The densification can increase the liquefaction resistance of sands. However, in most engineering practice, sands are not pure and contain a significant amount of fines with particle diameter smaller than 0.075 mm. Thus, it is necessary to quantitatively evaluate the influence of fines on the undrained cyclic behavior of dense sandy soils. In this study, a series of undrained cyclic triaxial tests were conducted on the dense saturated sand with various mean grain sizes and contents of nonplastic fines. A unified constitutive framework is modified to improve the capability of simulating the cyclic mobility behavior of sandy soils. The results indicate that the effect of the mean grain size on the cyclic stress ratio required to cause 5% double-amplitude axial strain for sandy soils depends on the amount of nonplastic fines added. Moreover, a good correlation between the cyclic resistance ratio and the initial value of the equivalent granular state parameter is obtained for various fines contents and mean grain sizes of nonplastic fines. The influence of the fines content and mean grain size of nonplastic fines on the liquefaction resistance of sandy soils can be reasonably characterized by the constitutive framework using a set of unique parameters. Additionally, the capability of the constitutive framework for describing the influence of the fines content on the cyclic instability behavior of sandy soils is also evaluated against the experimental data in the literature.

致密化可以增加砂子的抗液化性。但是，在大多数工程实践中，沙子不是纯净的，并且包含大量的粒径小于0.075毫米的细粉。因此，有必要定量评估细粉对稠密砂土不排水循环行为的影响。在这项研究中，对稠密的饱和砂土进行了一系列不排水的循环三轴试验，这些砂土具有各种平均粒度和非塑性细屑含量。修改了统一的本构框架，以提高模拟沙土循环流动性的能力。结果表明，平均粒径对引起砂土的5％双振幅轴向应变所需的循环应力比的影响取决于所添加的非塑料细粉的数量。而且，对于各种细粉含量和非塑性细粉的平均粒度，在循环阻力比与等效颗粒状态参数的初始值之间具有良好的相关性。可以通过使用一组唯一参数的本构框架来合理地表征细粒含量和非塑性细粒的平均粒径对沙土抗液化性的影响。此外，本构架描述细粉含量对砂土循环不稳定性行为的影响的能力也根据文献中的实验数据进行了评估。可以通过使用一组唯一参数的本构框架来合理地表征细粒含量和非塑性细粒的平均粒径对沙土抗液化性的影响。此外，本构架描述细粉含量对砂土循环不稳定性行为的影响的能力也根据文献中的实验数据进行了评估。可以通过使用一组唯一参数的本构框架来合理地表征细粒含量和非塑性细粒的平均粒径对沙土抗液化性的影响。此外，本构架描述细粉含量对砂土循环不稳定性行为的影响的能力也根据文献中的实验数据进行了评估。