为了研究颗粒级配对粒状材料不排水力学特性的影响，采用两种形状自相似度很高的材料（玻璃球和Hostun砂）进行了一系列传统三轴不排水压缩试验。对于每种材料，保持相近的相对密实度制作了6个不同颗粒级配（不均匀系数 1.1～20）的试样，然后进行剪切。试验结果表明，颗粒级配对粒状材料的不排水力学性能存在明显影响：两种材料试样的偏应力水平随着不均匀系数的增加而降低，抗剪强度随着材料的不均匀系数 的增加而降低，并在 5后呈现出趋稳势态。基于不排水剪切试验中颗粒集合体二阶功的演化规律，对材料受荷载过程中出现不稳定性的条件进行分析。结果表明，在相同密实度下，粒状材料的静态液化潜能随着材料不均匀系数 的提高而增强，高不均匀系数的材料变得不稳定。

This paper studies the influence of grain gradation on the undrained mechanical behavior of granular materials. A series of conventional undrained triaxial compression tests is carried out on two different materials (glass balls and Hostun sand), which have high degree of shape self-similarity. For each material, 6 samples with similar relative density and different gradations ( 1.1-20) are prepared, and then the samples are sheared. Test results show that the grain gradation has an obvious impact on the undrained mechanical behavior of granular material: both deviatoric stress level and undrained shear strength of two material samples decreases as the coefficient of uniformity ( ) of the material increases, their variations tend to converge as coefficient of uniformity surpasses 5. Based on the evolution of the value of the second-order work of the granular assembly during undrained triaxial loading, potential instability for the selected granular materials is also analyzed. The results demonstrate a significant influence of the grain gradation on stability: the higher of coefficient of uniformity ( ), the larger of the potential of static liquefaction and the unstabler of materials.