不同盐度溶液下的孔隙分布特征进行分析。结果表明:在盐溶液作用下,石英粉-膨润土混合土的渗透系数明显增加,其孔隙分布也具有明显的差异。推断盐溶液对渗透系数的影响是由于混合土的孔隙变化引起的。最后利用黏粒孔隙比(eb)的概念,建立了一种考虑盐溶液作用下石英粉-膨润土混合土渗透系数的表征公式,与已有预测公式相比,新建表征公式能够较好地预测盐溶液作用下石英粉-膨润土混合土的渗透系数。

This paper used the variable head permeability test and measured the hydraulic conductivity values of the mixtures of quartz powder and bentonite in distilled water and NaCl and CaCl2solution with different concentrations. It further used the magnetic resonance test(MRI) and the environmental scanning electron microscope(ESEM) and analyzed the pore distribution characteristics of the mixture saturated with different pore fluid salinity. It investigated the effect of pore fluid salinity and bentonite content on the hydraulic conductivity of the mixtures. The results show that the hydraulic conductivity of the mixture of quartz powder increases obviously under the action of salt solution, and the pore distribution also has obvious difference. At last, using the concept of clay porosity ratio(eb) was adopted and established a new characterization formula of hydraulic conductivity of quartz powder bentonite mixture under the action of salt solution. Compared with the existing formula, the new formula can better predict the hydraulic conductivity of quartz powder-bentonite mixture under the action of salt solution.