建筑垃圾在冲击荷载下的分形维数研究

Research on Fractal Dimension of Construction Waste Under Impact Load

初始分布均匀的废弃混凝土和废弃砖集料(19 mm~26.5 mm)在冲击荷载作用下,存在着一个趋向于分形分布的演化过程.通过相同初始粒径(19 mm~26.5 mm)的废弃混凝土和废弃砖集料进行冲击荷载试验,研究不同冲击荷载值下颗粒粒径的分形维数特征,并结合破碎过程中的颗粒破碎量来综合考虑,研究废弃混凝土和废弃砖集料破碎过程中粒径分布曲线的分形维数.试验结果表明:两种强度明显不同的均匀粒径混合,在冲击破碎时,存在保强弃弱效应,强度大的得到较多保存,强度小的优先破碎;随着冲击能量的提高,强度大的最大颗粒形成集料的空间骨架,破碎的混合集料填充于空间骨架的空隙;此外,集料强度越大,破碎后的分形维数越小,分形维数与集料的强度呈反比关系.

The uniformly distributed waste concrete and waste brick aggregates(from 19 mm to 26.5 mm)under impact load had an evolutionary process that tended to fractal distribution.The impact load test was carried out on waste concrete and waste brick aggregates with the same initial particle size(from 19 mm to 26.5 mm),and the fractal dimension characteristics of particle size under different impact load values were studied,combined with the amount of particle crushing in the crushing process,etc.Considering the amount of particle crushing in the crushing process comprehensively,the fractal dimension of the particle size distribution curve in the crushing process of waste concrete and waste brick aggregates was studied.The test results show that when two kinds of uniform particle sizes are mixed with obviously different strengths,there is an effect of maintaining strength and discarding weakness during impact crushing.The stronger one is more preserved,and the smaller one is firstly crushed.As the impact energy increases,the largest particle with high strength forms the space skeleton of the aggregate,and the broken mixed aggregate fills the voids of the space skeleton.In addition,the greater the strength of the aggregate,the smaller the fractal dimension after crushing,and the fractal dimension is inversely proportional to the strength of the aggregate.