This study explores the compression deformation characteristics of compacted loess after different wetting–drying (WD) cycles, by tracking microstructure changes by scanning electron microscope (SEM), laser particle size analyzer, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). Experimental results show that, as the number of wetting–drying cycles increases, the compression deformation of the compacted loess upon mechanical loading increases and the yield stress decreases. The first wetting–drying cycle causes the largest change in terms of mechanical response. As long as the number of wetting–drying cycles increases, their effect is less significant. Microstructural analyses have been exploited to interpret the evolution of the mechanical properties at the laboratory scale. With the increase in the number of wetting–drying cycles, FTIR results showed that the functional group strength gradually decreased, implying a reduction of the cementation strength between the particles of the compacted material. SEM images showed that the contacts among loess aggregates (composed by particles) varied from “face to face” to “point to point.” NMR results demonstrated that the total and inter-aggregate pores volume increased, while the intra-aggregate pores volume decreased upon wetting–drying cycling. The microstructure investigation allowed understanding the major role played by cementation strength, aggregate contact type, and pore size distribution on the compression behavior of compacted loess after wetting–drying cycles.

本研究通过扫描电子显微镜 (SEM)、激光粒度仪、傅里叶变换红外光谱 (FTIR) 和核磁共振跟踪微观结构变化，探索不同干湿 (WD) 循环后压实黄土的压缩变形特征。核磁共振）。实验结果表明，随着干湿循环次数的增加，压实黄土在机械载荷作用下的压缩变形增加，屈服应力减小。第一个干湿循环引起机械响应方面的最大变化。只要干湿循环次数增加，它们的影响就不那么显着了。已利用微观结构分析来解释实验室规模的机械性能的演变。随着干湿循环次数的增加，FTIR结果表明官能团强度逐渐降低，这意味着压实材料颗粒之间的胶结强度降低。SEM图像显示，黄土聚集体（由颗粒组成）之间的接触从“面对面”到“点对点”变化。核磁共振结果表明，在干湿循环过程中，总孔容和骨料间孔体积增加，而骨料内孔体积减少。微观结构研究有助于了解胶结强度、骨料接触类型和孔径分布对干湿循环后压实黄土压缩行为的主要作用。这意味着压实材料颗粒之间的胶结强度降低。SEM图像显示，黄土聚集体（由颗粒组成）之间的接触从“面对面”到“点对点”变化。核磁共振结果表明，在干湿循环过程中，总孔容和骨料间孔体积增加，而骨料内孔体积减少。微观结构研究有助于了解胶结强度、骨料接触类型和孔径分布对干湿循环后压实黄土压缩行为的主要作用。这意味着压实材料颗粒之间的胶结强度降低。SEM图像显示，黄土聚集体（由颗粒组成）之间的接触从“面对面”到“点对点”变化。核磁共振结果表明，在干湿循环过程中，总孔容和骨料间孔体积增加，而骨料内孔体积减少。微观结构研究有助于了解胶结强度、骨料接触类型和孔径分布对干湿循环后压实黄土压缩行为的主要作用。” NMR结果表明，在干湿循环过程中，总孔体积和团间孔体积增加，而骨料内孔体积减小。微观结构研究有助于了解胶结强度、骨料接触类型和孔径分布对干湿循环后压实黄土压缩行为的主要作用。” NMR结果表明，在干湿循环过程中，总孔体积和团间孔体积增加，而骨料内孔体积减小。微观结构研究有助于了解胶结强度、骨料接触类型和孔径分布对干湿循环后压实黄土压缩行为的主要作用。