文章摘要
任青文,殷亚娟,沈雷.混凝土骨料随机分布的分形研究及其对破坏特性的影响[J].水利学报,2020,51(10):1267-1277,1288
混凝土骨料随机分布的分形研究及其对破坏特性的影响
Fractal study of random distribution of concrete aggregate and its effect on damage characteristics
投稿时间:2020-02-19  
DOI:10.13243/j.cnki.slxb.20200089
中文关键词: 细观混凝土  骨料分布  多重分形维  盒维数  破坏特性
英文关键词: meso-concrete  aggregate distribution  multifractal spectrum  box dimension  damage characteristics
基金项目:国家自然科学基金项目(51739006);中国博士后科学基金项目(2020T130170)
作者单位E-mail
任青文 河海大学 力学与材料学院, 江苏 南京 210098
河海大学 水利水电学院, 江苏 南京 210098 
renqw@hhu.edu.cn 
殷亚娟 河海大学 水利水电学院, 江苏 南京 210098  
沈雷 河海大学 力学与材料学院, 江苏 南京 210098  
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中文摘要:
      混凝土的破坏特性和损伤破坏形态具有明显的离散性和随机性,骨料的随机分布形态是重要的影响因素之一。但是对骨料分布的量化表征一直是比较棘手的问题。在假定混凝土是由骨料、砂浆及两者之间的界面组成的三相复合材料基础上,建立了细观混凝土力学模型。对36组不同骨料分布形式下的混凝土试件的单轴拉伸力学行为进行了数值研究,并利用盒维数和多重分形谱表征骨料分布,研究其随机分布规律以及对混凝土破坏特性的影响。发现多重分形谱较盒维数可以更好地提取局部细节特征,为骨料分布的量化研究提供了一种新的方法。进而统计分析了骨料分布多重分形谱谱宽与拉伸强度、软化段曲线(脆性)和裂纹分布盒维数的相关关系,研究表明骨料分布多重分形谱谱宽与拉伸强度和脆性呈反相关关系,与裂纹分布盒维数成正相关关系,即骨料分布多重分形谱谱宽越小,骨料分布越均匀,峰值应力越大,脆性越明显,裂纹扩展越规则,裂纹分布盒维数越小。该研究有助于加深对混凝土破坏特性和开裂破坏形态的认识。
英文摘要:
      The damage characteristics and patterns of concrete have obvious dispersion and randomness, and the random distribution form of aggregate is one of the important influencing factors. However, the quantitative characterization of aggregate distribution has always been a tricky issue. Assuming that concrete is a three-phase composite material composed of aggregate,mortar,and the interface between the two,the mechanical model of mesoscopic concrete is established in this paper. The uniaxial tensile mechanical behavior of 36 groups of concrete specimens with different aggregate distributions was numerically studied. The box dimension and multifractal spectrum are used to characterize the aggregate distribution, in order to study its random distribution law, as well as its influence on the failure characteristics of concrete. It is found that the multifractal spectrum can extract local detail features better than box dimension, which provides a new method for quantitative study of aggregate distribution. Furthermore,the correlations of the multifractal spectral width of aggregate distribution with tensile strength, softening section curve (brittleness) and the box dimension of crack distribution are analyzed. The results show that the multifractal spectral width of aggregate distribution is negatively correlated with tensile strength and brittleness, but positively correlated with the box dimension of crack distribution. This means that the smaller the multifractal spectrum width of the aggregate distribution, the more uniform the aggregate distribution, the larger the peak stress,the more obvious the brittleness,the more regular the crack growth,and the smaller the box dimension of the crack distribution. This research is helpful to deepen the understanding of concrete damage characteristics and cracking patterns.
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