考虑细观组分影响的混凝土宏观力学性能理论预测模型

A THEORETICAL PREDICTION MODEL OF CONCRETE MACROSCOPIC MECHANICAL PROPERTIES CONSIDERING THE INFLUENCE OF MESOSCOPIC COMPOSITION

混凝土宏观力学性能与其内部细观结构构造密切相关。该文建立了一类能够考虑细观组分影响的混凝土宏观力学性能理论预测模型。首先,采用细观力学数值试验法对理论模型中的参数进行了标定;进而,基于该模型对混凝土断裂能和单轴抗拉强度在材料层次的尺寸效应行为进行了分析。结果表明:混凝土断裂能和单轴抗拉强度均随骨料级配(即最大骨料粒径)发生变化,且受到界面特性的影响。当界面过渡区力学性能相对薄弱时,混凝土强度较低,断裂能和单轴抗拉强度随骨料级配增大而呈现减小的趋势;当界面过渡区力学性能较强时,混凝土强度较高,断裂能和单轴抗拉强度随骨料级配增大亦呈现增大的趋势。计算结果与试验结果吻合良好,验证了该文建立的理论预测模型的准确性和合理性。

The macroscopic mechanical properties of concrete are highly related to its internal mesoscopic composition. This paper presents a theoretical prediction model of concrete macroscopic mechanical properties considering the mesoscopic composition. Firstly, the parameters in the theoretical model are calibrated by meso-scale numerical tests. Then, the size effect of the concrete fracture energy and the uniaxial tensile strength in material-level is analyzed based on the proposed model. The results show that the concrete fracture energy and the uniaxial tensile strength both vary with the aggregate gradation (i.e. the maximum aggregate size), and they are also influenced by the characteristics of aggregate-matrix interface. When the aggregate-matrix interfaces are weak, the concrete strength is low, and the concrete fracture energy and the uniaxial tensile strength both decrease with the increase of the aggregate gradation. When the aggregate-matrix interfaces are relatively strong, the concrete strength is high, and the concrete fracture energy and the uniaxial tensile strength both increase with the increase of the aggregate gradation. The calculation results are in good agreement with the test results and verify the accuracy and rationality of the theoretical prediction model established in this paper.