级配与骨料率对混凝土力学行为的影响

Influence of gradation and aggregate content on mechanical behavior of concrete

【目的】研究级配和骨料率对混凝土物理力学性质的影响,为揭示骨料率及级配对混凝土力学行为的影响机制提供参考。【方法】在颗粒流数值平台上进行了具有骨料破裂功能的混凝土单轴压缩虚拟试验,设计了不同骨料率(0%,50%,60%,70%,80%)和不同级配(一级配、二级配、三级配、四级配)混凝土虚拟试验,分析材料的破裂形态、裂纹扩展过程、应力应变曲线和破裂能量的演化规律。【结果】相同骨料率条件下(以70%骨料率为例),随着混凝土级配依次提高,相较于一级配,二、三、四级配的混凝土强度(峰值应力)分别降低6.14%,24.58%和33.61%,裂纹数和各种能量均有不同程度下降,表明级配越高,越容易形成架空结构,易造成局部不稳定,会影响增强效果。相同级配条件下(以二级配为例),随着混凝土骨料率依次提高,相较于50%骨料率,混凝土强度(峰值应力)分别提高7.32%,62.9%和143%,裂纹数相应减少而各种能量均有不同程度增大。【结论】混凝土骨料结构稳定程度对混凝土强度影响显著。

【Objective】This paper investigated the influence of gradation and aggregate content on physical and mechanical properties of concrete.【Method】Virtual experiment was conducted on granular flow platform with different aggregate ratios（0%,50%,60%,70%,and 80%）and gradations（first grade,second grade,third grade,fourth grade）,and the failure mode,crack propagation process,stress-strain curve and evolution of breaking energy were analyzed.【Result】With same aggregate content（taking 70%as example）,compared to first grade,second grade,third grade,fourth grade concrete strengths（the peak stress）decreased by 6.14%,24.58% and 33.61%,respectively.Crack number and various energies also declined in different degrees,indicating that high gradation was easy to form open structure,cause local instability and impact enhancement effect.With same gradation（taking second grade as example）,increase of aggregate content increased concrete strength（the peak stress）by 7.32%,62.9%and 143%,respectively.The crack number reduced accordingly and various energies increased in different degrees.【Conclusion】The structure stability of concrete had significant effect on strength.