水化学条件对高岭土压缩性的影响机理

研究在不同水化学条件下高岭土的压缩特性，开展了不同化学溶液饱和条件下高岭土的一维固结试验。试验结果表明：在较低压力水平下，Na+或Ca²⁺明显降低了高岭土的压缩性，但随着离子浓度的增加，高岭土的压缩性又有提高的趋势，而高应力水平下离子浓度对高岭土压缩性的影响不明显；同一浓度下，Ca²⁺对试样压缩性的影响比Na⁺更明显；在酸性或碱性条件下高岭土压缩性均较中性条件下有所提高；回弹曲线同样受到水化学条件的影响。试验结果的作用机理为:水化学条件变化对高岭土压缩性的影响以物理-化学机制为主导，阳离子交替吸附作用与溶蚀、沉淀作用是改变土体压缩性的重要因素。为进一步揭示水-土化学作用的力学效应机理提供了依据。

The effect of hydrochemical conditions on compression characteristics of kaolinite

In order to investigate the compression characteristics of kaolinite in various hydrochemical conditions, oedometer tests on kaolinite specimens saturated with acidic, alkaline and saline solutions were performed. The results indicated that Na⁺ and Ca²⁺ induced the compressibility of specimens significantly in low pressure level, while the increase of ion concentration made a growing trend in the compressibility of kaolinite; in the same concentration, the effect of Ca²⁺ on the compressibility of specimens was more obvious than Na⁺; in acidic or alkaline conditions, the compressibility of kaolinite was improved; hydrochemical condition also had effect on the rebound curve. Then the mechanism of the test was analyzed and it was considered that the effect of variation in hydrochemical conditions on compressibility of kaolinite included both mechanical model and physical-chemical model. Cation exchange and adsorption, dissolution and sedimentation were important influential factors of the compressibility of soil. The basis was provided for further revealing the mechanical mechanism of water-soil chemical interaction.