中国西部黄土因其广分布、易取材的特性，在道路建设中常作为路基填料而广泛应用。但是，黄土因其浸水湿陷特性和压缩变形特性，为中国西部道路的建设和安全服役带来严峻挑战。以过湿黄土为研究对象，提出了单掺粉煤灰、碱激发粉煤灰、炉渣粉煤灰和碱激发炉渣粉煤灰四种改良方案，从含水率，级配曲线，剪切强度和压缩特性四个方面进行评估，优选最佳改良方案。结论如下：①与未改良的天然黄土相比，四种改良方案对颗粒级配均有不同程度的改良，含水率经过14 d养护后，也均出现不同程度的下降，其中碱激发炉渣粉煤灰含水率下降幅度最大，由标准含水率25%下降至18.43%。②四种改良过湿黄土的剪切强度较未改良天然黄土有显著提升。其提升效果从大到小依次为碱激发炉渣粉煤灰改性黄土、炉渣粉煤灰改性黄土、碱激发粉煤灰改性黄土和单掺粉煤灰改性黄土，其中碱激发炉渣粉煤灰的黏聚力相较于天然黄土提升了181.95%，内摩擦角提升了67.41%。③四种改良过湿黄土的压缩特性较为改良天然黄土有显著提升，且均达到低压缩性土标准。其中碱激发粉煤灰改性黄土的压缩系数最小，炉渣粉煤灰改性黄土和碱激发炉渣粉煤灰改性黄土次之，单掺粉煤灰改性黄土的压缩系数最大。④碱激发炉渣粉煤灰改性黄土具有最低含水率、良好的级配、最大的剪切强度和良好的抗压缩变形特性，故认为其是四种过湿黄土改良方案中的最优方案。

Loess is extensively utilized as a roadbed filler in western China's transportation infrastructure due to its widespread availability and accessibility. However, significant engineering challenges are posed by the inherent collapsibility and high compressibility characteristics of this material during road construction and operational safety maintenance. Four improvement schemes were systematically examined for over-wet loess treatment: fly ash, alkali-activated fly ash, slag-fly ash, and alkali-activated slag-fly ash. Comprehensive evaluations were conducted through multiple parameters including water content, grain size accumulation curve, shear strength, and compressibility to determine the optimal improvement scheme. The conclusions show these as follows. Grain composition optimization is achieved in all four improvement schemes compared with untreated natural loess, accompanied by water content reduction after 14 days curing. The most significant water content reduction is achieved in the alkali-activated slag-fly ash improve loess, with its water content decreasing from the 25% to 18.43%. Significantly shear strength improvement is observed in all four improved over-wet loess, with performance hierarchy established as: alkali-activated slag-fly ash improved loess > slag-fly ash improved loess > alkali-activated fly ash improved loess > fly ash improved loess. The alkali-activated slag-fly ash improved loess exhibited a 181.95% enhancement in cohesion and a 67.41% increase in angle of internal friction compared to natural loess. Compressibility characteristics are substantially improved across all improvement schemes, meeting the standard for low-compressibility soil. The compressibility coefficients are quantified in ascending order as: alkali-activated fly ash improved loess < alkali-activated slag-fly ash improved loess < slag-fly ash improved loess < fly ash improved loess. The alkali-activated slag-fly ash improved loess demonstrates superior engineering properties, exhibiting the lowest water content, optimal grain composition, highest shear strength, and exceptional compression deformation resistance. Therefore, it is deemed the most effective improvement scheme among the four over-wet loess improvement methods.