中文摘要：

将混凝土看作由骨料、砂浆及它们之间的界面组成的三相复合材料,在细观层次上建立了均质混凝土棱柱体试件的随机骨料模型,分别赋予细观单元弹脆性和弹塑性本构关系,研究了采用不同本构关系的混凝土棱柱体试件在单轴压缩荷载作用下的细观损伤演化过程,分析了宏观应力应变曲线的差异,并将计算结果与试验结果做了比较。结果表明：混凝土试件的破坏是由于细观损伤的积累导致的;界面相是混凝土材料内部最薄弱的地方;砂浆单元采用弹塑性本构关系时所得混凝土棱柱体受压的宏观应力-应变全曲线与试验结果比较接近。

英文摘要：

In order to study the behavior of concrete under uniaxial compressive load on mesoscopic level,a random aggregate model at mesoscopic level using Monte Carlo method was developed,in which the concrete was regarded as a three-phase composite material of aggregate,motor and the interface between them.The development processes of mesoscopic damages of specimens with different elastic-brittle constitutive relationships for aggregate and interface elements and elasto-plastic constitutive relationships for mortar elements were studied.The results show that the failure of concrete is mostly due to the accumulation of damages at mesoscopic level.The predicted macro-stress strain relationships of concrete under uniaxial compression well agree with test results when using elasto-plastic relationship for mortar element.