膨润土-高岭土混合介质的表面电导率研究

Effects of bentonite fraction on surface electrical conductivity of bentonite-kaolinite mixed soils

由于自身矿物结构,天然黏性土颗粒表面会形成阳离子聚集的扩散层引起黏性土颗粒产生表面电导率(?s)。不同的黏性颗粒成分黏性土具有不同的双电层结构,引起表面电导率的变化,使得天然黏性土自身电导率(?mix)十分复杂。文章通过配置不同膨润土成分含量(BF=0~70%)的膨润土-高岭土混合介质,以评估表面电导率对混合电导率的影响。同时回顾电导率模型,介绍可以用于评价表面电导率的有效介质模型,并使用改进的4电极电导率测试设备,分析不同膨润土含量混合介质表面电导率导电模型。研究结果表明,混合介质总体电导率以及表面电导率随着膨润土含量的增加而显著增加;同时将文中试验的研究结果与有效介质导电模型相结合,得出不同表面电导率的混合介质有效模型;最后,根据改进的有效介质模型与相关文献研究进行对比验证模型的适用性。

The surface electrical conductivity(?s)of natural clay deposits was caused by the presence of double electric layers,which caused by its own mineral structure,around the clay particle.Different clay particle has different double layer structure,which makes the mixed conductivity(?mix)more complicated.Therefore,the aim of this study is to evaluate/estimate the influence of surface conductivity on the mixed conductivity of bentonite-kaolinite mixed soils with varying weight fraction of bentonite particles(BF=0~70%).The electrical conductivity formulas,including the effective media conductivity model used for surface conductivity assess,were reviewed,and a number of electrical conductivity measurements on bentonite-kaolinite mixtures were performed in this study using a developed oedometer cell equipped with a 4 electrodes conductivity probe.The results of this study demonstrate that the measured?mix and surface electrical conductivity?s of tested bentonite-kaolinite mixed soils increases considerably with an increase in BF.The comparison between the experimental results of this study and the effective media estimating formulas for mixed soils demonstrates that the modified effective media equation gives the most dependable estimate of?mix of tested bentonite-kaolinite mixed soils.Finally,the matrix conductivity in the modified effective media equation is compared with other related literature research data in this study.