基于细观结构性能和尺度的混凝土材料层次尺寸效应解析理论

Analysis theory for size effect of concrete in material-level based on properties and scales of meso structures

本文以细观为基本研究尺度,认为混凝土材料层次尺寸效应主要根源于粗骨料、砂浆以及界面等细观结构性能和尺度的不确定性。首先,基于建立的能够考虑细观结构影响的混凝土I-型裂缝断裂破坏分析模型,采用理论解析法对不同级配混凝土宏观力学性能预测方法进行了修正;进而,提出了一套混凝土材料层次尺寸效应解析理论,并分析了混凝土宏观力学性能随细观结构性能和尺度的变化行为。分析结果表明:单轴拉伸加载条件下,强骨料夹杂混凝土中界面力学性能、骨料含量和最大骨料粒径均显著影响细观断裂裂缝中界面裂缝的占比,从而影响到混凝土宏观力学性能随细观结构性能和尺度的变化行为。

The size effect of concrete in material-level is assumed to be attributed to the uncertainty of properties and scales of meso structures,including the coarse aggregates,the cement mortar and the interfaces. Firstly,the prediction method for the global mechanical properties of different graded concrete is modified through theoretical analysis,based on the established concrete mode-I fracture model that can take the meso structures into consideration. Secondly,an analysis theory for size effect of concrete in materiallevel is proposed and the variation of the global mechanical properties of concrete with properties and scales of meso structures is analyzed. The analysis shows that,the interface properties,the aggregate volume and the maximum aggregate size can significantly influence the percentage of interface cracks within the mesoscopic crack of concrete with strong aggregates under uniaxial tensile load,and,consequently the variation of the global mechanical properties of concrete with properties and scales of meso structures.