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将混凝土假定为一种由硬化水泥砂浆、粗骨料、界面粘结带所组成的三相复合材料,在满足骨料级配曲线算法的基础上,采用细观单元的弹塑脆性损伤本构关系,考虑材料的非均质特性,建立了基于细观力学的混凝土弹塑脆性损伤数值模型;分别研究了单轴受拉预置裂纹试样和单轴受压混凝土试样的细观弹塑脆性损伤破坏行为,并揭示了混凝土的宏观表征强度存在明显的尺寸效应,通过将计算结果与Bazant尺寸效应公式、单轴受压物理实验曲线进行对比,验证了模型的正确性。数值试验表明:该模型可以清晰地模拟混凝土细观塑性屈服和失效裂纹的萌生和扩展。骨料与水泥砂浆间的界面粘结带相对薄弱,在混凝土试件形成宏观损伤局部化带前,试件的屈服和破坏首先发生在骨料边缘处的界面位置,并沿着界面粘结带扩展、贯通;同时,导致宏观裂纹形成和发展的因素仍以细观单元的拉伸破坏为主。
The concrete is assumed to be a kind of three-phase composite material composed of hardened cement mortar, coarse aggregate and interface adhesive tape. On the basis of satisfying the algorithm of aggregate gradation curve, the meso- In this paper, the numerical model of the elastic-plastic brittleness damage of concrete based on meso-mechanics was established considering the heterogeneity of the material. The mesoscopic elastic-plastic model of uniaxial tension pre-cracked specimens and uniaxial- The results show that there is an obvious size effect on the macroscopic strength of concrete. The correctness of the model is verified by comparing the calculated results with the Bazant size effect formula and the uniaxial compression physical experiment curve. Numerical experiments show that this model can clearly simulate the plastic deformation of concrete and the initiation and propagation of failure cracks. The interface bond between the aggregate and the cement mortar is relatively weak. Before the macroscopic damage localization zone of the concrete specimen is formed, the yielding and failure of the specimen first occurs at the interface location at the edge of the aggregate and along the interface adhesive tape Expansion, through; the same time, leading to the formation and development of macro-cracks are still the main elements of the tensile damage.