骨料空间分布对混凝土压缩强度及软化曲线影响统计分析

Statistical investigation on effects of aggregate distribution on concrete compression strength and the descending part of stress-strain curve

混凝土材料的强度、宏观应力-应变曲线的软化段具有随机性和离散性,骨料分布形式是重要的影响因素。为探究混凝土强度和应力-应变曲线软化段的随机统计特性,从细观角度出发,假定混凝土是由骨料颗粒、砂浆基质及界面过渡区组成的三相复合材料,建立了混凝土细观尺度力学模型与方法。以单轴压缩情况为例,对64组不同骨料分布形式下混凝土试件的单轴压缩力学行为进行了数值研究,并基于概率理论对获得的混凝土强度及软化曲线的离散性进行了统计分析。研究表明:不同骨料分布形式下混凝土压缩强度和软化曲线均服从双参数Weibull分布;软化段上应力值的离散程度相近;软化段上应力值的离散性比峰值点应力的离散性大。

The strength and the descending stage of stress-strain curve of concrete present obvious discrete- ness and randomness, and the aggregate spatial distribution pattern turns out to be an important influencing factor. The purpose of this study is to obtain the statistical property of the strength and the descending stage of stress-strain curve of concrete. The meso-scale mechanical model and method were established, in which the concrete was assumed to be composed of aggregate particles, mortar matrix and the interfacial transition zones between the former two phases. Furthermore, the uniaxial compressive mechanical behavior of 64 sets of concrete with different aggregate distribution patterns was studied numerically, and the dis- creteness of concrete strength and softening curve was analyzed statistically. The results indicate that： （1） both the compression strength and the softening curve of concrete of different aggregate distribution obey the Weibull distribution; （2） the discreteness of the stresses in the softening curves are close; （3） compared the peak compressive Stress, the stresses in the softening curves have a larger discreteness.