摘要
混凝土动态力学行为具有明显的率相关性，探讨了加载速率及其突变对混凝土压缩破坏模式及宏观力学性能的影响。考虑混凝土细观结构非均质性的影响，从细观角度出发将混凝土看作由骨料、砂浆基质及过渡区界面组成的三相复合材料。采用耦合应变率效应的塑性损伤本构关系模型来描述砂浆基质及界面的动态力学行为；认为骨料不产生断裂破坏，为弹性体。采用Monte Carlo法建立了混凝土二维随机骨料模型，首先对Dilger等混凝土动态压缩试验进行数值模拟，数值与试验结果的良好吻合证明了方法的可行性及细观参数选取的准确性。进而探讨了细观组分应变率效应的影响，对比了混凝土非均质模型与宏观均匀模型的应变率效应，最后分析了软化阶段加载速率突变对混凝土破坏模式及宏观应力-应变关系的影响，并得到了一些有益结论。
Abstract
The dynamic mechanical behavior of concrete has obvious strain-rate dependency. The effects of loading rate and its sudden change on the compressive failure pattern and the macroscopic dynamic mechanical properties of concrete are studied. Taking the influence of concrete heterogeneity, at meso-scale concrete is treated as a three-phase composite composed of aggregate, mortar matrix and the interfacial transition zone (ITZ) between them. The damaged plasticity theory combined with strain effect is used to describe the dynamic mechanical properties of mortar matrix and the ITZ. It is assumed that the aggregate phase does not damage, and thus aggregate is set to be elastic. A plane concrete random aggregate structure is established by the Monte Carlo method. The dynamic compressive tests conducted by Dilger et al are simulated at first, and the good agreement between the present numerical results and the experimental observations indicates the feasibility of the present meso-scopic approach and the reasonability of the selected mechanical parameters. Subsequently, the material strain-rate effect is discussed, and the strain-rate effects in the concrete meso-scale heterogeneous model and macro-scale homogeneous model are compared and studied. Finally, the influence of the sudden change of loading rate during the softening stage on the failure mode and macroscopic mechanical properties of concrete is analyzed. Some useful conclusions are given.
关键词
混凝土 /
细观尺度 /
加载速率 /
应变率效应 /
速率突变 /
压缩破坏
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Key words
Concrete /
Meso-scale /
Loading rate /
Strain-rate effect /
Sudden change of loading rate /
Compressive failure
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金 浏;杜修力.
加载速率及其突变对混凝土压缩破坏影响的数值研究[J]. 振动与冲击, 2014, 33(19): 187-193
JIN Liu;DU Xiu-li.
Effects of loading rate and its sudden change on concrete compressive failure[J]. Journal of Vibration and Shock, 2014, 33(19): 187-193
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