In order to well optimize the mineral gradation, a method to numerically test the compactness and the California bearing ratio (CBR) of aggregates via PFC2D was proposed. Then, based on the reliability analysis, the variation laws of the compactness and the CBR were analyzed respectively for synthetic coarse aggregates, synthetic fine aggregates and coarse-fine combined aggregates, and a close-grained gradation of aggregates skeleton under strong interlocked force was proposed. Moreover, the mechanical performances of the aggregates skeleton were verified through laboratory tests. The results show that the optimal mass ratios of the coarse aggregates with the diameters of 19 - 31. 5mm, 9.5 ~ 19mm and 4. 75 ~ 9. 5mm are respectively 0 : 20 : 10, 60 : 30 : 10, 60 : 20 : 20 and 50 : 30 : 20, while those of the fine aggregates with the diameters of 2. 36 ~4.75mm, 0.6 ~2. 36mm and less than 0.6mm are respectively 38.5:16.5:45 , 33:22:45, 36:24:40 and 30:30:40, and that the optimal mass ratio of coarse-fine combined aggregates is 65 :35. It is also found that the graded broken stone composed of the aggregates skeleton with close-grained gradation under strong interlocked force is of excellent mechanical properties because its CBR and compressive strength are respectively 1.16 and 1.12 times those of the standard gradation.%为了充分优化矿料级配,应用PFC2D构建了矿料密实度和加州承载比(CBR)的数值试验方法,在可靠性验证的基础上,分析了合成粗集料、合成细集料、粗细混合集料的密实度和CBR变化规律,提出了矿料强嵌挤骨架密实级配,并对其力学性能进行了室内试验验证.结果表明:19～31.5mm集料、9.5 ～ 19mm集料和4.75～ 9.5 mm集料3种规格粗集料的最佳质量比分别为70∶20∶10、60∶30∶10、60∶20∶20和50∶30∶20,2.36 ～4.75mm集料、0.6 ～2.36mm集料和0.6mm以下集料3种规格细集料的最佳质量比为38.5∶16.5∶45、33∶22∶45、36∶24∶40和30∶30∶40,粗细混合集料的最佳比例为65∶35；由矿料强嵌挤骨架密实级配组成的级配碎石的CBR值和抗压强度分别为规范级配的1.16倍和1.12倍以上,证明该级配具有良好的力学性能.
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