Fully chemistry analysis of silicate.

The swelling characteristics and mechanisms of bentonite are significantly influenced by the chemical environment of the pore solution, making it essential to study its behavior under different pore solutions in various engineering applications. Taking magnesium-calcium-based bentonite (Mg/Ca-bentonite) as the research object, swelling tests with different concentrations of NaCl solution were carried out to study the effect of salt solution on the deformation characteristics of bentonite. The test results show that the soil expansion rate decreases from 43.7% to 37.1% with the increase of salt solution concentration. The swelling mechanism of bentonite under the influence of NaCl solution was explained from the aspects of lattice expansion theory, diffuse double layer (DDL) theory and comprehensive factors, scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) test were introduced to further explain it from the microscopic aspect. With the increase in salt solution concentration, SEM results reveal that the soil pores become more compact and uniform. Correspondingly, the dual-peak structure observed in the MIP results transitions as the large-pore peak disappears, gradually forming a single peak within the small-pore range. Besides, the function of the swelling and time relationship curve of bentonite was fitted; the relationship model between swelling and solution concentration was established based on this, and the swelling of NaCl solution of different concentrations was simulated and verified, which provides a theoretical model basis for the practical application and numerical simulation of bentonite engineering.

膨润土的膨胀特性与膨胀机制受孔隙溶液化学环境的显著影响，因此在各类工程应用中，研究其在不同孔隙溶液条件下的行为至关重要。本研究以镁钙基膨润土（Mg/Ca-bentonite）为研究对象，开展了不同浓度氯化钠（NaCl）溶液作用下的膨胀试验，以探究盐溶液对膨润土变形特性的影响。试验结果表明，随着盐溶液浓度的升高，土样膨胀率由43.7%降至37.1%。本研究从晶格膨胀理论、扩散双电层（DDL）理论及综合影响因素等方面，阐释了氯化钠溶液作用下的膨润土膨胀机制，并通过扫描电子显微镜（SEM）与压汞法（MIP）测试从微观层面进一步展开验证与阐释。随着盐溶液浓度升高，SEM结果显示土样孔隙愈发致密均匀。相应地，压汞法测试结果中的双峰结构发生演化：大孔峰逐渐消失，最终逐步形成小孔区间内的单峰结构。此外，本研究还拟合了膨润土膨胀量与时间的关系曲线，在此基础上建立了膨胀量与溶液浓度的关系模型，并对不同浓度氯化钠溶液作用下的膨润土膨胀行为进行了模拟与验证，为膨润土工程的实际应用及数值模拟提供了理论模型依据。