CBR particle flow simulation of aggregate and design of coarse aggregate skeleton gradation with strong interlocked force
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摘要: 应用PFC2D模拟了集料加州承载比(CBR) 试验, 分析了单规格粗集料、合成粗集料与粗细混合集料的CBR变化规律, 提出了强嵌挤粗集料骨架级配, 并对其力学性能进行了室内试验验证。研究结果表明: 19~31.5 mm集料构成了具有强嵌挤力的主骨架结构, 最佳质量分数为50%~70%;9.5~19 mm和4.75~9.5 mm集料具有填充主骨架空隙或干涉主骨架结构形成的作用, 4.75~9.5 mm集料最佳质量分数为10%;粗细集料最佳比例为65∶35, 此时粗细混合集料CBR值最大, 大于540%;由强嵌挤粗集料骨架级配组成的混合料的CBR和抗压强度分别为规范级配的1.19倍和1.10倍以上, 证明了粗集料级配具有良好的力学性能。Abstract: California bearing ratio (CBR) test was simulated by using PFC2D, CBR changing laws of single coarse aggregate, synthetic coarse aggregate and coarse-fine combined aggregate were analyzed, a coarse aggregate skeleton gradation with high interlocked force was put forward, and its performances were verified through laboratory test. Test result shows that the main skeleton structure composed of the aggregate with diameter 19-31.5 mm has high interlocked force, and the optimal mass fraction is 50%-70%. The aggregates with diameter 9. 5-19 mm and 4.75-9.5 mm have the effects of filling the void of main skeleton structure and interfering its composing, and the optimal mass fraction of the aggregate with diameter 4.75-9.5 mm is 10%. When the optimum proportion of coarse aggregate to fine aggregate is 65∶35, the CBR value of coarse-fine combined aggregate reaches the highest point, and is more than 540%. The CBR value and compressive strength of the mixture composed of the coarse gradation are over 1.19 times and 1.10 times than that of standard gradation respectively, so the coarse gradation has better mechanical properties.
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表 1 集料的表观密度
Table 1. Apparent densities of aggregates
表 2 微力学参数
Table 2. Micro mechanical parameters
表 3 CBR的实测值与模拟值
Table 3. Simulation values and measured values of CBR
表 4 单规格粗集料的CBR模拟结果
Table 4. CBR simulation result of single coarse aggregates
表 5 级配
Table 5. Gradations
表 6 强嵌挤粗集料骨架级配
Table 6. Coarse aggregate skeleton gradation with strong interlocked force
表 7 不同级配碎石的CBR室内试验结果
Table 7. Laboratory test results of CBR for different graded broken stones
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