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进行压汞试验和SEM-EDS试验研究复合改性前后水玻璃加固黄土,分析其孔隙分布特征、颗粒和孔隙形态以及胶结物形态和化学元素含量,探讨宏观力学特性与微观特征的联系。压汞测试结果表明,改性前后加固黄土具有相近的孔隙分布特征,入口孔径主要分布在0.06~8μm之间,大、中、小和微孔隙分界值分别为8、2、0.06μm,加固时生成的凝胶填充作用不显著。SEM-EDS测试结果表明,改性后黄土仍保持其粒状、架空、接触-胶结结构不变,但加入硅酸钾材料后黄土颗粒表面变得粗糙并吸附有絮状物,EDS数据显示K元素含量随着硅酸钾掺入量的增加而增大,且试样无侧限强度与K元素百分含量正相关。研究还表明,土的颗粒联结强度和结构形态特征是导致黄土宏观力学性质差异的本质原因,在复合改性水玻璃加固黄土时在保持黄土架空孔隙基本不变的前提下,生成的含K凝胶在改变颗粒表面形态的同时强化了骨架颗粒之间的连接强度,从而改善了土体的强度。
Mercury porosimetry and SEM-EDS were used to study the effect of water glass on the consolidation of loess before and after composite modification. The pore distribution, the morphology of particles and pores, the morphology of cement and the content of chemical elements were analyzed, and the relationship between macroscopic mechanical properties and microscopic features was also discussed. The results of mercury intrusion test show that the modified loess has similar pore distribution characteristics before and after modification. The entrance pore diameters are mainly distributed in the range of 0.06 ~ 8μm, and the demarcations of the large, medium, small and micropores are 8, 2 and 0.06μm, respectively The effect of gel filling was not significant. The results of SEM-EDS showed that the modified loess retained its granularity, overhead structure and contact-cementation structure. However, after adding potassium silicate, the surface of loess particles became rough and the floc was adsorbed. EDS data showed that K element The content increases with the increase of potassium silicate content, and the unconfined strength of the sample is positively correlated with the percentage of K element. The study also shows that the strength of soil particles and the structural features of the soil are the essential causes of the macroscopic mechanical properties of the loess. When the composite modified water glass is used to reinforce the loess, the pore-forming porosity of the loess is kept unchanged. Gums alter the surface morphology of the particles and at the same time enhance the bond strength between the framework particles, thereby improving the strength of the soil.