| 殷亚娟,任青文,沈雷,韩衍.基于分形维的混凝土裂纹扩展及损伤演化过程研究[J].水利学报,2021,52(11):1270-1280 |
| 基于分形维的混凝土裂纹扩展及损伤演化过程研究 |
| Study on crack propagation and damage evolution process of concrete based on fractal dimension |
| 投稿时间：2021-07-21 |
| DOI：10.13243/j.cnki.slxb.20210594 |
| 中文关键词: 混凝土 细观 裂纹扩展 损伤演化 分形维 突变点 |
| 英文关键词: concrete mesoscopic crack propagation damage evolution fractal dimension mutation point |
| 基金项目:国家自然科学基金项目（51739006） |
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| 摘要点击次数: 1297 |
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| 中文摘要: |
| 混凝土材料破坏过程中裂纹的演化具有随机无规律的特点，而外界条件的复杂性和混凝土自身的非线性使得裂纹的动态演化规律研究十分困难。为定量研究混凝土受力过程中裂纹及损伤的演变过程，本文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，提出一种基于裂纹分形维的损伤变量计算方法，对多组混凝土试件的单轴拉伸力学行为进行损伤数值研究，利用分形维对混凝土开裂全过程中的裂纹分布进行表征。研究表明：细观模拟的裂纹形态与试验结果相符；裂纹分形维能够更好地反映混凝土材料损伤的变化过程，可以定量描述材料损伤演化的特性；发现了混凝土从“均匀”损伤至局部破坏的临界点；细观模拟得到的应力-应变曲线、裂纹分形维曲线、损伤演化曲线受网格尺寸的影响很小；随着混凝土试件骨料级配数的增加，骨料颗粒和界面减少，整体耗能降低，应力峰值和裂纹分形维均减小。此外，本文建议应力峰值点后的裂纹分形维曲线的突变点为混凝土材料从“均匀”损伤进入局部破坏的临界点，是损伤和断裂的分界点，相应的损伤值约为0.8，该值可作为混凝土出现宏观裂纹的损伤阈值。本文研究加深了人们对混凝土破坏机理的认识。 |
| 英文摘要: |
| The cracks evolution during the cracking process of concrete materials shows randomness. The concrete materials are nonlinearity of themselves and the external conditions are complex. These results in largely difficult study on the dynamic evolution law of concrete cracks. To quantitatively study the evolution process of cracks and damage of concrete under loading, the meso-concrete mechanics model is established assuming that the concrete is a three-phase composite composed of aggregates, mortar, and the transition zone between them. A new calculation method of damage variable is proposed based on the crack fractal dimension, and the uniaxial tensile mechanical behavior of multiple groups of concrete specimens is studied in numerical simulation. The concrete damage crack distribution is characterized by fractal dimension. It shows that the results of meso-simulated crack pattern are consistent with the experimental results. The crack fractal dimension can better reflect the damage evolution process of concrete materials, and quantitatively describe the damage evolution characteristics of concrete materials. It finds the critical point of concrete materials from "uniform" damage to local failure. The stress-strain curve, the crack fractal dimension curve, and the damage evolution curve from meso-simulation results are all less affected by the element size. With the increase of aggregate gradation of concrete specimens, the aggregate particles and interface decrease, the overall energy consumption decreases, and the peak stress and crack fractal dimension decrease. In addition, it is suggested that the mutation point of the crack fractal dimension-strain curve after the stress peak point is the critical point of the concrete materials from the "uniform" damage distribution stage to local failure stage, which is the boundary point of damage and fracture. The corresponding damage value is about 0.8, which can be used as the damage threshold for the occurrence of concrete macroscopic crack. These findings in this paper deepen the understanding of the failure mechanism of concrete. |
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