为探究不同粉煤灰掺量粉砂土的动力特性和粉煤灰改良粉砂土的改性机理，以绥化—大庆高速公路路基填土为研究对象，开展无侧限压缩试验和动三轴试验，分析粉煤灰掺量对粉砂土静力学特征影响情况，以及围压、动荷载加载次数和粉煤灰掺量对改良粉砂土动强度的影响规律。结果表明：围压相同的情况下，土体的无侧限压缩强度和动强度，均随粉煤灰掺量增加先升高后降低；加载次数相同时，围压越大，土体动强度越大；选取加载次数为100次动强度进行拟合分析，得出粉煤灰掺入量与动剪切强度对应关系的经验公式。为改善路基强度，加快粉煤灰综合利用进程，结合试验结果与数据分析，建议在粉砂土路基掺加质量比15%粉煤灰进行路基施工。15%粉煤灰掺入量的改良粉砂土对比素土，存在颗粒紧凑，孔隙更小，结构相对致密，骨架更强等优点，可为东北地区粉砂土改良等工程建设提供参考。

In order to investigate the dynamic characteristics of fly ash mixed with different amounts of fly ash and the modification mechanism of fly ash improved fly sand soil, Suihua-Daqing Expressway roadbed fill was taken as the research object. The lateral limit compression test and dynamic triaxial test were conducted to analyze the influence of fly ash mixture on the static mechanical characteristics of fly sand soil, as well as the influence law of surrounding pressure, dynamic load loading times and fly ash mixture on the dynamic strength of improved fly sand soil. The results show that the unconfined compressive strength and dynamic strength of the soil, with the same circumferential pressure, both increase firstly and then decrease with the increase of fly ash admixture. For the same number of loadings, the dynamic strength of the soil increases with increasing circumferential pressure. The loading number of 100 times of dynamic strength is selected for fitting analysis, and the empirical equation corresponding to the relationship between fly ash admixture and dynamic shear strength is derived. In order to improve the strength of the roadbed and speed up the process of comprehensive utilization of fly ash, the test results were combined with data analysis. It is recommended to mix the quality ratio of 15% fly ash for roadbed construction in the pulverized sand soil roadbed. The improved chalk soil with 15% fly ash admixture has the advantages of compact particles, smaller pores, relatively dense structure and stronger skeleton compared with the plain soil, which can provide reference for the construction of chalk soil improvement and other projects in northeast China.